Traumatic brain injury (TBI) occurs in millions of people globally each year, with mild TBI (mTBI) representing over 90% of cases. Despite the common assumption of full recovery, significant disturbances persist in many patients with mTBI, including cognitive deficit, headache, dizziness, sleep problems, and symptoms of post-traumatic stress disorder (PTSD). Given that effective treatment is still scarce, the present study investigated the efficacy of transcranial photobiomodulation (tPBM) as an intervention for improving these sequelae in patients with mTBI. In this randomized placebo-controlled trial, 17 patients with mTBI were recruited. Participants were randomized to receive both real and sham tPBM conditions with a counterbalanced order, with a 1-week washout between interventions. Assessments were conducted at baseline, after real tPBM, and after sham tPBM. These included neuropsychological tests, measurements of oxygenated hemoglobin using functional near-infrared spectroscopy during a visual working memory task, and self-rated questionnaires assessing sleep quality, physical post-concussion symptoms, pain intensity, and PTSD symptoms. Compared with the baseline, participants demonstrated significant improvements. After receiving tPBM, patients showed enhanced cognitive efficiency, as evidenced by improved visual working memory performance, better learning in verbal memory tests, improved subjective sleep quality, fewer physical post-concussion symptoms, reduced pain intensity, and decreased PTSD symptoms. In contrast, no significant improvement was observed after patients received the sham tPBM. In addition, the statistically significant improvement in behavioral symptoms also reached the minimal clinically important difference, suggesting clinical significance. These findings support the potential of tPBM as a safe, non-invasive clinical intervention for cognitive deficits and associated symptoms in mTBI. Further exploration is encouraged to evaluate tPBM as a rehabilitation strategy for enhancing recovery in TBI patients.
Keywords: cognitive function; photobiomodulation; post-concussion symptoms; post-traumatic stress disorder; sleep; traumatic brain injury.