J Clin Pharmacol 1997 Aug;37(8):693-703 [MEDLINE record in process] Dose-dependent pharmacokinetics and psychomotor effects of caffeine in humans. Kaplan GB, Greenblatt DJ, Ehrenberg BL, Goddard JE, Cotreau MM, Harmatz JS, Shader RI Department of Psychiatry and Human Behavior, Brown University, Providence, Rhode Island. Twelve healthy volunteers received oral placebo, 250 mg of caffeine, and 500 mg of caffeine in a randomized, double-blind, single-dose crossover study. Caffeine kinetics were nonlinear, with clearance significantly reduced and elimination half-life prolonged at the 500-mg compared to the 250-mg dose. The lower dose of caffeine produced more favorable subjective effects than the higher dose (elation, peacefulness, pleasantness), whereas unpleasant effects (tension, nervousness, anxiety, excitement, irritability, nausea, palpitations, restlessness) following the 500-mg dose exceeded those of the 250-mg dose. The lower dose of caffeine enhanced performance on the digit symbol substitution test and a tapping speed test compared to placebo; high-dose caffeine produced less performance enhancement than the lower dose. The plasma concentration versus response relationship revealed concentration-dependent increases in anxiety and improvements in cognitive and motor performance at low to intermediate concentrations. Both caffeine doses reduced electroencephalographic amplitude over the 4 Hz to 30 Hz spectrum, as well as in the alpha (8-11 Hz) and beta (12-30 Hz) ranges; however, effects were not dose-dependent. While favorable subjective and performance-enhancing stimulant effects occur at low to intermediate caffeine doses, the unfavorable subjective and somatic effects, as well as performance disruption, from high doses of caffeine may intrinsically limit the doses of caffeine used in the general population. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [105 medline neighbors] Brain Res 1997 Jan 30;747(1):78-84 Caffeine and light effects on nighttime melatonin and temperature levels in sleep-deprived humans. Wright KP Jr, Badia P, Myers BL, Plenzler SC, Hakel M Department of Psychology, Bowling Green State University, OH, USA. The effects of caffeine ingestion and exposure to bright light, both separately and in combination, on salivary melatonin and tympanic temperature were assessed in humans. Four treatments during a 45.5 h sleep deprivation period were compared: Dim Light-Placebo, Dim Light-Caffeine, Bright Light-Placebo and Bright-Light Caffeine. The Dim Light-Caffeine condition (200 mg twice each night) relative to the Dim Light-Placebo condition suppressed nighttime melatonin levels and attenuated the normal decrease in temperature. Combining caffeine ingestion with bright light exposure (> or = 2000 lux) suppressed melatonin and attenuated the normal nighttime drop in temperature to a larger degree than either condition alone; i.e. effects were additive. Circadian effects were also observed in that the amplitude and phase of the temperature rhythm were altered during treatment. These findings establish that the human melatonin system is responsive to caffeine. Other evidence suggests that caffeine may influence melatonin and temperature levels through antagonism of the neuromodulator adenosine. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [143 medline neighbors] Biol Psychiatry 1996 Dec 15;40(12):1218-1221 A study of the potential confounding effects of diet, caffeine, nicotine and lorazepam on the stability of plasma and urinary homovanillic acid levels in patients with schizophrenia. Donnelly CL, McEvoy JP, Wilson WH, Narasimhachari N Duke University Medical Center, Durham, NC, USA. Ten men inpatients who met DSM-III-R criteria for schizophrenia participated. On five occasions at least one week apart, each subject had an intravenous line placed at 0730 after an overnight fast. On each occasion blood samples were drawn at 0800 and hourly thereafter through 1200 noon for measurement of plasma homovanillic acid (HVA). Total four-hour urine collections were obtained for measurement of urinary HVA. Subjects received five experimental conditions, in randomized sequence: no intervention, smoking one cigarette per hour, drinking one caffeinated cola per hour, lorazepam 2 mg IV push, or a high monoamine meal. Baseline (0800) plasma HVA measures showed only minor intrinsic variability. The average standard deviation in baseline plasma HVA over five occasions of measurement was low relative to the changes in HVA produced during treatment with antipsychotic medications. The high monoamine meal significantly elevated plasma HVA, with a similar trend for urinary HVA. Neither caffeine, nicotine, nor lorazepam significantly affected plasma or urinary HVA. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [162 medline neighbors] Psychosomatics 1996 Nov;37(6):518-522 Consumption of alcohol, nicotine, and caffeine among depressed outpatients. Relationship with response to treatment. Worthington J, Fava M, Agustin C, Alpert J, Nierenberg AA, Pava JA, Rosenbaum JF Depression Research Program, Clinical Psychopharmacology Unit, Massachusetts General Hospital, Boston 02114, USA. The authors present findings from the first investigation of the use of alcohol, nicotine, and caffeine in nonsubstance-abusing outpatients with major depressive disorder. The patients (N = 94) were assessed for their intake of alcohol, nicotine, and caffeine, and then treated openly for 8 weeks with 20 mg/day of fluoxetine. The degree of alcohol consumption at baseline was a significant predictor of poorer response to the antidepressant. This relationship remained significant even after adjusting for severity of depression at baseline. Even moderate levels of alcohol consumption appear to negatively affect pharmacologic treatment in depressed outpatients. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [172 medline neighbors] Psychol Rep 1996 Jun;78(3 Pt 1):915-923 Chronic psychiatric patients' use of caffeine: pharmacological effects and mechanisms. Kruger A University of British Columbia, Vancouver, Canada. The uses and effects of caffeine as a psychoactive drug in chronic psychiatric inpatient groups are described. Caffeine use and abuse is linked etiologically to diverse psychiatric disorders; its mechanisms of action are examined in relation to anxiety, anxiety neuroses, psychosis, schizophrenia, and caffeine intoxication and dependence. It is postulated that deleterious effects may result from the interaction of caffeine with commonly prescribed psychotropic drugs. A possible model of caffeine abuse is discussed. Increased public education about potential health problems related to caffeine consumption is suggested, and further controls of caffeine in psychiatric settings are recommended. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [109 medline neighbors] Mil Med 1996 Apr;161(4):230-232 Is caffeine involved in the pathogenesis of combat-stress reaction? Iancu I, Dolberg OT, Zohar J Psychiatric Division, Sheba Medical Center, Tel Hashomer, Israel. The role of caffeine in the pathogenesis of combat-stress reaction is discussed in light of the expanding literature on caffeine's influence on stress reactions in animals and in humans, and in regard to the two clinical entities concerning caffeine: caffeinism and caffeine withdrawal. It is proposed that caffeine is a contributing factor to the development of combat-stress reaction and that the use of decaffeinated coffee in military settings might reduce the prevalence of the various anxiety reactions, including combat-stress reaction. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [138 medline neighbors] Addiction 1996 Feb;91(2):269-273 The effect of caffeine on cue exposure responses in ex-smokers. Hepple J, Robson P Chilton Clinic, Warneford Hospital, Oxford, UK. The responses of ex-smokers to an experimental cue exposure trial, and the effect of caffeine on these responses, were compared with those of a matched group of control subjects in a placebo controlled single-blind cross-over design. In contrast to placebo, caffeine protected the ex-smokers from a surge of anxiety and rise in blood pressure associated with exposure to smoking-related cues. Caffeine had no significant effects on the control group at this dose (equivalent to a single cup of strong coffee). The results are discussed with reference to Stewart's conditioned appetitive motivational model of addiction. It is suggested that further work may identify caffeine as an adjunct to smoking relapse prevention measures. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [109 medline neighbors] Eur Arch Psychiatry Clin Neurosci 1996;246(2):83-92 Caffeine consumption in hospitalized psychiatric patients. Rihs M, Muller C, Baumann P Unite de biochimie et psychopharmacologie clinique, Departement universitaire de psychiatrie adulte, Lausanne, Switzerland. A total of 98 consecutively admitted psychiatric inpatients were asked for their daily consumption of coffee, tea and other products containing caffeine. Calculation of the corresponding daily caffeine intake was performed using data from the literature and from caffeine measurements carried out in different coffee and tea preparations in the hospital. Of the patients 13% presented a high (> or = 750 mg daily) caffeine consumption before hospitalization. The average caffeine consumption per day decreased from 405 mg before to 332 mg during hospitalization (P < 0.04), but the before and during hospitalization caffeine consumptions were highly correlated (rho = 0.651; P < 0.00001). The decrease in caffeine consumption seems to be influenced by a lower availability of caffeine at hospital. Among the diagnostic groups (DSM-III-R criteria), the caffeine intake was highest in schizophrenia and lowest in anxiety and major depression patients. Patients under a neuroleptic treatment before admission presented a higher caffeine intake. At hospital the high caffeine users showed the highest score on the factor depression (Hopkins Symptom Checklist; HSCL-58). However, the influence of other factors, such as weight and cigarette consumption, which correlated also with the caffeine intake (rho = 0.359; P < 0.001; and rho = 0.83; P < 0.00001, respectively), have also to be considered. Our data suggest that inquiry into caffeine consumption should be included routinely for psychiatric patients, e.g. at admission, because patients with a psychotic disorder undergo a higher risk for an excessive caffeine consumption. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [132 medline neighbors] J Clin Psychopharmacol 1995 Oct;15(5):376-377 Comments to "interaction between caffeine and clozapine". [LETTER] Carrillo JA, Jerling M, Bertilsson L --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [130 medline neighbors] Psychopharmacology (Berl) 1995 Oct;121(4):494-502 Pharmacokinetic and pharmacodynamic responses to caffeine in poor and normal sleepers. Tiffin P, Ashton H, Marsh R, Kamali F Department of Pharmacological Sciences, University of Newcastle upon Tyne, UK. Pharmacokinetic and pharmacodynamic responses to caffeine (2.5 mg/kg) were compared between ten healthy self-rated poor sleepers and ten normal sleepers. Sleep pattern assessed by the Pittsburgh Sleep Quality Index (PSQI). There was no significant difference in mean estimated daily caffeine consumption between the groups. The poor sleepers had significantly higher scores for neuroticism on the Eysenck Personality Questionnaire (EPQ) and anxiety on the Hospital Anxiety Depression (HAD) scale, compared with normal sleepers. Caffeine pharmacokinetics were assessed by measurement of saliva caffeine concentrations. Poor sleepers showed significantly greater variability in caffeine Cmax, clearance had half-life, compared to normal sleepers. Pharmacodynamic measures included heart rate, blood pressure, visual analogue scales for concentration, vigilance and relaxation, psychomotor performance [Digit Symbol Substitution Test (DSST) and tapping rate (TR)] and EEG activity [Contingent negative variation (CNV), auditory evoked potential and power spectral analysis]. Prior to caffeine administration, poor sleepers compared to normal sleepers had faster heart rates, lower ratings for concentration and relaxation, poorer performance on the DSST, greater CNV magnitude, faster peak alpha frequency and lower delta, theta and beta power. These differences persisted after caffeine ingestion and overall differences between the groups on these measures were significant (P < 0.01-.001). Post-dose, but not pre-dose, scores for vigilance and TR were significantly lower overall in poor compared with normal sleepers. Despite the baseline differences between poor and normal sleepers, the changes following caffeine administration were similar in direction and magnitude in both groups. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [197 medline neighbors] Clin J Pain 1995 Sep;11(3):214-219 Caffeine and chronic low back pain. Currie SR, Wilson KG, Gauthier ST Department of Medicine, School of Psychology, University of Ottawa, Ontario, Canada. OBJECTIVE: Although caffeine apparently plays a role in the modulation of pain perception in a variety of acute pain states, little is known about its effects on the experience of chronic pain. This exploratory study examined the relationship between dietary caffeine consumption and the symptoms reported by patients with chronic low back pain. DESIGN AND PATIENTS: A retrospective chart review was conducted of 131 patients with chronic low back pain (64 men and 67 women; mean age = 42.1 years; mean duration of pain = 6.1 years) referred to a multidisciplinary pain clinic over a 2-year period. Patients were classified as low (less than 100 mg; n = 34), moderate (100-400 mg; n = 68) or high (more than 400 mg; n = 29) caffeine users based on their self-reports of daily coffee, tea, and cola consumption. RESULTS: There were no significant differences among the low, medium, and high caffeine consumer groups on any self-report measure of pain severity, affective distress, anxiety-related symptoms, or sleeping behavior. High caffeine users were more likely to be tobacco smokers than low caffeine users (79% and 27%, respectively, p < 0.001). CONCLUSIONS: Our findings indicate that dietary caffeine consumption is not related to the global experience of pain and disability in patients with chronic low back pain, although high caffeine use may be embedded in a context of other unhealthy life-style behaviors. