Behavior disturbance since childhood among a 5-year birth cohort of all mentally retarded young adults in a city.

A behavior disturbance classification was described and its distribution in childhood and the postschool period examined in a 5-year bith cohort of mentally retarded young adults. Approximately 60 percent had some behavior disturbance in each period. Hyperactive behavior was most frequent among children with lower IQs and antisocial behavior among children and young adults with higher IQs. Aggressive conduct disorder in childhood was most frequent among those with IQs below 50. Emotional disturbance was more frequent among females in the postschool period, and antisocial behavior was more frequent among males, both in childhood and the later period.