BACKGROUND: Seasonal Affective Disorder (SAD) is a public health problem affecting 1.5% - 9% of the population, depending on latitude. It is a seasonal pattern of recurrent major depressive episodes that most commonly occur during autumn/winter and remit in spring. The predictable seasonal aspect of SAD provides a promising opportunity for prevention. Light therapy, second-generation antidepressants (SGA), melatonin, agomelatine and psychotherapy are established interventions to treat acute episodes of SAD. However, little is known about the efficacy and potential harms of these interventions for preventing SAD. Therefore we conducted a systematic review that will be published as four Cochrane Reviews.
METHODS: We searched electronic databases, trial registries and other sources (up to Feb/2015). We included RCTs on adults with a history of winter-type SAD. Two authors independently conducted study selection. When data were sufficient, we performed meta-analyses.
RESULTS: From 2982 citations 4 RCTs met our inclusion criteria (3: SGA, 1: light therapy). Overall, moderate quality evidence indicates that the SGA bupropion extended release (XL) is an efficacious intervention to prevent the recurrence of depressive episodes in patients with a history of SAD (RR 0.56, 95% CI 0.44 to 0.72; 3 RCTs, 1100 participants). Bupropion XL, however, leads to a higher risk of headaches, insomnia and nausea than placebo treatment. Overall, low quality of evidence (1 RCT, 46 participants) indicates that the preventive use of bright light and infrared light reduce the incidence of SAD compared to no light therapy.
CONCLUSION: Evidence indicates that bupropion XL and light therapy can prevent recurrence of SAD. Given the lack of comparative evidence, the decision for or against initiating preventive treatment of SAD and the choice of treatment should be strongly based on patient preferences.
