APOE and Alzheimer disease: 48.7% of subjects were APOE ε4 +, 13% had a positive or indeterminate QR-PiB scan, and of the subjects with CSF, 41.2% had Aβ42 levels in the AD range, 27.5% had p-tau levels in the AD range, and 15.6% had t-tau in the AD range (Table 3).