Abstract
Despite current medical therapy for Parkinson's Disease (PD), many experience persistent motor symptoms and significant unmanaged non-motor issues. Previous studies suggest that light therapy (LT) provides benefits for motor and non-motor features of PD. This study evaluated Circadian Effective LT (CELT) with a spectral band between 460 and 545 nm for the motor and non-motor features of PD. We conducted a multi-center, randomized, double-blind, controlled clinical trial of CELT in people with Parkinson's disease on standard-of-care therapy. Ninety-two participants (45 active, 47 control) were randomized 1:1 to active or control CELT for 1 h each evening for 6 months. Patients were evaluated in their ‘ON state’. The mean (SE) change on the primary endpoint of the MDS-UPDRS parts 1–3 was −17.7(2.8) active vs −9.7(3.5) control, for a LSM difference of −8.0 (4.4) (p = 0.074, 95% Confidence Interval: −16.7, 0.8), reflecting a trend toward improvement over control. Key secondary endpoints included PDQ-39 and CGI which favored active treatment (−5.7 ± 2.7; p = 0.038, and −0.4 ± 0.2; p = 0.066 respectively), while PDSS-2 Disturbed Sleep showed no difference between groups. Other secondary endpoints that supported the overall treatment effect of CELT included ESS (−1.52 ± 0.78; p = 0.054) and CGI-E (−0.3 ± 0.2; p = 0.088). Daily LT, with a circadian effective targeted spectrum of light, was well tolerated by PD patients, had no serious adverse effects and showed improvement in both motor and non-motor MDS-UPDRS and other scores. Larger double-blind studies are warranted to further assess the effectiveness of CELT in PD.