T-tau levels were significantly lower in iNPH patients than in AD (SMD = −1.26, 95% CI −1.95 to −0.57, P = 0.0004) and significantly lower than in healthy controls (SMD = −0.80, 95% CI −1.50 to −0.09, P = 0.03). This evidence concerns the gene MAPT and Alzheimer disease.