Safety and Efficacy of Ashwagandha Root Extract on Cognition, Energy and Mood Problems in Adults: Prospective, Randomized, Placebo-Controlled Study.

This prospective, randomized, placebo-controlled study assessed the effects of Ashwagandha root extract (ARE) on cognition, energy, and mood in adults with self-reported cognitive and energy problems. Healthy subjects aged 30-75 years were randomized to receive ashwagandha (Withania somnifera) root extract (ARE) 600 mg/day (n = 60)/identical placebo (n = 60) orally for 8 weeks. Cognitive function was assessed at baseline and week 8 using a Computerized Mental Performance Assessment System (COMPASS). Secondary outcomes were Profile of Mood States Abbreviated Version (POMS-A), Mental Fatigue Scale (MFS) and Behavior Rating Inventory of Executive Function-Adult (BRIEF-A) for effects on mood, mental fatigue and executive function, respectively, assessed at baseline, week 4 and 8. Greater improvement (p < .05) from baseline scores were seen with ARE as against placebo for COMPASS items episodic memory, working memory and accuracy of attention. ARE also improved the POMS-A, MFS and BRIEF-A scores from baseline suggesting an improvement in mood, vigor, and an increase in the executive functioning respectively with ARE. The herb was well tolerated and had a good patient compliance with no serious adverse events reported in either of the groups. This study suggests that a dose of 600 mg a day can improve cognition, energy, and mood in adults with self-reported cognitive and energy problems.

Cognitive effort increases the intensity of rewards.

An important body of literature suggests that exerting intense cognitive effort causes mental fatigue and can lead to unhealthy behaviors such as indulging in high-calorie food and taking drugs. Whereas this effect has been mostly explained in terms of weakening cognitive control, cognitive effort may also bias behavioral choices by amplifying the hedonic and emotional impact of rewards. We report parallel findings with animals and humans supporting this hypothesis. In rats, exerting cognitive effort immediately before access to cocaine self-administration significantly increased drug intake. In addition, exerting cognitive effort increased the psychostimulant effect of cocaine. The effects of cognitive effort on addiction-related behaviors were eliminated and even reversed when animals could rest in their home-cage for 2-4 h before access to cocaine self-administration. Among humans, we found that expending cognitive effort increased consumption of tasty (but unhealthy) food by increasing the hedonic enjoyment of consuming the food. In addition, the effects were specific for emotionally relevant stimuli (i.e. food rewards) and did not generalize to judgment about neutral objects. Altogether these data suggest that intense cognitive effort can increase the perceived intensity of rewards and lead to their overconsumption. This effect may contribute to bad decision making induced by excessive cognitive effort and make people more vulnerable to indulge in unhealthy behaviors such as use of addictive drugs.

Examining the Independent and Interactive Carryover Effects of Cognitive and Physical Exertions on Physical Performance.

OBJECTIVE: This study compared the effects of prior cognitive, physical, and concurrent exertion on physical performance. BACKGROUND: Fatiguing cognitive and physical exertions have been shown to negatively affect subsequent task performance. However, it is not clearly understood if concurrent physical and cognitive effort may exaggerate the negative carryover effects on physical task performance when compared to cognitive or physical exertion alone. METHOD: Twenty-five participants completed four isometric handgrip endurance trials on different days. The endurance trials were preceded by four, 15-minute experimental manipulations (cognitive, physical, concurrent, control). Electromyography (EMG) and force tracing performance were monitored, with handgrip strength measured pre and post. Subjective ratings of mental and physical fatigue, as well as affect, motivation, and task self-efficacy, were also assessed. RESULTS: Handgrip strength decreased following both physical (-14.4% MVC) and concurrent (-12.3% MVC) exertion manipulations, with no changes being observed for the cognitive and control conditions. No differences were observed across conditions for endurance time, EMG, nor tracing performance. When compared to the control conditions, perceptions of mental and physical fatigue were higher following the experimental manipulation. Endurance trial self-efficacy was lower for the mental, physical and concurrent conditions compared to control. CONCLUSION: The concurrent condition resulted in similar decreases in strength as the physical fatigue condition, but otherwise resulted in similar carryover effects on endurance performance across all conditions. Further study is required at higher exposure levels, or for longer exposure durations, to further probe the influence of concurrent physical and cognitive effort on task performance. APPLICATION: Concurrent cognitive and physical effort resulted in similar physical performance decrements to physical effort alone.

