CSF p-tau has shown high prognostic accuracy for AD and for predicting cognitive decline in cognitively unimpaired (CU) individuals and in patients with mild cognitive impairment (MCI) due to AD.2,3 As CSF p-tau levels are higher in AD compared to other non-AD neurodegenerative disorders, including progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), frontotemporal dementia (FTD), and vascular dementia (VaD), it has also proven of use in the differential diagnosis of AD vs other dementias.4 This evidence concerns the gene MAPT and frontotemporal dementia.