Affiliations: [a] Department of Psychology, The Chinese University of Hong Kong, Hong Kong, China
| [b] Research Centre for Neuropsychological Well-Being, The Chinese University of Hong Kong, China
| [c] Laser Research Centre, Faculty of Health Science, University of Johannesburg, Doornfontein, South Africa
| [d] Radiation Biology Research Center, Iran University of Medical Sciences, Tehran, Iran
| [e] Department of Social Work, The Chinese University of Hong Kong, Hong Kong, China
Correspondence:
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Correspondence to: Agnes S. Chan, Department of Psychology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. E-mail: aschan@cuhk.edu.hk.
Abstract: Background:Recent studies of photobiomodulation (PBM) in patients with cognitive or psychological disorders (including traumatic brain injury, stroke, and dementia) have yielded some encouraging results. Objective:In this study, we aimed to investigate the effect of a single stimulation on memory in older adults with mild cognitive impairment (MCI). Methods:After PBM, hemodynamic changes, as a measure of functional brain activity, were evaluated using functional near-infrared spectroscopy (fNIRS). Eighteen subjects who met the criteria of MCI were randomly assigned to control and experimental groups. A single real or sham PBM session was administered to the forehead of each patient in the experimental and control groups, respectively. All subjects performed a visual memory span test before and after the stimulation, and their hemodynamic responses during the tasks were measured using fNIRS. Results:The results showed that among the MCI subjects, only those who received PBM, but not those who received the sham stimulation, demonstrated significant improvement in the visual memory performance and a reduction in the hemodynamic response during the tasks. Conclusion:These findings suggest that PBM may reduce the cognitive efforts needed to complete tasks that require high memory loads, and thus improve the cognitive performance of individuals with MCI.
