In women and men, respectively, participants who had both high vitamin D and grip strength was associated with lower risk of dementia compared to those with both low vitamin D and grip strength among APOE e4 genotype carries (HR = 0.56, 95% CI 0.42–0.76, and HR = 0.48, 95% CI 0.36–0.64) and APOE e4 genotype non-carries (HR = 0.56, 95% CI 0.38–0.81, and HR = 0.34, 95% CI 0.24–0.47). This evidence concerns the gene APOE and dementia.