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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Efficacy of light therapy in nonseasonal depression: a systematic review

C Even, CM Schroder, S Friedman, and F Rouillon.

Review published: 2008.

CRD summary

This review concluded that bright light therapy was an excellent candidate for inclusion in the treatment options available for non-seasonal depression as additional therapy to antidepressant medication. Given the methodological limitations of the included studies and a lack of reporting on the review processes, the authors' conclusions need to be treated with some caution and confirmed in further studies.

Authors' objectives

To determine whether bright light therapy may be an alternative to antidepressant medication and / or an additional treatment to pharmacotherapy in non-seasonal depression

Searching

The authors searched MEDLINE and PsycInfo up to June 2006 with search terms listed in the report. They checked references in identified publications and previous reviews of the subject. Finally, they searched two reference books on light therapy and contacted the Society for Light Treatment and Biological Rhythms.

Study selection

The authors applied the following criteria to publications evaluating efficacy of light therapy in non-seasonal depression in adults: the use of a controlled parallel group design; and the use of light therapy under conditions previously demonstrated to be efficacious in seasonal affective disorder (SAD). Trials of less than a week in duration were excluded. Minimum criteria for light duration and intensity were (full details given in the report). Treatment duration ranged from one to five weeks. In all studies participants had a clinical diagnosis of depression. Ascertainment of the non-seasonal nature of the depression varied across the studies and was not always explicitly stated. Some trials included patients with a bipolar diagnosis and some had a specific sample (for example, pregnant women or older patients). Tools for measuring depression varied across the included studies.

The authors stated neither how studies were selected for the review nor how many reviewers were involved in the study selection process.

Assessment of study quality

The authors did not conduct a formal validity assessment of the included studies, but discussed some of the methodological limitations in the report.

Data extraction

The authors stated neitehr how the data were extracted for the review nor how many reviewers performed the data extraction.

Methods of synthesis

Studies were divided into three groups. The first group compared the efficacy of light therapy in seasonal versus non-seasonal depressed patients. The second group compared the efficacy of bright light therapy to a placebo low intensity light condition or to a sham air ionisation device in patients with non-seasonal depression said to be free of antidepressants. The third group compared the efficacy of light therapy to a placebo low-intensity light condition in patients using antidepressant medication.

Results of the review

Fifteen trials were identified (n=570).

Light therapy in seasonal depressed patients versus non-seasonal depressed patients.

All three studies reported statistically significantly better outcomes in patients with seasonal depression. Across the studies the percentage of non-seasonal responders varied from 0 to 14 per cent. All studies had methodological limitations.

Comparisons of bright light therapy versus placebo low intensity light condition or sham air ionisation device in patients with non-seasonal depression said to be free of antidepressants studies yielded inconsistent results: three studies found bright light to be more effective in reducing symptoms of depression than the placebo dim light condition; four other studies did not. Clinical heterogeneity was noted and the impact of a range of patient, treatment and study factors was investigated. None of the factors were found to consistently predict positive or negative outcomes.

Light therapy versus placebo low-intensity light condition in patients using antidepressant medication

Four of five studies reported positive results. No specific factors were identified to explain the results of the negative trial.

Authors' conclusions

Bright light therapy was an excellent candidate for inclusion in the treatment options available for non-seasonal depression as additional therapy to antidepressant medication. Further trials would be needed to determine whether light therapy might be suitable as a stand alone treatment for specific subgroups of patients with non-seasonal depression.

CRD commentary

This review had broadly defined inclusion criteria for participants, intervention and study design. The exclusion of studies that did not meet light duration and intensity criteria for SAD may have biased the results. Searching was based on two databases and a range of other sources. Only published material was eligible for inclusion, raising the possibility of publication bias (studies with positive results are more likely to be published than those showing no effects). No formal validity assessment was conducted, so the potential influence of study quality on results could not be ascertained. Methods to reduce bias and error in the selection and data extraction of studies were not reported. Studies appeared to be grouped appropriately and factors that might explain differing outcomes were investigated. Given these issues and methodological problems in the included studies, the authors' conclusions on the potential value of light therapy would need to be confirmed in further studies.

Implications of the review for practice and research

Practice: Not stated

Research: The authors advised that using predictors of response to light therapy already identified in SAD patients and conducting trials with non-seasonal patients who display these characteristics would be a sound approach. They also recommended the selection of patient subgroups for research according to predefined clinical and/or chronobiological criteria described in more detail in the report. The authors advocated larger multicentre trials to ascertain whether light therapy should be recommended and made available for the complementary management of depressed patients.

Funding

Not stated

Bibliographic details

Even C, Schroder C M, Friedman S, Rouillon F. Efficacy of light therapy in nonseasonal depression: a systematic review. Journal of Affective Disorders 2008; 108(1-2): 11-23. [PubMed: 17950467]

Indexing Status

Subject indexing assigned by NLM

MeSH

Antidepressive Agents /therapeutic use; Clinical Trials as Topic; Combined Modality Therapy; Depressive Disorder /diagnosis /psychology /therapy; Humans; Phototherapy; Publication Bias; Seasonal Affective Disorder /diagnosis /psychology /therapy; Treatment Outcome

AccessionNumber

12008103964

Database entry date

03/06/2009

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 17950467