MedWire News: Women with bipolar disorder tend to experience more 'mixed' mood episodes as their condition progresses than their male counterparts, Danish study results show.

Mixed episodes are when patient with bipolar disorder experience symptoms of both depression and mania at the same time.

Doctors should be more aware of mixed mood episodes in their patients with bipolar disorder, especially their female patients, as mixed episodes are more difficult to treat than episodes of either depression or mania alone, says Dr Lars Kessing, from the University Hospital of Copenhagen, who conducted the study.

"More than 40% of all patients with bipolar disorders show at least one mixed affective episode during the course of their illness," explains Dr Kassing.

But he adds: "It has not been systematically investigated in any larger longitudinal study whether the prevalence of mixed episodes increases during the course of illness in bipolar disorder."

To address this, Dr Kassing studied data on 1620 Danish patients with bipolar disorder who had suffererd a first mood episode between 1994 and 2003.

He recorded the occurance of mixed, depressive and manic mood symptoms at each subsequent mood episode experienced by the participants.

Analysis revealed that, in women, the prevalence of mixed episodes increased over time, from 7% of first mood episodes to 18% of tenth mood episodes.

In men, however, the number of mixed mood episodes remained low and constant over time, at around 5-7% of all episodes.

Dr Kassing also found that the presence of a current mixed episode significantly increased the risk of a future mixed episode.

Writing in the journal Acta Psychiatrica Scandinavica, he concludes: "Clinicians should pay more attention to mixed episodes, especially among women, as they may represent an increasing treatment challenge as the illness progresses."