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, h2 = 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, h2 = 0.32), RTT (F (1, 40) = 17, p < 0.001, h2 = 0.38), and PCT (F (1, 40) = 13, p < 0.001, h2 = 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, h2 = 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.

Cognitive and balance performance of older adult women during COVID-19 pandemic quarantine: an ex post facto study.

Introduction: Isolation and self-quarantine can expose individuals, particularly older people, to cognitive and physical decline. Due to a reduction in their musculoskeletal and neural flexibility, older adults are more likely to be affected by quarantine limitations. This study aimed to investigate the effect of self-quarantine on cognitive and balance performance of older women during the COVID-19 outbreak. Material and methods: In a convenience sampling method, a total of 75 older adult women were recruited in this ex post facto study. The mini-mental state exam, single leg stance test, and timed up and go test were used to assess cognitive functions, static, and dynamic balance, respectively. Fall risk was measured by the Johns Hopkins assessment tool. Evaluations were performed before and after 7 months of quarantine due to the COVID-19 outbreak (November 2019 - June 2020), in which volunteers were at the lowest level of physical and social interaction. Results: No significant difference was observed in the mean static balance performance of the older adult women between the baseline and quarantine phases [p = 0.095, t (df) = -1.69]. The dynamic balance performance [p < 0.001, t (df) = 5.6] and cognitive status (p < 0.001, t = -7.4) decreased and the fall rate increased [p < 0.001, t (df) = 7.35] after 7 months of quarantine. Conclusions: It seems that self-quarantine can cause a decline in cognitive functions and dynamic balance performance of older women. It implies that the decrease in social interactions and physical activities caused by the limitations of self-quarantine put individuals at greater risk of cognitive impairment and increase their falling rate by impairing dynamic balance.

Transcranial near-infrared photobiomodulation could modulate brain electrophysiological features and attentional performance in healthy young adults.

The aim of the present study was to investigate the electrophysiological effects of the photobiomodulation (PBM) by the quantitative electroencephalography (qEEG) as a diagnostic method. The neurotherapeutic potential of transcranial PBM has been recently investigated in preclinical and clinical studies. According to the PBM mechanisms of action on increasing the cerebral blood flow and the neuronal firing, a change may occur in cortical electrical activity after transcranial PBM that could be revealed in qEEG. A total of 30 participants (15 males and 15 females) were included in this experimental study in a convenience sampling method. A 19-channel EEG was obtained from subjects, before and after receiving sham or real 850-nm PBM by light emitting diode (LED) array on the right prefrontal cortex (PFC). An attentional task also was completed by the participant before and after the irradiation. Results presented that the effect of PBM on the reaction time was significant (p = 0.001) in favor of the real-treatment group (p < 0.05). For the absolute power, repeated-measures ANOVA showed a significant interaction of group × time × frequency (p = 0.04). In the real-treatment group, absolute power of delta band was significantly reduced in all electrodes (p < 0.05). Also, a similar significant interaction of group × time × frequency was seen for relative power (p = 0.04). Post-hoc analysis showed a significant decrease in delta band after PBM in the real treatment group (p < 0.05). The study presented that light irradiation with 850-nm LED source on right PFC could change brain electrical activity and has beneficial effects on attentional performance.

Near-infrared photobiomodulation combined with coenzyme Q10 for depression in a mouse model of restraint stress: reduction in oxidative stress, neuroinflammation, and apoptosis.

This study was aimed to evaluate the effects of near-infrared (NIR) photobiomodulation (PBM) combined with coenzyme Q10 (CoQ10) on depressive-like behavior, cerebral oxidative stress, inflammation, and apoptosis markers in mice. To induce a depressive-like model, mice were subjected to sub-chronic restraint stress for 5 consecutive days. NIR PBM (810 nm laser, 33.3 J/cm2) and/or CoQ10 (500 mg/kg/day, gavage) were administered for five days concomitantly with immobilization. Behavior was evaluated by the forced swim test (FST), tail suspension test (TST), and open field test (OFT). Mitochondrial membrane potential as well as oxidative stress, neuroinflammatory, and markers of apoptosis were evaluated in the prefrontal cortex (PFC) and hippocampus (HIP). The serum levels of pro-inflammatory cytokines, cortisol, and corticosterone were also measured. PBM or CoQ10, or the combination, ameliorated depressive-like behaviors induced by restraint stress as indicated by decreased immobility time in both the FST and TST. PBM and/or CoQ10 treatments decreased lipid peroxidation and enhanced total antioxidant capacity (TAC), GSH levels, GPx and SOD activities in both brain areas. The neuroinflammatory response in the HIP and PFC was suppressed, as indicated by decreased NF-kB, p38, and JNK levels in PBM and/or CoQ10 groups. Intrinsic apoptosis biomarkers, BAX, Bcl-2, cytochrome c release, and caspase-3 and -9, were also significantly down-regulated by both treatments. Furthermore, both treatments decreased the elevated serum levels of cortisol, corticosterone, TNF-α, and IL-6 induced by restraint stress. Transcranial NIR PBM and CoQ10 therapies may be effective antidepressant strategies for the prevention of psychopathological and behavioral symptoms induced by stress.