Psychological therapies for preventing seasonal affective disorder

Background Seasonal affective disorder (SAD) is a seasonal pattern of recurrent major depressive episodes that most commonly occurs during autumn or winter and remits in spring. The prevalence of SAD ranges from 1.5% to 9%, depending on latitude. The predictable seasonal aspect of SAD provides a promising opportunity for prevention. This is one of four reviews on the efficacy and safety of interventions to prevent SAD; we focus on psychological therapies as preventive interventions. Objectives To assess the efficacy and safety of psychological therapies (in comparison with no treatment, other types of psychological therapy, second‐generation antidepressants, light therapy, melatonin or agomelatine or lifestyle interventions) in preventing SAD and improving person‐centred outcomes among adults with a history of SAD. Search methods We searched Ovid MEDLINE (1950‐ ), Embase (1974‐ ), PsycINFO (1967‐ ) and the Cochrane Central Register of Controlled Trials (CENTRAL) to 19 June 2018. An earlier search of these databases was conducted via the Cochrane Common Mental Disorders Controlled Trial Register (CCMD‐CTR) (all years to 11 August 2015). Furthermore, we searched the Cumulative Index to Nursing and Allied Health Literature, Web of Science, the Cochrane Library, the Allied and Complementary Medicine Database and international trial registers (to 19 June 2018). We also conducted a grey literature search and handsearched the reference lists of included studies and pertinent review articles. Selection criteria To examine efficacy, we included randomised controlled trials (RCTs) on adults with a history of winter‐type SAD who were free of symptoms at the beginning of the study. To examine adverse events, we intended to include non‐randomised studies. We planned to include studies that compared psychological therapy versus no treatment, or any other type of psychological therapy, light therapy, second‐generation antidepressants, melatonin, agomelatine or lifestyle changes. We also planned to compare psychological therapy in combination with any of the comparator interventions listed above versus no treatment or the same comparator intervention as monotherapy. Data collection and analysis Two review authors screened s and full‐text publications against the inclusion criteria, independently extracted data, assessed risk of bias, and graded the certainty of evidence. Main results We identified 3745 citations through electronic searches and reviews of reference lists a