Brain photobiomodulation in Alzheimer’s disease and Parkinson’s disease: current clinical knowledge

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This review summarizes clinical studies on cerebral photobiomodulation conducted in Alzheimer’s disease and Parkinson’s disease. The authors report good tolerability but a low level of evidence, due to exploratory studies of varying quality, which does not justify widespread use.

What this study measured

This is a literature review focusing on the clinical application of cerebral photobiomodulation in patients with Alzheimer’s disease, related forms of dementia, or Parkinson’s disease. The authors summarize the available clinical data, describe the results of recent studies, and outline future research directions, including ongoing or unpublished trials.

The abstract does not specify either the number of studies included or the number of patients involved. This is not a meta-analysis, and no effect size is calculated.

Key Findings

The findings reported by the authors are qualitative. They focus on safety, evidence of efficacy, and the methodological soundness of existing studies.

Several clinical studies have evaluated cerebral photobiomodulation, using varying parameters, in patients with Alzheimer's and Parkinson's disease. The exact number is not specified in the abstract.
According to the authors, all of these studies demonstrate the safety of cerebral photobiomodulation.
The results are described as particularly encouraging for Alzheimer's disease, though no figures are provided.
The overall level of evidence is considered low, due to exploratory study designs and inconsistent quality.
To date, this level of evidence does not support widespread use in clinical practice.
No percentages, mean differences, or confidence intervals are reported in the summary.

How photobiomodulation works for this indication

The mechanistic hypotheses cited by the authors are based on preclinical studies—that is, animal or cellular studies—and cannot be directly applied to humans. Near-infrared light is thought to be absorbed by mitochondrial cytochrome c oxidase, which would increase ATP availability. Preclinical models also suggest a reduction in oxidative stress and neuroinflammation, an increase in cerebral blood flow, and stimulation of neurogenesis and synaptogenesis. These findings remain speculative and do not constitute clinical evidence.

Limits You Should Know

The authors explicitly state the main limitation: the level of evidence is low. The available studies are exploratory, of varying quality, with small sample sizes and heterogeneous exposure parameters. The authors identify two gaps that need to be addressed: randomized, double-blind trials against a light placebo with a larger number of patients and longer follow-up, as well as dosimetry studies designed to determine the optimal parameters.

This finding should be interpreted as a lack of conclusion, not as evidence of efficacy. Nothing in this study establishes an effect of photobiomodulation on the progression of Alzheimer’s disease or Parkinson’s disease. The proposed mechanisms are preclinical and remain exploratory. Finally, the first author is affiliated with a company that develops photobiomodulation devices, which calls for a cautious interpretation of the favorable conclusions.

What This Means in Practice

Nothing will change in the short term for patients or caregivers. Cerebral photobiomodulation remains a subject of research for both of these diseases and is not a validated treatment option. It is not a substitute for any prescribed treatment or neurological follow-up. Any personal decision regarding this treatment should be discussed with a neurologist or primary care physician.

Frequently Asked Questions

Is cerebral photobiomodulation a treatment for Alzheimer's disease?

No. The authors of this review conclude that the current level of evidence is weak and does not support widespread use in clinical practice. Existing clinical studies are exploratory in nature. Photobiomodulation is not a substitute for any prescribed treatment or follow-up care.

Is it well tolerated by patients?

The authors report that all of the clinical studies reviewed demonstrate the safety of cerebral photobiomodulation. However, the abstract does not provide either the incidence of adverse effects or the duration of follow-up. Good tolerability observed in short-term studies does not guarantee long-term safety.

What's missing to make a decision?

The authors cite two specific needs. First, randomized, double-blind trials comparing the treatment to a light placebo, with a larger number of patients and a longer follow-up period. Second, dosimetry studies designed to identify the optimal light parameters, which currently vary widely from one study to another.

Reference

Blivet G, Touchon B, Cavadore H, Guillemin S, Pain F, et al. Brain photobiomodulation: a potential treatment for Alzheimer’s and Parkinson’s diseases. The Journal of Prevention of Alzheimer’s Disease, 2025;12(7):100185. PMID 40287365. DOI 10.1016/j.tjpad.2025.100185. https://pubmed.ncbi.nlm.nih.gov/40287365/

This summary is provided for informational purposes only and does not constitute medical advice. Photobiomodulation is not a substitute for prescribed treatment. Consult a healthcare professional.