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [118 medline neighbors] J Nerv Ment Dis 1995 Sep;183(9):559-565 Alcohol, cannabis, nicotine, and caffeine use and symptom distress in schizophrenia. Hamera E, Schneider JK, Deviney S School of Nursing, University of Kansas Medical Center, Kansas City 66160-7700, USA. The high prevalence of substance use, e.g., alcohol and illegal and nonprescribed drugs, in schizophrenia is widely recognized. One explanation for this high prevalence is that substance use may be a self-initiated method for managing symptoms. To test whether the intake of four substances--alcohol, cannabis, nicotine, and caffeine--would increase with increases in symptom distress, daily self-reports of symptom distress and substance intake over 12 weeks were analyzed with pooled time series analyses. Compliance with neuroleptic medication was added to the analyses to control for any changes in prescribed medication compliance while using nonprescribed drugs or alcohol. Of the four substances studied, only nicotine was significantly related to symptom distress. Higher distress with prodromal symptoms was related to decreases in nicotine use. Analysis of caffeine did not meet the criteria for significance but does provide direction for further research. Higher distress, with neurotic symptoms, was related to increases in caffeine use. Further research is needed to clarify the relationship between nicotine and symptoms. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [203 medline neighbors] BMJ 1995 Aug 26;311(7004):531-535 Preterm delivery: effects of socioeconomic factors, psychological stress, smoking, alcohol, and caffeine. Peacock JL, Bland JM, Anderson HR Department of Public Health Sciences, St George's Hospital Medical School, London. OBJECTIVE--To examine the relation between preterm birth and socioeconomic and psychological factors, smoking, and alcohol, and caffeine consumption. DESIGN--Prospective study of outcome of pregnancy. SETTING--District general hospital in inner London. PARTICIPANTS--1860 consecutive white women booking for delivery; 1513 women studied after exclusion because of multiple pregnancy and diabetes, refusals, and loss to follow up. MEASUREMENTS--Gestational age was determined from ultrasound and maternal dates; preterm birth was defined as less than 37 completed weeks. Independent variables included smoking, alcohol and caffeine consumption, and a range of indicators of socioeconomic status and psychological stress. MAIN RESULTS--Unifactorial analyses showed that lower social class, less education, single marital status, low income, trouble with "nerves" and depression, help from professional agencies, and little contact with neighbours were all significantly associated with an increased risk of preterm birth. There were no apparent effects of smoking, alcohol, or caffeine on the length of gestation overall, although there was an association between smoking and delivery before 32 weeks. Cluster analysis indicated three subgroups of women delivering preterm: two predominantly of low social status and a third of older women with higher social status who did not smoke. Mean gestational age was highest in the third group. CONCLUSIONS--Adverse social circumstances are associated with preterm birth but smoking is not, apart from an association with very early births. This runs counter to findings for fetal growth (birth weight for gestational age) in this study, where a strong effect of smoking on fetal growth was observed but there was no evidence for any association with psychosocial factors. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [138 medline neighbors] Physiol Behav 1995 Jun;57(6):1117-1125 Caffeine and time of day effects on a force discrimination task in humans. Miller LS, Lombardo TW, Fowler SC Department of Psychology, University of Georgia, Athens 30602-3013, USA. The effects of caffeine (0 mg/kg, 1 mg/kg, 3 mg/kg) and time of day (TOD) on human performance were studied using a multiple forceband discrimination task (MFDT) and subjective ratings. Self-rated measures of energy level were affected by TOD and caffeine, while mood was affected by TOD. Energy level decreased throughout the day and was offset by caffeine which increased energy level independent of TOD. Self-reported anxiety was not affected by TOD or caffeine. Mood was affected by TOD in a complex cubic trend with late morning and late evening peaks 12 h apart. MFDT performance was affected by TOD, caffeine dosage, and their interaction. Trend analyses showed varying patterns of TOD effects across peak force variability, response latency, response duration, and correct responding. Results support and extend previous findings of TOD influences on the MFDT and support the utility of multicomponent proprioceptive tasks for examining drug effects on performance. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [206 medline neighbors] Behav Res Ther 1995 Jun;33(5):561-566 Alcohol and caffeine use by social phobics: an initial inquiry into drinking patterns and behavior. Holle C, Heimberg RG, Sweet RA, Holt CS Department of Psychology, University at Albany, State University of New York 12205, USA. Social phobics are often fearful that their anxiety symptoms will cause them embarrassment and lead to negative evaluation from others. Thus, it was hypothesized that they might attempt to control the intake of substances such as alcohol and caffeine that may affect their anxiety in social situations. The current investigation sought to determine, via a self-report questionnaire, whether the alcohol and caffeine consumption patterns of social phobics differ from those of community controls in terms of typical and greatest weekly quantities and how social phobics differ from controls in alcohol and caffeine use in a variety of socially threatening and nonthreatening situations. Social phobics reported less typical weekly beverage consumption than community subjects. Specifically, social phobics reported less consumption of wine and liqueur than community subjects but did not differ from community subjects in typical weekly consumption of caffeinated beverages. Further, social phobics reported a significantly greater intent to drink alcohol while in social situations involving strangers and significantly less intent to drink caffeinated coffee in meetings than did community subjects. Finally, a number of gender differences were found for both alcohol and caffeine consumption in specific situations, and the implications of these findings are discussed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [173 medline neighbors] Psychophysiology 1995 Jan;32(1):19-27 Caffeine and smoking: subjective, performance, and psychophysiological effects. Pritchard WS, Robinson JH, deBethizy JD, Davis RA, Stiles MF Psychophysiology Laboratory, Bowman Gray Technical Center, R.J. Reynolds Tobacco Company, Winston-Salem, NC 27102. The effects of caffeine and smoking on cognitive performance, subjective variables, heart rate, and EEG were assessed in two sessions. In one session, subjects received caffeine (2.5 mg/kg bodyweight), while in the other they received placebo. In both sessions they smoked a cigarette (8 cued puffs) having a nicotine yield of 1.2 mg. Caffeine produced an increase in self-reported muscular tension and tended to increase anxiety and delta magnitude. Smoking facilitated performance of a paper-and-pencil math task and increased heart rate. Smoking also appeared to produce cortical activation as indexed by decreased right frontal delta, decreased right centro-parietal theta, globally increased alpha, and increased centro-occipital/decreased posterior-temporal beta 1. Smoking also increased central/decreased posterior-temporal beta 2. Smoking and caffeine did not interact for any measure, suggesting that the epidemiological link between smoking and coffee drinking may have a non-pharmacological basis. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [133 medline neighbors] Drugs 1995 Jan;49(1):37-50 Pharmacological rationale for the clinical use of caffeine. Sawynok J Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada. Caffeine is widely consumed in beverages to obtain mild CNS stimulant effects. Long term use produces tolerance to some of the pharmacological effects. Withdrawal of caffeine, even from moderate intake levels, can produce symptoms such as headache, fatigue and anxiety. Caffeine is used therapeutically in combination with ergotamine for migraine headaches and in combination with nonsteroidal anti-inflammatory drugs in analgesic formulations. Caffeine alone is used as a somnolytic, to treat various headache conditions, respiratory depression in neonates, postprandial hypotension and obesity, and to enhance seizure duration in electroconvulsive therapy. In some headache and in pain paradigms, caffeine may produce direct adjuvant analgesic properties, while in other headache conditions (perioperative, postdural puncture) caffeine may be effective by alleviating a manifestation of caffeine withdrawal. Other uses, such as to promote wakefulness, for respiratory stimulation and seizure prolongation, rely on central stimulant properties of caffeine. Effects of caffeine on the vasculature may contribute to the relief of some headaches and in postprandial hypotension. Blockade of methylxanthine-sensitive adenosine receptors is the currently accepted mechanism of action of caffeine. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [166 medline neighbors] Radiat Res 1994 Dec;140(3):393-400 Increased expression of cyclin B1 mRNA coincides with diminished G2-phase arrest in irradiated HeLa cells treated with staurosporine or caffeine. Bernhard EJ, Maity A, Muschel RJ, McKenna WG Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia 19104. The irradiation of cells results in delayed progression through the G2 phase of the cell cycle. Treatment of irradiated HeLa cells with caffeine greatly reduces the G2-phase delay, while caffeine does not alter progression of cells through the cell cycle in unirradiated cells. In this report we demonstrate that treatment of HeLa cells with the kinase inhibitor staurosporine, but not with the inhibitor H7, also results in a reduction of the G2-phase arrest after irradiation. Cell cycle progression in unirradiated cells is unaffected by 4.4 nM (2 ng/ml) staurosporine, which releases the radiation-induced G2-phase arrest. In HeLa cells, the G2-phase delay after irradiation in S phase is accompanied by decreased expression of cyclin B1 mRNA. Coincident with the reduction in G2-phase delay, we observed an increase in cyclin B1 mRNA accumulation in irradiated, staurosporine-treated cells compared to cells treated with irradiation alone. Caffeine treatment of irradiated HeLa cells also resulted in an elevation in the levels of cyclin B1 message. These results support the hypothesis that diminished cyclin B1 mRNA levels influence G2-phase arrest to some degree. The findings that both staurosporine and caffeine treatments reverse the depression in cyclin B1 expression suggest that these two compounds may act on a common pathway of cell cycle control in response to radiation injury. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [174 medline neighbors] Br J Clin Pharmacol 1994 Dec;38(6):573-576 Inhibition of caffeine metabolism by ciprofloxacin in children with cystic fibrosis as measured by the caffeine breath test. Parker AC, Preston T, Heaf D, Kitteringham NR, Choonara I Institute of Child Health, Alder Hey Children's Hospital, Liverpool. The caffeine breath test was carried out in six children with cystic fibrosis, before and during a course of ciprofloxacin. There was a significant decrease in the 2 h cumulative labelled CO2 exhaled during ciprofloxacin treatment, mean difference (s.d.) -5.2(3.3)%, P < 0.02. The results suggest an inhibition of 3-N-demethylation of caffeine (CYP1A2 enzyme activity) by ciprofloxacin. Ciprofloxacin may cause significant drug interactions in children with cystic fibrosis. The caffeine breath test can be used to study drug interactions involving CYP1A2 in children. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [152 medline neighbors] Neurotoxicol Teratol 1994 Nov;16(6):531-543 Potential teratogenic and neurodevelopmental consequences of coffee and caffeine exposure: a review on human and animal data. Nehlig A, Debry G INSERM U 398, Universite de Nancy I, Faculte de Medecine, France. The teratogenic effect of caffeine has been clearly demonstrated in rodents. The sensitivity of different animals species is variable. Malformations have been demonstrated in mice at 50-75 mg/kg of caffeine, whereas the lowest dose usually needed to induce malformations is 80 mg/kg in rats. However, when caffeine is administered in fractioned amounts during the day, 330 mg/kg/day are necessary to reach teratogenicity in rats. In rodents, the most frequently observed malformations are those of the limbs and digits, ectrodactyly, craniofacial malformations (labial and palatal clefts) and delays in ossification of limbs, jaw and sternum. Nevertheless, even in rodents, caffeine can be considered as a weak teratogenic agent, given the quite large quantities of caffeine necessary to induce malformations and the small number of animals affected. In humans, caffeine does not present any teratogenic risk. The increased risk of the most common congenital malformations entailed by moderate consumption of caffeine is very slight. However, caffeine potentiates the teratogenic effect of other substances, such as tobacco, alcohol, and acts synergistically with ergotamine and propranolol to induce materno-fetal vasoconstrictions leading to malformations induced by ischemia. Therefore, even though caffeine does not seem to be harmful to the human fetus when intake is moderate and spread out over the day, some associations, especially with alcohol, tobacco, and vasoconstrictive or anti-migraine medications should be avoided. Maternal consumption of caffeine affects brain composition, especially in case of a low-protein diet and also seems to interfere with zinc fixation in brain. Maternal exposure to caffeine induces also long-term consequences on sleep, locomotion, learning abilities, emotivity, and anxiety in rat offspring, whereas in humans, more studies are needed to ascertain long-term behavioral effects of caffeine ingestion by pregnant mothers. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [100 medline neighbors] Sports Med 1994 Aug;18(2):109-125 Caffeine and endurance performance. Tarnopolsky MA Department of Physical Medicine and Rehabilitation, Henderson General Hospital, Hamilton, Ontario, Canada. Caffeine is consumed in many beverages and foods throughout the world. It is the most commonly used drug in North America and, probably, in many other countries. The short term consumption of caffeine may result in increased urination, gastrointestinal distress, tremors, decreased sleep, and anxiety symptoms in certain individuals. The long term consumption of caffeine at < 5 cups/day does not appear to increase the risk of cancer, cardiovascular disease, peptic ulcer disease or cardiac arrhythmias. At the cellular level, caffeine is a competitive antagonist of adenosine receptors and probably acts directly on the ryanodine receptor (Ca++ release channel) to potentiate Ca++ release from skeletal muscle sarcoplasmic reticulum. As a result of these 2 cellular mechanisms of action, caffeine causes increased lipolysis, a facilitation of central nervous system transmission, a reduction in plasma potassium during exercise, an increased force of muscle contraction at lower frequencies of stimulation, and a sparing of muscle glycogen (partially or wholly due to an increase in free fatty acid oxidation). These mechanisms of action would predict that caffeine should be of ergogenic benefit during endurance exercise performance, especially when glycogen depletion would be rate limiting to performance. A review of the literature suggests that caffeine at doses of approximately 6 mg/kg is not of ergogenic benefit to high intensity exercise performance, but similar doses are ergogenic in endurance exercise performance. These doses (approximately 6 mg/kg) would result in urinary caffeine concentrations less than the current International Olympic Committee restricted level of 12 mg/L, and consideration should be given to lowering this level. