Autism Spectrum Disorder



  • Neurodevelopmental disorder characterized by:
    • Delays/impairments in development of social communication and social interaction
    • Restricted, repetitive patterns of behavior, interests, or activities
    • Symptoms present in early childhood
    • Significant impairment in functioning
  • Diagnostic criteria changes since 2013:
    • DSM-IV previously included autistic disorder, Asperger disorder, Rett disorder, childhood disintegrative disorder, and pervasive developmental disorder, not otherwise specified within overall category
    • DSM-5 has eliminated these separate diagnoses due to insufficient evidence.
    • DSM-5 added severity levels (1 to 3) based on the level of support required.
  • Associated with specific known genetic disorder (e.g., fragile X) in a minority (15%) of cases
  • Behaviors exist along continuum with unclear boundaries between trait and disorder.



  • Approximately 1 in 68 (14.6 per 1,000) of 8 year-old children, according to the Centers for Disease Control and Prevention (CDC) 2016 report
  • Rate rising over past decades
  • 4 times more common in males than females
    • Females are more frequently severely impaired with intellectual disability.

Risk Factors

  • Strong genetic influence: risk in 1st-degree relatives 2–18%; identical twins 35–95%
  • Multiple genes implicated (>100), suggesting polygenic risk. Approximately 15% of children with autism have identifiable genetic anomaly.
  • Other risk factors: closer spacing of pregnancies, advanced maternal or paternal age, extreme premature birth (<26 weeks), possible maternal inflammation in utero
  • Link to vaccinations not supported by scientific evidence
  • Pathophysiology unknown but may be associated with abnormalities in cortical laminar architecture during prenatal brain development

Commonly Associated Conditions

  • Intellectual disability
  • Gastrointestinal (GI) problems
  • Epilepsy
  • Sleep disorders
  • ADHD
  • Anxiety, depression, mood disturbances
  • Aggression and self-injury

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