People with autism spectrum disorder (ASD) have trouble communicating and forming social relationships, and they may also have restricted interests and repetitive behaviors. These symptoms impair their ability to function well in school, work, and other areas of life. The U.S. Centers for Disease Control and Prevention estimates that ASD affects 1 in 59 children in the United States, primarily boys, with the initial signs and symptoms usually appearing in the first two years of life.
ASD is called a “spectrum” disorder because of the wide variation in the type and severity of its symptoms. Roughly 40% of individuals with ASD have intellectual disability (defined as an IQ of less than 70), but many have normal to above-average intelligence, and some have exceptional abilities.
There’s no single cause of ASD. Research suggests that the disorder often develops from a combination of genetic and environmental influences that affect critical aspects of early brain development—particularly how neurons or entire brain regions communicate with one another. Becoming a parent at an older age increases the risk of having a child with ASD. Complications related to pregnancy, such as extreme prematurity, low birth weight, and closely spaced pregnancies, can also increase the risk. Vaccines do not affect the risk of developing ASD.
ASD is usually treated with early-intervention services, which include a mix of speech and occupational therapies and applied behavior analysis (the main evidence-based treatment for ASD).