Genetic Covaration of Grip Strength and General Cognitive Ability in Octogenarian Swedish Twins

Grip strength is a strong predictor of later-life disability, morbidity and mortality. Likewise, reduced grip strength has been associated with cognitive decline. Using quantitative genetic techniques, we surveyed the contribution of genetic and environmental factors to the relationship between grip strength and general cognitive ability in 100 monozygotic and 131 dizygotic twin pairs. The sample was selected from the longitudinal study, “Origins of Variance in the Old-Old.” For the analysis, a latent general cognitive ability factor was constructed using measures of verbal ability, spatial ability, speed of processing, and memory. Bivariate model fitting revealed that genetic factors accounted for 74% of the phenotypic correlation ( r = .47) between grip strength and general cognitive ability. These results suggest that shared genetic factors underlie the relationship between grip strength and general cognitive ability and may also support the theory that common factors contribute to overall age-related deterioration of cognitive and non-cognitive functioning.

Supported by grants from the National Institute on Aging at the National Institutes of Health (AG08861 and AG000276).