Psychopathology and mental retardation: a statistical study of 100 mentally retarded children treated at a psychiatric clinic: II. hyperactivity.

The authors studied 100 mentally retarded children referred to a psychiatric clinic and found that 39 were hyperactive. However, there was no significant relationship between hyperactivity and mental retardation (with or without psychosis) or brain damage. Comparison with a group of nonretarded children revealed no significant difference regarding hyperactivity, thus suggesting that the disorder is not an inevitable concomitant of mental retardation.