Introduction: Cognitive performance is crucial across every domain of life - from optimizing the performance of war fighters and athletes to simply managing day-to-day tasks. But what happens when cognitive function is impaired? Cognitive impairment can take on different forms and look like trouble remembering, learning new things, concentrating, or making decisions (Velindre University NHS Trust, n.d.).
Luckily, transcranial photobiomodulation (tPBM) has been showing promising results in improving cognitive function (Gao et al., 2023). When Dr. Michael Lundie’s team at Applied Research Associates, Inc. and Dr. Daniel Krawczyk’s group at the University of Texas, Dallas caught wind of this, they decided to take a closer look at this phenomenon, specifically with the intention of benefiting war fighters dealing with the repercussions of repeated head trauma.
In their recent pilot study, Lundie and his colleagues explored how near-infrared light could support cognitive performance in healthy adults. Their findings suggest tPBM could offer a safe, portable, and effective way to enhance mental agility, resilience, and working memory with exciting military, clinical, and personal applications.
Study Overview
This study included eight healthy participants, with four randomly assigned to a tPBM group and four to a sham (placebo) group. Over two sessions, participants wore the Neuradiant 1070, emitting 1070 nm near-infrared light targeting the dorsolateral prefrontal cortex (DLPFC), a region crucial for attention, working memory, and executive function.
The protocol used was…
Step 1: 5 mins of continuous wave
Step 2: 5 mins break
Step 3: 5 mins of continuous wave
Step 4: 5 mins break
Participants completed a variety of tasks, including:
- Working Memory Tasks - participants were shown a picture of shapes (“orientation task”) or coloured boxes (“color task”), which soon after disappeared. Then, a second image was shown and they were asked to state if it was the same image as the one previously shown.
- Psychomotor Vigilance Tasks (PVT) and Pupillometry - participants were presented with a dot on the screen that appeared periodically. Participants were asked to click the space bar as quickly as possible. The speed of responses evaluates how focussed and vigilant the participants were when doing the task, and their ability to sustain attention. With pupillometry, researchers were able to track pupil dilation to infer norepinephrine-related attention engagement.
- Brain Gauge Testing (measuring plasticity, reaction time, and cognitive fatigue) - asses how well the brain can zone in on a particular stimulus and ignore other distractions. Brain Gauge contains what looks like a computer mouse that vibrates at different intensities on either prong of the mouse. Participants were asked to click on the side with the higher intensity. This was used to assess the brain's ability to evaluate minute changes in stimuli, as well as their response time.
- Participants also filled out a pre and post Depression, Anxiety, Stress Scale (DASS) in order to assess scales of mental well being, but did not undergo any inferential statistical analysis, due to small sample size.
Key Findings
- Reduced DASS Scores in the Active Group:
- Three of four participants showed a reduction in depression scores by an average of 3 points.
- All participants started with anxiety scores in the ‘normal’ range yet still finished with reduced scores by 6.5 points.
- All participants showed a reduction in stress scores by 6 points.
- The sham group did not exhibit these changes, with two participants increasing and two decreasing in the depression and anxiety scores. Three participants showed no change in the stress group, with one having increased scores.
- Enhanced Speed and Plasticity: Evidenced by statistically significantly higher scores in the tPBM group on the Brain Gauge test, tPBM participants show faster reaction times and greater flexibility (plasticity). These reaction times were not different from the sham group at the start of the test, but became significantly faster towards the end of the test suggesting better resilience against cognitive fatigue.
- Improved Working Memory in Specific Domains: Significant gains were observed in high-load working memory tasks involving orientation (but not color), highlighting that tPBM may selectively enhance spatial and visuospatial memory.
- Stabilized Attention Systems: Pupillometry results with the PVT showed that tPBM participants had larger and more consistent pupil dilation, indicating greater attentional engagement and norepinephrine system stability. Increased reaction times were also observed in the tPBM group
Why this Matters The results align with the growing body of research suggesting that tPBM is most beneficial when cognitive demands are high. By supporting mitochondrial function, blood flow, and perhaps effecting neuromodulatory systems like norepinephrine as proposed in this study, tPBM appears to help the brain sustain performance under pressure (Hamblin, 2017; Salgado et al., 2015).
While this was a small pilot study, the findings are promising: they suggest that tPBM could become a useful tool for enhancing mental stamina, attention control, and working memory in both healthy individuals and those recovering from cognitive impairments.
Conclusion As research into brain optimization accelerates, tPBM offers a compelling, low-risk avenue for supporting cognitive health from people from all walks of life. Future studies with larger, more diverse samples are needed to confirm these early findings. But for now, studies by Lundie and his colleagues illuminate an exciting future: a world where a simple beam of light could help sharpen our minds and fortify our mental resilience.
References:
Gao, Y., An, R., Huang , X., Liu, W., Yang, C., & Wan, Q. (2023, October 16). Effectiveness of photobiomodulation for people with age-related cognitive impairment: A systematic review and meta-analysis. Effectiveness of photobiomodulation for people with age-related cognitive impairment: a systematic review and meta-analysis. https://pubmed.ncbi.nlm.nih.gov/37843594/
Hamblin, M. R. (2017). Mechanisms and applications of the anti-inflammatory effects of photobiomodulation. AIMS biophysics. https://pmc.ncbi.nlm.nih.gov/articles/PMC5523874
Salgado, A. S. I., Zângaro, R. A., Parreira, R. B., & et al. (2015). The effects of transcranial LED therapy (TCLT) on cerebral blood flow in elderly women. Lasers in Medical Science, 30(2), 339–346. https://doi.org/10.1007/s10103-014-1669-2
What is cognitive impairment?. Velindre University NHS Trust. (n.d.). https://velindre.nhs.wales/velindrecs/patient-information/dementia-information/what-is-cognitive-impairment/
