Joint associations of handgrip strength and chair-stand performance with motoric cognitive risk syndrome in older adults

BACKGROUND: Motor dysfunction is associated with cognitive vulnerability, but whether impairments across body regions jointly contribute to motoric cognitive risk syndrome (MCR) remains unclear. We examined the independent and joint associations of handgrip strength and chair-stand test (CST) with MCR. METHODS: This cross-sectional study included 6258 dementia-free older adults (mean age 71.5 ± 6.6 years; 63.1% women) from a community-based cohort. Handgrip strength and CST performance were used to define upper- and lower-extremity motor impairment. Participants were classified as normal, handgrip weakness only, CST impairment only, or combined motor impairment. Multivariable logistic regression was performed with adjustment for demographic, socioeconomic, lifestyle, and clinical factors. Additive and multiplicative interactions were assessed. RESULTS: MCR was present in 10.4% of participants. Using the A/B CST cutoff as the primary definition, adjusted odds ratios (95% confidence intervals) for MCR, compared with normal function, were 1.84 (1.14-2.97) for handgrip weakness only, 4.17 (2.97-5.85) for CST impairment only, and 9.17 (6.56-12.81) for combined motor impairment. Associations were directionally consistent across alternative CST cutoffs. A positive additive interaction was observed at the A/B CST cutoff (relative excess risk due to interaction = 3.48; attributable proportion = 0.40; and synergy index = 1.83), whereas multiplicative interaction was not positive. CONCLUSIONS: Combined handgrip weakness and poorer CST performance were strongly associated with prevalent MCR. A positive additive interaction at the primary CST cutoff suggests that joint motor impairment may help characterize MCR-related vulnerability in older adults.