Does baseline cognitive performance predict the response to mental fatigue in healthy individuals?

Introduction: Mental fatigue (MF), a psychobiological state induced by prolonged demanding cognitive activity, is implied to cause an increased injury risk in a healthy population.1-3 However, the level of emergence of MF is highly variable between different subjects, making it difficult to screen which people are more sensitive to its effects.4 Meanwhile, almost no factors have reliably been identified that can predict the response to MF.5 Since cognitive processes, such as attention and decision-making, are crucial for physical activities, this study aimed to investigate the link between cognitive abilities and the response to mental fatigue. Methods: We employed a randomized single-blinded placebo-controlled counter- balanced cross-over design. First, participants completed three cognitive tests (sustained attention to response task, psychomotor vigilance task, and N-BACK task) to measure attention, working memory, and response inhibition. During the experimental and control trial, participants completed either a 45-minute modified Stroop task or watched a documentary of the same duration. Before and after the experimental and control trial, all 48 participants were asked to rate their feeling of MF on a visual analogue scale (M-VAS). After the Stroop task/documentary, participants performed a Go-NoGo task and a 15-minute time trial to assess cognitive and physical performance. Linear regression was used to evaluate the relationship between cognitive performance and MF effects. Results: Baseline cognitive functions did not significantly relate to differences between scores on the M-VAS (F=2.126; p=.094). No significant relationship was found between baseline cognitive functions and the extent to which MF affects physical performance (F=1.315, p=.286). Finally, a marginally significant relationship was found between baseline cognitive performance and accuracy scores on the Go stimuli of the Go-NoGo task when participants are mentally fatigued (F=2.485; p=.063) but not for reaction time (F=.664; p=.621) or accuracy on the NoGo stimuli (F=.629; p=.646). Conclusion: It is of the utmost importance to identify athletes who are more susceptible to MF, as this could help us in developing effective injury prevention strategies. The present study revealed no significant relationship between baseline cognitive performance and susceptibility to MF. More research is needed to fully elucidate the individual response to MF.