Efficacy and Safety of Light Therapy as a Home Treatment for Motor and Non-Motor Symptoms of Parkinson Disease: A Meta-Analysis

Background: Non-visual effects of the retina have been increasingly confirmed in developing Parkinson disease (PD). Light therapy (LT) has been proven to be an effective non-pharmacotherapy for improving the prognosis of PD, but the pathway of action is unclear, and there is a lack of a unified and standardized LT regimen. We aimed to evaluate the efficacy and safety of various LT measures in improving motor and non-motor symptoms in patients with idiopathic PD via a meta-analysis. Material/Methods: CENTRAL, EMBASE, CINAHL, PEDro, and PubMed were searched for randomized controlled trials (RCTs) investigating the efficacy of LT for PD. Cochrane's Risk of bias tool and the GRADE approach were used to assess evidence quality. A meta-analysis and subgroup analyses evaluated the differences in efficacy produced by the different LT protocols. Trial sequential analysis (TSA) verified the analyses outcome and quantified the statistical relevance of the data. Results: Patients receiving LT had significantly better scores for motor function (MD=-4.68, 95% Cl -8.25 to -1.12, P=0.01) compared with the control group exposed to dim-red light. In addition, in terms of non-motor symptoms, depression (SMD=-0.27, 95% Cl -0.52 to -0.02, P=0.04) and sleep disturbance-related scores (MD=3.45, 95% Cl 0.12 to 6.78, P=0.04) similarly showed significant optimization after receiving LT. Conclusions: The results of this meta-analysis show strong evidence that LT has significant efficacy on motor and non-motor function in PD patients.