Neurobiology of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a developmental condition characterized by significant and persistent difficulties with social interaction and communication and by restricted and repetitive behaviors. Signs are often noted during the first 3 years of a child’s life, often worsening with stress or environmental exigencies. There is no single cause for ASD; research suggests a multifactorial condition associated with multiple gene effects and environmental factors. Many of the autism risk genes have also been shown to be involved in intellectual disability and epilepsy. Comorbidities abound (e.g., seizures, GI disturbances, sleep problems, anxiety disorders) and are associated with worse outcomes and increased health needs. Comorbidities often manifest themselves in preschool years, can detrimentally reinforce each other (e.g., epilepsy and sleep disorders), and may be a predictor of maladaptive behaviors. The imaging and neuropathological literature suggest that multiple brain regions (e.g., cerebral cortex, limbic system, cerebellum) are affected. These neuroanatomical differences in the brain are already visible in the first 2 years of life and are highly variable across the human life span. Currently, there are no medications approved to treat the core symptoms of ASD. Identification and treatment of comorbidities may serve to improve the quality of life of affected patients. Behavioral treatments may be delivered to change targeted symptoms. Well-planned and carefully delivered treatments, both developmental and behavioral, improve children’s functioning, particularly IQ and language abilities, both over the shorter and longer term.