EEG spatial inter-channel connectivity analysis: A GCN-based dual stream approach to distinguish mental fatigue status.

Mental fatigue is defined as a decline in the ability and efficiency of mental activities. A lot of research suggests that the transition from alertness to fatigue is accompanied by alterations in correlation patterns among various brain regions. However, conventional methods for detecting mental fatigue seldom emphases inter-channel connectivity in the spatial domain. To fill this gap, this paper explores the spatial inter-channel connectivity in alertness and fatigue, employing spectral graph convolutional networks (GCN) for mental fatigue detection. We utilized Pearson correlation coefficients (PCC) to establish temporal connections and magnitude-squared coherence (MSC) for spectral connections. Topological features of the brain network were then analysed. To enhance the learning of spatial inter-channel connectivity, a dual-graph strategy transforms edge features into node features, serving as inputs to the spectral GCN. By simultaneously learning PCC and MSC features, the model results indicate significant differences in some brain network characteristics between alert and fatigue states. It confirms that the synchronicity of brain operations differs in the alert state compared to mental fatigue, and indicates that fatigue states can influence correlation patterns among different brain regions. Our approach is evaluated on a self-designed experimental dataset containing 7 subjects, demonstrating a classification accuracy of 89.59 % in group-level experiments and 95.24 % at the subject level. Additionally, on the public dataset SEED-VIG containing 23 subjects, our method achieves an accuracy of 86.58 %. In summary, this paper proposes a neural network approach based on a dynamic functional connectivity network. The network integrates both temporal and spectral connections with the goal of simultaneously learning spatial inter-channel connectivity in time and frequency domains. This effectively accomplishes fatigue state detection, highlighting that fatigue significantly influences correlations among different brain regions.

Fatigue management: a systematic review of objective measurement techniques for cognitive fatigue.

BACKGROUND: Cognitive fatigue is a complex psychobiological state whereby task performance cannot be maintained. Return-to-work protocols typically rely on self-report measures, therefore the current systematic review aimed to identify "real-time" measures of objective cognitive fatigue to inform return-to-work protocols. METHODS: Studies were included if participants were at least 18 years old, assessed "real-time" objective cognitive fatigue that could be used outside of the lab (neuroimaging measures were, therefore, excluded), used an induction task that was separate to the measurement, were adequately powered, compared objective cognitive fatigue at baseline and post-induction, and included a cognitive fatigue induction task that was at least 30 minutes long.Nine electronic databases were searched until 31 December 2022 (MEDLINE; PsychArticle; PubMED, ProQuest; ProQuest for gray literature; Google Scholar; The Cochrane Library; The Health Technology Assessment Database; and Web of Science), with alerts set up on Google Scholar to notify of new relevant research since this date (reviewed until December 2023). The checklist for quasi-experimental studies (Joanna Briggs Institute, 2014) was used to assess the risk of bias. Whilst a meta-analysis was planned, the data were unsuitable so only a narrative synthesis was conducted. RESULTS: Fifty-seven studies were included, which were conducted within a variety of settings including naturalistic work scenarios, driving, aviation, and artificial computer-based tasks.Whilst the review found a range of potential measurements, there were inconsistencies in findings across studies highlighting the need for more research into the reliable measurement of objective cognitive fatigue in natural settings. DISCUSSION: The findings suggest that eye- and body-related measures may be sensitive measures of objective cognitive fatigue. However, comparisons across measurement types should be cautiously interpreted because eye-related and cognitive measures were far more common. The review highlighted the need for more consistent and transparent reporting across the field to advance our understanding of cognitive fatigue.

Do prolonged social media use or cognitive tasks impair neuroelectric and visuomotor performance in taekwondo athletes? A randomized and controlled trial.

