APOE-genotyping among cognitively normal research volunteers enlisted in an online recruitment registry identified 25 % heterozygous and 2 % homozygous APOE-ε4 carriers, which aligns with the expected frequencies in the general population [12,15].We had anticipated a higher enrichment of APOE-ε4 carriers given the relatively high proportion of participants with a family history of dementia. Here, APOE is linked to dementia.