MAPT and Alzheimer disease: Recent results such as these have been taken to suggest that early WM deterioration may be at least partially separate (Agosta et al., 2011; Selnes et al., 2012) from the β-amyloid and tau pathologies of gray matter, whose evolution is known to characterize Alzheimer’s disease (AD) (Braak and Braak, 1996), and have even raised the question whether Alzheimer’s should be considered a disease of the WM (Sachdev et al., 2013).