Bright Light Therapy as Augmentation of Pharmacotherapy for Treatment of Depression:

A Systematic Review and Meta-Analysis

Thomas M. Penders, MS, MDa,*; Cornel N. Stanciu, MDa; Alexander M. Schoemann, PhDb; Philip T. Ninan, MDa;
Richard Bloch, PhDa; and Sy A. Saeed, MDa

ABSTRACT

Background: Bright light therapy has demonstrated efficacy and is an accepted treatment for seasonal depression. It has been suggested that bright light therapy may have efficacy in nonseasonal depressions. Also, there is evidence that bright light therapy may improve responsiveness to antidepressant pharmacotherapy.

Data Sources: We searched PubMed/MEDLINE, PsycINFO, PsycARTICLES, CINAHL, EMBASE, Scopus, and Academic OneFile for English-language literature published between January 1998 and April 2016, using the keywords bright light therapy AND major depression, bright light therapy AND depress*, bright light therapy AND bipolar depression, bright light therapy AND affective disorders, circadian rhythm AND major depression, circadian rhythm AND depress*, and circadian rhythm AND affective disorder.

Study Selection and Data Extraction: Studies that reported randomized trials comparing antidepressant pharmacotherapy with bright light therapy ≥ 5,000 lux for ≥ 30 minutes to antidepressant pharmacotherapy without bright light therapy for the treatment of nonseasonal depression were included. Studies of seasonal depression were excluded. Following review of the initial 112 returns, 2 of the authors independently judged each trial, applying the inclusionary and exclusionary criteria. Ten studies were selected as meeting these criteria. Subjects in these studies were pooled using standard techniques of meta-analysis.

Results: Ten studies involving 458 patients showed improvement using bright light therapy augmentation versus antidepressant pharmacotherapy alone. The effect size was similar to that of other accepted augmentation strategies, roughly 0.5.

Conclusions: Analysis of pooled data from randomized trials provides evidence for the efficacy of use of bright light therapy ≥ 5,000 lux for periods ≥ 30 minutes when used as augmentation to standard antidepressant pharmacotherapy in the treatment of major depressive disorder and bipolar depression without a seasonal pattern.

Prim Care Companion CNS Disord 2016;18(5):doi:10.4088/PCC.15r01906

© Copyright 2016 Physicians Postgraduate Press, Inc.

aDepartment of Psychiatry and Behavioral Medicine, Brody School of Medicine, East Carolina University, Greenville, North Carolina

bDepartment of Psychology, East Carolina University, Greenville, North Carolina

*Corresponding author: Department of Psychiatry and Behavioral Medicine, Brody School of Medicine, East Carolina University, Ste 400E, 600 Moye Blvd, Greenville, NC 27834 (penderst@ecu.edu).

Depressive disorders are highly prevalent worldwide. Lifetime prevalence is estimated to be 21% of the population of the United States1 and at least 15% globally. Depression is a strong contributor to disability and burden of disease,2,3 as well as a risk for death by suicide. Depression is a factor affecting the course, morbidity, and mortality of several common and chronic medical illnesses such as heart disease, cancer, and diabetes. Depression contributes to untold suffering for those affected and their loved ones. Analysis of large naturalistic clinical trials4,5 has shown the limits of current treatments for both major depressive disorder and bipolar disorder. Development of new approaches to treatment of refractory depression has been identified as a significant unmet need among psychiatric clinicians.6

When a single antidepressant agent fails to produce significant improvement or remission in a patient with a depressive disorder, use of multiple pharmacologic agents or psychosocial interventions has been an accepted standard. Such augmentation strategies include addition of lithium carbonate, thyroid hormone, a second antidepressant, or certain second-generation antipsychotics. In the case of bipolar depression, strategies include use of mood stabilizers or antipsychotic medications.7,8

Bright light therapy is an accepted modality for treatment of major depressive disorder with a seasonal pattern, commonly referred to as seasonal affective disorder.9 Studies10 have also suggested that bright light monotherapy may have some efficacy in the treatment of depressive illnesses with no seasonal pattern. Also, several studies11 have suggested that bright light therapy may augment the efficacy of established pharmacotherapies in the treatment of nonseasonal depression. A comprehensive review11 published in 2005 of literature relating to the use of bright light therapy for treatment of mood disorders concluded that “bright light for nonseasonal depression is efficacious, with effect sizes equivalent to those in most antidepressant pharmacotherapy trials.”(p31) Despite the very limited risks and costs associated with the use of bright light therapy, there has been little utilization in clinical practice outside treatment for seasonal affective disorder.12 This systematic review and meta-analysis was conducted to assess the current state of evidence favoring use of bright light therapy as an augmentation to antidepressant pharmacotherapy in the treatment of depressive disorders with no seasonal pattern.

METHODS

This meta-analysis complies with the criteria provided in the Preferred-Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Two members of the research team (T.M.P. and C.N.S.) reviewed initial returns and selected trials on the basis of predefined inclusionary and exclusionary criteria.13–23

Data Sources

We searched PubMed/MEDLINE, PsycINFO, PsycARTICLES, CINAHL, EMBASE, Scopus, and Academic OneFile for English-language medical literature published between January 1998 and April 2016 using the search terms bright light therapy AND major depression, bright light therapy AND depress*, bright light therapy AND bipolar depression, bright light therapy AND affective disorders, circadian rhythm AND major depression, circadian rhythm AND depress*, and circadian rhythm AND affective disorder. Search results were supplemented by references gleaned from recent reviews and citations of searched returns.

