Medial temporal lobe atrophy patterns in early-versus late-onset amnestic Alzheimer's disease

BackgroundThe medial temporal lobe (MTL) is hypothesized to be relatively spared in early-onset Alzheimer's disease (EOAD). Yet, detailed examination of MTL subfields and drivers of atrophy in amnestic EOAD is lacking.MethodsBioFINDER-2 participants with memory impairment, abnormal amyloid-beta and tau-PET were included. Forty-one amnestic EOAD individuals <= 65 years and, as comparison, late-onset AD (aLOAD, >= 70 years, n = 154) and amyloid-beta-negative cognitively unimpaired controls were included. MTL subregions and biomarkers of (co-)pathologies were measured.ResultsAD groups showed smaller MTL subregions compared to controls. Atrophy patterns were similar across AD groups: aLOAD showed thinner entorhinal cortices than aEOAD; aEOAD showed thinner parietal regions than aLOAD. aEOAD showed lower white matter hyperintensities than aLOAD. No differences in MTL tau-PET or transactive response DNA binding protein 43-proxy positivity were found.ConclusionsWe found evidence for MTL atrophy in amnestic EOAD and overall similar levels to aLOAD of MTL tau pathology and co-pathologies.