Parkinson’s disease (PD) affects more than 10 million people worldwide, causing tremor, stiffness, slowed movement, balance problems, and cognitive decline. While medications like levodopa can help manage these symptoms, their effectiveness often wanes over time and may bring side effects. Photobiomodulation (PBM)—the application of gentle red to near‑infrared light—has shown promise in animal models for protecting dopamine‑producing neurons and reducing PD signs. A proof‑of‑concept clinical study by Liebert et al. (2021) investigated whether PBM could safely improve motor and cognitive symptoms in people with PD. The aim of the study was to assess the effectiveness of a combined transcranial and remote (neck and abdominal) PBM protocol in mitigating the clinical signs of PD and to inform the design of future randomized, placebo‑controlled trials.
In this study, twelve adults aged 60–80 with mild‑to‑moderate PD were divided into two groups. One group began a 12‑week clinic‑based PBM regimen immediately, while the second group waited 14 weeks (serving as their own controls) before starting identical treatment. The PBM protocol delivered 810 nm light through an array of LEDs targeting the scalp and nasal passages to reach the brain, and 904 nm light via laser diodes to the upper neck (around the vagus nerve) and abdomen (to engage the gut–brain axis). Treatment frequency tapered from three times weekly in the first month, to twice weekly in the next month, and once weekly in the final month. Afterward, all participants continued self‑administered PBM at home three times per week for up to 40 weeks.
The findings were encouraging: PBM was well tolerated with no reported side effects. Participants showed significant gains in mobility—Timed Up‑and‑Go times improved from a median of 8.0 seconds to 7.1 seconds after 12 weeks (p<0.01) and further to 6.6 seconds with extended home treatment. Ten‑meter walking speed increased from 1.12 to 1.70 m/s (p<0.01), and balance measures such as the step test demonstrated meaningful improvements. Fine motor control, assessed by a spiral‑drawing test, also improved, indicating steadier hand movements. Cognitive scores on the Montreal Cognitive Assessment rose from a median of 26 to 28 after clinic PBM (p<0.01) and approached 30 after home treatment. Many of these individual changes exceeded the Minimal Clinically Important Difference, meaning participants perceived the gains as significant.
These results suggest that PBM may counteract the typical decline seen in PD by enhancing mitochondrial energy production, reducing inflammation, and improving blood flow—both directly in the brain and via the gut–brain axis. The sustained, home‑based nature of the therapy makes it a practical complement to existing drugs or surgical options. While this proof‑of‑concept study was small and lacked a sham control, its positive safety profile and clinically meaningful improvements underscore the need for larger, double‑blind, placebo‑controlled trials to confirm efficacy, optimize dosing schedules, and evaluate long‑term outcomes.
Reference:
Liebert A, Bicknell B, Laakso E-L, et al. Improvements in clinical signs of Parkinson’s disease using photobiomodulation: a prospective proof‑of‑concept study. BMC Neurology. 2021;21:256. doi:10.1186/s12883-021-02248-y