In contrast, brain aging accelerates more in APOE ε4 carriers during follow-up as compared to non-carriers in the pMCI and AD groups, i.e. already starting with a higher baseline BrainAGE score of about 6 years, brain aging accelerates during follow-up with the speed of 1.1 additional year in brain atrophy per follow-up year in pMCI ε4 carriers, but only about 0.6 years in pMCI ε4 non-carriers, and 1.7 additional years in brain atrophy per follow-up year in AD ε4 carriers and 0.9 years in AD ε4 non-carriers. This evidence concerns the gene APOE and Alzheimer disease.