Birth dates and admission dates in schizophrenia and bipolar disorder

Abstract

The well established phenomenon of seasonality 0/ birth dates (winter excess) and admission dates (summer excess) of patients with schizophrenia and bipolar disorder was re-examined in a Southern African study 0/ ill-patients. Monthly and seasonal analyses respectively resulted in a May (late autumn and winter) excess of schizophrenic male births and a March (late summer and autumn) excess among schizophrenic females, which revealed a gender difference. Bipolar births peaked in May (autumn). Admission rates peaked in May (late autumn) for schizophrenic patients and in March (early autumn) for bipolar patients. Birth rates peaked one season earlier but admission rates one season later than in previous studies. The apparent coincidence of the birth and admission peaks among patients with schizophrenia and bipolar disorder suggests that these patients are more often admitted around their birthdays. This concurrence remains to be tested.