Objectives: Most prior research has focused on functional impairment as a consequence, rather than a predictor, of mood symptoms in bipolar disorder (BD). Yet the majority of this research has been cross-sectional, thus limiting conclusions regarding directionality of effects. Indeed, just as functional impairment may represent an important outcome of BD, it may also serve as a risk factor for future affective symptoms or episodes. Thus, the primary aim of this study was to evaluate functional impairment as a predictor of mood symptoms in BD.
Methods: Ninety-two patients with bipolar I disorder, recruited from hospital settings, were administered the Modified Hamilton Rating Scale for Depression, Bech–Rafaelson Mania Scale, and UCLA Social Attainment Survey (SAS) at baseline and at four-month follow-up.
Results: Overall, patients evidenced a moderate level of functional impairment at both time points. Whereas baseline functional impairment was not associated with subsequent manic symptoms, baseline functional impairment was significantly predictive of depressive symptom levels at four-month follow-up. When individual SAS subscales were evaluated, impaired romantic relationship functioning and activity involvement were each significantly predictive of subsequent depressive symptoms, whereas baseline peer functioning was not.
Conclusions: The study results suggest that functional impairment may be predictive of subsequent depressive, but not manic, symptoms over a relatively short-term follow-up period. Future studies that evaluate illness course over longer follow-up periods would be useful to further clarify the potential bidirectional relationship between depression and functional impairment in BD.