MAPT and Alzheimer disease: Total Tau and p181Tau levels also statistically increased at Braak stages V and VI, compared with those substantial levels at Braak stage I. It should be noted that the levels of NAD (Braak stages I–III) occupied 1/4–1/5 levels of Braak stage VI of AD, implying their physiological roles of total Tau and p181Tau in NAD.