A prospective cohort study on the association between grip strength and cognitive function in adults aged 50 years and above

Abstract

Objective: To evaluate the association between grip strength (GS) and cognitive function in a population-based longitudinal cohort of Chinese adults aged ≥50 years. Methods: The study population of 3 600 adults was from the baseline survey and two rounds of follow up of World Health Organization (WHO) study of global ageing and adult health (SAGE) in five districts of Shanghai (Hongkou, Huangpu, Minhang, Qingpu and Pudong) after excluding individuals with self-report stroke and depression. The effects of baseline GS on cognitive function and its changes were evaluated. Factor analysis was applied to generate an overall cognition score based on verbal recall trials, verbal fluency test, forward digit span test and backward digit span test. Linear mixed effects model was used to examine the predictive capability of baseline GS for changes in cognitive function. Results: A total of 3 600 participants aged (61.2±8.1) years at baseline survey were included in this study, including 1 668 (46.3%) men and 1 932 (53.7%) women. The average of baseline GS and total cognitive function score were (28.19±12.18) kg and (58.93±14.56) respectively. Cognitive function score declined significantly during the follow-up, however, the changes were different among different age groups, education level groups and household income groups. After adjusted for age, education level, marital status, household income, co-morbidity of chronic conditions, drinking status, smoking status, physical activity level, vegetable/fruit intakes and BMI, no relationships between the baseline GS and cognitive score at baseline survey and at 1st follow-up were observed, however, compared with lower GS quartile group, there was a significant relationship between higher baseline GS level and better cognitive function at 2nd follow-up. The participants with highest GS quartile had better cognitive performance over time (male: β=1.938,95%CI:0.644-3.231,P=0.003, female: β=2.192,95%CI:0.975-3.409,P<0.001 and those aged 50-64 years: β=1.652,95%CI:0.646-2.659,P=0.001) than those with the lowest quartile. Conclusions: Higher baseline GS was significantly related to better cognitive function with slow decline. Thus, it is an indicator of cognitive function in middle-aged and elderly Chinese.