Photobiomodulation therapy in mood disorders: a systematic review.

Mood disorders are common, debilitating and impose a high-cost burden on society. Side effects and resistance to psychiatric drugs justify finding new treatment methods. Photobiomodulation therapy (PBMT) uses photons of light to repair, modulate and improve the function of target tissue. The purpose of this study is to systematically review the use of PBMT for the treatment of mood disorders and to identify the useful parameters of PBMT, the level of evidence of its effectiveness, and the degree of its practical recommendation. "Google scholar," "Pub Med," "Scopus," and "Science direct" online databases were searched based on Preferred Reporting Items for Systematic Reviews and meta-analyses (PRISMA) guidelines. The human or animal studies written in English and published from January 2009 to August 2021 were included. Sixteen studies, which included four randomized controlled trials (RCTs), met the inclusion criteria. Infrared wavelength ranges from 800 to 830 nm, power density of 250 mW/cm 2 and energy density of 60 to 120 J/ cm 2 were the most used PBMT parameters. Bias risk assessment was performed to evaluate the quality of RCTs in which 2 out of 4 RCTs were evaluated as high quality. Based on grade practice recommendations, PBMT can be classified as strongly recommended for moderate grade of major depressive disorder (MDD) and recommended for anxiety disorder. In bipolar disorder, further studies are needed to recommend this therapeutic method.