Differential associations of APOE-ε2 and APOE-ε4 alleles with PET-measured amyloid-β and tau deposition in older individuals without dementia

Research output: Contribution to journalArticle

Abstract

Purpose: To examine associations between the APOE-ε2 and APOE-ε4 alleles and core Alzheimer’s disease (AD) pathological hallmarks as measured by amyloid-β (Aβ) and tau PET in older individuals without dementia. Methods: We analyzed data from 462 ADNI participants without dementia who underwent Aβ ([18F]florbetapir or [18F]florbetaben) and tau ([18F]flortaucipir) PET, structural MRI, and cognitive testing. Employing APOE-ε3 homozygotes as the reference group, associations between APOE-ε2 and APOE-ε4 carriership with global Aβ PET and regional tau PET measures (entorhinal cortex (ERC), inferior temporal cortex, and Braak-V/VI neocortical composite regions) were investigated using linear regression models. In a subset of 156 participants, we also investigated associations between APOE genotype and regional tau accumulation over time using linear mixed models. Finally, we assessed whether Aβ mediated the cross-sectional and longitudinal associations between APOE genotype and tau. Results: Compared to APOE-ε3 homozygotes, APOE-ε2 carriers had lower global Aβ burden (βstd [95% confidence interval (CI)]: − 0.31 [− 0.45, − 0.16], p = 0.034) but did not differ on regional tau burden or tau accumulation over time. APOE-ε4 participants showed higher Aβ (βstd [95%CI]: 0.64 [0.42, 0.82], p < 0.001) and tau burden (βstd range: 0.27-0.51, all p < 0.006). In mediation analyses, APOE-ε4 only retained an Aβ-independent effect on tau in the ERC. APOE-ε4 showed a trend towards increased tau accumulation over time in Braak-V/VI compared to APOE-ε3 homozygotes (βstd [95%CI]: 0.10 [− 0.02, 0.18], p = 0.11), and this association was fully mediated by baseline Aβ. Conclusion: Our data suggest that the established protective effect of the APOE-ε2 allele against developing clinical AD is primarily linked to resistance against Aβ deposition rather than tau pathology.

Details

Authors
  • Gemma Salvadó
  • Michel J. Grothe
  • Colin Groot
  • Alexis Moscoso
  • Michael Schöll
  • Juan Domingo Gispert
  • Rik Ossenkoppele
Organisations
External organisations
  • Hospital del Mar Medical Research Institute
  • University Hospital Virgen del Rocío
  • University College London
  • Pompeu Fabra University
  • CIBER Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN)
  • Vrije Universiteit Amsterdam
  • Amsterdam UMC - Vrije Universiteit Amsterdam
  • Pasqual Maragall Foundation for Research on Alzheimer
  • University of Gothenburg
  • University of Seville
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurology
  • Radiology, Nuclear Medicine and Medical Imaging

Keywords

  • Amyloid-β, APOE, Cognition, Cross-sectional, Hippocampal volumes, Longitudinal, PET, Sex interaction, Tau
Original languageEnglish
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Publication statusE-pub ahead of print - 2021 Feb 1
Publication categoryResearch
Peer-reviewedYes