No association of salivary total tau concentration with Alzheimer’s disease

Neurobiology of Aging
|

Nicholas J. Ashton, Mark Ide, Michael Schöll, Kaj Blennow, Simon Lovestone, Abdul Hye, Henrik Zetterberg

Neurobiology of Aging

DOI: doi.org/10.1016/j.neurobiolaging.2018.06.014

Abstract

There is a need for an accessible biomarker that can complement current cerebrospinal fluid (CSF) and imaging biomarkers in an accurate and early diagnosis of Alzheimer disease (AD). Saliva is a rich source of potential biomarkers and proteins related to neurodegenerative disorders have been shown to be present in this matrix, including tau. In this study, we quantified salivary total tau (t-tau) concentration in 160 healthy elderly control (HEC), 68 mild cognitive impairment (MCI) and 53 Alzheimer’s disease (AD) participants using ultra-sensitive Single molecule array (Simoa) technology. No median difference in salivary t-tau concentration was found between AD and MCI or HEC (12.3 ng/L, 9.8 ng/L and 9.6 ng/L, respectively, P = 0.219). In addition, there was no association of salivary t-tau concentration with neurophysiological assessment or structural MRI. Despite a nominal increase in AD, due to the large overlaps in concentrations between clinical groups, we conclude that salivary t-tau is neither a suitable biomarker for AD nor for cognitive impairment.