A plasma tau marker gains support for diagnosing Alzheimer’s disease
Where blood tests for tau could fit into Alzheimer’s clinical care and research
Two studies published this week advance the search for blood tests for Alzheimer’s disease, but it’s not yet clear how transformative the plasma markers will be.
Both studies came to the same conclusion: one form of tau -- the phosphorylated fragment p-tau217 -- represents the clearest indicator of β amyloid status and clinical disease, and mass spectrometry is sensitive enough to detect tiny amounts of pathological forms of the Alzheimer’s target tau in plasma. Both studies also found that another tau form, p-tau181, performed well.
Plasma p-tau217 tightly correlated with PET imaging of amyloid. Although PET is the current standard for enrolling subjects in clinical trials, its high price, lack of reimbursement, and requirement for special equipment put it out of reach for many patients, making the need for better biomarkers acute.
Open questions include where the plasma indicators fit into the landscape of putative biomarkers for Alzheimer’s, and how precisely they can stage patients and predict progression. The answers will determine