Psychological therapies for prevention of winter depression

Why is this review important?

Many people in northern latitudes suffer from seasonal affective disorder (SAD), which occurs as a reaction to reduced sunlight. Three-quarters of those affected are women. Lethargy, overeating, craving for carbohydrates and depressed mood are common symptoms. In some people, SAD becomes a depression that seriously affects their daily lives. Up to two-thirds experience depressive symptoms every winter.

Who will be interested in this review?

Anyone who has experienced SAD or who has relatives and friends who have experienced SAD will be interested in this review.

What questions does this review aim to answer?

The predictable seasonal aspect of SAD provides a promising opportunity for prevention. However, little is known about the efficacy and potential harms of interventions for preventing SAD. This is one of four reviews conducted to examine the efficacy and side effects of interventions used to prevent SAD; this review focuses on psychological therapy as a preventive intervention in patients with a history of SAD who were free of symptoms at the time the preventive intervention was started.

Which studies were included in the review?

We searched databases up to 11 August 2015 for studies on psychological therapies to prevent SAD. Overall, we found no completed studies that met the criteria for inclusion in this review.

What does evidence from this review reveal?

Through our literature search, we found no studies that addressed the efficacy of psychological therapy in preventing SAD, and we can make no recommendations in support of, or against, its use in the treatment of patients with SAD.

What should happen next?

Review authors recommend that future studies should evaluate the efficacy of psychological therapy in preventing SAD and should directly compare these interventions versus other effective treatments such as light therapy, antidepressants and agomelatine, to determine the best treatment option for prevention of SAD.

Authors' conclusions: 

Presently, there is no methodologically sound evidence available to indicate whether psychological therapy is or is not an effective intervention for prevention of SAD and improvement of patient-centred outcomes among adults with a history of SAD. Randomised controlled trials are needed to compare different types of psychological therapies and to compare psychological therapies versus placebo, light therapy, SGAs, melatonin, agomelatine or lifestyle changes for prevention of new depressive episodes in patients with a history of winter-type SAD.

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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 (SGAs), light therapy, melatonin or agomelatine or lifestyle interventions) in preventing SAD and improving patient-centred outcomes among adults with a history of SAD.

Search strategy: 

We conducted a search of the Cochrane Depression, Anxiety and Neurosis Review Group Specialised Register (CCDANCTR) to 11 August 2015. The CCDANCTR contains reports of relevant randomised controlled trials from EMBASE (1974 to date), MEDLINE (1950 to date), PsycINFO (1967 to date) and the Cochrane Central Register of Controlled Trials (CENTRAL). Furthermore, we searched the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Knowledge, The Cochrane Library and the Allied and Complementary Medicine Database (AMED) (to 26 May 2014). We conducted a grey literature search (e.g. in clinical trial registries) and handsearched the reference lists of all included studies and pertinent review articles.

Selection criteria: 

To examine efficacy, we planned to include randomised controlled trials 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 any other type of psychological therapy, placebo, light therapy, SGAs, melatonin, agomelatine or lifestyle changes. We also intended to compare psychological therapy in combination with any of the comparator interventions listed above versus the same comparator intervention as monotherapy.

Data collection and analysis: 

Two review authors screened abstracts and full-text publications against the inclusion criteria. Two review authors planned to independently extract data and assess risk of bias. We planned to pool data for meta-analysis when participant groups were similar and when studies assessed the same treatments versus the same comparator and provided similar definitions of outcome measures over a similar duration of treatment; however, we included no studies.

Main results: 

We identified 2986 citations through electronic searches and reviews of reference lists after de-duplication of search results. We excluded 2895 records during title and abstract review and assessed 91 articles at full-text review for eligibility. We found no controlled studies on use of psychological therapy to prevent SAD and improve patient-centred outcomes in adults with a history of SAD.

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