Childhood behavioral characteristics have not been fully investigated in patients with schizophrenia. To elucidate the picture of them, and to find out indicators which predict later development of schizophrenia, childhood behaviors of the adult schizophrenia subjects were investigated in a questionnaire-based retrospective study.

Twenty-five schizophrenia outpatients in his/her twenties and normal healthy subjects (n = 100) were investigated. All patients are diagnosed according to DSM-IV-TR as schizophrenia, and who presents now mainly negative symptoms after passing an acute stage. By modified use of the Child Behavior Checklist (CBCL) as a retrospective assessment questionnaire, the parents of the patients and of control subjects rated their childhood behavior.

Among eight subscales of the CBCL, those of Withdrawal, Depression/Anxiety, Social Problems, and Attention Problems were significantly associated with schizophrenia, although any of these scores were not in clinical range. A discriminant analysis using all items of CBCL correctly classified 96.5% of the population. Notable in an item-level analysis was an extremely attenuated aggression in personal relations in the schizophrenia subjects.

It was suggested that subclinical behavioral and psychological characteristics of schizophrenia already exist in the patients' childhood, among which lack of aggressive behaviors might be one of the core features.