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [198 medline neighbors] J Clin Psychopharmacol 1994 Aug;14(4):284-285 Interaction between caffeine and clozapine. [LETTER] Vainer JL, Chouinard G --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [198 medline neighbors] Addict Behav 1994 May;19(3):229-256 Caffeine and nicotine: a review of their joint use and possible interactive effects in tobacco withdrawal. Swanson JA, Lee JW, Hopp JW School of Public Health, Loma Linda University, CA. There is a strong, significant relationship between coffee consumption and smoking. In six epidemiological studies reviewed and analyzed here, 86.4% of smokers consumed coffee versus 77.2% of nonsmokers. Exsmokers use more coffee than nonsmokers but somewhat less than smokers. Seventeen experimental studies suggest that the pharmacologic effect of caffeine in coffee may be partially but not totally responsible for the relationship. Conditioning, a reciprocal interaction (caffeine intake increases anxiety/arousal--nicotine decreases it), or joint effect of a third variable (e.g., stress, alcohol) may account for the relationship. In abstinent smokers, blood caffeine levels increase and remain elevated for as long as 6 months. These higher caffeine plasma levels may be sufficient to produce caffeine toxicity syndrome. A review of 86 studies of nicotine withdrawal, caffeine withdrawal, and caffeine toxicity suggests that the symptoms are similar enough to be confused, and that reported nicotine withdrawal symptoms may be a mixture of nicotine withdrawal and caffeine toxicity. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [176 medline neighbors] Paediatr Perinat Epidemiol 1994 Apr;8(2):145-155 Symptoms and health problems in pregnancy: their association with social factors, smoking, alcohol, caffeine and attitude to pregnancy. Meyer LC, Peacock JL, Bland JM, Anderson HR Department of Public Health Sciences, St George's Hospital Medical School, London, UK. This paper describes the prevalence and correlates of symptoms and health problems in pregnancy using data from a prospective population study in London. Data on the prevalence of 11 symptoms and 12 health problems were obtained at three points in pregnancy from a consecutive sample of 1513 white women. Relationships were examined between these symptoms and a range of psychosocial factors including social class, education, marital status, income, smoking, alcohol, caffeine, attitude to pregnancy and whether the pregnancy was planned. Most women reported nausea and breast tenderness in early pregnancy. Heartburn, backache, constipation and headaches were also common. The prevalence of symptoms tended to increase with gestation except for nausea and vomiting. Women with manual occupations, minimum education, low income, single marital status and unplanned pregnancy reported more of most symptoms except nausea which was associated with higher social status. A negative attitude to pregnancy was associated with more headaches but was unrelated to nausea. Women who smoked reported more 'nerves and depression' but less nausea. In general, nausea and vomiting showed a different pattern of associations from all other symptoms. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [203 medline neighbors] J Am Acad Child Adolesc Psychiatry 1994 Mar;33(3):407-415 Caffeine effects on learning, performance, and anxiety in normal school-age children. Bernstein GA, Carroll ME, Crosby RD, Perwien AR, Go FS, Benowitz NL Department of Psychiatry, University of Minnesota Medical School, Minneapolis 55455. OBJECTIVE: The purpose of this investigation was to study the acute effects of caffeine on learning, performance, and anxiety in normal prepubertal children. METHOD: Twenty-one children were evaluated in a double-blind, placebo-controlled crossover design. Subjects were studied during four sessions, 1 week apart, under the following conditions: baseline, placebo, 2.5 mg/kg caffeine, and 5.0 mg/kg caffeine. Subjects were randomized to order of placebo and the two dosages of caffeine. Dependent measures included tests of attention, manual dexterity, short-term memory, and processing speed. Anxiety rating scales were also administered. Saliva samples were analyzed for caffeine levels. RESULTS: Caffeine improved performance on two of four measures of the Test of Variables of Attention and on a test of manual dexterity in the dominant hand. There was a trend toward increased current level of self-reported anxiety after caffeine on a visual analogue measure of anxiety. Children reported feeling significantly less "sluggish" after caffeine ingestion than after placebo ingestion. CONCLUSIONS: In a small sample size, there was indication that caffeine enhanced performance on a test of attention and on a motor task. Children also reported feeling less "sluggish" but somewhat more anxious. Because caffeine is so widely available and frequently consumed by children, these results are important and need replication. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [178 medline neighbors] Psychopharmacology (Berl) 1994 Mar;114(2):281-287 Acute dose-effect relationships of caffeine and mental performance, EEG, cardiovascular and subjective parameters. Hasenfratz M, Battig K Comparative Physiology and Behavioral Biology Laboratory, Swiss Federal Institute of Technology, ETH-Zentrum, Zurich. The present study investigated the dose-effect relationship of caffeine on mental performance using a caffeine-sensitive rapid information processing task (RIP) in a pre/post cross-over design. Twenty female nonsmoking regular coffee drinkers received 0, 1.5, 3 and 6 mg/kg caffeine in a balanced order and the measurements were extended to cardiovascular, EEG and mood parameters. Surprisingly, the dose-effect curves for the different parameters were rather heterogeneous. Whereas increasing effects with increasing caffeine doses were observed for alpha- and beta-EEG frequencies, anxiety, wakefulness, and some coffee ratings, negative dose-effect relationships were obtained for RIP processing rate and blood pressure. No apparent dose-effect relationships were seen for reaction time and motor activity. Thus, it was concluded that the dose-response relationships are rather shallow and heterogeneous and that the different parameters have different ranges in which they are sensitive to caffeine. The caffeine doses which might have beneficial behavioral effects are at the lower end of the tested dose range and comparable to those found in caffeine-containing beverages. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [136 medline neighbors] Anxiety 1994;1(4):161-168 Dose-response effects of intravenous caffeine in normal volunteers. Nickell PV, Uhde TW Department of Behavioral Medicine and Psychiatry, West Virginia University School of Medicine, Morgantown, USA. The administration of caffeine has been developed as a chemical model for the study of anxiety. However, previous researchers investigating caffeine-induced anxiety states in humans have administered oral caffeine. In this dose-response study, we investigated the effects of blindly administered intravenous caffeine (3, 5, and 7 mg/kg) versus placebo in normal control subjects. We report the first series of subjects experiencing olfactory hallucinations (10 of 10 subjects, 24 of 30 infusions) immediately following intravenous caffeine infusion. In addition, consistent with our previous work with oral caffeine, we found dose-related increases in ratings of anxiety and blood levels of cortisol and lactate. One subject experienced a DSM-III-R panic attack. Further questioning revealed that his mother suffers panic attacks. Our findings of olfactory hallucinations are discussed within the context of localized limbic system dysfunction, noting the phenomenologic and possible neuroanatomic overlap between panic disorder and complex partial seizures. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [166 medline neighbors] Anxiety 1994;1(3):138-140 Lactic acid response to caffeine in panic disorder: comparison with social phobics and normal controls. Tancer ME, Stein MB, Uhde TW Section on Anxiety and Affective Disorders, National Institute of Mental Health, Bethesda Maryland 20892, USA. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [175 medline neighbors] J Gynecol Obstet Biol Reprod (Paris) 1994;23(3):241-256 Effects of coffee and caffeine on fertility, reproduction, lactation, and development. Review of human and animal data. [Article in French] Nehlig A, Debry G INSERM U 272, Universite de Nancy I. In the present review, we have examined the effects of coffee ingestion on fertility, reproduction, lactation and development. The potential effects of coffee consumption on fertility, spontaneous abortion and prematurity are not clearly established but appear to be quite limited. In rodents, caffeine can induce malformations but this effect appears in general at doses never encountered in humans. Indeed, as soon as the quantity of caffeine is divided over the day, as is the case for human consumption, the teratogenic effect of caffeine disappears in rodents. Coffee ingested during gestation induces a dose-dependent decrease in birth weight, but usually only when ingested amounts are high (i.e. more than 7 cups/day), whereas coffee has no effect at moderate doses. Caffeine consumption during gestation affects hematologic parameters of the new-born infant or rat. In animals, caffeine induces long-term consequences on sleep, locomotion, learning abilities, emotivity and anxiety, whereas, in children, the effects of early exposure to coffee and caffeine on behavior are not clearly established. The quantities of caffeine found in maternal milk vary with authors, but it appears clearly that caffeine does not change maternal milk composition and has a tendency to stimule milk production. In conclusion to this review, it appears that maternal coffee or caffeine consumption during gestation and/or lactation does not seem to have measurable consequences on the fetus of the newborn, as long as ingested quantities remain moderate. Therefore, pregnant mothers should be advised to limit their coffee and caffeine intake to 300 mg caffeine/day (i.e. 2-3 cups of coffee or 2.5-3 l of coke) especially because of the increase of caffeine half-life during the third trimester of pregnancy and in the neonate. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [171 medline neighbors] Am J Psychiatry 1993 Dec;150(12):1897-1898 Olfactory hallucinations after the infusion of caffeine during sleep. [LETTER] Koenigsberg HW, Pollak CP, Fine J --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [151 medline neighbors] Am J Gastroenterol 1993 Sep;88(9):1464 Caffeine withdrawal, metoclopramide, and depression. [LETTER] Wenokur B, Lessem P --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [67 medline neighbors] Int J Neurosci 1993 Sep;72(1-2):1-14 Incidental information processing: effects of mood, sex and caffeine. Turner J Department of Psychology, Fylde College, University of Lancaster, U.K. This experiment assessed the effects of various parameters on incidental information processing. Participants from a nonclinical population were asked to fill out mood and personality questionnaires before completing a simple explicit and implicit memory task. It was predicted that participants with more depressive symptoms would show lower implicit memory scores. A number of sex differences were revealed: data from male participants supported the prediction; however, female participants showed a negative correlation between increasing depressive mood symptoms and implicit memory; sex differences were also present along other cognitive dimensions. Socioeconomic effects and hemispheric biases were factors considered as possible explanations for these sex differences; hemispheric bias could have resulted in differential female/male strategies being used; these may have been responsible for the consistently higher female scores found throughout the experiment. It is also suggested that implicit memory might have a separate store; this may be influenced by the default/habitual preference for a particular processing strategy (unique to the individual participant and/or the presence of depressive symptoms). --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [93 medline neighbors] Br J Psychiatry 1993 Apr;162:543-545 Caffeine: use and effects in long-stay psychiatric patients. Mayo KM, Falkowski W, Jones CA Springfield Hospital, London. In a double-blind crossover study of 26 long-stay schizophrenic patients, no correlation was found between caffeine consumption and levels of anxiety and depression. No significant changes in patients' behaviour or levels of anxiety and depression occurred when the wards changed to decaffeinated products. Serum caffeine levels confirmed compliance. No evidence was found to support a removal of caffeinated products from this group of patients. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [140 medline neighbors] Am J Psychiatry 1993 Feb;150(2):294-301 Depressive symptoms and the self-reported use of alcohol, caffeine, and carbohydrates in normal volunteers and four groups of psychiatric outpatients. Leibenluft E, Fiero PL, Bartko JJ, Moul DE, Rosenthal NE Clinical Psychobiology Branch, NIMH, Bethesda, MD 20892. OBJECTIVE: The authors examined the relationship between depressive symptoms and the self-reported use of alcohol, carbohydrates, and caffeine in normal volunteers and four groups of psychiatric outpatients. METHOD: Outpatients and normal volunteers were given a questionnaire asking about their use of each of the three substances in response to each of the 14 depressive symptoms on the Hamilton Rating Scale for Depression. They also rated how much each substance improved each symptom. Twenty-six normal volunteers, 35 patients with major depression, 117 patients with seasonal affective disorder, 16 patients with alcohol dependence, and 24 patients with comorbid primary depression and secondary alcohol dependence completed the questionnaire. Test-retest reliability was established. Analysis of variance and stepwise multivariate discriminant function analyses were used to determine if diagnostic groups differed in the reported use and effect of each of the three substances. RESULTS: The responses concerning use and effect of alcohol of patients with alcohol dependence with or without depression were indistinguishable from each other. The responses of the patient groups regarding caffeine and carbohydrate use did not differ from each other, but all differed significantly from the responses of normal volunteers. Discriminant function analysis distinguished alcoholics from nonalcoholics in the relationship between drinking and the symptoms of anger and anhedonia. CONCLUSIONS: The relationship between symptoms and substance use varied depending on the substance. Alcoholics without depression were as likely to report drinking in response to depressive symptoms as were those who had had depression. Patients of all diagnostic groups were more likely than normal volunteers to report using caffeine and carbohydrates in response to depressive symptoms. