APOE and dementia: Probability of conversion to dementia in the subsample was 1.7 times more frequent between APOE-Ɛ4 carriers than in non-carriers (χ2 = 15.4, p < .001), but the distribution of APOE-Ɛ4 carriers was homogeneous between the 4 class groups (χ2 = .14, p = .99).