Several studies have now addressed the relationship between tau imaging ([11C]THK5351 and [18F]AV1451 binding) and CSF p-tau levels [41, 153, 166, 185–187]; there is a moderate to strong positive correlation between these biomarkers across CN subjects and varied patient groups AD (prodromal and dementia), amyloid-β-negative MCI, dementia of unclear aetiology, and several non-AD disorders (PSP, CBS, and frontotemporal dementia). This evidence concerns the gene MAPT and Alzheimer disease.