Recent updates to the Alzheimer’s Association diagnostic criteria have redefined Alzheimer’s disease to be a biological entity characterised by Alzheimer’s dementia neuropathologic change, regardless of symptoms.11 As such, abnormal CSF biomarkers (Aβ 42/40, p-tau 181/Aβ 42 and t-tau/Aβ 42) are now considered diagnostic of Alzheimer’s dementia, even in individuals without dementia. This evidence concerns the gene MAPT and Alzheimer disease.