OBJECTIVES: We aimed to compare whether: (1) social media use (SMU) would induce a similar state of mental fatigue compared to the Modified Stroop task (MST); (2) the SMU and the MST would affect neuroelectric responses; and (3) sport-specific visuomotor performance in the taekwondo (TKD) athletes was impaired by mental fatigue. METHODS: Fifteen TKD athletes underwent a 60-min Modified Stroop Task (MST), engaged in SMU, or watched a documentary (CON) in a randomized order. Pre and post-each conditions they responded to a Stroop task (ST) while the event-related potentials (ERP) were measured. The Visual Analogue Scale for mental tiredness (VAS-MT) was used to measure subjective feelings of mental fatigue Then, the athletes completed TKD-specific visuomotor tests. RESULTS: The VAS-MT response increases progressively in the MST condition (p < 0.001). The response time of ST was slower in the MST than in SMU (p = 0.04). The accuracy dropped in MST comparing pre- and post-manipulation (p < 0.001) and was lower than post-CON (p = 0.005). The peak amplitude for N200 ERP was higher post-than pre for all conditions (p < 0.001) on the Fz channel. N200 amplitude was higher on CON than MST on post-manipulation (p = 0.02). The amplitude increased significantly from pre-to post in the CON condition (p = 0.009) on the Cz channel. There was no difference in visuomotor performance among conditions (all ps > 0.05). CONCLUSION: Prolonged performance of the MST, but not SMU, induces a state of mental fatigue. Neuroelectric and cognitive responses were impaired by mental fatigue induced by MST, but the visuomotor performance remained unaffected by any condition.

Physiological Predictors of Operator Performance: The Role of Mental Effort and Its Link to Task Performance.

OBJECTIVE: The present study investigated how pupil size and heart rate variability (HRV) can contribute to the prediction of operator performance. We illustrate how focusing on mental effort as the conceptual link between physiological measures and task performance can align relevant empirical findings across research domains. BACKGROUND: Physiological measures are often treated as indicators of operators' mental state. Thereby, they could enable a continuous and unobtrusive assessment of operators' current ability to perform the task. METHOD: Fifty participants performed a process monitoring task consisting of ten 9-minute task blocks. Blocks alternated between low and high task demands, and the last two blocks introduced a task reward manipulation. We measured response times as primary performance indicator, pupil size and HRV as physiological measures, and mental fatigue, task engagement, and perceived effort as subjective ratings. RESULTS: Both increased pupil size and increased HRV significantly predicted better task performance. However, the underlying associations between physiological measures and performance were influenced by task demands and time on task. Pupil size, but not HRV, results were consistent with subjective ratings. CONCLUSION: The empirical findings suggest that, by capturing variance in operators' mental effort, physiological measures, specifically pupil size, can contribute to the prediction of task performance. Their predictive value is limited by confounding effects that alter the amount of effort required to achieve a given level of performance. APPLICATION: The outlined conceptual approach and empirical results can guide study designs and performance prediction models that examine physiological measures as the basis for dynamic operator assistance.

Brain endurance training improves soccer-specific technical skills and cognitive performance in fatigued professional soccer players.

OBJECTIVES: Brain Endurance Training (BET) - the addition of mentally fatiguing cognitive tasks to standard physical training - could improve performance in soccer. We tested whether BET, with cognitive tasks intermixed with physical training activities, improved players' cognitive and soccer-specific technical performance compared to physical training alone when fresh and fatigued. DESIGN: The study employed a pre/training/midtest/training/posttest design. METHODS: 31 professional male soccer players were randomly assigned to BET or control groups and completed 18 physical training sessions over 6 weeks. In between the physical training activities, the BET group completed demanding cognitive tasks, whereas the control group rested. Players completed the Loughborough soccer passing (LSPT) and shooting test (LSST) before and after completing a 30-min Stroop task. A brief psychomotor vigilance test (PVT-B), a visual analog rating of mental fatigue (MF-VAS), and rating of perceived exertion (RPE) were measured during testing and training. RESULTS: During testing, the 30-min Stroop task elicited a state of MF, confirmed by higher subjective ratings (P < .01). Compared to pre-testing, at mid- and post-testing, the BET group improved passing (all P < .01), shooting (all P < .01), and PVT-B performance (all P < .01) when tested after (fatigued) but not before (fresh) the Stroop task, whereas the control group did not change performance either way. During training the BET group reported higher MF (P < .01) and exhibited slower PVT-B responses (P < .01) compared to control. CONCLUSIONS: Intermixed BET was more effective than physical training alone at improving cognitive and soccer-specific technical performance of professional soccer players when fatigued.

