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Marlies Gijs, Rudy M Nuijts, Inez Ramakers, Frans Verhey, Carroll A.B. Webers; Differences in tear protein biomarkers between patients with Alzheimer’s disease and controls. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1744.
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Tears are valuable resources for biomarker research. Tear biomarkers have been identified for a number of ocular diseases as well as neurological diseases (migraine, Parkinson’s disease and multiple sclerosis). Up to date, no studies assessed the diagnostic potential of tear biomarkers for Alzheimer's disease (AD). Given the pathological heterogeneity of AD and related dementias, the next generation of peripheral biomarkers must be able to characterize the individual's underlying pathophysiology. This requires an expansion of the biomarker panel beyond what is currently available. Developing these biomarkers will be critical for a broader characterization of pathology in patients with AD by identifying different patient sub-types based on biological phenomenon. We investigated the diagnostic potential of tears as source of peripheral biomarkers for AD.
We investigated the tear biomarker level of total-tau and amyloid-beta 42 (Aβ42) in a cohort of 25 patients with Alzheimer’s disease (AD), mild cognitive impairment (MCI) or subjective cognitive impairment (SCI), and nine age-matching healthy controls (HC). Tears were collected using Schirmer strips. The levels of tear total-tau and Aβ42 were examined using multiplex immunoassays from Meso Scale Discovery (MSD).
The levels of tear total-tau and Aβ42 changed with increasing AD stage. The ability of tear total-tau and Aβ42 to discriminate between patients and controls (expressed as area under the Receiver Operating Characteristic curve, or AUC) was 0.81 (95% CI 0.62-1.00, p=0.005) and 0.725 (95% CI 0.54-0.91, p= 0.058), respectively. Furthermore, a significant increase in total-tau in tears of AD patients compared with SCI patients (p=0.019) and with MCI patients (p=0.028) was demonstrated.
Our results suggest that tear total-tau and Aβ42 have reasonable discriminatory power for the AD state and the potential for utility as a diagnostic markers. However, a limitation of this study is the small sample size. Larger scale studies are required to confirm these results.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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