Inclusion and Exclusion Criteria and Study Selection

All studies that reported randomized trials comparing antidepressant pharmacotherapy with bright light therapy ≥ 5,000 lux for ≥ 30 minutes to antidepressant pharmacotherapy without bright light therapy for the treatment of nonseasonal depression were included. Studies that included subjects with seasonal depression, subsyndromal symptoms, dementia, eating disorders, bright light therapy alone, or premenstrual dysphoric disorder were excluded. The original search yielded 112 reports. After elimination of studies with exclusionary criteria, 10 studies13–22 met our original search criteria (Figure 1, Table 1). In the case of 2 disputed exclusions, 1 reviewer (S.A.S.) mediated an agreement on proper allocation.

Data Extraction and Analysis

Our statistician (A.M.S.) extracted the number of subjects and the outcomes by trial arm. All studies meeting inclusion criteria that reported the statistical information necessary to compute an effect size were included in all analyses. We used standard meta-analytic methods based on Lipsey and Wilson.23 On the basis of the reported results for each study, we computed a standardized mean effect size and its 95% confidence interval, with small sample size corrections when appropriate.24 Across the 10 studies, the weighted mean of the effect sizes and the variance of the effect sizes were computed using inverse variance weights from each study (Figure 2). All analyses were conducted with the metafor25 package using the statistical software R.26

RESULTS

Publication bias was assessed with a visual inspection of a funnel plot and a rank correlation test of funnel plot asymmetry.27 Neither the funnel plot (Figure 2) nor the rank correlation test (Kendall τ = −0.022, P = .999) showed evidence of publication bias among the studies.

Across the 10 studies that met inclusion criteria, bright light therapy had a positive and significant effect (g = 0.545, P < .001; 95% CI, 0.385–0.732). The variance of the effect sizes was not significantly different from zero (τ2 = 0.00; 95% CI, 0.000–0.170), and there was no significant heterogeneity in effect sizes (Q9 = 6.54, P = .685) (Figure 3).

Quality of Studies

Two reviewers (P.T.N. and R.B.) independently evaluated the quality of each study using guidelines established by the GRADE28 (Grading of Recommendations, Assessment, Development, and Evaluation) method. Only 3 studies18,19,21 were judged to be of high quality. Three others16,17,22 were rated as medium or low to medium. The remaining studies13,14,15,20 were rated as low quality (Table 2). Studies included subjects with bipolar and major depressive disorder, introducing a possible bias on the basis of this selection.

DISCUSSION

Many patients with depressive disorder fail to respond to standard antidepressant pharmacotherapy, psychotherapy alone, or the combination. Augmentation strategies improve outcome in many cases, but treatment resistance remains common, leaving many patients with disabling or distressing residual symptoms. Adoption of bright light therapy for treatment of nonseasonal depression by psychiatric clinicians remains quite limited despite a recommendation for use by the American Psychiatric Association.29 Insurance coverage for bright light therapy for nonseasonal depression is also severely limited. However, the quality of current evidence supports a recommendation for efficacy. This meta-analysis supports conclusions reached by others,10 suggesting that bright light therapy is effective and can add to the armamentarium of interventions available to patients with refractory depressive disorders. Recently reported studies30 add substantially to evidence in support of bright light therapy to augment the therapeutic actions of antidepressant agents.

The studies meeting criteria for inclusion in this analysis varied substantially in their design, measured outcomes for improvement in depression, length of light exposure, type of placebo, and lengths of the trials. Antidepressant treatments varied from study to study. The study19 with the largest number of subjects utilized a single antidepressant and controlled dosing. Another study16 provided outcomes after only 3 days and also included an additional intervention, wake therapy, introducing additional significant confounds. Leibenluft et al20 reported a study of a limited number of subjects with rapid-cycling bipolar disorder, a group substantially different from those of most other included studies.

Limitations

The resultant heterogeneity in the studies included in this pooled analysis somewhat confounds interpretation of the data. However, all included studies were consistent in reporting antidepressant action of bright light therapy for depressions with no seasonal pattern. Future trials will benefit from designs that limit these confounds as attempts are made to better define the effect of bright light therapy in the several subtypes of depressive disorders. There also may be a potential for development of markers and predictors of response to bright light therapy when used as an augmentation strategy.

CONCLUSION

Analysis of pooled data from randomized trials provides evidence for the efficacy for use of bright light therapy administered at ≥ 5,000 lux for periods ≥ 30 minutes when used as augmentation to standard antidepressant treatment. Methodological flaws, small sample sizes, and heterogeneity of published studies have resulted in strength of evidence that is moderate overall.

Submitted: November 6, 2015; accepted August 2, 2016.

Published online: October 20, 2016.

Drug names: lithium (Lithobid and others).

Disclosure of off-label usage: The authors have determined that, to the best of their knowledge, lithium is not approved by the US Food and Drug Administration for augmentation of antidepressant action.

Financial disclosure: Dr Ninan has served as a consultant to Lundbeck. Drs Penders, Stanciu, Schoemann, Bloch, and Saeed have no personal affiliations or financial relationships with any commercial interest to disclose relevant to the activity.

Funding/support: None.

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