P-tau levels were significantly lower in iNPH patients than in AD (SMD = −1.54, 95% CI −2.34 to −0.74, P = 0.0002) and significantly lower than in healthy controls (SMD = −1.12, 95% CI −1.38 to −0.86, P < 0.00001). Here, MAPT is linked to Alzheimer disease.