MAPT and Alzheimer disease: In a study combining two large national cohorts (National Alzheimer’s Coordinating Center, NACC, n = 22,760 and Alzheimer’s Disease Neuroimaging Initiative, ADNI, n = 1733), lower Aβ42 was associated with a steep increase in apathy, while higher tau was associated with a marked decrease in apathy over a five-year period [69].