Background: Several two-sample Mendelian randomization studies have reported discordant results concerning the association between grip strength and cardiovascular disease, possibly due to the number of instrumental variables used, pleiotropic bias, and/ or effect modification by age and sex.
Methods: We conducted a sex- and age-stratified one-sample Mendelian randomization study in the Canadian Longitudinal Study on Aging. We investigated whether grip strength is associated with carotid intima media thickness (cIMT), a marker of vascular atherosclerosis event risk, using eighteen single nucleotide polymorphisms (SNP) identified as specifically associated with grip strength.
Results: A total of 20,258 participants of self-reported European ancestry were included in the analytic sample. Our Mendelian randomization findings suggest a statistically significant association between grip strength and cIMT (MR coefficient of 0.02 (95% CI: 0.01, 0.04)). We found no statistically significant differences between sexes (p-value = 0.201), or age groups [(≤ 60 years old versus >60 years old); p-value = 0.421].
Conclusion: This study provides evidence that grip strength is inversely associated with cIMT. Our one-sample MR study design allowed us to demonstrate that there is no evidence of heterogeneity of effects according to age group or biological sex.
Keywords: Aging; Atherosclerosis; CLSA; Cardiovascular disease; Genetic risk score; SNP.
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