The effect of transcranial photobiomodulation on cognitive function and attentional performance of older women with mild cognitive impairment: a randomized controlled trial

INTRODUCTION: Mild cognitive impairment (MCI) is a progressive age-related condition caused by physiological and structural changes in the brain, such as neurodegeneration and hypometabolism. Transcranial photobiomodulation (tPBM) is a neuromodulation technique that improves brain metabolism and oxygenation by irradiating red to near-infrared light on a specific area of the head. This study aimed to investigate the effect of multi-session tPBM on the cognitive capacities and attentional function of older women with MCI. MATERIAL AND METHODS: In this randomized controlled trial, 42 older women with MCI were randomly assigned to 2 equal groups: real and sham. The mini-mental state examination (MMSE) and the attentional Go/No-Go task were used to examine the patients. On the right frontal-pole of the cortex, 5 sessions of 850 nm tPBM were given. Re-examinations were conducted on the participants. For the Go/No-Go task, the reaction time to the target (RTT), the percentage of correct trials (PCT), and the efficiency score (ES) were measured. RESULTS: The findings revealed a significant interaction between group × time for MMSE (F (1, 40) = 20, p < 0.001, h(2) = 0.33), and the post-hoc paired-samples t-tests revealed a substantial rise in the mean MMSE in the real group (t = 15.9; p = 0.001; d = 9.3). Additionally, for ES (F (1, 40) = 19, p < 0.001, h(2) = 0.32), RTT (F (1, 40) = 17, p < 0.001, h(2) = 0.38), and PCT (F (1, 40) = 13, p < 0.001, h(2) = 0.31), a significant group × time interaction was discovered, and post-hoc paired-samples t-tests revealed a significant improvement in attention performance of the real group for increases in the mean of ES (F (1,40) = 20, p < 0.001, h(2) = 0.33), (t = 5.3, p < 0.001, d = 0.034), decreases in the mean of RTT (t = 4.8; p = 0.001; d = –37.4), and increases in the mean of PCT (t = 2.67; p = 0.015; d = 6.3) CONCLUSIONS: According to the findings of this study, tPBM had a positive effect on older people’s attention and cognitive abilities.