CSF T‐tau and P‐tau were highly correlated overall (R = 0.92, P < 0.001), and in controls (R = 0.91, P < 0.001), prodromal AD (R = 0.74, P = 0.0025), and AD dementia (R = 0.94, P < 0.001). This evidence concerns the gene MAPT and Alzheimer disease.