Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by persistent deficits in social communication and social interaction across multiple contexts. Symptoms of ASD are typically recognized during the second year of life, but may be noted before 12 months if the symptoms are severe, or after 24 months if the symptoms are subtle. Symptoms of ASD vary in severity and can interfere with social, occupational, and other important areas of life.

According to the Centers for Disease Control and Prevention (CDC), about 1 in 54 children are diagnosed with ASD. ASD is four times more common among boys than girls and occurs in all racial, ethnic, and socioeconomic groups.

ASD and Genetics

According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, a variety of nonspecific risk factors may contribute to development of ASD. These can include advanced parental age, low birth weight, or fetal exposure to valproate. The DSM-5 also states that heritability estimates range from as low as 37 percent to higher than 90 percent, based on twin concordance rates.

Given the complexity of the disorder, and the way symptom severity varies, there are probably many causes of ASD. In addition to potential environmental triggers identified in the DSM-5, researchers are also studying whether potential triggers such as viral infections, medications, or complications during pregnancy, or air pollutants play a role in the development of ASD.

According to the Mayo Clinic, several different genes appear to be involved in ASD, adding to the complexity of the disorder. ASD can be associated with a genetic disorder, genetic changes may increase the risk of ASD, or genes may affect brain development or the ways brain cells communicate.

A recent study, published in JAMA Psychiatry, analyzed the data among 2 million people across five countries. It is the largest family-based genetic autism to date, including children with autism, their siblings, their cousins, their parents, and the siblings of their parents. Results of the study showed that 80 percent of autism can be traced to inherited genes, rather than maternal effects. The study did account for the range of heritability data resulting from each country’s culture around autism. If a country tends to diagnose ASD less frequently, the heritability is lower.

Known Risk Factors

As researchers continue to study both genetics and environmental factors to gain a clearer picture of what contributes to the development of ASD, there are a few known risk factors to consider.

  • Gender: Males are 4 times more likely to develop ASD than females.
  • Family history: Families with one child diagnosed with ASD are more likely to have a second child with ASD.
  • Other medical conditions
  • Advanced parental age
  • Preterm birth

Though there is no way to prevent ASD, there are treatment options available. Early intervention can improve social and communication skills and help kids function well in school, their families, and their communities, though intervention at any age is helpful.

Functional Consequences

In young children, impaired social and communication abilities may affect learning, particularly learning in group settings. Fixed routines and difficulty with transitions (low flexibility), combined with possible sensory sensitivities, can also make mealtimes and schedule changes difficult both in the school setting and at home.

For teens and young adults with ASD, social and communication impairments can affect friendships and other relationships and deficits in executive functioning skills can impair both academics and functional daily living skills, but teens with ASD also go through similar behavioral changes as neurotypical teens. Talking back, sleeping late, and procrastination are fairly among teens, regardless of social and communication skills.

Last Updated: Aug 13, 2020