Background: Psychosocial disability after remission from a unipolar major depressive episode (MDE) can be due to (1) residual symptoms (state effect), (2) the continuation of premorbid disability (trait effect), and/or (3) disability that developed during the MDE and persisted beyond recovery (scar effect).
Methods: Data came from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a prospective Dutch psychiatric population-based survey. We obtained psychiatric data (Composite International Diagnostic Interview) and information on psychosocial functioning (work, housekeeping, spouse/partner, and leisure-time domains) from 4796 respondents in 1996 (T1), 1997 (T2), and 1999 (T3). We evaluated trait effects using between-subject comparisons, and state and scar effects using within-subject comparisons.
Results: In 216 and 118 respondents, a first and a recurrent MDE developed, respectively, after T1 that remitted before T3. Compared with never-MDE individuals, first-MDE subjects had higher disability scores long before their episode (effect size, 0.42-0.57 U). During the MDE, disability further increased in first- and recurrent-MDE subjects (effect size, 0.44-0.79 U), but returned to its premorbid level after MDE remission, except in subjects who experienced a severe recurrent episode. If the premorbid period (T1 to MDE onset) was longer than the postmorbid period (MDE remission to T3), disability at T3 was higher than at T1, misleadingly suggesting scar effects. The reverse occurred if the premorbid period was shorter than the postmorbid period.
Conclusions: Postmorbid psychosocial disability reflects largely the continuation of premorbid psychosocial disability. Scarring does not occur routinely, but may occur in a severe recurrent episode. Within-subject premorbid-postmorbid comparisons are sensitive to state effects of prodromal and residual symptoms. These findings point at the following 2 independent processes: (1) the ongoing expression of trait vulnerability to depression in mild psychosocial dysfunctioning; and (2) synchrony of change between severity of depressive symptoms and psychosocial disability.