Diagnostic value of plasma phosphorylated tau181 in Alzheimer's disease and frontotemporal lobar degeneration
With the potential development of new disease modifying Alzheimer's disease (AD) therapies, simple, widely available screening tests are needed to identify which individuals, who are experiencing symptoms of cognitive or behavioral decline, should be further evaluated for initiation of treatment. A blood based test for AD would be a less invasive and less expensive screening tool than the currently approved cerebrospinal fluid or amyloid b positron emission tomography (PET) diagnostic tests. We examined whether plasma tau phosphorylated at residue 181 (pTau181) could differentiate between clinically diagnosed or autopsy confirmed AD and frontotemporal lobar degeneration. Plasma pTau181 concentrations were increased by 3.5 fold in AD compared to controls and differentiated AD from both clinically diagnosed (receiver operating characteristic area under the curve of 0.894) and autopsy confirmed frontotemporal lobar degeneration (area under the curve of 0.878) Plasma pTau181 identified individuals who were amyloid b PET positive regardless of clinical diagnosis and correlated with cortical tau protein deposition measured by 18 F flortaucipir PET. Plasma pTau181 may be useful to screen for tau pathology associated with AD. Plasma pTau181 concentrations are elevated specifically in patients diagnosed with Alzheimer's disease compared to those diagnosed with frontotemporal lobar degeneration or elderly controls, supporting its further development as a blood based biomarker for AD.
Nature Medicine