The following article is part of conference coverage from the International Congress of Parkinson’s Disease and Movement Disorders (MDS) Virtual Annual Meeting. Neurology Advisor’s staff will be reporting breaking news associated with research conducted by leading experts in neurology. Check back for the latest news from the MDS 2021 Virtual Annual Meeting.


Specialized light therapy (SLT) in Parkinson disease (PD) may improve mood disorders, urinary problems, swallowing and chewing, tremor, daytime sleepiness, and fatigue, according to study results presented at the International Congress of Parkinson’s Disease and Movement Disorders (MDS) Virtual Congress 2021, held from September 17 to 22, 2021.

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Previous studies have supported the benefits of SLT on motor and nonmotor symptoms in patients with PD, including clinical improvement, according to the MDS-Unified Parkinson’s Disease Rating Scale (UPDRS) 1 to 3 combined scores.

The current exploratory analysis aimed at determining the impact of SLT on MDS-UPDRS 1-3 subitems for patients with PD.

The prospective, double-blind, multicenter, controlled study included 92 patients with PD from 3 centers. Participants were randomly assigned 1:1 to receive narrow band blue/green light (SLT group; n=45) or low-intensity white light (control group; n=47). Patients received dopaminergic therapy and continued their standard-of-care treatments.

The primary endpoint was change in MDS-UPDRS 1 to 3 subitems from baseline to 6 months.

Treatment with SLT was associated with an improvement of 17.7 points in MDS-UPDRS 1-3 compared with an improvement of 9.7 points among control participants (P =.074).  

Of the 13 subparts in MDS-UPDRS 1, 3 subitems favored SLT, including depressed (P =.0171) or anxious mood (P =.0040), and urinary problems (P =.0012). Another 3 subitems favored SLT, including apathy (P =.0604), daytime sleepiness (P =.0507), and fatigue (P =.0713).

Of the 13 subparts in MDS-UPDRS 2, 2 subitems favored SLT, including chewing and swallowing (P =.0210), and eating tasks (P =.0143). Practicing hobbies or other activities also favored SLT (P =.0881).

Of the 33 subparts in MDS-UPDRS 3, 2 subitems favored SLT, including tremor amplitude right upper extremity (P =.0206) and right lower extremity (P =.0101). Kinetic tremor of right hand (P =.0881) and rest tremor amplitude left lower extremity (P =.589) favored SLT.

The MDRS-UPDRS 1-3 has 59 subscales in total; none of them favored or tended in favor of the control group.

“SLT had an impact across a broad range of sub-items measured by MDS-UPDRS,” the researchers noted. They added that “these effects were demonstrated on top of current drug therapies. If confirmed in larger studies SLT would provide a safe and convenient therapy to improve many persistent motor and non-motor symptoms in [patients with] PD.”


Wyman B, Hendrix S, Hennessey S, et al. Impact of specialized light therapy in Parkinson’s disease on MDS-UPDRS parts 1-3 subscales. Presented at: MDS Virtual Congress 2021; September 17-22, 2021. Poster 450.