Few studies have looked at the very long-term outcome of individuals with autism who were diagnosed in childhood. A longitudinal, prospective, community-based follow-up study of adults who had received the diagnosis of autism (classic and atypical) in childhood was conducted with the purpose of investigating diagnostic categories, outcome, symptoms, and symptom patterns. The present study is a follow-up study of 120 individuals with autism diagnosed in childhood 13-22 years after original diagnosis.

Diagnostic Interview for Social and Communicative Disorders (DISCO-10), Vineland Adaptive Behaviour Scales (VABS), Global Assessment of Functioning scale (GAF), outcome criteria and neuropsychiatric examination.

Eighty-five percent of both the classic and atypical autism groups now received the diagnosis of classical autism when re-examined. Overall outcome was poor in 78% of cases. Only four individuals were independent albeit leading fairly isolated lives. Childhood IQ-level was positively correlated with better adult outcome. In the majority of cases symptoms typical of the childhood period were still present in adulthood, but some clusters of behaviour (particularly hyperactivity) were much less prevalent than they had been in the past.

Children with autism as diagnosed in the 1960s, 1970s, and 1980s may have an even worse psychosocial outcome than previously believed.