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [121 medline neighbors] Arch Gen Psychiatry 1992 Nov;49(11):867-869 Anxiogenic effects of caffeine in patients with anxiety disorders. Bruce M, Scott N, Shine P, Lader M Department of Psychiatry, Institute of Psychiatry, London, England. The effects on measures of anxiety from two doses of oral caffeine (250 and 500 mg) and placebo were compared in 12 patients with generalized anxiety disorder (GAD), 12 patients with panic disorder, and 12 normal subjects. Caffeine produced significantly less decrease in electroencephalographic alpha wave activity, greater decrease in N1-P2 auditory evoked potential amplitude, and greater increased in skin conductance level, systolic and diastolic blood pressure, critical fusion flicker frequency, and self-ratings of anxiety and sweating in patients with GAD than in normal patients. Patients with panic disorder showed different reactivity than normal patients did with respect to electroencephalographic alpha waves, N2 latency, N2-P2 auditory evoked potential amplitude, and physical tiredness but were less reactive than patients with GAD on several variables. It is concluded that patients with GAD are abnormally sensitive to caffeine and that the data support the view that panic disorder is a separable disorder from GAD. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [112 medline neighbors] N Engl J Med 1992 Oct 15;327(16):1109-1114 Withdrawal syndrome after the double-blind cessation of caffeine consumption. Silverman K, Evans SM, Strain EC, Griffiths RR Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21224. BACKGROUND. People who stop consuming caffeine may have symptoms, but the incidence and severity of caffeine withdrawal are not known. This study was performed to determine the effects in the general population of ending one's dietary intake of caffeine. METHODS. We studied 62 normal adults whose intake of caffeine was low to moderate (mean amount, 235 mg--the equivalent of 2.5 cups of coffee--per day). They completed questionnaires about symptoms and tests of their mood and performance when consuming their normal diets (base-line period) and at the end of each of two two-day periods during which they consumed caffeine-free diets and under double-blind conditions received capsules containing placebo (placebo period) or caffeine (caffeine period) in amounts equal to their daily caffeine consumption. RESULTS. More subjects had abnormally high Beck Depression Inventory scores (11 percent), high scores on the trait scale of the State-Trait Anxiety Inventory (8 percent), low vigor scores (11 percent) and high fatigue scores (8 percent) on the Profile of Mood States, and moderate or severe headache (52 percent) during the placebo period than during either the base-line period (2, 0, 0, 0, and 2 percent, respectively; P less than 0.05) or the caffeine period (3, 2, 2, 0, and 6 percent; P less than 0.05). More subjects reported unauthorized use of medications during the placebo period (13 percent) than during the caffeine period (2 percent, P = 0.017). Performance of a tapping task was slower during the placebo period than during the base-line and caffeine periods (P less than 0.01). CONCLUSIONS. Persons who consume low or moderate amounts of caffeine may have a withdrawal syndrome after their daily consumption of caffeine ceases. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [106 medline neighbors] Addict Behav 1992 Sep;17(5):447-457 The effects of caffeine and nicotine consumption on mood and somatic variables in a penitentiary inmate population. Hughes GV, Boland FJ Psychology Department, Queen's University, Kingston, Ontario, Canada. A sample of 144 inmates from a maximum security penitentiary responded to a request for information regarding their average daily intake of nicotine and caffeine. They also rated the quality of their appetite and sleep, their level of concentration, their mood and specific feelings of anger, anxiety, frustration, and irritability. Factor analysis generated a two-factor solution of these variables, namely general mood state (mood, anxiety, anger, frustration, and irritability) and a somatic state (appetite, concentration, and sleep). Analysis of variance showed an interaction between level of smoking (nonsmokers, low and high cigarette smokers) and caffeine use (moderate vs. high) on the general mood factor. Nonsmokers who consumed high levels of caffeine experienced poorer general mood than any other group. There was a main effect of cigarette smoking status on the somatic factor, such that greater dissatisfaction was associated with greater consumption. Caffeine consumption was generally high, averaging 800 mg of caffeine per day, per inmate, well above the amount considered to be potentially damaging to health. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [128 medline neighbors] Psychiatry Res 1992 Aug;45(2):105-113 Quantitative electroencephalographic effects of caffeine in panic disorder. Newman F, Stein MB, Trettau JR, Coppola R, Uhde TW Clinical Brain Disorders Branch, St. Elizabeths Hospital, National Institute of Mental Health, Washington, DC. It has been demonstrated that patients with panic disorder are more sensitive than normal control subjects to the anxiogenic effects of caffeine. The underlying physiologic basis for this difference is unclear. We examined the electroencephalographic (EEG) activity of seven patients with panic disorder and seven normal control subjects during the randomized double-blind, placebo-controlled administration of oral caffeine (7 mg/kg). EEG data were collected on-line from 28 electrodes; artifact-free epochs were selected manually for off-line Fourier transformation. Caffeine was associated with a significant increase in peak occipital alpha frequency and significant decreases in occipital alpha amplitude, central beta amplitude, and central theta amplitude. Despite the observation that caffeine increased anxiety more in the patients with panic disorder than in the normal control subjects, the two groups did not differ in their EEG responses to caffeine. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [108 medline neighbors] Psychophysiology 1992 May;29(3):272-282 Cardiovascular responses to the combination of caffeine and mental arithmetic, cold pressor, and static exercise stressors. France C, Ditto B Department of Psychology, Ohio University, Athens 45701-2979. The present study examined cardiovascular responses to the combination of caffeine (250mg) and mental arithmetic, cold pressor, and static exercise stressors in 48 healthy males. Subjects were tested in a within-subject, placebo-controlled, double-blind design. Repeated measurements of heart rate, finger temperature, respiratory sinus arrhythmia, forearm blood flow, and blood pressure were obtained during a pre-drug resting baseline, a post-drug resting baseline, the three stressor tasks, and a recovery baseline. The primary analyses were 2(Drug) x 5(Period) x 6(Stress Order) MANCOVAs using pre-drug baseline values as covariates. Significant period main effects were observed for all measures. Significant drug main effects were observed for blood pressure, finger temperature, respiratory sinus arrhythmia, and forearm blood flow. The significant changes in blood pressure and finger temperature produced by caffeine combined in an additive fashion with the effects produced by the stressors. Significantly greater increases in forearm blood flow and heart rate during mental arithmetic on the caffeine day suggested a potentiation of sympathetic, beta-adrenergic activity. Questionnaires administered during baseline periods to assess psychological responses to stress and caffeine revealed a potentiation of anxiety and anger responses to stress on the caffeine day. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [118 medline neighbors] Brain Res Brain Res Rev 1992 May;17(2):139-170 Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Nehlig A, Daval JL, Debry G INSERM U 272 Universite de Nancy I, France. Caffeine is the most widely consumed central-nervous-system stimulant. Three main mechanisms of action of caffeine on the central nervous system have been described. Mobilization of intracellular calcium and inhibition of specific phosphodiesterases only occur at high non-physiological concentrations of caffeine. The only likely mechanism of action of the methylxanthine is the antagonism at the level of adenosine receptors. Caffeine increases energy metabolism throughout the brain but decreases at the same time cerebral blood flow, inducing a relative brain hypoperfusion. Caffeine activates noradrenaline neurons and seems to affect the local release of dopamine. Many of the alerting effects of caffeine may be related to the action of the methylxanthine on serotonin neurons. The methylxanthine induces dose-response increases in locomotor activity in animals. Its psychostimulant action on man is, however, often subtle and not very easy to detect. The effects of caffeine on learning, memory, performance and coordination are rather related to the methylxanthine action on arousal, vigilance and fatigue. Caffeine exerts obvious effects on anxiety and sleep which vary according to individual sensitivity to the methylxanthine. However, children in general do not appear more sensitive to methylxanthine effects than adults. The central nervous system does not seem to develop a great tolerance to the effects of caffeine although dependence and withdrawal symptoms are reported. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [114 medline neighbors] Pharmacol Toxicol 1992 Apr;70(4):286-289 Caffeine moderately antagonizes the effects of triazolam and zopiclone on the psychomotor performance of healthy subjects. Mattila ME, Mattila MJ, Nuotto E Department of Pharmacology and Toxicology, University of Helsinki, Finland. To determine whether caffeine antagonizes the decremental effects of triazolam and zopiclone on human performance, oral single doses of 0.250 mg triazolam, 7.5 mg zopiclone, or respective placebos, with and without 300 mg caffeine, were given to parallel groups of student volunteers in two double-blind studies. Objective tests and subjective visual analogue ratings were done at baseline and 30 min. and 90 min. after the intake. In Study I, triazolam produced drowsiness at 30 min. but did not differ from the placebo in other tests. Caffeine induced alerting effects in various tests and differed from triazolam in some (digit substitution, drowsiness, calmness, mental slowness) but not all variables measured. Caffeine and triazolam were interpreted as being antagonists. In Study II, zopiclone impaired digit substitution and flicker fusion, produced exophoria and lowered systolic blood pressure. Caffeine differed from zopiclone in several test functions, but it also differed from caffeine + zopiclone whereas zopiclone differed from caffeine + zopiclone only in two tests (Maddox wing, systolic blood pressure). Thus, zopiclone counteracted the effects of caffeine more easily than caffeine counteracted the decremental effects of zopiclone. We conclude that triazolam may not differ importantly from diazepam as regards their antagonism towards caffeine, whereas further research on the antagonism between zopiclone and caffeine needs to be done. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [110 medline neighbors] Neuropsychopharmacology 1992 Feb;6(2):101-118 Evidence for hypothalamo-growth hormone dysfunction in panic disorder: profile of growth hormone (GH) responses to clonidine, yohimbine, caffeine, glucose, GRF and TRH in panic disorder patients versus healthy volunteers. Uhde TW, Tancer ME, Rubinow DR, Roscow DB, Boulenger JP, Vittone B, Gurguis G, Geraci M, Black B, Post RM Section on Anxiety and Affective Disorders, National Institute of Mental Health, Bethesda, Maryland 20892. Given the abrupt and time-limited nature of daytime-awake and nocturnal-sleep panic attacks, several chemical and neuroendocrine challenge tests have been employed to investigate the neurobiology of "spontaneous" panic attacks. Previously we demonstrated that panic disorder patients have blunted growth hormone (GH) responses to clonidine, an alpha 2-adrenergic agonist. However, the mechanism of this blunted response and the role of hypothalamic-GH dysfunction, if any, remains unclear. To further delineate the status of hypothalamic-GH function in panic disorder, we review the literature and present original data on the GH responses to a number of different chemical and neuroendocrine challenge paradigms. Although stress-mediated increases in GH are thought to be a common correlate of stress in humans, our findings indicate that panic disorder patients have significantly blunted GH responses to clonidine, yohimbine, growth-hormone releasing factor, and caffeine compared to normal control subjects. A similar trend was noted in the delayed rise in GH after glucose challenge. There was no difference in the rate of abnormal GH responses to thyrotropin-releasing hormone in panic disorder compared to normal control subjects. No drug or neuroendocrine challenge, even if associated with marked increases in anxiety, produced a significantly enhanced GH response compared to normal control subjects. These findings provide support for a hyporesponsive hypothalamic-GH system in panic disorder. These observations, combined with preliminary observations from our clinic of short stature in several cases of prepubescent children with anxiety disorders, also underscore the need for assessing early growth patterns in individuals with panic disorder. Strategies for investigating the site(s) of possible neurotransmitter or hypothalamic-GH-somatomedin dysfunction are discussed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [144 medline neighbors] Psychopharmacology (Berl) 1992;108(1-2):51-59 Caffeine tolerance and choice in humans. Evans SM, Griffiths RR Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Behavioral Biology Research Center, Baltimore, MD 21224. Thirty-two healthy subjects with histories of moderate caffeine consumption abstained from dietary caffeine throughout the study. Subjects were stratified into two groups based on several factors including caffeine preference, which was assessed using a caffeine versus placebo choice procedure. Subsequently, subjects received either caffeine (300 mg t.i.d.) or placebo (placebo t.i.d.) for 18 consecutive days, and thereafter were exposed again to a caffeine versus placebo choice procedure. The study documented tolerance development to the subjective effects of caffeine: after chronic dosing, administration of caffeine produced significant subjective effects in the chronic placebo group but not in the chronic caffeine group. The study also provided indirect evidence for tolerance development: during chronic dosing, the chronic caffeine and placebo groups did not differ meaningfully on ratings of mood and subjective effect. When subjects were categorized into caffeine choosers or nonchoosers, caffeine choosers tended to report positive subjective effects of caffeine and negative subjective effects of placebo. Nonchoosers, in contrast, tended to report negative subjective effects of caffeine. Chronic caffeine did not alter the reinforcing effects of caffeine as assessed by caffeine versus placebo choice, possibly because the relatively short duration of caffeine abstinence in the placebo condition was not sufficient to result in maximal withdrawal effects after termination of the relatively high caffeine dose. This study provides the clearest evidence to date of complete tolerance development to a CNS effect of caffeine in humans. