Association of handgrip strength asymmetry and weakness with cognitive function: a nationally representative cohort study

Objective: To describe the association of handgrip strength asymmetry and weakness with cognitive function among Chinese middle-aged and older adults. Study design: We used data from four waves (2011, 2013, 2015, and 2018) of the China Health and Retirement Longitudinal Study. Handgrip strength was measured at baseline. Handgrip strength asymmetry was defined on the basis of the ratio of handgrip strength of the non-dominant hand to that of the dominant hand (i.e. nondominant/dominant): a ratio of <0.9 defined as dominant handgrip strength asymmetry and >1.1 as nondominant handgrip strength asymmetry. Weakness was defined as a handgrip strength of <28 kg for males or <18 kg for females. Main outcome measures: Cognitive function with its two core dimensions (episodic memory and mental status) at each wave was assessed and standardized. Results: 9333 participants (48.3 % female, age 58.2 +/- 9.0 years) were included. Non-dominant but not dominant handgrip strength asymmetry was significantly associated with poorer cognitive function at baseline (8 = -0.121, -0.092, and -0.132 for mental status, episodic memory, and global cognition, respectively). In longitudinal analyses over 2 years, dominant handgrip strength asymmetry significantly slowed cognitive decline (8 = -0.078 and -0.069 for mental status and global cognition, respectively), and non-dominant handgrip strength asymmetry accelerated cognitive decline (8 = 0.053 and 0.043 for episodic memory and global cognition, respectively). Weakness was associated with poorer cognitive function at baseline and cognitive decline over 2, 4, and 7 years (all P < 0.05). Conclusions: In middle-aged and older adults, non-dominant handgrip strength asymmetry and weakness were associated with poorer cognitive function and predicted accelerated cognitive decline. Dominant handgrip strength asymmetry may be beneficial for maintaining cognitive function.