Cognitive and Behavioral Predictors of Light Therapy Use

University of Granada, Spain
PLoS ONE (Impact Factor: 3.23). 06/2012; 7(6):e39275. DOI: 10.1371/journal.pone.0039275
Source: PubMed


Although light therapy is effective in the treatment of seasonal affective disorder (SAD) and other mood disorders, only 53-79% of individuals with SAD meet remission criteria after light therapy. Perhaps more importantly, only 12-41% of individuals with SAD continue to use the treatment even after a previous winter of successful treatment.
Participants completed surveys regarding (1) social, cognitive, and behavioral variables used to evaluate treatment adherence for other health-related issues, expectations and credibility of light therapy, (2) a depression symptoms scale, and (3) self-reported light therapy use.
Individuals age 18 or older responded (n = 40), all reporting having been diagnosed with a mood disorder for which light therapy is indicated. Social support and self-efficacy scores were predictive of light therapy use (p's<.05).
The findings suggest that testing social support and self-efficacy in a diagnosed patient population may identify factors related to the decision to use light therapy. Treatments that impact social support and self-efficacy may improve treatment response to light therapy in SAD.

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    ABSTRACT: Low serum 25-hydroxyvitamin D levels (25(OH)D) have been associated with a higher likelihood of seasonal affective disorder (SAD) and poor mental well-being, yet firm evidence for either remains lacking. Thus, vitamin D supplementation may alleviate symptoms associated with SAD. This study was a randomized, single-centre, double-blind, placebo-controlled trial including healthcare professionals employed in psychiatric and somatic hospitals. 3345 healthcare professionals were invited to participate, 50 participants were screened, and 34 were able to complete the study. The main inclusion criterion was 8 points or more on question no. 2 of the Seasonal Pattern Assessment Questionnaire (SPAQ-SAD). During a 3-month period, the participants received a daily dose of 70 μg vitamin D or placebo. The primary outcome was the sum of the self-reported questionnaire Structured Interview Guide for the Hamilton Depression Rating Scale, Seasonal Affective Disorders (SIGH-SAD). The secondary outcome was World Health Organization-Five Well-Being Index (WHO-5) of the healthcare professionals during the winter period and the exploratory outcome measures were weight, waist circumference, blood pressure, absenteeism from work and 25(OH)D. There were no significant between-group differences in SIGH–SAD sums at 12 weeks (p = 0.7 (CI: - 3.27 to 4.81)). However, there was a significant improvement of primary SIGH-SAD over time from inclusion (autumn-winter) to the completion of the study (winter-spring) for all participants. The secondary and exploratory outcome measures were all insignificant between groups. The sums of the SIGH–SAD at 12 weeks were not significantly different [p = 0.701 (CI: 4.81–3.27)] between the groups. There was, however, a significant improvement in primary SIGH-SAD sums over time from inclusion (autumn-winter) to the completion of the study (winter-spring) in both groups. The secondary and explorative outcome measures were not significantly different between groups. There were no significant between-group differences in the primary (SIGH-SAD) and secondary (WH0-5) as well as the exploratory outcome measures (weight, waist circumference, blood pressure, absenteeism from work and 25(OH)D. Thus, the study failed to demonstrate an effect of vitamin D on SAD symptoms, but our findings may be limited by confounders. Furthermore, the study was underpowered and did not allow us to assess the ability of vitamin D to improve mood in those with low 25(OH)D. Trial registration ( registration number: NCT01462058).
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