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [110 medline neighbors] Psychopharmacology (Berl) 1992;109(3):283-290 No psychophysiological interactions between caffeine and stress? Hasenfratz M, Battig K Comparative Physiology and Behavioral Biology Laboratory, Swiss Federal Institute of Technology. In earlier studies, the predominantly beta-adrenergic effects of mental tasks and the alpha-adrenergic effects of caffeine on cardiovascular functions were observed to be simply additive without interaction. In the present study, annoying electrical shocks were superimposed on a mental task affording either active coping, which specifically raises beta-adrenergic activation, or passive coping, and the 40 female subjects were preselected so as to differ in subjective stress susceptibility. Caffeine as well as the type of coping and the considered personality dimension produced significant effects, but almost no interactions were obtained. The stress resistant subjects, who tended toward more extraversion, emotional stability and more masculinity, had lower anxiety scores, rated their performance higher and had a greater cardiac output than the stress non-resistant subjects, who represented a rather normal population according to the FPI personality dimensions. Caffeine increased EEG alpha and beta frequency and delta power and decreased beta power, raised blood pressure and enhanced stress reactions in respiration amplitude and pre-ejection period. Active stress coping induced greater stress reactions in heart rate (increase), left ventricular ejection time (decrease) and ear pulse arrival time (decrease) than passive coping. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [117 medline neighbors] Biol Psychiatry 1991 Nov 15;30(10):973-984 Anxiogenic effects of m-CPP in patients with panic disorder: comparison to caffeine's anxiogenic effects. Klein E, Zohar J, Geraci MF, Murphy DL, Uhde TW Section of Anxiety and Affective Disorders, National Institute of Mental Health, Bethesda, MD 20892. The behavioral and neuroendocrine effects of meta-chlorophenylpiperazine (m-CPP), a serotonergic agonist, were compared with the effects of caffeine, an adenosine antagonist, in panic disorder patients. Patients with panic disorder were given single oral doses of 0.5 mg/kg m-CPP, 480 mg caffeine, and placebo on separate days under double-blind conditions. Both m-CPP and caffeine had significantly greater anxiogenic and panic-inducing effects than placebo, although caffeine produced nonsignificantly greater increases on all anxiety rating scales than m-CPP. Both m-CPP and caffeine produced significant equivalent increases in plasma cortisol concentrations, but only m-CPP produced plasma prolactin increases. These findings provide further evidence implicating both the serotonergic and adenosinergic receptor systems in the neurobiology of panic disorder. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [134 medline neighbors] DICP 1991 Oct;25(10):1079-1080 Caffeine in electroconvulsive therapy. Cantu TG, Korek JS Department of Pharmacy, Johns Hopkins Hospital, Baltimore, Maryland 21205. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [102 medline neighbors] Med Hypotheses 1991 Oct;36(2):157-161 Exploring the role of an endogenous caffeine-like substance in the pathogenesis of schizophrenia. Missak SS In a previous paper, I have proposed that the deficiency of an endogenous caffeine-like substance is the underlying pathogenic mechanism in schizophrenia (1). In the present paper, my new concept is used to explain many of the clinical, biochemical, radiologic and pharmacologic facts about schizophrenia. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [116 medline neighbors] Clin Pharmacol Ther 1991 Aug;50(2):157-164 Effects of caffeine on tobacco withdrawal. Oliveto AH, Hughes JR, Terry SY, Bickel WK, Higgins ST, Pepper SL, Fenwick JW Department of Psychiatry, University of Vermont, Burlington 05401. Smoking cessation increases caffeine blood levels, and this has been hypothesized to cause some of the symptoms of tobacco withdrawal (e.g., anxiety and insomnia). To test this hypothesis, 10 coffee drinkers who smoked cigarettes were entered into a completely within-subjects experimental design in which the effects of caffeine dose (0, 50, and 100 mg/coffee serving) and smoking status (smoking versus abstinence) were examined over a 4-day period. Self-reported and observed measures of tobacco withdrawal, caffeine withdrawal, and intoxication, as well as psychomotor tasks and vital signs, were completed daily; blood was drawn at the end of each period. Temporary abstinence produced typical withdrawal symptoms but did not significantly increase caffeine blood levels. Caffeine did not increase the severity of symptoms but did decrease the severity of withdrawal-induced hunger. These findings suggest that, in the absence of increased blood levels, caffeine does not increase the severity of tobacco withdrawal. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [125 medline neighbors] Hosp Community Psychiatry 1991 Mar;42(3):313-315 Caffeine consumption in patients with eating disorders. Krahn DD, Hasse S, Ray A, Gosnell B, Drewnowski A University of Michigan Medical Center, School of Public Health, Ann Arbor 48109. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [114 medline neighbors] Biol Psychiatry 1991 Feb 15;29(4):391-396 Caffeine-induced anxiety and increase of kynurenine concentration in plasma of healthy subjects: a pilot study. Orlikov A, Ryzov I Laboratory of Psychopharmacology, Leningrad V.M. Bekhterev Psychoneurological Research Institute, USSR. The concentration of kynurenine, a neuroactive tryptophan metabolite, in blood plasma after pharmacologically induced anxiety was studied. Anxiety was provoked in 15 healthy volunteers by an anxiogenic dose of caffeine. Kynurenine concentration was markedly increased at the peak of anxiety and returned to normal after anxiety had abated. Possible causes responsible for this effect are discussed. There is a correlation between kynurenine concentration in blood plasma and indices of state and trait anxiety (Spielberger-Khanin scale) and anxiety (Hamilton scale) at baseline. The correlation disappears at the peak of anxiety. It is suggested that kynurenine is involved in caffeine-induced anxiety in humans. The absence of correlation at the peak of caffeine-induced anxiety is discussed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [123 medline neighbors] J Gen Psychol 1991 Jan;118(1):5-12 Efficacy of caffeine versus expectancy in altering caffeine-related symptoms. Christensen L, Miller J, Johnson D Department of Psychology, Texas A&M University, College Station 77843. The study investigated the independent and interactive effects of caffeine and expectancy on caffeine-related symptoms. High- and low-caffeine consumers were randomly assigned to either an expectancy or nonexpectancy instructional set and one of four caffeine doses. Subjects were administered the State-Trait Anxiety Inventory, (Spielberger & Gorsuch, 1970) and a Symptom Questionnaire (Christensen, White, Krietsch, & Steele, 1990) prior to and 45 min following consumption of one of the four caffeine doses. An analysis of covariance identified a significant main effect for the State-Trait Anxiety Inventory scores and significant main and interaction effects for four Symptom Questionnaire items. However, when the alpha levels were corrected for the increased probability of Type I error, using the Bonferroni procedure, these effects failed to achieve significance. These results suggest that previous reports of subjective caffeine effects are also suspect because of their failure to control for the increased probability of Type I error. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [103 medline neighbors] Psychophysiology 1991 Jan;28(1):65-71 Subjective and objective measures of sleepiness: effect of benzodiazepine and caffeine on their relationship. Johnson LC, Freeman CR, Spinweber CL, Gomez SA Naval Health Research Center, San Diego, CA 92186-5122. As part of a larger project on the effects of benzodiazepine and caffeine on daytime sleepiness, performance and mood, this study examined the relationship among the Multiple Sleep Latency Test, lapses during a tapping task, a Visual Analog Scale, and the Stanford Sleepiness scale. Subjects were 80 male, adult nonsmokers aged 20.3 +/- 2.7 years. The Multiple Sleep Latency Test, Stanford Sleepiness Scale, and the Visual Analog Scale were obtained at two-hour intervals beginning at 0700 h and ending at 1700 h. The tapping task (lapses) was administered each day at 0600 h, 1000 h, and 1400 h. A lapse was a 3-s or greater pause between taps. Correlations between the Multiple Sleep Latency Test and subjective (Visual Analog Scale and the Stanford Sleepiness Scale) measures were significant at 0600 h, but became nonsignificant as the day progressed. Correlations between lapses and the two subjective measures were generally nonsignificant. The two objective measures were significantly correlated in the total group but not in all treatment groups. The subjective measures were significantly correlated in the total sample and in each treatment group. This study reaffirms the importance of time of day when measuring sleepiness, and suggests that subjective and objective measures may measure different aspects of sleepiness. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [134 medline neighbors] Int J Psychophysiol 1990 Dec;10(2):171-179 The influence of user status and anxious disposition on the hypertensive effects of caffeine. James JE Department of Psychology, Flinders University, Bedford Park, Australia. The present study examined the influence of consumer status and anxious disposition on the hypertensive effects of caffeine. A secondary aim of the study was to investigate possible gender differences in response to caffeine. Sixty normotensive subjects were assigned to 4 groups representing high and low scorers on the variables of habitual caffeine consumption and anxious disposition. A randomized double-blind crossover design was used in which all subjects received a placebo (lactose) at one of two 120-min laboratory sessions and caffeine (6 mg/kg) at the other. Systolic and diastolic blood pressure, heart rate, hand steadiness, and EMG were monitored before and after exposure to a psychological stressor. Caffeine produced significant elevations in systolic and diastolic blood pressure, and these effects were additive to the pressor effects of stress and anxiety. While the general pattern of results was similar for both sexes, reactions to caffeine were more pronounced in males than in females. Notwithstanding the need for clarification of the chronic effects of caffeine, present findings add further weight to current concerns about the acute hypertensive effects of the drug. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [128 medline neighbors] Arukoru Kenkyuto Yakubutsu Ison 1990 Dec;25(6):486-496 Caffeine consumption and anxiety and depressive symptomatology among medical students. Mino Y, Yasuda N, Fujimura T, Ohara H Department of Public Health, Kochi Medical School. Caffeine is one of the most widely consumed psychoactive substances in the world and is ingested in a variety of favorites, such as coffee, tea, cola and so on. Although it has been suggested that high dose caffeine users have more anxiety and depressive symptoms than low users, this relationship is not clear in Japan, where caffeine consumption is considered to be less than in Western countries. A questionnaire survey was conducted among medical students and 291 out of 423 initial subjects completed it. Among males, caffeine consumption was significantly and positively correlated with anxiety symptoms, when alcohol use and smoking habit were adjusted. However, there was no relationship between caffeine consumption and depressive symptoms. Among females, although there was no association between caffeine consumption and anxiety symptoms, high dose caffeine users showed less depressive symptoms than moderate and low users, when alcohol use was adjusted. It is suggested that caffeine use is one of the important factors, in researching psychological health among the general population. We need further epidemiological studies to determine whether there is a causal relationship between caffeine and psychological ill health or not. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [121 medline neighbors] Acta Psychiatr Scand 1990 Jul;82(1):17-22 Behavioral and cerebrovascular effects of caffeine in patients with anxiety disorders. Mathew RJ, Wilson WH Department of Psychiatry, Duke University Medical Center, Durham, North Carolina 27710. Caffeine is believed to induce anxiety in normal people and anxiety disorder patients and panic attacks in panic disorder patients. The drug is also known to reduce cerebral blood flow (CBF). Findings suggesting an anxiety-related cerebral vasoconstrictive factor have been reported. We examined the relationship between changes in anxiety and CBF induced by intravenously injecting 250 mg of caffeine (comparable to 2 cups of coffee) in 8 patients with generalized anxiety disorder, 9 patients with panic disorder and 9 normal controls. CBF measurements were also obtained before and after an injection of normal saline in another group of 9 normal volunteers. The anxiety disorder patients did not show any evidence of increase in anxiety and panic after caffeine. Both patients and controls who received caffeine but not normal controls who received saline showed significant CBF decrease. The CBF changes were unrelated to changes in mood, autonomic activity and carbon dioxide levels. