MAPT and Alzheimer disease: CSF sPDGFRβ correlated positively with t-tau in AD (r = 0.50, p = 0.0017) but not in controls (r = 0.03, p = 0.83) (Fig. 1d), and with p-tau in AD (r = 0.41, p = 0.013) but not in controls (r = 0.26, p = 0.10) (Fig. 1e).