Effectiveness of Photobiomodulation to Treat Motor and Non-Motor Symptoms of Parkinson’s Disease: A Randomised Clinical Trial with Extended Treatment

<b>Background/Objective:</b> Few treatment options improve symptoms and the quality of life of Parkinson's disease (PD); more treatment choices are needed. This study examined the effectiveness of photobiomodulation therapy (PBMt) combined with exercise to improve PD symptoms and quality of life. <b>Methods:</b> Participants were randomised into Active (<i>n</i> = 32) or Sham (<i>n</i> = 31) PBMt groups. Stage 1 was an 8-week double-blind, randomised, placebo-controlled trial using either active or sham PBMt to the head, back of the neck and abdomen three times weekly at home, followed by a 4-week washout. Stage 2 was 8 weeks of active PBMt for all participants. In Stage 3, participants chose to continue active PBMt treatment ('continuers') or receive no PBMt treatment ('non-continuers') for up to 48 weeks. Participants continued vigorous exercise throughout the study. Participants were assessed on enrolment and after each stage. The primary outcome measure was timed up-and-go, with a range of secondary motor and non-motor outcomes, including UPDRS. <b>Results:</b> There was no significant difference between the Active and Sham Groups after Stages 1 or 2, apart from minimal increase in MoCA score/cognition (Sham Group) in Stage 1. After Stage 3, continuers showed a significant improvement in the primary outcome measure compared to non-continuers. Anxiety and the motor experiences of daily living (MDS-UPDRS Part II) were also significantly improved, while other outcomes approached significance, including MDS-UPDRS Total score (<i>p</i> = 0.062). <b>Conclusions:</b> As the largest study to date, results add increasing weight to previous clinical trials and highlight potential for at-home, scalable treatment as adjunctive therapy alongside medication and exercise.