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [107 medline neighbors] Biol Psychiatry 1990 Jul 1;28(1):35-40 Effects of the acute administration of caffeine in patients with schizophrenia. Lucas PB, Pickar D, Kelsoe J, Rapaport M, Pato C, Hommer D Section of Clinical Studies, National Institute of Mental Health, Bethesda, Maryland 20892. Caffeine, 10 mg/kg, was administered to 13 schizophrenic patients in a double-blind placebo-controlled study of its behavioral effects. Some measures of psychopathology were significantly increased: Brief Psychiatric Rating Scale (BPRS) total, BPRS subscales thought disorder, unusual thought content, and euphoria-activation, and several individual BPRS items. Nurses' Bunney-Hamberg ratings of psychosis and mania, comparing the day before with the day after pharmacological challenge, increased significantly. Compared to placebo, caffeine also produced significant increases of diastolic blood pressure and cortisol. Thus, these findings indicate that caffeine increases arousal and has a psychotogenic effect when administered to schizophrenic patients. The possible roles of various neurotransmitters is discussed with special emphasis on caffeine's actions on dopaminergic and adenosinergic systems. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [111 medline neighbors] Postgrad Med J 1990;66 Suppl 2:S18-S24 The anxiogenic effects of caffeine. Bruce MS Unit of Clinical Psychopharmacology, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London, UK. The contrast of attitudes to the psychiatric effects of caffeine between North America and Britain is highlighted. A summary of the dietary sources, pharmacology and effects on caffeine on normal subjects is given. The emphasis in normal subjects is on the acute, chronic, toxic and withdrawal effects. With this background information, a more specific evaluation of the anxiogenic effects are discussed. In conclusion, the case is made for a trial of caffeine abstention to become part of the management of anxious patients. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [110 medline neighbors] Int J Addict 1990 Jan;25(1):27-31 Expectancy effects in caffeine research. Christensen L, White B, Krietsch K, Steele G College of Liberal Arts, Texas A & M University, College Station 77843-4235. The impact of expectancy on the experience of caffeine-related symptoms was investigated by randomly assigning subjects to an expectancy or nonexpectancy instructional condition. Subjects were administered the State-Trait Anxiety Inventory and a Symptom Questionnaire prior to and 45 minutes after receiving their designated instructional set and ingesting a cellulose-filled gelatin capsule which ostensibly was filled with caffeine. Results revealed that a significant expectancy effect existed on five Symptom Questionnaire items. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [129 medline neighbors] Life Sci 1990;47(13):1141-1146 Caffeine and human cerebral blood flow: a positron emission tomography study. Cameron OG, Modell JG, Hariharan M Department of Psychiatry, University of Michigan Medical Center, Ann Arbor 48109-0722. Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decreased paCO2 and increased systolic blood pressure significantly; the change in paCO2 did not account for the change in CBF. Smaller increases in diastolic blood pressure, heart rate, plasma epinephrine and norepinephrine, and subjectively reported anxiety were also observed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Lnks: [125 medline neighbors] Schizophr Bull 1990;16(3):371-372 Response to "Effects of caffeine on behavior of schizophrenic inpatients". Hyde AP Psychiatric Hospital, Columbia, SC 29203. This article addresses itself to the apparent conflict between those reports indicating that caffeine affects schizophrenic behavior and the present study which failed to show substantial behavior or medication changes with caffeine. It is suggested that there are important subgroups of schizophrenic patients who are unusually sensitive to caffeine's apparent psychotogenic actions as reported in case reports and data on violence and destruction. It is also suggested that there are subgroups of schizophrenia which seem to require increased medication doses to "cover" caffeine effects. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [152 medline neighbors] Psychopharmacology (Berl) 1990;101(2):160-167 Benzodiazepines and caffeine: effect on daytime sleepiness, performance, and mood. Johnson LC, Spinweber CL, Gomez SA Naval Health Research Center, San Diego, CA 92138-9174. In a double-blind parallel group design, 80 young adult males were divided into eight treatment groups. Subjects received 15 or 30 mg flurazepam, 0.25 or 0.50 mg triazolam, or placebo at bedtime, and 250 mg caffeine or placebo in the morning for 2 treatment days. Two objective (Multiple Sleep Latency Test and lapses) and two subjective (Stanford Sleepiness Scale and Visual Analog Scale) measures of sleepiness, five performance tests, and two mood measures (Profile of Mood Scale and Visual Analog Mood Scale) were administered repeatedly on both days. Significant treatment effects were found for sleepiness but not for performance or mood. Early morning caffeine significantly antagonized next day hypnotic-induced drowsiness and enhanced alertness in the subjects who received bed-time placebo. Flurazepam, 30 mg, subjects were more sleepy than all other groups. Although not significantly different, the flurazepam, 30 mg, group demonstrated a trend toward poorer performance and a more negative mood than all other groups. Caffeine most improved performance of this group. In all groups, sleepiness was greatest and performance and mood poorest in early morning trials and caffeine was most effective at this time. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [109 medline neighbors] Psychiatry Res 1989 Dec;30(3):231-242 Caffeine taste test for panic disorder: adenosine receptor supersensitivity. DeMet E, Stein MK, Tran C, Chicz-DeMet A, Sangdahl C, Nelson J Department of Psychiatry and Human Behavior, University of California, Irvine 92717. The present study introduces a novel measure of adenosine receptor sensitivity that is based on the action of specific receptor blockers (e.g., caffeine) to potentiate the ability to detect threshold quinine concentrations. The test is used to compare gustatory adenosinergic responses to caffeine challenges in normal controls and patients with panic disorder or posttraumatic stress disorder (PTSD). Panic disorder patients had an exaggerated response to the caffeine challenge that was not found in controls or PTSD patients, although the latter had higher anxiety scores on psychometric tests. The results are related to a model in which A1-adenosine receptors up-regulate in an attempt to modulate hyperactive excitatory neuronal systems. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [106 medline neighbors] Zh Vyssh Nerv Deiat 1989 Nov;39(6):1010-1013 Elevation of the blood kynurenine level in caffeine-induced anxiety. [Article in Russian] Orlikov AB, Ryzhov IV Concentration of neuroactive tryptophane--kynurenine metabolite was studied in healthy men volunteers in conditions of anxiety artificially elicited by caffeine. At peak of the alarm the level of the kynurenine significantly increased and came to norm after anxiety cessation. Possible causes of this increase are discussed. High correlation has been obtained between the kynurenine concentration and initial values of personal and reactive anxiety. The conclusion is made about the participation of the kynurenine in formation of personal and reactive anxiety in man. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [104 medline neighbors] Biol Psychiatry 1989 Jul;26(3):315-320 Depersonalization disorder: effects of caffeine and response to pharmacotherapy. Stein MB, Uhde TW Unit on Anxiety and Affective Disorders, National Institute of Mental Health, Bethesda, MD 20892. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [135 medline neighbors] Ann Intern Med 1989 Apr 15;110(8):593-598 The effect of caffeine on exercise tolerance and left ventricular function in patients with coronary artery disease. Hirsch AT, Gervino EV, Nakao S, Come PC, Silverman KJ, Grossman W Charles A. Dana Research Institute, Boston, Massachusetts. STUDY OBJECTIVE: To determine whether acute oral caffeine ingestion by patients with coronary artery disease results in decreased treadmill exercise performance or deterioration of echocardiographic measures of systolic or diastolic left ventricular function. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Referral-based cardiovascular exercise laboratory at an urban teaching hospital. PATIENTS: Thirteen volunteers with clinically stable coronary artery disease who had exercise tests after a 2-week caffeine-free washout period. Patients continued treatment with standard antianginal medications during the study period. INTERVENTIONS: Maximal exercise treadmill testing and exercise echocardiography were done at baseline, after acute ingestion of a placebo beverage (97% caffeine-free coffee), or after drinking an identical beverage containing 250 mg of caffeine sodium benzoate. MEASUREMENTS AND MAIN RESULTS: Acute ingestion of caffeine produced a serum level of 4.50 +/- 0.16 micrograms/mL, but had no effect on resting supine heart rate, blood pressure, left ventricular fractional shortening, posterior left ventricular wall thinning or peak rates of increase in left ventricular diastolic dimension. Despite a small increase in peak systolic blood pressure during exercise (baseline, 153 +/- 8; placebo, 154 +/- 8; caffeine, 161 +/- 7 mm Hg; P less than 0.05), exercise duration, time to onset of angina, and time to 0.1 mV ST depression did not differ after ingestion of placebo or caffeine. Rate-pressure product at onset of angina and onset of 0.1 mV of ST depression were also unchanged. In response to exercise, echocardiographic measures of left ventricular systolic and diastolic function were unchanged after caffeine compared with placebo ingestion. CONCLUSIONS: These data suggest that patients with exercise-induced ischemia who are receiving appropriate antianginal therapy tolerate the caffeine-equivalent of three cups of coffee without detrimental effect on intensity of ischemia, myocardial function, or exercise duration. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [118 medline neighbors] BMJ 1989 Mar 25;298(6676):795-801 Effects on birth weight of smoking, alcohol, caffeine, socioeconomic factors, and psychosocial stress. Brooke OG, Anderson HR, Bland JM, Peacock JL, Stewart CM Department of Child Health, St George's Hospital Medical School, London. OBJECTIVE--To investigate the effects of smoking, alcohol, and caffeine consumption and socio-economic factors and psychosocial stress on birth weight. DESIGN--Prospective population study. SETTING--District general hospital in inner London. PARTICIPANTS--A consecutive series of 1860 white women booking for delivery were approached. 136 Refused and 211 failed to complete the study for other reasons (moved, abortion, subsequent refusal), leaving a sample of 1513. Women who spoke no English, booked after 24 weeks, had insulin dependent diabetes, or had a multiple pregnancy were excluded. MEASUREMENTS--Data were obtained by research interviewers at booking (general health questionnaire, modified Paykel's interview, and Eysenck personality questionnaire) and at 17, 28, and 36 weeks' gestation and from the structured antenatal and obstetric record. Variables assessed included smoking, alcohol consumption, caffeine consumption, and over 40 indicators of socio-economic state and psychosocial stress, including social class, tenure of accommodations, education, employment, income, anxiety and depression, stressful life events, social stress, social support, personality, and attitudes to pregnancy. Birth weight was corrected for gestation and adjusted for maternal height, parity, and baby's sex. MAIN RESULTS--Smoking was the most important single factor (5% reduction in corrected birth weight). Passive smoking was not significant (0.5% reduction). After smoking was controlled for, alcohol had an effect only in smokers and the effects of caffeine became non-significant. Only four of the socioeconomic and stress factors significantly reduced birth weight and these effects became non-significant after smoking was controlled for. CONCLUSIONS--Social and psychological factors have little or no direct effect on birth weight corrected for gestational age (fetal growth), and the main environmental cause of its variation in this population was smoking. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [125 medline neighbors] Psychol Med 1989 Feb;19(1):211-214 Caffeine abstention in the management of anxiety disorders. Bruce MS, Lader M Department of Psychiatry, Institute of Psychiatry, London. Caffeine toxicity remains a rarely reported condition, which may mimic anxiety disorders. Anxiety disorder patients do not consume toxic amounts of caffeine. However, increased sensitivity to caffeine in these patients has been suggested as contributing to their symptoms. Six cases of anxiety disorder are presented who improved with only caffeine abstention, and remained well for at least a six-month follow-up period. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [121 medline neighbors] Schizophr Bull 1989;15(2):339-344 Effects of caffeine on behavior of schizophrenic inpatients. Koczapski A, Paredes J, Kogan C, Ledwidge B, Higenbottam J Dept. of Psychology, Riverview Hospital, Coquitlam, BC, Canada. The present study replicates that of De Freitas and Schwartz (1979), using more typical chronic patients (on open wards rather than locked wards), and monitoring coffee intake with serum caffeine levels. The serum caffeine levels observed indicate that caffeine can be effectively manipulated on an open ward by switching the type of coffee served. Contrary to our predictions, no significant improvements in patients' behavior occurred when decaffeinated coffee was first introduced, nor was there any deterioration when regular coffee was reinstated. Only after decaffeinated coffee was introduced for the second time did any of the predicted changes occur; however, the improvements were few in number and may be accounted for by the considerable effect of time per se across all time periods. Although the findings cannot be generalized to all psychiatric patients, the results do not support recent calls for a switch to decaffeinated coffee for this population of inpatients (i.e., chronic schizophrenic patients on high doses of neuroleptics who drink large amounts of coffee). --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [112 medline neighbors] J R Nav Med Serv 1989;75(2):65-67 Caffeine and caffeinism. Mackay DC, Rollins JW Caffeine is a widely ingested and generally beneficial drug. However, when taken in excess, anxiety related symptoms become increasingly apparent. A case of caffeinism, which presented as a paranoid delusion, is reported as an extreme example of this. A study of 60 hospital inpatients revealed that about 40% of them consumed sufficient caffeine to produce symptoms of caffeinism. It is thus recommended that all patients should be questioned on their caffeine intake. Also, caffeinism should be considered as a differential diagnosis of anxiety states. