Mental Fatigue and Physical Function of Older People: A Scoping Review

Background: Mental fatigue is a common complaint of older adults. The possible impact of mental fatigue on the physical function of older people is concerning since physical function losses are associated with more visits to medical centres and higher medical expenses. The review examined studies that investigated the effects of mental fatigue on the physical function of older people. We searched the PubMed/MEDLINE, Scopus, and Web of Science databases. Methods: The review tracked the state of studies through the categorisation of studies by features, a tabular summary of study characteristics, and risk of bias analysis. Seventeen studies met the inclusion criteria. Publications on the effects of mental fatigue in the older adult's population are relatively scarce. Results: The most common combined method to induce mental fatigue was mental maths and quiet sitting, but when analysing experimental and control conditions separately, the most common methods were laboratory-based tasks for induction with low ecological validity and the use of a movie, documentary or reading as a control condition. The review suggested the lack of experimental research design. Most studies were interested in understanding the differences in mental fatigue effects between age groups of healthy participants. Conclusion: Overall, older people display greater force fluctuations. Studies have mainly examined balance and muscle function using low ecological fatigue induction and a combination of subjective and objective measures for manipulation checks. Chronic conditions are underrepresented. The existing evidence calls for more rigorous research to inform healthcare decisions.