Functional outcomes with bright light in monotherapy and combined with fluoxetine in patients with major depressive disorder: Results from the LIFE-D trial

Background: Bright light therapy has been shown to improve depressive symptoms in patients with nonseasonal major depressive disorder (MDD) but there are few studies examining functional outcomes. Methods: We examined secondary functional outcomes in the 8-week randomized, placebo-sham-controlled LIFE-D trial comparing light therapy, fluoxetine, and the combination in patients with nonseasonal MDD. Functional assessments included the Sheehan Disability Scale (SDS) and, for employed participants, the Lam Employment Absence and Productivity Scale (LEAPS). Analysis of covariance (ANCOVA) was conducted with SDS and LEAPS change scores from baseline to week 8 as dependent variables, treatment modality (light, fluoxetine) as an independent variable, and baseline SDS and LEAPS scores as covariates. Results: Of 122 randomized participants, SDS data were available for 105 and LEAPS data for 70. For the SDS, there were no interaction effects, but there was a significant small- to medium-sized main effect of light treatment on total SDS scores with corresponding significant effects in the Social Life and Family Life domains, but not in the Work/Study domain. There were no significant interaction or main effects with LEAPS scores. Conclusion: Light therapy significantly improved social and family life functioning in patients with MDD. However, work functioning was not significantly improved despite large effect sizes; these results were limited by low statistical power because of small sample sizes. Future studies should use longer treatment durations and be powered to detect clinically relevant differences in functional outcomes.