Designing a practical fatigue detection system: A review on recent developments and challenges.

INTRODUCTION: Fatigue is considered to have a life-threatening effect on human health and it has been an active field of research in different sectors. Deploying wearable physiological sensors helps to detect the level of fatigue objectively without any concern of bias in subjective assessment and interfering with work. METHODS: This paper provides an in-depth review of fatigue detection approaches using physiological signals to pinpoint their main achievements, identify research gaps, and recommend avenues for future research. The review results are presented under three headings, including: signal modality, experimental environments, and fatigue detection models. Fatigue detection studies are first divided based on signal modality into uni-modal and multi-modal approaches. Then, the experimental environments utilized for fatigue data collection are critically analyzed. At the end, the machine learning models used for the classification of fatigue state are reviewed. PRACTICAL APPLICATIONS: The directions for future research are provided based on critical analysis of past studies. Finally, the challenges of objective fatigue detection in the real-world scenario are discussed.

Brain activity during working memory in patients with autoimmune Addison's disease.

Autoimmune Addison's disease (AAD) is treated with daily oral hormone replacements for cortisol and aldosterone. The current treatment is sub-optimal, and frequently results in supra- and infra-physiological cortisol levels that might negatively affect the brain and cognitive functioning. It is currently unclear if the brains of these patients need to be better protected. The present study investigates brain function during working memory in young adults with AAD compared to healthy controls. All participants (56 AAD (33 females), 62 controls (39 females), 19-43 years), underwent MRI brain scanning while performing a visuo-spatial and verbal working memory task. No main group differences in accuracy, reaction time or brain activity during the tasks were found. These findings suggest that patients perform equal to controls, and achieve similar levels of brain activity during working memory. However, variations in the patient population may have confounded this outcome. Controlled studies on larger cohorts are therefore needed to confirm these findings and test if having AAD affects the brain on the long term.

Exploring Risk Perception, Mental Health, Mental Fatigue, Stigma, and the Quality of Life among UAE Healthcare Workers during the COVID-19 Pandemic: A National Multicentric Cross-Sectional Study.

Globally, the COVID-19 pandemic has presented serious mental health challenges for healthcare professionals. This study investigated the mental health, mental fatigue, quality of life, and stigma of social discrimination among healthcare workers in the United Arab Emirates (UAE) during the COVID-19 pandemic. A correlational, cross-sectional, multi-centric design was employed to collect data from 1383 healthcare workers across various healthcare settings. Participants were recruited using combined cluster and purposive sampling techniques. Standardized questionnaires, including the COVID-19 Pandemic Mental Health Questionnaire (CoPaQ), the Mental Fatigue Scale (MFS), the Social Discrimination Scale-Stigma Subscale (SDS), and the WHO Quality of Life Questionnaire-Brief (WHOQOL-BREF), were administered to assess the study variables. The results indicated significant mental health impacts, with high average scores for post-traumatic stress disorder (PTSD) (9.37 ± 6.74) and positive coping by inner strengths (17.63 ± 5.72). Mental fatigue was prevalent (8.15 ± 8.62), and stigma of social discrimination scored notably (23.83 ± 7.46). Quality of life was the highest in the social domain (65.38 ± 24.58). Significant correlations were observed between mental health subscales, mental fatigue, and quality of life domains. These findings highlight the critical need for targeted mental health support programs, improved social support networks, and personalized interventions to mitigate the mental health challenges faced by healthcare workers. Healthcare organizations can guarantee a resilient workforce that can handle future health crises by giving mental health resources and support systems top priority.

