In 2018, the Centers for Disease Control’s Autism and Developmental Disabilities Monitoring (ADDM) reported that approximately 1 in 59 children in the United States has been identified with an Autism Spectrum Disorder (ASD). This estimate is a 14% increase from the 1 in 68 rate in 2016 and a 47% increase from the 1 in 88 rate in 2012. In the 1980s autism prevalence was reported as 4 in 10,000. In the nineties, prevalence was 1 in 2500 and later 1 in 1000.

It is problematic to compare autism rates over the last three decades, as the diagnostic criteria for autism have changed with each revision of the Diagnostic and Statistical Manual (DSM), which outlines which symptoms meet the criteria for an ASD diagnosis. In 1983 the DSM did not recognize PDD-NOS or Asperger’s syndrome, and the criteria for autistic disorder (AD) were more restrictive. The previous edition of the DSM, DSM-IV, included autistic disorder, childhood disintegrative disorder, PDD-NOS, and Asperger’s Syndrome. Due to inconsistencies in diagnosis and how much we are still learning about autism, the most recent DSM (DSM 5) only has one diagnosis, autism spectrum disorder (ASD), which encompasses each of the previous four disorders. According to the new diagnostic criteria for ASD, one must have both deficits in social communication and interaction, and restricted repetitive behaviors, interests, and activities (RRBs).

ASDs continue to be over 4 times more common among boys (1 in 37) than among girls (1 in 151) and they are reported in all racial, ethnic, and socioeconomic groups. Studies have been conducted in several continents (Asia, Europe, and North America) that report a prevalence rate of approximately 1 percent. A 2011 study reported a 2.6 percent prevalence of autism in South Korea.