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [123 medline neighbors] Psychopharmacol Bull 1989;25(3):473-478 Smooth pursuit eye movements in schizophrenia: effects of neuroleptic treatment and caffeine. Litman RE, Hommer DW, Clem T, Rapaport MH, Pato CN, Pickar D Abnormal smooth pursuit eye movement (SPEM) has been proposed as a trait marker in schizophrenia. We utilized high resolution infra-red oculography to measure SPEM in 11 neuroleptic-treated schizophrenic patients, 10 drug-free schizophrenic patients, and 11 normals. The most characteristic abnormality was a significant increase in saccadic intrusions during SPEM in schizophrenic patients (p less than .001). SPEM gain was reduced in schizophrenic patients (p less than .005). No significant effects of neuroleptic treatment on SPEM were found, including analysis of seven patients in whom paired data was available. We also measured SPEM prior to and after caffeine ingestion (10 mg/kg) in 10 normals. We found reduced saccadic interruptions as a result of caffeine ingestion compared with placebo (p less than .05). As caffeine has been shown to selectively increase dopaminergic neurotransmission in mesocortical neurons, further study utilizing dopamine agonists during SPEM in schizophrenic patients is warranted. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [116 medline neighbors] Encephale 1989 Jan;15 Spec No:177-180 Use of the methylxanthines, caffeine and theophylline, in the treatment of extrapyramidal disorders caused by treatment with neuroleptics. Development of a therapeutic hypothesis. [Article in French] Casas M, Torrens M, Duro P, Pinet C, Alvarez E, Udina C Programa Sant Pau-CITRAN, Fundacio d'Investigacio Santa Creu i Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Espagne. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [160 medline neighbors] Psychopharmacology (Berl) 1989;98(1):81-88 Reinforcing and subjective effects of caffeine in normal human volunteers. Stern KN, Chait LD, Johanson CE Department of Psychiatry, Pritzker School of Medicine, University of Chicago, IL 60637. The reinforcing and subjective effects of caffeine (100 and 300 mg, PO) were determined in a group of 18 normal, healthy adults. Subjects (eight females, ten males) were light to moderate users of caffeine, and had no history of drug abuse. A discrete-trial choice procedure was used in which subjects were allowed to choose between the self-administration of color-coded capsules containing either placebo or caffeine. The number of times caffeine was chosen over placebo was used as the primary index of reinforcing efficacy. Subjective effects were measured before and several times after capsule ingestion. The low dose of caffeine was chosen on 42.6% of occasions, not significantly different from chance (50%). The high dose of caffeine was chosen on 38.9% of occasions, significantly less than expected by chance, indicating that this dose served as a punisher. Both doses of caffeine produced stimulant-like subjective effects, with aversive effects such as increased anxiety predominating after the high dose. When subjects were divided into groups of caffeine-sensitive choosers and nonchoosers, a consistent relationship emerged between caffeine choice and subjective effects; nonchoosers reported primarily aversive effects after caffeine (increased anxiety and dysphoria), whereas choosers reported stimulant and "positive" mood effects. When compared with previous findings, these results demonstrate that caffeine is less reinforcing than amphetamine and related psychomotor stimulants. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [113 medline neighbors] Br J Clin Psychol 1988 Sep;27( Pt 3):265-266 Caffeine reduction as an adjunct to anxiety management. Smith GA Department of Clinical Psychology, Seaford Court Lodge, Malvern Link, Worcs, UK. A reduction in tea and coffee drinking is popularly advocated for the relief of tension and anxiety symptoms, and it was decided to collect empirical data on this matter in the course of normal clinical practice. It was found that patients who made substantial reductions in caffeine drinking also made the greatest improvements in anxiety, irritability, sleep disturbance, headaches and abdominal symptoms. The methodology leaves an ambiguity in the interpretation of this result, but the data provide a useful basis for the design of further studies. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [170 medline neighbors] J Pharmacol Exp Ther 1988 Jul;246(1):21-29 Reinforcing effects of caffeine in humans. Griffiths RR, Woodson PP Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland. The reinforcing and subjective effects of caffeine were studied under double-blind conditions in 12 normal humans. After 2 forced exposure days on which subjects received color-coded capsules containing either caffeine (100, 200, 400 or 600 mg) or placebo, subjects had a choice day on which they chose which one of the two types of color-coded capsules would be ingested. Subjects were exposed to 10 experimentally independent choices (i.e., involving exposure and choice between novel color-coded capsule conditions) at each of several dose levels. All forced exposure and choice opportunities occurred when subjects were overnight abstinent from their normal dietary caffeine intake (mean, 116 mg/day). Significant caffeine positive reinforcement was demonstrated in 5 of 12 subjects at one or more doses. Percentage of selection of caffeine was inversely related to dose, with four subjects showing significant caffeine avoidance at 400 and/or 600 mg. Choice behavior was correlated positively with feelings of contentedness and was correlated negatively with prestudy trait anxiety scores and with ratings of capsule disliking. Compared to placebo, caffeine produced increases in subjective ratings indicating arousal while producing decreases in headache and "craving" for caffeine-containing foods, even at the lowest dose of 100 mg. At higher doses caffeine produced dysphoric anxiety-like subjective effects. Overall, this study provides the first demonstration in humans of the positive reinforcing effects of caffeine alone (i.e., in capsules) and documents individual differences among normal subjects in both caffeine positive reinforcement and caffeine avoidance. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [113 medline neighbors] Int Clin Psychopharmacol 1988 Jul;3(3):215-229 Anxiogenic effect of yohimbine in healthy subjects: comparison with caffeine and antagonism by clonidine and diazepam. Mattila M, Seppala T, Mattila MJ Department of Pharmacology and Toxicology, University of Helsinki, Finland. Three placebo-controlled double-blind and crossover trials were carried out to analyze the effects of oral yohimbine (YOH) 0.8 mg/kg on mood and performance in 16 healthy students. Subjective assessments (visual analogue scales, side-effects on questionnaire) and objective measurements (digit symbols, flicker fusion, tapping, heterophoria) were done at baseline, and post treatment. YOH shifted the healthy subjects' mood towards feeling panicked, elevated systolic blood pressure and plasma prolactin concentrations, reduced digit symbol substitution, and induced drowsiness and passiveness. Caffeine (CAF) 10 mg/kg raised plasma cortisol and rendered the subjects slightly panicked. Muzziness, clumsiness, tremor, chills and nausea were common after both YOH and CAF. Diazepam (DZ) 0.3 mg/kg given at 60 min antagonized some effects of CAF but failed to antagonize YOH. Clonidine (CLO) 100 micrograms counteracted YOH effects on blood pressure but less the subjective and hormonal effects. CLO 200 micrograms partly antagonized the pressor, sedative but not the hormonal responses of YOH. DZ counteracted YOH effects on plasma cortisol on panic but not on other subjective measures or plasma prolactin. Since CLO did not abolish YOH-induced prolactin increase, it is suggested that these effects of YOH are mediated not only via adrenergic alpha 2-receptors; other mechanisms made important contributions. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [103 medline neighbors] Br J Addict 1988 Jun;83(6):689-694 The concurrent use of alcohol, cigarettes and caffeine in British benzodiazepine users as measured by a general population survey. Dunbar GC, Morgan DD, Perera KM --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [189 medline neighbors] Am J Psychiatry 1988 May;145(5):632-635 Anxiogenic effects of caffeine on panic and depressed patients. Lee MA, Flegel P, Greden JF, Cameron OG Department of Psychiatry, University of Michigan Medical School, Ann Arbor 48109. Caffeine increases anxiety in people with anxiety disorders. To determine whether caffeine exerts a similar effect in depression, the authors compared retrospective reports of caffeine intake and symptoms produced by caffeine ingestion in patients with panic disorder, patients with major depression, and control subjects. Panic patients consumed less caffeine and reported more symptoms than depressed or control subjects. Although depressed patients did not differ from control subjects in caffeine intake or most symptoms, more depressed patients reported that caffeine induced anxiety. These data support prior reports that panic patients have increased sensitivity to caffeine; some depressed patients may also have increased sensitivity. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [126 medline neighbors] Am Fam Physician 1988 May;37(5):167-172 Psychotropic effects of caffeine. Clementz GL, Dailey JW University of Illinois College of Medicine, Peoria. Chronic, heavy caffeine ingestion may cause or exacerbate anxiety and may be associated with depression and increased use of antianxiety drugs. Caffeine may cause anxiety and panic in panic disorder patients and may aggravate the symptoms of premenstrual syndrome. Chronic users who are caffeine-sensitive may have symptoms of caffeinism at relatively low doses. Individuals who regularly consume moderate to heavy amounts of caffeine may develop caffeinism, or they may show signs of caffeine withdrawal syndrome after abstaining from the drug. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [202 medline neighbors] Psychiatry Res 1988 Apr;24(1):61-65 Chronic caffeine consumption and the dexamethasone suppression test in depression. Lee MA, Flegel P, Cameron OG, Greden JF Department of Psychiatry, University of Michigan, Ann Arbor. Acute caffeine administration increases cortisol and converts the dexamethasone suppression test (DST) to nonsuppression in normal humans; data concerning chronic administration as well as effects in depressed patients are minimal. To determine whether caffeine intake influenced DST results in depression, we retrospectively studied the relationship between regular daily caffeine consumption and pretreatment DST status in major depressives. Daily intake was not correlated with either post-DST cortisol levels or symptom ratings. These data suggest that chronic caffeine use is unlikely to be a major factor in dysregulation of the hypothalamic-pituitary-adrenal axis in depression, perhaps because of the development of tolerance. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [137 medline neighbors] Psychopharmacology (Berl) 1988;94(4):437-451 Caffeine physical dependence: a review of human and laboratory animal studies. Griffiths RR, Woodson PP Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205. Although caffeine is the most widely used behaviorally active drug in the world, caffeine physical dependence has been poorly characterized in laboratory animals and only moderately well characterized in humans. In humans, a review of 37 clinical reports and experimental studies dating back to 1833 shows that headache and fatigue are the most frequent withdrawal symptoms, with a wide variety of other signs and symptoms occurring at lower frequency (e.g. anxiety, impaired psychomotor performance, nausea/vomiting and craving). When caffeine withdrawal occurs, severity can vary from mild to extreme (i.e. incapacitating). The withdrawal syndrome has an onset at 12-24 h, peak at 20-48 h, and duration of about 1 week. The pharmacological specificity of caffeine withdrawal has been established. The proportion of heavy caffeine users who will experience withdrawal symptoms has been estimated from experimental studies to range from 25% to 100%. Withdrawal symptoms have been documented after relatively short-term exposure to high doses of caffeine (i.e. 6-15 days of greater than or equal to 600 mg/day). Although animal and human studies suggest that physical dependence may potentiate the reinforcing effects of caffeine, human studies also demonstrate that a history of substantial caffeine intake is not a necessary condition for caffeine to function as a reinforcer. The similarities and differences between caffeine and classic drugs of abuse are discussed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [101 medline neighbors] J Subst Abuse 1988;1(1):67-70 A survey of physician advice about caffeine. Hughes JR, Amori G, Hatsukami DK Department of Psychiatry, University of Vermont, Burlington 05401. Six hundred and ninety-seven medical specialists were surveyed to determine whether there is any consensus on the harmful effects of caffeine. More than 75% of the specialists recommended reduction in caffeine in patients with anxiety, arrhythmias, esophagitis/hiatal hernia, fibrocystic disease, insomnia, palpitations, and tachycardia. