Association of tear fluid amyloid and tau levels with disease severity and neurodegeneration

Marlies Gijs, Inez H. G. B. Ramakers, Pieter Jelle Visser, Frans R. J. Verhey, Marjo P. H. van de Waarenburg, Casper G. Schalkwijk, Rudy M. M. A. Nuijts, Carroll A. B. Webers

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There has been increasing interest in finding non-invasive biomarkers for neurodegenerative diseases such as Alzheimer’s disease (AD). This observational study investigated AD-specific biomarkers in tear fluid. Tear fluid was collected from a total of 65 subjects, including 23 patients with subjective cognitive decline (SCD), 22 patients with mild cognitive impairment (MCI), 11 dementia patients and 9 healthy controls (HC). Levels of amyloid-beta peptides (AB38, AB40, AB42), total-tau (t-tau) and phosphorylated-tau (p-tau) were determined using multiplex immunoassays. Levels of AB40 and t-tau were detectable in the vast majority (> 94%) of tear fluid samples. Cerebrospinal fluid (CSF) was available from a subset of patients. In this group, tear t-tau levels were significantly higher in people with dementia compared to SCD patients. Tear t-tau levels were elevated in patients with neurodegeneration (classified according to the A/T/N system) compared to patients without neurodegeneration. Negative correlations were found between CSF AB42 and CSF t-tau, and between CSF AB42 and tear t-tau. In summary, this study shows the potential of tau proteins in tear fluid to be associated with disease severity and neurodegeneration.
Original languageEnglish
Article number22675
JournalScientific reports
Issue number1
Publication statusPublished - 1 Dec 2021

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