Study of Ancestry, Health, Environment, and Late-Life Neurodegeneration (SAHEL)

INTRODUCTION: Dementia research in sub-Saharan Africa remains limited despite rapid population aging and substantial ancestral, environmental, and vascular diversity. The Study of Ancestry, Health, Environment, and Late-Life Neurodegeneration (SAHEL) characterizes late-life cognitive decline and neurodegeneration in north-eastern Nigeria. METHODS: SAHEL comprises community and hospital cohorts of adults aged 55 years or older in Yobe and Borno States. Participants undergo cognitive, functional, environmental, cardiovascular, metabolic, neuropsychiatric, and neurological assessments. Blood is collected for clinical profiling and biobanking, and consenting hospital participants provide skin biopsies for induced pluripotent stem cell generation. Planned analyses will integrate gut microbiota profiling, retinal imaging, and brain magnetic resonance imaging to investigate biological pathways and markers associated with healthy aging and cognitive outcomes. RESULTS: From August 2025 through February 2026, 1,044 community participants were screened (mean age, 69.4 years; 56.4% female); 379 (36.3%) screened positive for cognitive concern and entered longitudinal follow-up. The hospital cohort enrolled 102 participants (mean age, 73.5 years; 57.8% male), including participants with Alzheimers disease, vascular dementia, mixed dementia, and mild cognitive impairment. Blood was collected from 809 community participants and all hospital participants. The cohort includes Kanuri, Fulani, Hausa, Babur/Bura, and Shuwa Arab participants. DISCUSSION: SAHEL has established a large, deeply characterized aging and dementia research platform in north-eastern Nigeria. Its linked clinical, environmental, biomarker, genomic, imaging, microbiome, and cellular resources will enable investigation of population-specific risk and resilience mechanisms and strengthen dementia research and precision medicine in African populations.