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.

Examined hypothalamic-pituitary-adrenal axis (HPA axis) function in 30 children with attention-deficit hyperactivity disorder (ADHD) by measuring the diurnal variation and response to the dexamethasone suppression test (DST) of saliva cortisol. Normal diurnal saliva cortisol rhythm was found in only 43.3% of the ADHD children. DST showed suppression in 46.7% of the ADHD children. An abnormal diurnal rhythm and nonsuppression to the DST were more frequent in the severely hyperactive group than in the mildly were more frequent in the severely hyperactive group than in the mildly hyperactive group of children with ADHD. These results suggest abnormalities in HPA axis function in some children with ADHD, especially those exhibiting severe hyperactivity.

The function of the hypothalamic-pituitary-adrenal axis (HPA-axis) and its association with clinical features in chronic schizophrenia were investigated. Twenty of 33 chronic schizophrenics exhibited an abnormal diurnal variation of the saliva cortisol level. The patients with abnormal diurnal variation gave higher scores for some negative symptoms than those with normal diurnal variation. On the dexamethasone suppression test (DST) of saliva samples, 13 of 34 chronic schizophrenics were abnormal. The patients with DST nonsuppression were more frequently classified into disorganized type and exhibited low scores of anxiety compared with the patients with normal suppression. The 9 patients who showed abnormal diurnal variation and DST nonsuppression were more frequently classified into disorganized type and showed higher scores of negative symptoms than the 9 patients who did not show any abnormal cortisol data. These results suggest that there might be some disturbance in the function of the HPA-axis in a group of chronic schizophrenics and that these patients might have severe negative symptoms.

In order to examine the function of hypothalamic‐pituitary‐adrenal axis (HPA‐axis) in autistic children, the diurnal rhythm of saliva Cortisol and the response of Cortisol to the DST was investigated using saliva samples. The plasma and saliva Cortisol levels showed a positive correlation in normal healthy adults. Moreover, the saliva Cortisol level exhibited a similar diurnal rhythm and DST response as did the plasma Cortisol level. The saliva Cortisol level in normal children showed a similar diurnal rhythm and DST response as that in normal healthy adults. Some children with infantile autism showed an abnormal diurnal rhythm or DST response for saliva Cortisol. Moreover, the latter abnormality was observed more frequently in poorly‐developed cases than in highly‐developed cases. These results suggest that the negative feedback mechanism of the HPA‐axis may be disturbed in autistic children, especially the poorly‐developed cases, owing to a disorder inthe regulation by serotonin metabolism.