Longitudinal Predictors of Cognitive Decline and Dementia Conversion in Older Nigerians with Mild Cognitive Impairment: The IBADAN AGING COHORT

Mild cognitive impairment (MCI) is a high-risk transitional state between normal aging and dementia, yet longitudinal predictors of dementia conversion in Nigerian older adult populations remain unknown. This study investigates longitudinal predictors of cognitive decline and dementia conversion among older Nigerians with MCI as part of the Ibadan Aging Cohort, an ongoing population-based aging study in Oyo State, South West Nigeria. Four hundred adults aged 65 and above with baseline MCI diagnoses will be followed annually for four years. Neuropsychological assessments using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) battery and the Clinical Dementia Rating (CDR) scale will track cognitive trajectories. Biomarker data including APOE genotype, CRP, insulin resistance indices, and neuroimaging where accessible will be incorporated. Vascular risk factors (hypertension, diabetes, obesity), educational attainment, physical activity, and social engagement will serve as modifiable predictors. Group-based trajectory modeling and competing risks survival analysis will identify conversion predictors. This study directly addresses the scarcity of longitudinal dementia data from sub-Saharan Africa and will contribute original population-level evidence to global dementia risk models and prevention strategies. Keywords: mild cognitive impairment, dementia conversion, longitudinal, Ibadan, aging cohort