This study examines the incidence rate of setback in 80 autistic children, the correlation between the type of onset and clinical features, developmental level and prognosis based on an originally developed questionnaire. Moreover, this study seeks to investigate the possibility that infantile autism might be classified into subgroups by the type of onset. The acquired (including questionably acquired) group consisted of 39 cases (49%), while the natal group was made up of 41 cases (51%). The age when the setback occurred was 21–22 months in the acquired group. Precipitating psychological events were observed in 22 cases (56%) of the acquired group. The mental developmental level including speech and sociability function at 5 years of age was significantly lower in the acquired group than in the natal group. The acquired group showed severe behavioral disorderssuch as “stereotypic behavior,”“extremely hyperkinetic behavior” and “self‐abusive behavior” compared with the natal group. The adaptive levels at schools or institutions were lower in the acquired group than in the natal group. There was a higher incidence of epileptic seizures orfebrile convulsions in the acquired group than in the natal group. Moreover, there was a higher incidence of severe perinatal abnormalities in the acquired group. The above‐mentioned results suggest that infantile autism might be classified into two subgroups, acquired and natal groups, based on the typeof onset, and also suggest that some types of brain dysfunctions are more severe in the acquired group than in the natal group.

For the purpose of clarifying the pathophysiological meaning of sleep disturbance in autistic children, the sleep pattern of 75 such children was examined by a questionnaire method. Forty‐nine of them showed sleep disturbance in their early life with an incidence of 65%. The poorly‐developed group showed a high rate of sleep disturbance as compared with the relatively well‐developed group. There was a negative correlation between the developmental level and duration period of sleep disturbance. The investigation of circumstances in which autistic children often exhibited sleep disturbance proved that abrupt changes in life environment or various problems in the way of bringing up children brought about their sleep disturbance. These findings suggest that sleep disturbance might be one of the main symptoms and related to the pathophysiology of infantile autism.

A survey of children aged under 18 years in Fukushima‐ken (prefecture) in Japan showed that 2.33 per 10,000 children suffered from early infantile autism. The average of prevalence rates of autistic children born between 1968 and 1974 was 4.96 per 10,000 children. Based on a comparison between cities and rural districts, the prevalence rates of the former were significantly higher than those of the latter. Autistic boys outnumbered autistic girls with a sex ratio of 9: 1. Psychiatric illnesses; were very rare among the relatives of autistic children. The rate of prenatal and perinatal complications was higher than the national norm among autistic children. Parents of autistic children had a significantly higher education than the national norm. There were more nuclear families in the autistic group than in the national norm.

In order to make a checklist for the early diagnosis of autism, the abnormalities of mental development before the age of two were examined retrospectively in autistic children. Additionally, the correlation between these early symptoms and the prognosis of autistic children were investigated. The subjects were 85 autistic children, 64 mentally retarded children and 150 normal children. The parents of these children were interviewed by child psychiatrists based on original questionnaires. The 27 early symptoms indicating disorders in personal relations, perception and sleeping as well as the setback course were found in autistic children. The onset ages of imitating others, pointing at objects and saying Yes were retarded in the poorly developed group as compared with the highly developed group.

The DSM‐III diagnostic criteria were applied to school refusal cases, and the possibility of a subclassification of school refusal through the DSM‐III was studied. The subjects were 50 cases diagnosed as school refusal following the criteria defined by Sumi and Tatara. As for the Axis I diagnoses, the subjects fell under the separation anxiety disorder (7 cases), avoidance disorder (13 cases), overanxious disorder (8 cases), identity disorder (5 cases), adjustment disorder (11 cases) and others. On Axis II, no case was diagnosed as having the personality disorder, but 14 cases showed pathological personality traits. On Axis III, nine cases showed some physical disorders or conditions. Among the five major diagnostic groups, there were some definite differences concerning the onset age, clinical course, psychosocial stress, response to therapy and prognosis of disorders. These results suggest the availability of a subclassification of school refusal by means of the DSM‐III criteria.