Association of plasma biomarkers with cognitive function in persons with dementia and cognitively healthy in the Democratic Republic of Congo

Abstract

AbstractBackgroundCross‐sectional and longitudinal measurements of plasma biomarkers of Alzheimer’s disease (AD) in Western countries are being applied in clinical practice, whereas their associations with culturally validated cognitive tests in other settings remain unknown. We aim to examine cross‐sectional association of plasma protein biomarker concentrations and APOE proteotype with cognitive function and explore the discriminative role of these AD biomarkers in such an association.MethodThis is a cross‐sectional retrospective study completed from 2018 to 2022 in the Democratic Republic of Congo (DRC). Subjects were recruited from clinics, hospitals, churches, and across DRC. The study started in January 2018 until December 2022. Data were analyzed from May 2022 to December 2022. The DRC Memory clinic team recruited 1430 individuals 65 years and over. Based on Community Screening Instruments for Dementia (CSID), and Alzheimer’s Questionnaire (AQ), and DSM‐5 diagnostic criteria, participants included 44 individuals classified as major neurocognitive disorder (dementia) and 41 as healthy controls (HC). Subjects underwent cognitive assessment with a validated, culturally‐tailored cognitive battery. AD plasma biomarkers (Aβ42, Aβ40, Aβ42/40, p‐tau 181), APS (derived from Aβ42/40, APOE status, and age), and APOE proteotype were utilized to assess for genetic risk.ResultIndividuals with dementia had significantly lower Aβ42/40 levels, higher APS, and higher APOE ε4 prevalence compared to HC. Linear regressions showed significantly associations between Aβ42/40 and APS with ANT, ALMT, and AVMT scores, while APOE ε4 presence was associated with ANT, ALMT, AVMT, and APT scores. APS showed the highest AUC value (AUC = 0.78, 95% CI: 0.68‐0.88) followed by Aβ42/40 (AUC = 0.75, 95% CI: 0.66‐0.86) and APOE ε4 (AUC = 0.69 (CI 0.57‐0.81) in discriminating dementia from HC.ConclusionSelect AD biomarkers were associated with cognition and differentiated dementia from HC, consistent with extant research. These findings may have implications for the assessment of AD biomarkers in DRC.