We are confident that this sample is representative of people with MCI who have an increased risk of AD as the prevalence of APOE ε4 in 47% of this sample is consistent with the Australian Imaging, Biomarker, & Lifestyle Flagship Study of Ageing (AIBL), which reported 46% APOE ε4 positivity in people with MCI (carrying ε4 allele; N = 150).42 This evidence concerns the gene APOE and Alzheimer disease.