The Association of Alzheimer's Disease-Related Blood-Based Biomarkers with Cognitive Screening Test Performance in the Congolese Population in Kinshasa

Background: Alzheimer's disease (AD), the most common cause of dementia, poses a significant global burden. Diagnosis typically involves invasive and costly methods like neuroimaging or cerebrospinal fluid (CSF) biomarker testing of phosphorylated tau (p-tau) and amyloid-β42/40 (Aβ42/40). Such procedures are especially impractical in resource-constrained regions, such as the Democratic Republic of Congo (DRC). Blood-based biomarker testing may provide a more accessible screening opportunity. Objective: This study aims to examine if AD-related blood-based biomarkers are associated with cognitive test performance in the Congolese population, where limited research has been conducted. Methods: In this cross-sectional study of 81 Congolese individuals, cognitive assessments (Alzheimer's Questionnaire (AQ) and Community Screening Interview for Dementia (CSID)) distinguished dementia cases from controls. Blood draws were taken to assess p-tau 181 and Aβ42/40 biomarkers. Relationships between the biomarkers and cognitive performance were analyzed using multiple linear regression models. Results: Lower plasma Aβ42/40 was significantly associated with lower CSID scores and higher AQ scores, indicative of AD (p < 0.001). These relationships were observed in healthy controls (CSID p = 0.01, AQ p = 0.03), but not in dementia cases. However, p-tau 181 did not exhibit significant associations with either measure. Factors such as age, sex, education, presence of APOE ϵ4 allele, did not alter these relationships. Conclusions: Understanding relationships between AD-related screening tests and blood biomarkers is a step towards utilization of blood-based biomarker tests as a screening tool for AD, especially in resource-limited regions. Further research should be conducted to evaluate blood biomarker test efficacy in larger samples and other populations.