The effect of increased genetic risk for Alzheimer's disease on hippocampal and amygdala volume

Michelle K. Lupton*, Lachlan Strike, Narelle K. Hansell, Wei Wen, Karen A. Mather, Nicola J. Armstrong, Anbupalam Thalamuthu, Katie L. McMahon, Greig I. de Zubicaray, Amelia A. Assareh, Andrew Simmons, Petroula Proitsi, John F. Powell, Grant W. Montgomery, Derrek P. Hibar, Eric Westman, Magda Tsolaki, Iwona Kloszewska, Hilkka Soininen, Patrizia MecocciBruno Velas, Simon Lovestone, Alzheimer's Disease Neuroimaging Initiative, Henry Brodaty, David Ames, Julian N. Trollor, Nicholas G. Martin, Paul M. Thompson, Perminder S. Sachdev, Margaret J. Wright

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

92 Citations (Scopus)

Abstract

Reduction in hippocampal and amygdala volume measured via structural magnetic resonance imaging is an early marker of Alzheimer's disease (AD). Whether genetic risk factors for AD exert an effect on these subcortical structures independent of clinical status has not been fully investigated. We examine whether increased genetic risk for AD influences hippocampal and amygdala volumes in case-control and population cohorts at different ages, in 1674 older (aged >53 years; 17% AD, 39% mild cognitive impairment [MCI]) and 467 young (16-30 years) adults. An AD polygenic risk score combining common risk variants excluding apolipoprotein E (APOE), and a single nucleotide polymorphism in TREM2, were both associated with reduced hippocampal volume in healthy older adults and those with MCI. APOE ε4 was associated with hippocampal and amygdala volume in those with AD and MCI but was not associated in healthy older adults. No associations were found in young adults. Genetic risk for AD affects the hippocampus before the clinical symptoms of AD, reflecting a neurodegenerative effect before clinical manifestations in older adults.

Original languageEnglish
Pages (from-to)68-77
Number of pages10
JournalNeurobiology of Aging
Volume40
DOIs
Publication statusPublished - Apr 2016
Externally publishedYes

Keywords

  • Alzheimer's disease
  • polygenic risk score
  • APOE
  • TREM2
  • hippocampus
  • amygdala

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