Alzheimer's Disease Biomarker-Nigeria (ADIBIO-N): Cohort description and baseline data report

Abstract

Background There is knowledge gap between the West and sub-Saharan Africa on dementia biomarkers. To bridge this, the Alzheimer's Disease Biomarker-Nigeria (ADIBIO-N) cohort was established. Objective This study reported baseline data for Alzheimer's disease (AD) blood-based biomarkers in ADIBIO-N and the association of these biomarkers with measures of cognition. We also reported demographic differences in plasma biomarkers. Methods Three hundred older adults were recruited. At baseline, blood samples were analyzed for amyloid-β 42/40 (Aβ 42/40 ), phosphorylated tau 181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL). Cognition was measured at baseline and two follow-up visits. Results Results showed significant sex differences for NfL. Significant relationships were found between GFAP, education, and composite cognition. The same is true for NfL and composite cognition. Significant negative associations were found between GFAP, memory, and language. A significant negative relationship was found between NfL and visuospatial cognition. Equally, significant positive associations were found for GFAP and age (0.26), and Aβ 42/40 ratio and age (0.17) while adjusting for sex and education. Using the area under the curve for receiver operating characteristics, GFAP demonstrated good discriminative ability (0.70) for classifying cognitively unimpaired from non-amnestic mild cognitive impairment. Finally, a reference value was established for all the biomarkers across three diagnostic categories. Conclusions We found a baseline significant association of GFAP and NfL with composite and domain-specific cognitions, respectively, but not on amyloid and p-tau, contrary to findings from outside Africa that have repeatedly shown an association of amyloid and p-tau with cognition.