Characterisation of Amyloid Beta Oligomers and Tau Phosphorylation Patterns in Cerebrospinal Fluid of Patients with Alzheimer-Type Dementia in South West Nigeria

Alzheimer-type dementia is increasingly documented in ageing Nigerian populations, yet the biochemical characterisation of disease-specific cerebrospinal fluid biomarkers in West African patients using current state-of-the-art methods has not been accomplished. This study characterises cerebrospinal fluid amyloid beta 42, amyloid beta 40, total tau, phosphorylated tau-181, and amyloid beta oligomers in patients with clinically diagnosed Alzheimer-type dementia at memory clinics in Ibadan and Lagos, South West Nigeria. A case-control design was employed, with 60 Alzheimer-type dementia patients, 40 patients with mild cognitive impairment, and 40 cognitively normal elderly controls. CSF was obtained by lumbar puncture, and Alzheimer biomarkers were quantified by single molecule array (Simoa) digital ELISA. Amyloid beta oligomers were characterised by conformation-specific antibody-based assays and native polyacrylamide gel electrophoresis. Tau phosphorylation site specificity was assessed by a multi-site phospho-tau immunoassay panel including pTau-181, pTau-217, and pTau-231. Neuroinflammatory markers including YKL-40, sTREM2, and GFAP were simultaneously characterised. Biomarker profiles were integrated with neuropsychological testing data to construct biochemical staging models. This study constitutes the first detailed CSF biomarker characterisation of Alzheimer-type dementia in a West African population and generates original biochemical reference frameworks for a neglected neurological condition in Nigeria. Keywords: amyloid beta, tau phosphorylation, Alzheimer disease, cerebrospinal fluid biomarkers, South West Nigeria.