Eichenlaub, Udo

AbstractIntroductionThe prognostic utility of cerebrospinal fluid (CSF) phosphorylated tau 217 (p‐tau217) and p‐tau181 is not understood.MethodsAnalyses included 753 Mayo Clinic Study on Aging participants (median age = 71.6; 57% male). CSF amyloid beta (Aβ)42 and p‐tau181 were measured with Elecsys immunoassays. CSF p‐tau181 and p‐tau217 were also measured with Meso Scale Discovery (MSD). We used Cox proportional hazards models for risk of mild cognitive impairment (MCI) and linear mixed models for risk of global and domain‐specific cognitive decline and cortical thickness. Analyses were stratified by elevated brain amyloid based on CSF Aβ42 or amyloid positron emission tomography for those with imaging.ResultsCSF p‐tau217 was superior to p‐tau181 for the diagnosis of Alzheimer's disease (AD) pathology. CSF MSD p‐tau181 and p‐tau217 were associated with risk of MCI among amyloid‐positive individuals. Differences between CSF p‐tau measures predicting cortical thickness were subtle.DiscussionThere are subtle differences for CSF p‐tau217 and p‐tau181 as prognostic AD markers.

Abstract Introduction We aimed to provide cut points for the automated Elecsys Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers. Methods Cut points for Elecsys amyloid beta 42 (Aβ42), total tau (t‐tau), hyperphosphorylated tau (p‐tau), and t‐tau/Aβ42 and p‐tau/Aβ42 ratios were evaluated in Mayo Clinic Study of Aging (n = 804) and Mayo Clinic Alzheimer's Disease Research Center (n = 70) participants. Results The t‐tau/Aβ42 and p‐tau/Aβ42 ratios had a higher percent agreement with normal/abnormal amyloid positron emission tomography (PET) than the individual CSF markers. Reciever Operating Characteristic (ROC)‐based cut points were 0.26 (0.24–0.27) for t‐tau/Aβ42 and 0.023 (0.020–0.025) for p‐tau/Aβ42. Ratio cut points derived from other cohorts performed as well in our cohort as our own did. Individual biomarkers had worse diagnostic properties and more variable results in terms of positive and negative percent agreement (PPA and NPA). Conclusion CSF t‐tau/Aβ42 and p‐tau/Aβ42 ratios are very robust indicators of AD. For individual biomarkers, the intended use should determine which cut point is chosen.