Efficacy of light therapy on non-seasonal depression and inflammatory markers

Abstract

Background and objectivesThe evidence for efficacy of light therapy in non-seasonal depression remains controversial. The primary aim of this study was to investigate the efficacy of bright light therapy when it was combined with antidepressant treatment in the course of major depressive disorder without seasonal pattern. The secondary aim was to assess the inflammatory response to bright light therapy. MethodsPatients who had a Hamilton Depression scale score of 17 or above, who were receiving antidepressant monotherapy for at least 4 weeks were included in the study (n=74). Patients were assigned to either antidepressant monotherapy (n=40) or combination of antidepressant and bright light therapy (n=34). The severity of the depression and suicidal ideation was evaluated by Hamilton Depression Scale and The Beck Scale for suicide ideation. The effect of light therapy on inflammatory markers was investigated based on the neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, platelet counts and mean platelet volume. Their clinical state was monitored at the baseline, 1 day and 2 weeks after treatment. ResultsIndependent from treatment group, patients showed decreased depression and suicidal ideation scores after treatment. The results of statistical analysis of time×group interactions regarding depression and suicidal ideation scores also showed significant differences between groups over time. For inflammatory markers, only the lymphocyte count showed significant difference between groups over time. Except platelet/lymphocyte ratio, all inflammatory markers showed significant alterations with time independent from treatment arm. ConclusionCombining light therapy with oral antidepressants can be helpful in non-seasonal depression as well.