Racial disparities in Alzheimer’s Disease (AD): Correlating a novel neuropsychological screening test to established AD fluid and imaging biomarkers in African Americans and Caucasians

Background: The Montreal Cognitive Assessment (MoCA) is a commonly used screening tool for the diagnosis of neurocognitive disorders such as mild cognitive impairment (MCI) and Alzheimer’s Disease (AD). The current cut-off threshold for detection of MCI on the MoCA increases risk for false positives, particularly in ethnic minorities and those of lower educational attainment. African Americans (AA) have experienced inaccurate detection of MCI and AD, leading to a delay in diagnosis and a decreased enrollment in AD-related clinical trials. This underscores the importance of clarified cut-offs for AD plasma biomarkers in AA and a standardized cognitive screening test independent of language and cultural norms. The Visual-based Cognitive Assessment Test (VCAT) is a newly developed language-neutral cognitive screening test that has good sensitivity (85.6%) and specificity (81.1%) in diagnosing MCI and mild AD. Our study will correlate VCAT scores to MRI brain findings and established AD plasma biomarkers in AA and Caucasians with and without cardiovascular diseases (i.e. prior myocardial infarction, stroke, and chronic kidney disease). Methods: AA and Caucasians diagnosed with MCI, AD, and normal cognition have been recruited (n=50) over a period of one year (recruitment remains ongoing). Plasma samples were collected, MRI brain imaging and Neuroquant data were obtained (for volumetric analyses), and the VCAT along with the MoCA were completed. Phosphorylated-tau 181 (p-tau 181) and phosphorylated-tau 217 (p-tau 217) will be measured in the samples using the Quanterix HDX device. Results: Preliminary results reveal that levels of p-tau 181 are elevated (from a normative cut-off value of 1.81 pg/mL per the Youden index) in all groups, and highest in the group of patients with both CSF findings consistent with AD and a medical history of cardiovascular diseases (MI, CKD, and/or stroke). Conclusion: Established cut-off values for p-tau 181 and p-tau 217 in the literature likely underestimate these results in AA patients. In addition to elucidating the cut-off normative values for established plasma AD biomarkers in a diverse cohort, our goal is to validate the VCAT, a cultural and language-neutral screening assessment. This will allow for application to multilingual populations without the need for translation of its test contents.

Duke Scholars

Author Andrew John Liu Neurology, Behavioral Neurology