Transcranial photobiomodulation increases cognition and serum BDNF levels in adults over 50 years: A randomized, double-blind, placebo-controlled trial

Background: There is a significant lack of therapeutic options for mild cognitive impairment (MCI), which is rapidly becoming a global epidemic due to aging. Transcranial photobiomodulation (t-PBM) involves delivering near-infrared light (NIR) to the scalp, targeting cortical areas of the brain. NIR t-PBM has recently emerged as a potential therapy for various neurodegenerative conditions, including memory issues.

Aims: This study aimed to evaluate cognition scores (primary outcome), depression, anxiety, resilience scores, neuroplasticity, and neurodegeneration biomarkers (secondary outcomes) in individuals with MCI undergoing t-PBM therapy or receiving a placebo.

Materials and methods: A total of 93 older adult individuals with MCI were randomly assigned to either a t-PBM (n = 47) or Placebo (n = 46) group. Clinical assessments were conducted at baseline, 60 days post-treatment, and a 150-day follow-up. We also measured serum levels of brain-derived neurotrophic factor (BDNF), a neuroplasticity biomarker, as well as neuron-specific enolase (NSE) and calcium-binding protein B (S100B), which are neurodegeneration biomarkers. Intervention effects were analyzed using repeated measures (RM) two-way ANOVA followed by Tukey post hoc test. Fischer's exact test and Generalized Estimating Equations (GEE) were also applied.

Results: Of the 93 older adults individuals invited to participate, 76 (t-PBM: 40, placebo: 36) completed the study. The t-PBM significantly improved cognition as measured by the Montreal Cognitive Assessment (MoCA) compared to placebo (p = 0.0301). The delta values for MoCA scores were 3.20 in the t-PBM group and 1.97 in the placebo group. This effect persisted until the three-month follow-up, accompanied by increased BDNF levels in the t-PBM group but not in the placebo group (p = 0.0046). The delta values for BDNF were 821.94 in the t-PBM group and 359.41 in the placebo group. t-PBM did not alter depression, anxiety, resilience scores, nor the levels of NSE and S100B in individuals with MCI.

Conclusion: The t-PBM increases cognitive function and BDNF levels in adults with MCI. Its application as an adjunctive treatment may play a crucial role in preventing neurodegenerative diseases.