The pathophysiology of extrapyramidal side effects of typical antipsychotic drugs and the role of gender as a risk factor is poorly understood.

To elucidate the role of gender and the oestrogen hypothesis in extrapyramidal side effect severity.

To investigate gender differences in side effects of antipsychotic drugs and explore the role of oestrogen levels in side effect severity.

25 women and 23 men with a diagnosis of schizophrenia were examined for side effects using the Extrapyramidal Side Effects Rating Scale (ESRS), the Simpson Angus Rating Scale for Extrapyramidal Side Effects and the Abnormal Involuntary Movements Scale (AIMS).

Higher antipsychotic doses and use of anticholinergics were noted in males.Women had higher ESRS scores and Simpson Angus scores. Men had higher mean scores for AIMS and the Barnes Akathisia Rating Scale. Age was significantly correlated with scores on ESRS, AIMS and Simpson Angus Rating Scale. There was a highly significant correlation between ESRS score and absence of a regular menstrual cycle. No association with age or antipsychotic dose was found between the groups. Women without a regular cycle scored significantly higher on Simpson Angus Rating Scale. Women with regular cycles scored significantly higher on Barnes Akathisia Rating Scale. There was no difference in AIMS score between the groups. No significant difference was found on any measure between women who were in the high and low oestrogen phases of the cycle.

Gender, age and the presence of a menstrual cycle should be considered when prescribing antipsychotic medication.