Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that manifests in early childhood and lasts a lifetime. It is defined by two core symptoms, according to the most recent diagnostic criteria: persistent deficits in social communication and social interaction, and restricted, repetitive patterns of behavior, interests, and activities. Clinical observation is used to make the diagnosis, which is then confirmed by standardized testing of the patient using the Autism Diagnostic Observation Schedule and/or a parental interview using the Autism Diagnostic Interview-Revised. There are currently no behavioral, neuroimaging, electrophysiological, or genetic testing that can diagnose ASD precisely. Intellectual disability, seizures, and sleep issues are common comorbid conditions, although anxiety, depression, and obsessive compulsive disorder (OCD) are less common. ASD stands apart from most other behavioral disorders because of its remarkable clinical and pathogenesis heterogeneity.
