The STA and t-tau ratio significantly differed according to Braak NFT staging1 (P < 0.0001) and was significantly lower in both individuals with Braak V and VI and Braak III–IV staging versus Braak 0–II staging (P < 0.05; Fig. 6b), with a sharp decrease between Braak III and IV (Fig. 6c,d) suggesting that pathologically relevant changes occur in incipient AD, before isocortical association areas are affected in stages V and VI. Here, MAPT is linked to Alzheimer disease.