Autism Spectrum Disorder (ASD) is a developmental disorder that involves impairments in social interaction and communication, challenges with sensory processing, and repetitive behaviors. The term "spectrum" reflects the fact that symptoms vary across different individuals, ranging in type and severity.
ASD is an umbrella diagnosis in the DSM-5, replacing the four pervasive developmental disorders described in the previous edition — autistic disorder, Asperger's syndrome, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified. Individuals display ASD symptoms on a continuum, or spectrum, showing ranges of mild to severe symptomatology. Those on the mild-to-moderate end of the spectrum are sometimes colloquially referred to as having Asperger's syndrome, though this is no longer a formal diagnostic category.
People with autism may appear indifferent and remote and can have difficulty forming emotional bonds with others. They may have unusual responses to sensory experiences — the noise of a leaky faucet, for example, might become extremely disruptive.
Autism is found in many different countries and across racial, ethnic, religious, and economic backgrounds. Its prevalence has been estimated at roughly 1 percent of the world population. In a study by the Centers for Disease Control and Prevention (CDC), 1 in 59 U.S. children were identified as having ASD. The earlier the disorder is diagnosed, the sooner a child can be helped through treatment interventions.