Independent and Combined Associations of Handgrip and Knee Extension Strength With Cognitive Function in...

To examine the independent and combined associations of handgrip strength (HGS) and knee extension strength (KES) with global cognition in community-dwelling older adults.

Cross-sectional analysis of baseline data from a prospective cohort.

A total of 279 community-dwelling adults aged 65 years or older living independently (mean age 76.8 ± 5.9; 26.5% men).

Low strength was defined as the sex-specific lowest quartile (Q1). Multiple linear regression estimated differences in Mini-Mental State Examination (MMSE) scores adjusting for age, sex, education, and depressive symptoms (GDS-15). We examined (1) HGS and KES together, (2) 4 exclusive groups (low KES only, low HGS only, both low, neither), and (3) sensitivity analyses including skeletal muscle index and sex-stratified analyses using weight-normalized KES.

Low KES related to lower MMSE (Model 1 B, -0.882; 95% CI, -1.542 to -0.223, P = .009; Model 2 B, -0.892; 95% CI, -1.564 to -0.219; P = .010). Low HGS was not significant (P ≥ .27). When both were included, low KES remained significant (B, -0.814; 95% CI, -1.509 to -0.119; P = .022) but low HGS did not. In 4-group analysis, both low KES and HGS vs neither showed lower MMSE (B, -1.054; 95% CI, -1.984 to -0.112; P = .027). Associations for KES persisted after adjusting for skeletal muscle index (B, -0.842; 95% CI, -1.522 to -0.161; P = .016). In sex-stratified models, weight-normalized KES was associated with MMSE in men (B, 6.598; 95% CI, 2.258 to 10.939; P = .004) but not in women.

Lower KES shows a consistent and independent association with global cognition; combined weakness in upper and lower limbs signals greater cognitive deficit. Adding KES to community screening may improve early detection of cognitive vulnerability.