The hazard ratios (HRs) for apoE level in HDL that contained or lacked apoC3 with dementia risk were statistically significantly different (HR per 1-SD higher apoE in HDL that contained apoC3: 1.07 [95% CI, 0.95-1.19] vs 0.86 [95% CI, 0.76-0.99]; P for heterogeneity = .03). Here, APOC3 is linked to dementia.