A Proof-of-Concept Study Investigating the Effects of Transcranial Plus Intranasal Photobiomodulation on Cognitive Function after Repetitive Head Acceleration Events

<b><i>Objective:</i></b> Investigate the effects of transcranial plus intranasal photobiomodulation (PBM) treatment on cognitive function, using an 810 nm light emitting diode headset and intranasal applicator every other day for 8-10 weeks. <b><i>Background Data:</i></b> An effective gold standard for the rehabilitation of repetitive head acceleration events (RHAEs) does not yet exist. <b><i>Methods:</i></b> Forty-four participants with a history of RHAEs completed a battery of cognitive tests before and after PBM treatment. Data were analyzed at the group level (paired samples <i>t</i>-tests, controlling for multiple comparisons) and on the individual-person level (reliable change indices). <b><i>Results:</i></b> On a group level, participants demonstrated statistically significant improvements with moderate-to-large effect sizes in fluid cognition, verbal learning and memory, attention and working memory, and aspects of executive function following PBM treatment. Specific improvements were observed in verbal learning/encoding and delayed recall, sustained attention, errors of omission and commission, working memory, inhibition, and cognitive switching. On the individual level, 0-36% of participants showed reliable improvement across cognitive measures, depending on the subtest; changes were greatest on measures of attention and memory. <b><i>Conclusions:</i></b> Results suggest that PBM treatment may be a promising intervention for improving cognitive function in individuals with a history of RHAEs. Observed improvements in cognitive function following PBM treatment may have important implications for the prevention and treatment of cognitive impairments associated with RHAEs. Further studies with more robust research designs that utilize clinical trial methodologies are needed to confirm and extend these findings.