Corrigendum: Lateral prefrontal cortex thickness is associated with stress but not cognitive fatigue in exhaustion disorder.

[This corrects the article DOI: 10.3389/fpsyt.2023.1314667.].

High Cognitive Effort Prior to Velocity-Based Training Sessions Reduces Rate of Force Development but Not Maximum Strength Gains in Untrained Male Adults.

This study aimed to analyze the chronic effect of high cognitive effort immediately before resistance exercise sessions on neuromuscular performance in untrained male adults. We used a mixed experimental design, with the group as between-participants factor and time as within-participants factor. Thirty-four participants were randomly assigned to two parallel groups: high cognitive effort (n = 17) and control (n = 17). Subjects in the control group were seated for 30 min before the resistance exercise sessions, while the high cognitive effort group completed incongruent trials of the Stroop task until subjective mental fatigue was present immediately before resistance exercise sessions. Participants attended 45 sessions over 15 weeks, consisting of three familiarizations, three baseline evaluations, 36 velocity-based training sessions, and three postexperiment evaluation sessions. Rate of force development (RFD) during the isometric mid-thigh pull, half back-squat 1-RM, and countermovement jump (CMJ) were measured before and after the 12-week intervention. A significant group × time interaction effect was found for the average RFD at 0-250 ms (p < 0.05), with greater improvements for the control group than for the high cognitive effort group. There was no group × time interaction for half back-squat 1-RM (p > 0.05). Also, there was no group × time interaction for CMJ (p > 0.05). In conclusion, repeated high cognitive effort immediately prior to resistance exercise sessions is a phenomenon that can induce greater early velocity loss and, consequently, impairs the improvements in RFD. However, this did not inhibit the increased performance for explosive strength and CMJ in male untrained adults. High cognitive effort before resistance exercise sessions should be avoided.

Does mental fatigue affect performance in racket sports? A systematic review.

Mental fatigue impairs performance across several sports domains. However, a systematic review on its effects on racket sports performance has been lacking due to the previous scarcity of studies. This review aims to provide a comprehensive review the effects of mental fatigue on racket players' performance, with a discussion of the underlying mechanisms. A thorough search was conducted across five databases, including Web of Science, PubMed, SCOPUS, SPORTDiscus (via EBSCOhost), and the Psychological and Behavioral Science Collection (via EBSCOhost). The PICOS framework established the inclusion criteria: (1) healthy racket sports players; (2) induction of mental fatigue in both field and laboratory settings; (3) comparison of mental fatigue interventions with a control group (e.g., watching a movie or reading a magazine); (4) assessment of performance outcomes, including physical performance, skilled performance, and perceptual-cognitive performance; and (5) randomized controlled trials (RCTs), non-randomized controlled trials (non-RCTs), and non-randomized non-controlled trials. Mental fatigue manipulation, subjective evaluation, and (neuro)physiological markers were synthesized to support the successful induction of mental fatigue. Performance was categorized into tennis, table tennis, badminton, and padel based on the characteristics of specific racket sports domains. Secondary outcomes, such as the rate perception of effort (RPE) and motivation, were synthesized to explain the mechanisms based on the prominent theory of the Psychobiological model of endurance performance. Six studies revealed that mental fatigue impacts stroke performance in table tennis, affecting speed, accuracy, faults, and only second-serve accuracy in tennis. The response time of psychomotor performance increased in table tennis, padel, and badminton. Meanwhile, mental fatigue increased the RPE and remained unchanged in heart rate, blood glucose, and lactate, consistent with the Psychobiological model of endurance performance. Additionally, attention is suggested as a significant underlying psychobiological factor.

Overt and Covert Effects of Mental Fatigue on Attention Networks: Evidence from Event-Related Potentials during the Attention Network Test.

