Significant advances in the research of sport-related concussion (SRC) and repetitive head impacts (RHI) over the previous decade have translated to improved injury identification, diagnosis, and management. However, an objective gold standard for SRC/RHI treatment has remained elusive. SRC often result in heterogenous clinical outcomes, and the accumulation of RHI over time is associated with long-term declines in neurocognitive functioning. Medical management typically entails an amalgamation of outpatient medical treatment and psychiatric and/or behavioral interventions for specific symptoms rather than treatment of the underlying functional and/or structural brain injury. Transcranial photobiomodulation (tPBM), a form of light therapy, has been proposed as a non-invasive treatment for individuals with traumatic brain injuries (TBI), possibly including SRC/RHI. With the present proof-of-concept pilot study, we sought to address important gaps in the neurorehabilitation of former athletes with a history of SRC and RHI by examining the effects of tPBM on neurocognitive functioning.

The current study included 49 participants (45 male) with a history of SRC and/or RHI. Study inclusion criteria included: age 18-65 years and a self-reported history of SRC and/or RHI. Exclusion criteria included: a history of neurologic disease a history of psychiatric disorder, and MRI contraindication. We utilized a non-randomized proof-of-concept design of active treatment over the course of 8-10 weeks, and neurocognitive functioning was assessed at pre- and post-treatment. A Vielight Neuro Gamma at-home brain tPBM device was distributed to each participant following baseline assessment.

Participants completed standardized measures of neurocognitive functioning, including the California Verbal Learning Test (CVLT-3), Delis Kaplan Executive Function System (D-KEFS), Continuous Performance Test (CPT-3), and The NIH Toolbox Cognition Battery. Neurocognitive assessments were collected prior to and following tPBM treatment. Paired t-tests and Wilcoxon’s signed-rank tests were used to evaluate change in performance on measures of neurocognitive functioning for normal and nonnormal variables, respectively, and estimates of effect size were obtained.

Study participants’ ability for adapting to novel stimuli and task requirements (i.e., fluid cognition; t=5.96; p<.001; d=.90), verbal learning/encoding (t=3.20; p=.003; d=.48) and delayed recall (z=3.32; p=.002; d=.50), processing speed (t=3.13; p=.003; d=.47), sustained attention (t=-4.39; p<.001; d=-.71), working memory (t=3.61; p=.001; d=.54), and aspects of executive functioning improved significantly following tPBM treatment. No significant improvements in phonemic and semantic verbal fluencies, reading ability, and vocabulary were shown following tPBM treatment.

The results of this pilot study demonstrate that following 8-10 weeks of active tPBM treatment, retired athletes with a history of SRC and/or RHI experienced significant improvements in fluid cognition, learning and memory, processing speed, attention, working memory, and aspects of executive functioning. Importantly, the majority of effect sizes ranged from moderate to large, suggesting that tPBM has clinically meaningful improvements on neurocognitive functioning across various cognitive domains. These results offer support for future research employing more rigorous study designs on the potential neurorehabilitative effects of tPBM in athletes with SRC/RHI.