Sex-modified association between grip strength and mild cognitive impairment: a cross-sectional and follow-up study in rural China.

BACKGROUND: The sex difference in the association between grip strength and mild cognitive impairment (MCI) remains controversial and unclear. METHODS: This is a part of a chronic disease cohort study conducted in rural areas, Fuxin, Liaoning Province, China. At the baseline survey, a total of 2633 participants aged 35- 85 were included in the cross-sectional study. Handgrip strength (HGS, kg) was measured by a dynamometer (Jamar +). MCI were assessed using the Chinese version of the Montreal Cognitive Assessment-Basic (MOCA-BC). Then, a total of 1667 cognitively normal individuals (NCs) were planed to follow up and to assess the incident MCI after two years. We used logistic regression to examine the association between HGS (as a continuous variable and quintiles) and MCI and analyzed the interaction between sex and HGS on MCI. Models stratified by sex were adjusted for demographic information (age, ethnicity, education, marital status, income, physical labor level), modifiable risk factors (body mass index, smoking, drinking) and disease history (hypertension, diabetes, dyslipidemia and coronary heart disease). Baseline MOCA-BC scores were additionally adjusted in the longitudinal study. RESULTS: In the cross-sectional study, participants were on average 56.6 ± 9.8 years, and 1713 (65.1%) were females. In the cohort study, 743 individuals were followed up with an average age of 55.9 ± 9.6 years, which included 530 (71.3%) females. The cumulative incidence of MCI over a two-year period was 17.1%. In the cross-sectional study, compared to the highest quintile of HGS, the lowest HGS was associated with higher risk of MCI in males (odds ratio [OR]: 2.66; 95% confidence interval [CI]: 1.54, 4.64) and females (OR: 1.70; 95% CI: 1.17, 2.49) with adjustment of potential confounding factors. In the cohort study, compared to the highest quintile of HGS, the lowest HGS was associated with an increased risk of incident MCI in females (OR: 3.93; 95% CI: 1.39, 13.01) but not in males (OR: 0.56; 95% CI: 0.11, 2.94, P for interaction = 0.015). CONCLUSIONS: Lower grip strength is a risk factor for mild cognitive impairment and predicts a higher risk of MCI in females.