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [188 medline neighbors] J Clin Psychopharmacol 1987 Oct;7(5):315-320 The effects of caffeine and aspirin on mood and performance. Lieberman HR, Wurtman RJ, Emde GG, Coviella IL Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139. Caffeine, in addition to being a food constituent, is also a common analgesic adjuvant that is used in combination with aspirin in certain over-the-counter preparations. Caffeine has previously been shown to significantly improve certain aspects of human performance, particularly sustained vigilance, when administered in low and moderate doses (32 to 256 mg). We therefore attempted to determine whether caffeine, in the dose (64 mg) found in some over-the-counter drugs, retains this beneficial property when combined with aspirin. We also measured self-reported mood state, using various standardized questionnaires, since caffeine has been reported to have both beneficial and adverse effects on alertness and anxiety. We observed that caffeine (64 mg), when added to aspirin (800 mg), significantly improves vigilance performance and increases self-reported efficiency when compared with either placebo or aspirin alone. As previously reported, this caffeine dose alone significantly increased vigilance and decreased reaction time. No adverse effects of caffeine were detected on any of the parameters that were assessed. This study therefore demonstrated that the addition of caffeine to aspirin, in a dose commonly employed in over-the-counter drugs, has significant beneficial consequences with respect to mood and performance. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [202 medline neighbors] Psychiatry Res 1987 Jul;21(3):247-255 Plasma adenosine levels: measurement in humans and relationship to the anxiogenic effects of caffeine. Boulenger JP, Salem N Jr, Marangos PJ, Uhde TW The effects of caffeine on plasma adenosine were examined in eight healthy normal volunteers. Subjects were randomly administered on 4 separate days, in a double-blind fashion, either placebo or three different doses of caffeine (240, 480, and 720 mg). Adenosine concentrations, measured by high performance liquid chromatography, were in the micromolar range when samples were drawn into tubes containing dipyridamole to prevent adenosine reuptake by red blood cells. Plasma adenosine levels did not change after caffeine administration. The effects of caffeine on anxiety were related to changes in plasma caffeine but not plasma adenosine levels. The potential interest of caffeine as a chemical model of anxiety is discussed. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [141 medline neighbors] Acta Psychiatr Scand 1987 Jun;75(6):608-613 Dexamethasone suppression test in severe schizophrenic illness: effects of plasma dexamethasone and caffeine levels. Holsboer-Trachsler E, Buol C, Wiedemann K, Holsboer F A dexamethasone suppression test (DST) was administered to 31 inpatients with a severe acute schizophrenic exacerbation 4 or 5 days following admission and repeated after 4 weeks or prior to discharge. We identified 15 patients (48%) who were nonsuppressors on the DST at the first test. To exclude major confounders of DST results we monitored weight constancy and plasma concentrations of dexamethasone. In a subgroup of patients also plasma caffeine contents were determined. Our results indicate that DST nonsuppression occurs frequently among patients with schizophrenic crisis. Since caffeine plasma levels were indistinguishable between suppressors and nonsuppressors we reject that excessive caffeine intake accounts for DST nonsuppression among individuals with schizophrenia. Nonsuppressors had lower plasma dexamethasone levels than suppressors and reversal of the DST status from nonsuppression to suppression was associated with an increase of plasma concentrations of the test drug. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [159 medline neighbors] Int J Psychophysiol 1987 May;5(1):33-41 Autonomic nervous system effects of acute doses of caffeine in caffeine users and abstainers. Zahn TP, Rapoport JL The effects of caffeine on autonomic nervous system (ANS) activity were tested in 20 adult males who were either high or low consumers of caffeine. Subjects received placebo, 3 mg/kg, and 10 mg/kg of caffeine in a counterbalanced order (double-blind) before 3 test sessions 48 h apart. Skin conductance (SC), heart rate, and skin temperature (ST) were recorded during a rest period, a series of non-signal tones, and a simple reaction time task. Caffeine increased resting electrodermal activity (EDA) and increased the SC orienting response to the first non-signal tone, but reduced the increase in tonic EDA due to task performance. ST was reduced by caffeine in both rest and task periods. Increases in nervous/jittery ratings occurred after caffeine ingestion, but task performance was not affected. Low consumers of caffeine showed significantly more ANS responsivity than high consumers under all conditions and did not differ in ANS, behavioral, or subjective effects of caffeine. The acute physiological changes are partly similar to those reported for patients with anxiety disorders, suggesting a possible role of ANS activity in mediating the anxiogenic effects of caffeine. Effects of user status may reflect a predisposing trait, but an effect of chronic caffeine use on ANS sensitivity cannot be ruled out. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [206 medline neighbors] Psychopharmacology (Berl) 1987;92(3):308-312 The effects of low doses of caffeine on human performance and mood. Lieberman HR, Wurtman RJ, Emde GG, Roberts C, Coviella IL Caffeine is thought to have stimulant-like behavioral effects on mood and performance. However few behavioral studies have examined this substance's acute effects when administered in a range of doses that include the low doses typically found in foods and over-the-counter drugs. We therefore gave single doses of caffeine (32, 64, 128 and 256 mg) to 20 healthy male subjects and assessed various aspects of performance and self-reported mood states, as well as plasma caffeine concentration. As little as 32 mg (which elevated plasma caffeine concentration to less than 1 microgram/ml), typical of the dose found in a single serving of a cola beverage, and less than that found in a single cup of coffee or a single dose of over-the-counter drugs, significantly improved auditory vigilance and visual reaction time. All other caffeine doses administered also significantly improved performance on these tests. No adverse behavioral effects, such as increased anxiety or impaired motor performance, were noted even at the highest dose administered. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [124 medline neighbors] Psychopharmacology (Berl) 1987;91(1):40-44 Acute autonomic nervous system effects of caffeine in prepubertal boys. Zahn TP, Rapoport JL The effects of caffeine on autonomic activity were tested in 19 normal prepubertal boys. Subjects received placebo, 3 mg/kg, and 10 mg/kg caffeine in a random order (double blind) before three test sessions 48 h apart. Skin conductance (SC), heart rate (HR), and skin temperature (ST) were recorded during a rest period, a series of nonsignal tones, and a simple reaction time (RT) task. Caffeine increased the frequency of both spontaneous and elicited SC responses (SCR) under all conditions. Resting SC base level (SCL) was increased, and shorter SCR half recovery time also occurred in some periods. In contrast, caffeine decreased HR and motor activity at 3 mg/kg. Evidence of improved attention on caffeine was also obtained. The physiological effects are partially similar to the effects seen in clinical anxiety states, and they are also consistent with the physiological concomitants of good sustained attention. The profile of effects did not resemble those of dextroamphetamine in a similar population. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [135 medline neighbors] Med J Aust 1986 Nov 17;145(10):518-521 Caffeine: a toxicological overview. Abbott PJ The health effects of caffeine have been examined in a review of its toxicological and pharmacological properties together with its effect on children. Caffeine commonly causes symptoms of an acute overdose and withdrawal symptoms. These may be identified as anxiety in moderate consumers and can lead to severe central nervous system effects in heavy consumers. Pharmacological effects occur even at low doses but their severity is influenced by wide individual variation and the development of tolerance. Nevertheless, chronic consumption of caffeine is implicated in various minor symptoms of ill health and is associated with elevated serum cholesterol levels. At the doses that are consumed by humans, there is little evidence at present to suggest effects on reproduction, teratogenesis, tumour formation or the incidence of myocardial infarction. A reduced consumption of caffeine is advocated for all age groups. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [121 medline neighbors] J Clin Psychol 1986 Nov;42(6):860-863 Caffeine and memory performance on the AVLT. Terry WS, Phifer B The Auditory-Verbal Learning Test (AVLT) is a memory test that assesses recall of lists of words on single and multiple trials. College students (N = 33) were given the AVLT, either with or without a prior administration of 100 mg caffeine. Caffeine subjects recalled fewer words than did control subjects, both after single presentations of lists and across repeated trials. Caffeine subjects showed a greater deficit in recalling the middle-to-end portions of the lists. Personality scores on the Maudsley Personality Inventory showed a positive correlation of recall on a pretest with Neuroticism, and no correlation with Introversion. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [205 medline neighbors] Pharmacotherapy 1986 Sep;6(5):240-247 Analgesic effect of an aspirin-codeine-butalbital-caffeine combination and an acetaminophen-codeine combination in postoperative oral surgery pain. Forbes JA, Jones KF, Smith WK, Gongloff CM The efficacy of an aspirin-caffeine-codeine-butalbital combination was compared to an acetaminophen-codeine combination and placebo in outpatients who had moderate or severe pain after the surgical removal of impacted third molars. Using a self-rating record, patients rated their pain, relief, anxiety and relaxation hourly for up to 6 hours after medicating. Each active medication was significantly superior to placebo for measures of analgesia and relaxation. Although the butalbital-containing combination provided consistently greater analgesia, the differences between active medications were not statistically significant. The acetaminophen-codeine combination significantly reduced anxiety; however, the butalbital containing combination did not. The results of this study suggest that female patients may have greater efficacy than male patients. All adverse effects were transitory and consistent with the known pharmacologic profiles of the study medications or the backup analgesic. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [172 medline neighbors] Psychol Rep 1986 Aug;59(1):83-86 Potentiation of performance-induced anxiety by caffeine in coffee. Shanahan MP, Hughes RN --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [114 medline neighbors] Psychiatr J Univ Ott 1986 Jun;11(2):105-106 Hyponatremic coma and elevated serum creatine phosphokinase following excessive caffeine intake. Kirubakaran V --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [157 medline neighbors] Eur Arch Psychiatry Neurol Sci 1986;235(4):206-209 Caffeine-induced cerebral blood flow changes in schizophrenia. Mathew RJ, Wilson WH, Tant S Cerebral blood flow (CBF) measurements and mental status examinations were performed before and 30 min after oral administration of 250 mg of caffeine or a placebo given under double-blind conditions, in two groups of patients with schizophrenia. Caffeine produced significant CBF reductions but no changes in the patient's clinical condition. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [134 medline neighbors] Servir 1986 Jan;34(1):34-38 Caffeine, stress and anxiety. [Article in Portugese] Boulenger JP --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [152 medline neighbors] Cardiovasc Res 1985 Dec;19(12):727-733 Electromechanical effects of caffeine in isolated human atrial fibres. Lin CI, Chiu TH, Chiang BN, Cheng KK Effects of caffeine on the action potential and contractile force of human atrial fibres obtained at cardiac surgery were studied with standard microelectrode technique. In 4 mmol . litre-1 [K]o, the only significant action produced by 0.3 to 3 mmol . litre-1 caffeine on the electro-mechanical activity of relatively normal atrial fibres was a slight shortening of the action potential duration at 50% repolarisation. When the fibres were depolarised in 27 mmol . litre-1 [K]o or in atrial fibres showing slow responses in 4 mmol . litre-1 [K]o, however, caffeine could increase the upstroke of slow response and the force. In 18% of atrial fibres showing slow responses in 4 mmol . litre-1 [K]o, caffeine induced spontaneous discharges and potentiated afterdepolarisations. The positive inotropic and the arrhythmogenic effects of caffeine could be diminished by pretreating the fibres with propranolol or Ca antagonists (diltiazem and verapamil). In fibres beating spontaneously in normal [K]o, caffeine accelerated spontaneous rhythms initially and then depressed them. Propranolol potentiated the later depression but did not block the initial acceleration. The results suggest that caffeine increases the transmembrane Ca influx and enhances the release of Ca from the intracellular stores in human atrial fibres. As a consequence, caffeine could induce arrhythmias in atria from certain individuals. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [123 medline neighbors] Psychol Rep 1985 Aug;57(1):39-42 Patterns of caffeine use and prescribed medications in psychiatric inpatients. Shisslak CM, Beutler LE, Scheiber S, Gaines JA, La Wall J, Crago M --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [134 medline neighbors] Arch Gen Psychiatry 1985 Jul;42(7):737-738 Caffeine-induced escape from dexamethasone suppression. [LETTER] Uhde TW, Bierer LM, Post RM --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [156 medline neighbors] Psychiatry Res 1985 Jul;15(3):211-217 Anxiety and caffeine consumption in people with anxiety disorders. Lee MA, Cameron OG, Greden JF Forty-three anxiety disorder patients (DSM-III) who completed the Hopkins Symptom Checklist (SCL-90-R) and a caffeine questionnaire were compared to 124 medical inpatients. Eighty-four percent of the anxious patients were low caffeine consumers (0-249 mg/day) compared to 41% of medical inpatients; 65% of anxiety patients consumed less than 100 mg/day. In anxiety patients, there were no significant correlations between subscale scores of the SCL-90-R and amount of caffeine consumption. Patients who consumed less than 100 mg/day did not differ on anxiety subscale scores of the SCL-90-R from those who consumed more. However, patients who reported becoming anxious in response to drinking coffee had higher SCL-90-R anxiety subscale scores than patients who did not, even though their daily consumption was not different. It appears that anxiety disorder patients have increased caffeine sensitivity which leads to decreased consumption. --------------------------------------------------------------------------- Other Formats: [Citation Format] [MEDLINE Format] Links: [138 medline neighbors] Arch Gen Psychia