NEFL and Alzheimer disease: In cohort 1 at follow-up, plasma levels of Aβ42 and Aβ42/Aβ40 were significantly lower in the AD group (Aβ42: P = 3.57 × 10−38, PBON = 2.14 × 10−37; Aβ42/Aβ40: P = 1.42 × 10−12, PBON = 8.52 × 10−12; Fig. 1a, c) compared to the control groups, whereas plasma levels of p-tau181 and NfL were significantly higher in the AD group (p-tau181: P = 1.04 × 10−31, PBON = 6.24 × 10−31; NfL: P = 1.10 × 10−14, PBON = 6.60 × 10−14; Fig. 1e, f).