The Grip Strength Loss Rate and the Subsequent Cognitive Decline Rate in Older Adults: The Moderating Role of Social Isolation.

BACKGROUND AND OBJECTIVES

Accumulating evidence suggests that low grip strength (GS) is associated with a faster cognitive decline, but most previous studies have measured GS at a single time point, ignoring changes in GS. We aimed to explore the association of the GS loss rate with the sequent cognitive decline, as well as the moderating role of social isolation in older adults.

RESEARCH DESIGN AND METHODS

Data were from the English Longitudinal Study of Ageing. Absolute and relative GS loss rates were calculated as the annual losses from Wave 2 (2004-05) to Wave 4 (2008-09). Participants were divided into 3 groups according to the tertiles of GS loss rates. Linear mixed models were used to assess the association of the GS loss rate during Waves 2-4 with the cognitive decline rate during Waves 4-9 (Wave 9, 2018-19).

RESULTS

Of the 4 356 participants included in analyses, 1 938 (44.5%) were men, with a mean age of 68.4 (: 8.4) years. Compared with Tertile 1 of the absolute GS loss rate, Tertile 2 (β = -0.009 [95% CI: -0.018 to -0.001] /year) and Tertile 3 (β = -0.018 [95% CI: -0.027 to -0.010] /year) were associated with a faster cognitive decline rate. The results of relative GS were similar to those of absolute GS. Social isolation was a significant modifier in the associations of the absolute GS loss rate with decline rates in global cognition and episodic memory, but not in temporal orientation. We did not observe that social isolation moderated the association of the relative GS loss rate with the cognitive decline rate.

DISCUSSION AND IMPLICATIONS

Both absolute and relative GS loss rates were positively associated with the cognitive decline rate in older adults. Low social isolation scores attenuated the association of the absolute GS loss rate with the cognitive decline rate.