Bipolar disorder affects men and women in roughly equal numbers, but there are gender differences in the ways that the illness manifests itself.

Women with the disorder tend to have more depressive and fewer manic episodes and are more likely to have bipolar II. They also appear to be more prone than men to rapid-cycling.

Some research suggests this might be connected to abnormal thyroid levels as such imbalances are more common in women than men. Other associated conditions that are seen more often in women with bipolar than men include anxiety, migraines, obesity and panic disorders.

Hormones are suspected of playing a significant role in bipolar disorder in women, evidenced by the mood swings often experienced in connection with menstruation, perimenopause and menopause.

It is thought this may be connected to fluctuating levels of oestrogen but research needs to be done to find out how this is implicated and the mechanisms that are involved.