MAPT and Alzheimer disease: Seven hundred and three participants from the Alzheimer’s Disease Neuroimaging Initiative were classified into one of the four groups (A−/T−, A−/T+, A+/T− and A+/T+) based on PET positivity or negativity for cortical amyloid-beta (A−/A+) and early-to-moderate stage (i.e. meta-temporal) tau (T−/T+).