The Longitudinal Associations of Handgrip Strength and Cognitive Function in Aging Americans.

Objectives: Factors that are responsible for age-related neurologic deterioration of noncognitive and cognitive processes may have a shared cause. We sought to examine the temporal, directional associations of handgrip strength and cognitive function in a national sample of aging Americans.
Design: Longitudinal panel.
Setting: Enhanced interviews that included physical, biological, and psychosocial measures were completed in person. Core interviews were often conducted over the telephone.
Participants: The analytic sample included 14,775 Americans aged at least 50 years who participated in at least 2 waves of the 2006-2016 waves of the Health and Retirement Study.
Measures: Handgrip strength was measured with a hand-held dynamometer. Participants were considered cognitively intact, mildly impaired, or severely impaired according to the Telephone Interview of Cognitive Status questionnaire. Separate lagged general estimating equations analyzed the directional associations of handgrip strength and cognitive function.
Results: The overall time to follow-up was 2.1 ± 0.4 years. Every 5 kg higher handgrip strength was associated with 0.97 [95% confidence interval (CI) 0.93, 0.99] lower odds for both future cognitive impairment and worse cognitive impairment. Those who were not weak had 0.54 (CI 0.43, 0.69) lower odds for future cognitive impairment and 0.57 (CI 0.46, 0.72) lower odds for future worse cognitive impairment. Conversely, any (β = -1.09; CI -1.54, -0.64), mild (β = -0.85; CI -1.34, -0.36), and severe cognitive impairment (β = -2.34; CI -3.25, -1.42) predicted decreased handgrip strength. Further, the presence of any, mild, and severe cognitive impairment was associated with 1.82 (CI 1.48, 2.24), 1.65 (CI 1.31, 2.08), and 2.53 (CI 1.74, 3.67) greater odds for future weakness, respectively.
Conclusions/implications: Strength capacity and cognitive function may parallel each other, whereby losses of functioning in 1 factor may forecast losses of functioning in the other. Handgrip strength could be used for assessing cognitive status in aging Americans and strength capacity should be monitored in those with cognitive impairment.
(Copyright © 2019 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.)