APOE and dementia: The 90+ study (hazard ratio [HR] 1.04; 95% confidence interval [CI] 0.71–1.53) and the Vantaa 85+ study (HR 1.78; 95% CI 0.88–3.60) did not find an effect of the APOE ɛ4 allele on dementia risk,14, 16 while the Leiden 85+ study found an increased dementia risk among APOE ɛ4 carriers (odds ratio [OR] 4.1; 95% CI 2.1–8.4).15