With respect to genetic risk for AD, 17 of 28 individuals (58%) in the SCT fail group (those who failed the SCT at the time of their baseline exams) had at least one copy of the APOE ε4 allele, whereas 13 of 30 individuals (43%) in the SCT pass group (those who passed the SCT at the time of their baseline exams) had at least one copy of the APOE ε4 allele. Here, APOE is linked to Alzheimer disease.