Mental fatigue is a variation in the psychophysiological state that subjects encounter during or after prolonged cognitive activity periods, affecting top-down attention and cognitive control. The present study aimed to investigate the effects of mental fatigue on attention in the context of the three attention networks according to the Posnerian model (alerting, orienting, and executive networks) by combining the Attentional Network Test (ANT) and event-related potentials technique. Thirty healthy subjects were enrolled in the study. A continuous arithmetic task lasting one hour induced mental fatigue, and EEG recordings were conducted before and after the task while subjects were performing the ANT. The efficiencies of three networks were comparable between groups, while RTs shortened only in the control group and the accuracy related to the alerting and conflict networks declined only after mental effort. Mental fatigue reduced N1 amplitude during alerting network engagement and p3 amplitude during orienting. It also reduced N2 and P3 amplitude during the conflict, particularly the incongruent target-locked response. These findings underscore the covert effects of mental fatigue on attention, suggesting that even in healthy young subjects, compensatory mechanisms may maintain adequate overt performances, but fatigue still has a detrimental effect on top-down attentional mechanisms.

The moderating role of coping styles on the associations of fatigue with life satisfaction in Chinese nurses: a cross-sectional study.

BACKGROUND: Fatigue affects nurses negatively and may influence life satisfaction. According to the stress process model, active coping might influence the impact of adverse conditions such as fatigue on well-being measures such as life satisfaction. However, no research examined the associations among nurses' fatigue, coping styles, and life satisfaction. METHODS: The cross-sectional study was conducted in Liaoning Province, China. 482 effective questionnaires were collected (effective response rate of 80.3%). The questionnaire included Fatigue Scale-14, Simplified Coping Style Questionnaire and Satisfaction with Life Scale. The association among fatigue, coping styles and fatigue × coping styles interaction with life satisfaction was examined by hierarchical multiple regression analysis. The interaction was visualized by simple slope analysis. RESULTS: Mean score of life satisfaction was 22.74 ± 6.11. Active coping moderated the relationship between mental fatigue and life satisfaction. The impacts of mental fatigue on life satisfaction gradually decreased in the low (1 SD below the mean, ß=-0.400, P < 0.001), mean (ß=-0.312, P < 0.001), and high (1 SD above the mean, ß=-0.224, P < 0.001) groups of active coping. CONCLUSION: The life satisfaction of Chinese nurses was relatively low. Active coping could alleviate the impact of mental fatigue on life satisfaction. Developing active coping styles might be a crucial strategy to alleviate nurses' mental fatigue and improve life satisfaction.

Mental fatigue recognition study based on 1D convolutional neural network and short-term ECG signals.

BACKGROUND: Mental fatigue has become a non-negligible health problem in modern life, as well as one of the important causes of social transportation, production and life accidents. OBJECTIVE: Fatigue detection based on traditional machine learning requires manual and tedious feature extraction and feature selection engineering, which is inefficient, poor in real-time, and the recognition accuracy needs to be improved. In order to recognize daily mental fatigue level more accurately and in real time, this paper proposes a mental fatigue recognition model based on 1D Convolutional Neural Network (1D-CNN), which inputs 1D raw ECG sequences of 5 s duration into the model, and can directly output the predicted fatigue level labels. METHODS: The fatigue dataset was constructed by collecting the ECG signals of 22 subjects at three time periods: 9:00-11:00 a.m., 14:00-16:00 p.m., and 19:00-21:00 p.m., and then inputted into the 19-layer 1D-CNN model constructed in the present study for the classification of mental fatigue in three grades. RESULTS: The results showed that the model was able to recognize the fatigue levels effectively, and its accuracy, precision, recall, and F1 score reached 98.44%, 98.47%, 98.41%, and 98.44%, respectively. CONCLUSION: This study further improves the accuracy and real-time performance of recognizing multi-level mental fatigue based on electrocardiography, and provides theoretical support for real-time fatigue monitoring in daily life.

The Influence of Changes in Daily Life Habits and Well-Being on Fatigue Level During COVID-19 Pandemic.

