Chronic traumatic brain injury (TBI) remains a major challenge among military veterans, often leading to long-term cognitive dysfunction and reduced cerebral blood flow. In the search for innovative therapeutic approaches, photobiomodulation therapy (PBMT) using red and near-infrared (NIR) light has emerged as a non-invasive method with promising potential.
The Intervention: Pulsed Transcranial Photobiomodulation Therapy
This case series investigated the effects of pulsed transcranial PBMT (tPBMT) using light-emitting diodes (LEDs) in twelve military veterans diagnosed with chronic TBI (more than 18 months post-trauma). The intervention consisted of red/NIR light delivered through two neoprene therapy pads placed over the cranium, each containing 220 infrared and 180 red LEDs. The light was pulsed at three distinct frequencies (73, 587, and 1175 Hz) with a 35% duty cycle, for 6.7 minutes per frequency—totaling 20 minutes per session. Participants received the treatment three times a week over six weeks, for a total of 18 sessions.
The average power output was 3.3 W, with a power density of 6.4 mW/cm². Outcome measures included standardized neuropsychological test scores and both qualitative and quantitative assessments of regional cerebral blood flow (rCBF) using single-photon emission computed tomography (SPECT).
Results: Improvements in Cognition and Brain Perfusion
The findings showed that pulsed tPBMT significantly improved cognitive function in 40% of the evaluated neuropsychological subscales. Furthermore, 66.7% of the participants experienced increased regional cerebral blood flow, as detected by SPECT. Quantitative analysis confirmed a statistically significant rise in rCBF within this subgroup, highlighting potential physiological improvements in brain perfusion following treatment.
Authors’ Conclusions
The authors suggest that pulsed tPBMT using LEDs may offer a viable strategy to enhance cognitive function and cerebral blood flow, even years after the initial brain injury. This study was the first to use sequentially pulsed LED technology combined with quantitative SPECT imaging in chronic TBI patients. Although the study design presents some limitations—such as the small sample size and lack of a control group—the results align with previous research and support the continued investigation of LED-based tPBMT.
The hypothesized mechanisms include nitric oxide release, mitochondrial stimulation, vasodilation, and neuroprotective effects, contributing to improved energy metabolism and vascular health. As new interventions for neuropsychiatric conditions are developed, integrating quantitative biomarkers like rCBF could enhance both clinical outcomes and scientific validation.
Reference: Hipskind SG, Grover FL Jr, Fort TR, Helffenstein D, Burke TJ, Quint SA, Bussiere G, Stone M, Hurtado T. Pulsed Transcranial Red/Near-Infrared Light Therapy Using Light-Emitting Diodes Improves Cerebral Blood Flow and Cognitive Function in Veterans with Chronic Traumatic Brain Injury: A Case Series. Photobiomodul Photomed Laser Surg. 2019; 37(2):77-84. doi: 10.1089/photob.2018.4489.