Zhao Y. et al. - Photobiomodulation and Cognitive Function in Alzheimer's Disease: A Bayesian Network Meta-Analysis

A Bayesian network meta-analysis published in 2026 compared pharmacological and non-pharmacological interventions for cognition in Alzheimer’s disease. Photobiomodulation was found to have the highest estimated effect, with a standardized effect size of 0.66, compared with pharmacological therapy, which was estimated at 0.36.

What this study measured

Of all the approaches available for people with Alzheimer’s disease—including medications—which ones are most effective at improving cognitive function? To answer this question, a team from the School of Public Health at Tongji Medical College conducted a Bayesian network meta-analysis, a technique that allows interventions to be ranked even when they have never been directly compared.

Two investigators screened five English-language databases (PubMed, MEDLINE, Embase, Cochrane CENTRAL, Web of Science) and three major Chinese databases (CNKI, Wanfang, VIP), significantly expanding the usual scope of the search; the initial screening identified 4,788 cases. The protocol is registered on PROSPERO (CRD420251075628). Risk of bias and publication bias were assessed, and a meta-regression was performed to complement the analysis. The outcome of interest was cognitive function, expressed as the standardized mean difference (SMD).

Key Findings

Five interventions were associated with a significant improvement in cognition. Photobiomodulation and enriched environments stood out in the rankings, but a high ranking does not imply superiority demonstrated by direct testing.

• Photobiomodulation: SMD = 0.66 (95% credible interval: 0.29 to 1.02).
• Enriched environment: SMD = 0.69 (95% credible interval: 0.08 to 1.31).
• Drug therapy: SMD = 0.36 (95% credible interval: 0.17 to 0.55).
• Cognitive stimulation therapy: SMD = 0.32 (95% credible confidence interval: 0.11 to 0.55).
• Physical activity: SMD = 0.28 (95% credible interval: 0.06 to 0.51).
• SUCRA ranking: 87.3% for photobiomodulation, 83.8% for enriched environments, 54.7% for drug therapy.

One negative finding is worth noting: music therapy did not differ statistically from the control group.

How photobiomodulation works for this indication

The mechanism remains hypothetical and has not been measured in this study. Red and near-infrared light is thought to be absorbed by cytochrome c oxidase, the terminal enzyme of the mitochondrial respiratory chain, which would increase ATP production and support the energy metabolism of neurons. Modulation of oxidative stress and brain inflammation, as well as an effect on cerebral blood flow, are also suggested in the preclinical literature.

Limits You Should Know

The credibility intervals are wide, particularly for the enriched environment, whose lower bound is close to zero: this reflects a limited number of relevant studies and genuine uncertainty. The SUCRA ranking is often overinterpreted; it indicates the probability of being ranked highly, not a significant difference compared with other options. The abstract does not specify the number of trials ultimately included, the number of participants analyzed, the GRADE certainty level, or the duration of follow-up. Finally, comparing drugs and non-pharmacological approaches within the same network remains challenging, as the blinding conditions are not comparable.

What This Means in Practice

This study does not suggest replacing drug therapy with photobiomodulation. It indicates that, in published trials, several non-pharmacological approaches achieve effects on cognition that are estimated to be at least equivalent to those of medications, which argues for incorporating them into a comprehensive treatment plan rather than pitting them against one another. The parameters used—wavelength, power, and number of sessions—are not reported in this abstract.

Frequently Asked Questions

Is photobiomodulation more effective than medication for Alzheimer's disease?

In this meta-analysis, its estimated effect on cognition (SMD 0.66) was greater than that of drug therapy (SMD 0.36). This is an indirect comparison based on a statistical model, not a trial directly comparing the two approaches. Under no circumstances does this justify discontinuing a prescribed treatment.

What other non-drug approaches have been shown to be beneficial?

An enriched environment (SMD 0.69), cognitive stimulation therapy (SMD 0.32), and physical exercise (SMD 0.28) were associated with significant improvement. Music therapy, on the other hand, did not differ from the control group.

Are these results reliable?

The findings are encouraging but preliminary. The credibility intervals are wide, and the summary does not provide a GRADE assessment of the certainty of the evidence. The authors present their approach as an innovative method of comparison, which suggests that confirmation through independent studies is warranted.

Reference

Zhao Y, Luo G, Huang C, et al. Comparative effects of some pharmacological and non-pharmacological interventions on cognitive function in Alzheimer’s disease: A Bayesian network meta-analysis. The Journal of Prevention of Alzheimer’s Disease, 2026. PMID 41966601. View the study on PubMed

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.