Psychosocial disability in the course of bipolar I and II disorders: a prospective, comparative, longitudinal study.

Context: Evidence of psychosocial disability in bipolar disorder is based primarily on bipolar I disorder (BP-I) and does not relate disability to affective symptom severity and polarity or to bipolar II disorder (BP-II).

Objective: To provide detailed data on psychosocial disability in relation to symptom status during the long-term course of BP-I and BP-II.

Design: A naturalistic study with 20 years of prospective, systematic follow-up.

Setting: Inpatient and outpatient treatment facilities at 5 US academic centers. Patients One hundred fifty-eight patients with BP-I and 133 patients with BP-II who were followed up for a mean (SD) of 15 (4.8) years in the National Institute of Mental Health Collaborative Depression Study.

Main Outcome Measures: The relationship, by random regression, between Range of Impaired Functioning Tool psychosocial impairment scores and affective symptom status in 1-month periods during the long-term course of illness from 6-month and yearly Longitudinal Interval Follow-up Evaluation interviews.

Results: Psychosocial impairment increases significantly with each increment in depressive symptom severity for BP-I and BP-II and with most increments in manic symptom severity for BP-I. Subsyndromal hypomanic symptoms are not disabling in BP-II, and they may even enhance functioning. Depressive symptoms are at least as disabling as manic or hypomanic symptoms at corresponding severity levels and, in some cases, significantly more so. At each level of depressive symptom severity, BP-I and BP-II are equally impairing. When asymptomatic, patients with bipolar disorder have good psychosocial functioning, although it is not as good as that of well controls.

Conclusions: Psychosocial disability fluctuates in parallel with changes in affective symptom severity in BP-I and BP-II. Important findings for clinical management are the following: (1) depressive episodes and symptoms, which dominate the course of BP-I and BP-II, are equal to or more disabling than corresponding levels of manic or hypomanic symptoms; (2) subsyndromal depressive symptoms, but not subsyndromal manic or hypomanic symptoms, are associated with significant impairment; and (3) subsyndromal hypomanic symptoms appear to enhance functioning in BP-II.