Levels of tau protein in plasma are associated with neurodegeneration and cognitive function in a population-based elderly cohort

Abstract

Introduction: Tau protein levels in plasma may be a marker of neuronal damage. We examined associations between plasma tau levels and Alzheimer's disease (AD)-related magnetic resonance imaging (MRI) and positron emission tomography (PET) neuroimaging measures among nondemented individuals.

Methods: Participants included 378 cognitively normal (CN) and 161 mild cognitive impairment (MCI) individuals enrolled in the Mayo Clinic Study of Aging with concurrent neuropsychological measures and amyloid PET, fluorodeoxyglucose PET, and MRI. Baseline plasma tau levels were measured using the Quanterix Simoa-HD1 tau assay.

Results: Plasma tau levels were higher in MCI compared with CN (4.34 vs. 4.14 pg/mL, P = .078). In regression models adjusted for age, gender, education, and APOE, higher plasma tau was associated with worse memory performance (b = -0.30, P = .02) and abnormal cortical thickness in an AD signature region (odds ratio = 1.80, P = .018).

Discussion: Plasma tau is associated with cortical thickness and memory performance. Longitudinal studies will better elucidate the associations between plasma tau, neurodegeneration, and cognition.

Keywords: Amyloid; Cognition; Cortical thickness; MCI; MRI; Memory; Plasma tau.

Fig. 1. Median log plasma tau levels by cognitive and neuroimaging amyloid and neurodegeneration biomarker status

Amyloid positive (A+) was defined as amyloid PET SUVR > 1.40. Neurodegeneration positive (N+) was defined as either an AD-signature region cortical thickness <2.74 mm or FDG-PET SUVR<1.32 in AD-signature regions. CN = cognitively normal; MCI = Mild cognitive impairment. The number of subjects in each group are as follows: 62 CN A−N−; 90 CN A+N−; 133 CN A+N+; 89 CN A−N+; 27 MCI A−N−; 25 MCI A+N−; 76 MCI A+N+; 31 MCI A−N+.