With every increase or decrease in depressive symptom severity, there is a corresponding significant and stepwise increase or decrease in psychosocial disability among patients with bipolar disorder, according to a study in the December issue of Archives of General Psychiatry.

Lewis L. Judd, MD, of the University of California, San Diego School of Medicine, and colleagues conducted a study to provide detailed data on psychosocial disability in relation to symptom status during the long-term course of patients with bipolar-I and bipolar-II.

They analyzed data on 158 patients with bipolar-I and 133 patients with bipolar-II who were followed for an average of 15 years in the National Institute of Mental Health Collaborative Depression Study.

The authors found that symptom severity and psychosocial disability fluctuate together during the course of illness.

“Psychosocial impairment increases significantly with each increment in depressive symptom severity for bipolar-I and bipolar-II and with most increments in manic symptom severity for bipolar-I,” they wrote.

When patients with either form of bipolar disorder are asymptomatic, their psychosocial functioning is good, but not as good as that of healthy controls.

“When patients with bipolar-I or bipolar-II have no mood disorder symptoms, their psychosocial functioning normalizes and is rated as good; when they are experiencing subsyndromal depression, psychosocial functioning is between good and fair; when minor depressive or dysthymic symptoms are present, functioning is fair; and when patients have symptoms at the threshold for major depression, functioning is poor,” the authors noted.

“These findings indicate that the depressive phase of bipolar illness is equal in importance to the manic or hypomanic phase, and they confirm the advantage of studying bipolar-I and bipolar-II separately,” the authors concluded.