Tear-based neurodegenerative biomarkers in mild cognitive impairment and dementia: A pilot feasibility study in Peru

Background Alzheimer’s disease (AD) prevalence is rising globally, with low- and middle-income countries (LMICs) facing diagnostic challenges. We investigated the feasibility of tear-based neurodegenerative biomarkers as a non-invasive screening approach for neurocognitive disorders in a resource-limited setting. Methods Tear samples were collected from 10 participants with MCI or dementia (neurocognitive disorder [NCD]) and 4 cognitively healthy controls at a public hospital in Lima, Peru. Proteins were analyzed for neurodegeneration-associated biomarkers (amyloid-beta 40/42, total tau, phosphorylated tau181 [pTau181], alpha-synuclein, and neurofilament light). Results Using two-sided exact Mann-Whitney U tests, tear total tau and pTau181 concentrations were higher in the NCD group than in controls (U=40.0, p=0.002 for both comparisons). Conclusion These findings support the feasibility of detecting neurodegenerative biomarkers in tears and suggest that tear-based total tau and pTau181 measurements may warrant further study as non-invasive biomarkers in neurocognitive disorders in resource-limited settings.