Gender and the use of neuroleptics in schizophrenia. Further testing of the oestrogen hypothesis.

According to the oestrogen hypothesis, the lower need for neuroleptic drugs in female schizophrenics is caused by the antidopaminergic effect of oestrogens. Due to the decreased oestrogen production during the menopause, this 'neuroleptic' effect is lost and the need for neuroleptic drugs increases in female schizophrenics. This hypothesis was tested by studying a sample of 1097 schizophrenic patients (DSM-III-R), who were discharged from hospital and followed for three years. Prescribed daily doses of neuroleptic drugs were recorded and converted to chlorpromazine equivalents. Males had higher daily doses of neuroleptics than females; this gender difference, however, was only significant in middle-aged groups. Daily doses were also associated with age at the onset of illness, duration of illness and clinical status. Results did not support the oestrogen hypothesis: In females, there was no consistent increase in daily doses of neuroleptics after menopause age. Results are discussed from the viewpoint of testosterone secretion, body weight and smoking habits, which are gender-bound and thus can, at least in part, explain gender differences in the use of neuroleptic drugs in schizophrenic patients. It is pointed out that the age at the onset of illness and the duration of illness should be taken into account when the effects of gender and age on the need for neuroleptics are studied.