The COVID-19 pandemic and its lockdown in March 2020 have led to changes in lifestyle and increased levels of anxiety, depression, and fatigue. This survey examined a number of factors (anxiety state, sleep quality, daily activities, mental load, work-related variables) influencing mental and physical fatigue during lockdown and how these relations have evolved one year later. A cohort of 430 workers and 124 retirees were recruited in April-May 2020 (lockdown period, data set 1), and a subsample (133 workers and 40 retirees) completed the same questionnaire in April-May 2021 (data set 2). Linear regression models showed a significant subjective increase in both physical and mental fatigue in both worker and retiree groups during lockdown, and a supplementary increase in physical fatigue and anxiety level in spring 2021 compared to the lockdown period. During lockdown, anxiety level, concerns about COVID-19, work flexibility, mental load, and sleep metrics were associated with the evolution of fatigue among workers. For retirees, only anxiety and physical activity levels were linked to changes in physical fatigue. In April-May 2021, the only associations which remained significant were those in workers between fatigue and anxiety level and workload. These findings suggest that the increased fatigue levels during the lockdown are likely due to the swift and significant changes in daily routines (such as sleep patterns and work dynamics) and psychological states (including increased anxiety and concerns) prompted by the sanitary crisis. On the other hand, the increase in fatigue observed one year after the beginning of the pandemic seems to result from more psychological factors associated with the health situation.

The effect of transcranial electrical stimulation on the relief of mental fatigue.

Objective: The presence of mental fatigue seriously affects daily life and working conditions. Non-invasive transcranial electrical stimulation has become an increasingly popular tool for relieving mental fatigue. We investigated whether transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS) could be used to alleviate the state of mental fatigue in a population of healthy young adults and compared their effects. Methods: We recruited 10 participants for a blank control, repeated measures study. Each participant received 15 min of anodal tDCS, α-tACS, and blank stimulation. Participants were required to fill in the scale, perform the test task and collect ECG signals in the baseline, fatigue and post-stimulus states. We then assessed participants' subjective fatigue scale scores, test task accuracy and HRV characteristics of ECG signals separately. Results: We found that both anodal tDCS and α-tACS significantly (P < 0.05) reduced subjective fatigue and improved accuracy on the test task compared to the blank group, and the extent of change was greater with tACS. For the HRV features extracted from ECG signals. After tACS intervention, SDNN (t = -3.241, P = 0.002), LF (t = -3.511, P = 0.001), LFn (t = -3.122, P = 0.002), LFn/HFn (-2.928, P = 0.005), TP (t = -2.706, P = 0.008), VLF (t = -3.002, P = 0.004), SD2 (t = -3.594, P = 0.001) and VLI (t = -3.564, P = 0.001) showed a significant increasing trend, and HFn (t = 3.122, P = 0.002), SD1/SD2 (t = 3.158, P = 0.002) and CCM_1 (t = 3.106, P = 0.003) showed a significant decreasing trend. After tDCS intervention, only one feature, TINN, showed a significant upward trend (P < 0.05). The other features showed non-significant changes but roughly the same trend as the tACS group. Conclusion: Both tDCS and α-tACS can be effective in relieving mental fatigue, and α-tACS is more effective than tDCS. This study provides theoretical support for tDCS with α-tACS having a alleviating effect on mental fatigue and the use of ECG as a valid objective assessment tool.

Nature-Based Therapeutic Intervention for Individuals with Post-Concussion Symptoms.

This study investigated the efficacy of a 10-session nature-based therapeutic intervention for people with post-concussion symptoms. The intervention involved physical and vestibular exercises, sensory training, relaxation, and psychoeducation, all of which were integrated with the natural environment in a forest therapy garden. This study was designed with a passive control period followed by the intervention (n = 30). The Mental Fatigue Scale (MFS) was the primary outcome measure. The secondary outcome measures were the Warwick-Edinburg Mental Wellbeing Scale and the short version of the Quality of Life after Brain Injury. A Likert scale was used to examine the mental strain of the sessions themselves. The MFS (primary outcome) exhibited a significant decrease with a medium-sized effect from before to after the intervention. The secondary outcomes exhibited significant increases from the beginning to the end of the intervention. All outcomes were sustained at follow-up ten weeks later. No significant difference was found from the control period. This study indicates that the described nature-based intervention is a feasible treatment for reducing prolonged post-concussion symptoms. However, it should be studied more in-depth to understand the impact of the natural environment and to validate the results on a larger representative population.