MAPT and Alzheimer disease: Numerous studies (Chatterjee et al., 2022, 2023; Karikari et al., 2020, 2021; Simrén et al., 2021; Thijssen et al., 2020) have consistently reported plasma tau phosphorylated at threonine 181 (P‐tau181) as a potential and specific biomarker for (a) detecting AD pathology via distinguishing Aβ+ from Aβ− in cognitively normal (CN) adults as well as AD dementia from non‐AD dementias and (b) predicting clinical progression via forecasting gradual cognitive decline and disease development, that is, from CN Aβ+ to MCI or AD dementia.