Progress of Photobiomodulation for Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative disease with global burden. The mechanisms and therapeutic effects of photobiomodulation (PBM) correspond to main mechanisms in the pathogenesis of PD. Numerous research results applying PBM for PD were published during the past two decades. Although several systematic review or review articles provided complete introduction, they are either mainly basic research or clinical research, and the year of the article publication is up to 2020. Comprehensive systematic review or review articles containing basic and clinical studies including those published articles is lacking. Hence, this systematic review aimed to include both basic and clinical studies published up to 2022. Results were obtained by retrieving articles from PubMed with the intersection of the articles derived from the terms of PBM synonyms and Parkinson’s disease followed by exclusion. Sixty-nine articles were included ultimately. Among them, 40 original articles were identified, which were composed of 31 basic research and 9 original articles of clinical research. Twenty-one review articles, a systematic review with focused content on PD, and 7 review articles with the term PD under general illustration of PBM were presented. Mechanisms regarding the therapeutic effects of PBM on the vitro studies were reviewed. Positive outcomes on motor symptoms after PBM treatments were shown in most in vivo and clinical studies. The immunohistochemical examination of in vivo studies reflect the therapeutic effects of PBM on the preservation even reverse of the pathogenic insults of PD on the in vitro studies. The most frequently used wavelength among original articles included was 670nm. Considering the acceptability of PBM for patients with PD, noninvasive transcranial PBM (tPBM) had crucial roles in respect to invasive intracerebral PBM. To match the penetration depth reaching deep brain target, Substantia nigra pars compacta, in human brains of patients with PD, the wavelength 810nm might match the need in the clinical setting of tPBM. More future clinical studies were needed. In conclusion, therapeutic approaches applying PBM for PD are promising. Recent studies revealed positive outcomes. Future clinical practices containing PBM are to be expected.