Season of birth of schizophrenics in Tokyo, Japan

The monthly distribution of births of 7,960 schizophrenic patients in Tokyo born during the period of 1841-1950 was studied in comparison with that of a control population in Tokyo. A spring excess of schizophrenic births were found after 1901 as in previous studies in Western countries. Before 1900, however, there was no significant spring excess. The maximum excess of schizophrenic births occurred in May before 1900 and in April after 1901. The possibility of a shift in the seasonality of schizophrenic births was discussed.