Value of muscle strength in improving the predictive capability for cognitive decline in older women by established risk factors: A prospective cohort study in the Otassha Study

BackgroundWith a growing aging global population, dementia has become an important public health concern. However, few predictive models of cognitive decline include muscle strength as a variable.ObjectiveThis study aimed to assess whether handgrip and knee extensor muscle strengths could be associated with cognitive decline in older Japanese women and to examine the potential contribution of these measurements to established dementia onset prediction models.MethodsA prospective cohort study was conducted involving the data analyzed from 787 community-dwelling aged 65 years and older women, originally from the "Otassha Study." The baseline handgrip and knee extensor muscle strengths were measured. Cognitive decline was defined as a decrease of three or more points from the baseline score of the Japanese version of the Mini-Mental State Examination. Multivariate analyses were performed adjusting for various potential confounding factors, and interaction effects were explored. The discriminative performances of the extended models were evaluated using receiver operating characteristic (ROC) curve analysis.ResultsNotably, lower handgrip and knee extensor muscle strengths were associated with cognitive decline in participants ≥ 75-year-old. Adding handgrip strength to the established models slightly improved the predictive performance, thereof; however, adding knee extensor muscle strength did not.ConclusionsOur study revealed the values of handgrip and knee extensor muscle strengths were associated with cognitive decline among women aged 75 years and older. Incorporating handgrip strength into predictive models enhanced their accuracy, which highlighted the importance of assessing muscle strength to predict cognitive decline in older women.