Schizophrenia is thought to be the result of a culmination of biological and environmental factors. While there is no known cause of schizophrenia, there are genetic, psychological, and social factors thought to play a role in the development of this chronic disorder.1

Risk Factors

Risk factors for schizophrenia include a family history of the disorder, a father who is older in age, autoimmune system abnormalities, and drug abuse during adolescence and early adulthood. Complications during pregnancy or birth are linked to schizophrenia. This includes exposure to viruses or toxins in utero, premature labor, low birth weight, and lack of oxygen during birth.2 Higher rates of schizophrenia are found in urban areas, among low-income families, where income inequality is significant.3

Researchers have not pinpointed a single gene that leads to the development of schizophrenia; many genes are thought to play a role. Having a first-degree relative with schizophrenia increases the risk of developing the illness. For example, if you have no first degree relatives (parents or siblings) or second degree relatives (grandparents, aunts, or uncles) diagnosed with schizophrenia, your odds of developing the illness are about one percent. If you have one biological parent who suffers from schizophrenia, your odds of developing it are about 10 percent. Genetics alone, however, do not explain schizophrenia. The majority of people who develop the illness—over 63 percent—do not have first or second degree relatives diagnosed with the illness.4

The majority of children who later develop schizophrenia are not different in childhood than other children. Longitudinal research studies find that few children who grew up to be diagnosed with the illness showed any poor academic achievement, poor social skills, delay in developmental milestones (i.e., learning to talk), speech, or coordination problems.5

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Early Warning Signs

Early warning signs of schizophrenia often cannot be detected until adolescence. Indicators include social withdrawal, depression, difficulty paying attention, suspiciousness or hostility, expressionless gaze, difficulty sleeping, lack of personal hygiene, or irrational beliefs.6

Schizophrenia is not predictable. Instead, a person has a certain level of risk that determines whether they may or may not develop the illness. Stress and drug abuse are considered common triggers in people who are at risk, which may result in the onset of psychosis. A person who is considered at risk for developing schizophrenia may also be triggered by stressors such as suffering a loss, experiencing abuse, or trauma. Using illicit drugs, particularly cannabis, amphetamines, LSD, or cocaine, can also trigger the onset.7


Typically there is no single precipitating event that leads to the onset of schizophrenia. Onset usually occurs during late adolescence and early adulthood, a time when young people are transitioning into independent roles as adults. They take on more responsibilities, are thrust into new situations (e.g., going to college—sometimes far from home), and are making decisions and connections that will shape their career and life path in general. If they did not learn adequate coping skills to handle these rapid changes and without mental health support (e.g., counseling at a college health center), this transition can be fraught with turmoil. These types of situations could trigger the onset of schizophrenia. It could also drive an individual to self-medicate with drugs or alcohol, which are also considered triggers.8

So what is happening in the mind of someone with schizophrenia that is different? While there is no definitive answer to this question, neurotransmitters— the chemical messengers that send information throughout the brain and body—appear to play an important role in the development of schizophrenia symptoms.Neuroimaging studies have found structural differences in the brains and central nervous systems of people with schizophrenia.10 It is possible that hundreds of genes play a subtle role in disrupting brain development itself. The brains of individuals with schizophrenia also have less gray matter, which plays an important role in information processing, memory, and evaluating rewards and consequences.11 Some of these brain changes occur during fetal development, childhood development, the onset of schizophrenia, and relapse into active psychosis. Longer relapses into active phase schizophrenia are associated with greater gray matter loss.12

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Last Updated: Oct 13, 2019