Neurodegenerative plasma biomarkers for prediction of hippocampal atrophy in older adults with suspected Alzheimer's disease in Kinshasa, Democratic Republic of Congo.

BackgroundHippocampal atrophy is a key feature of Alzheimer's disease (AD), but neuroimaging is often inaccessible in low-resource settings. Blood-based biomarkers such as amyloid-β (Aβ42/40), phosphorylated tau-181 (p-tau181), neurofilament light (NfL), and glial fibrillary acidic protein (GFAP) may offer a practical alternative, though their utility in African populations remains understudied.ObjectiveThis study investigated the ability of plasma biomarkers of AD and AD-related dementias-Aβ42/40, p-tau181, NfL, and GFAP-to predict hippocampal atrophy in older adults in Kinshasa, Democratic Republic of Congo.MethodsEighty-five adults aged over 65 (40 healthy; 45 suspected AD) were recruited. Core AD (Aβ42/40, p-tau181) and non-specific (NfL, GFAP) biomarkers were analyzed. Hippocampal volumes were measured using MRI. Linear and logistic regressions assessed biomarker differences by age, sex, and neurological status, and predicted hippocampal atrophy.ResultsElevated p-tau181 was associated with left hippocampal (LH) atrophy (p = 0.020), with 4.2-fold increased odds [OR = 4.2 (1.5-18.4)] of LH atrophy per standard deviation increase. The areas under the curve of plasma biomarkers without clinical covariates to discriminate LH, right hippocampal (RH), and total hippocampal (TH) atrophy ranged from 90%-94%, 76%-82%, and 85%-87%, respectively. Models including clinical covariates and biomarkers improved discrimination to 94%-96% (LH), 81%-84% (RH), and 88%-90% (TH).ConclusionsConsistent with findings from other settings, core AD plasma biomarkers can effectively predict hippocampal atrophy in a Sub-Saharan African population, supporting their potential for scalable dementia screening where imaging is limited.