MedWire News: Patients with bipolar disorder who are depressed are less likely to have a job - and take more time off when employed - than those without depression, researchers have found.

A growing number of studies suggest that bipolar disorder is a cause of substantial impairment and disability. This may be due in part to the severity of mood symptoms, the team explains in the journal Bipolar Disorders.

Dr Gregory Simon (University of Washington, Seattle, USA) and colleagues assessed employment status, functional disability and symptoms of depression and mania/hypomania in 441 outpatient bipolar patients.

The patients were interviewed every 3 months over 2 years. At each point, the researchers classified the severity of depressive and manic symptoms, employment status and time missed from work due to illness.

Patients with major depression were 15% less likely to be employed than those without major depression, regardless of co-occurring symptoms of mania or hypomania. And bipolar patients with a depressive episode missed approximately 4 more days of work per month than those without depression.

Furthermore, the number of days missed from work rose with increasing severity of depression - in other words, the more severe patients' depression was, the more days they took off work.

"Among patients being treated for bipolar disorder, symptoms of depression are strongly and consistently associated with important differences in work productivity," conclude the researchers.