Methods
Study background
This research stems from a follow-up study of individuals diagnosed with autism as children at the Institute of Psychiatry/Maudsley Hospital, London, between 1950 and 1979. This study focuses on those with a nonverbal childhood IQ in the normal range (i.e. ≥70). Ethical approval was obtained from the Joint South London and Maudsley/Institute of Psychiatry NHS Research Ethics Committee. All participants gave their consent (either verbally or nonverbally) to participate.