Behavioral observations concerning differential diagnosis between the Rett syndrome and autism.

The behavior of girls with the Rett syndrome was compared to that of patients with infantile autism (Kanner syndrome) and with autism associated with infantile organic brain damage. Visual, acoustic, tactile and gustatory stimuli, and social contact were used. Motor stereotypes and disturbances were recorded and the mental development was categorized. Behavioral traits were classified into 4 groups: Behavior observed only in the Rett syndrome (at least optionally), Behavior observed in each case of the Rett syndrome (at most optionally in the autistic syndrome), Behavior observed only in the autistic syndrome (at least optionally), Behavior observed in each case of the autistic syndrome (at most optionally in the Rett syndrome). These traits were adequate criteria for differential diagnosis. It was concluded that the Rett syndrome is characterized by definite signs of dementia with almost overall developmental retardation and that it does not show several attributes regularly found in autistic children. A neuropsychological theory was proposed to explain the coming about of specific autistic behavior.