Hand Grip Strength, Cognitive Function and the Role of Cognitive Reserve: Results from a Sample of Community Dwelling Elderly in China
ObjectivesTo examine the association between hand grip strength (HGS) and cognitive function, and the potentially moderating effects of cognitive reserve on this relationship using a sample of community dwelling elderly in China. MethodsThe subjects included 1291 community-dwelling elderly aged 60 or over and without dementia who participated in the baseline survey of an elderly cohort in Anhui province, China. Cognitive function was assessed using Mini-Mental State Examination (MMSE) and HGS was measured using an electronic grip strength dynamometer. The education (EDU) in early life, cognitive level of the job (CLJ) in middle age, cognitive leisure activities (CLA) in late life, and other covariates were collected through a face-to-face interview and physical examination. ResultsThe differences in MMSE scores across tertiles of HGS were significant (MMSE scores across tertiles of HGS: 20.26{+/-}7.02 vs 22.83{+/-}5.99 vs 24.76{+/-}6.36, F=62.05, P<0.001). After adjustment for covariates, the lower tertiles of HGS was related to lower MMSE scores when compared to the upper tertiles of HGS ({beta}={beta} [95%CI]: -2.02[-2.87~-1.17], P<0.001). However, no significant association existed between the intermediate tertiles of HGS and lower MMSE scores ({beta}={beta} [95%CI]: -0.28[-1.05~0.50], P=0.483). Moderation analyses revealed that the correlation between the lower tertiles of HGS and decreased MMSE scores was less pronounced in middle EDU ({beta}={beta} [95%CI]: -1.62[-3.22~-0.02], P=0.047), and in middle CLJ ({beta}={beta} [95%CI]: -2.17[-3.31~-1.24], P<0.0001) than in low EDU ({beta}={beta} [95%CI]: -2.46[-3.80~-1.12], P<0.0001), and in low CLJ ({beta}={beta} [95%CI]: -3.72[-6.92~-0.53], P=0.023). Furthermore, this relationship was not significant among the elderly with high EDU or the high CLJ. ConclusionsThe lower HGS is associated with poor cognitive function in older age, and cognitive reserve may attenuate or eliminate the relationship of lower HGS with cognitive function.