Increased hippocampal activation in ApoE-4 carriers and non-carriers with amnestic mild cognitive impairment

Tammy T. Tran, Caroline L. Speck, Aparna Pisupati, Michela Gallagher, Arnold Bakker

Research output: Contribution to journalArticlepeer-review

Abstract

Increased fMRI activation in the hippocampus is recognized as a signature characteristic of the amnestic mild cognitive impairment (aMCI) stage of Alzheimer's disease (AD). Previous work has localized this increased activation to the dentate gyrus/CA3 subregion of the hippocampus and showed a correlation with memory impairments in those patients. Increased hippocampal activation has also been reported in carriers of the ApoE-4 allelic variation independently of mild cognitive impairment although these findings were not localized to a hippocampal subregion. To assess the ApoE-4 contribution to increased hippocampal fMRI activation, patients with aMCI genotyped for ApoE-4 status and healthy age-matched control participants completed a high-resolution fMRI scan while performing a memory task designed to tax hippocampal subregion specific functions. Consistent with previous reports, patients with aMCI showed increased hippocampal activation in the left dentate gyrus/CA3 region of the hippocampus as well as memory task errors attributable to this subregion. However, this increased fMRI activation in the hippocampus did not differ between ApoE-4 carriers and ApoE-4 non-carriers and the proportion of memory errors attributable to dentate gyrus/CA3 function did not differ between ApoE-4 carriers and ApoE-4 non-carriers. These results indicate that increased fMRI activation of the hippocampus observed in patients with aMCI is independent of ApoE-4 status and that ApoE-4 does not contribute to the dysfunctional hippocampal activation or the memory errors attributable to this subregion in these patients.

Original languageEnglish (US)
Pages (from-to)237-245
Number of pages9
JournalNeuroImage: Clinical
Volume13
DOIs
StatePublished - 2017

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Clinical Neurology
  • Cognitive Neuroscience

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