Line chart showing the proportion of autistic people, up to age 21, who have IQs ranging from less than 50 to more than 130. People were either diagnosed by a clinician, or were identified to have autism during a research study using narrow or inclusive DSM-IV criteria. People with a clinical autism diagnosis tended to have the highest rate of IQs less than 50.
Data are based on 187 people in Minnesota with a clinical diagnosis of autism, 453 people who meet criteria for a narrow definition of autism in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), and 890 people who meet more inclusive DSM-IV criteria for autism, Asperger syndrome or pervasive developmental disorder-not otherwise specified. IQ scores are based on the most recent test taken by the participants, with an average age of about 11 years for each group.