Early diagnosis of Alzheimer's disease (AD), particularly during its preclinical and prodromal phases, remains a major challenge. Plasma biomarkers such as phosphorylated tau at threonine 217 (p-tau21 Show more
Early diagnosis of Alzheimer's disease (AD), particularly during its preclinical and prodromal phases, remains a major challenge. Plasma biomarkers such as phosphorylated tau at threonine 217 (p-tau217), amyloid-β (Aβ) isoforms, neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) show promise for early detection; however, their relationships with medial temporal lobe (MTL) subfield atrophy and potential inter-biomarker pathways remain unclear. This study aimed to address this gap by investigating the associations between plasma biomarkers and MTL subfield atrophy, and by assessing potential mediation pathways. We conducted a cross-sectional study using data from 330 participants in the Alzheimer's Disease Neuroimaging Initiative (ADNI), including cognitively normal (CN) and mild cognitive impairment (MCI) groups. High-resolution coronal T2-weighted MRI quantified MTL subfield volumes using the ASHS protocol. Plasma biomarkers were measured using ultrasensitive immunoassays. The cohort included 209 CN participants (mean age [SD] = 69.3 [6.9] years; 64.2% women; 24.4% APOE ε4 carriers) and 121 MCI participants (mean age [SD] = 71.3 [7.3] years; 48.8% women; 27.9% APOE ε4 carriers). MCI individuals showed significantly higher plasma concentrations of p-tau217, p-tau217/Aβ Show less