Longitudinal relationships between grip strength, subjective memory complaints and cognitive function among middle-aged and older adults in China

Background Subjective memory complaints are considered an early sign of cognitive decline. Recent evidence shows that grip strength is an important predictor of cognitive function. However, few studies have compared whether one condition is uniquely associated with cognitive function when another condition is controlled for. Aims To explore the longitudinal associations of cognitive function with subjective memory complaints and grip strength in middle-aged and older adults, with a particular focus on whether one condition is uniquely associated with cognitive function when another condition is considered. Methods A total of 3,877 middle-aged and older adults (aged 45–92 years) from the China Health and Retirement Longitudinal Study reported on their demographic and health status and completed measures of grip strength and subjective memory complaints, as well as a series of cognitive tests, every two years between 2011 and 2015. Generalized estimating equation models were used to assess the relationships between grip strength, subjective memory complaints, and cognitive function. Results Grip strength was longitudinally associated with cognitive function (β = 0.021, 95% confidence interval [CI]: 0.011, 0.030, P < 0.001) independent of subjective memory complaints. In contrast, changes in the subjective memory complaints were not related to cognitive function over time (β = 0.107, 95% CI: − 0.025, 0.238, P = 0.112). Only at baseline subjective memory complaints were associated with poorer cognitive function (β = − 1.142, 95% CI: − 1.309, − 0.975, P < 0.001). Conclusions Grip strength might be a more important clinical correlate of cognitive function decline over time than subjective memory complaints. Discussion Regular assessment and close monitoring of grip strength might help identify individuals who might be at high risk for cognitive impairment.