Is there a specific memory signature associated with Aβ-PET positivity in patients with amnestic mild cognitive impairment?

Neurobiol Aging. 2019 May;77:94-103. doi: 10.1016/j.neurobiolaging.2019.01.017. Epub 2019 Jan 31.

Abstract

Amnestic mild cognitive impairment (aMCI) is a clinical entity with various potential etiologies including but not limited to Alzheimer's disease. We examined whether a positive ([18F]Florbetapir) beta amyloid positron emission tomography scan, supporting underlying Alzheimer's disease pathophysiology, was associated with specific memory deficits in 48 patients with aMCI (33 beta amyloid positive, 15 beta amyloid negative). Memory was evaluated using an autobiographical fluency task and a word-list learning task with 2 different encoding types (shallow/incidental versus deep/intentional). Compared with 40 beta amyloid-negative controls, both aMCI subgroups demonstrated severe deficits in the global memory score and in most subscores of both tasks. Finer-grained analyses of memory tests showed subtle association with beta amyloid status, revealing a stronger impairment of the primacy effect in beta amyloid-positive patients. Structural magnetic resonance imaging showed that both aMCI subgroups exhibited comparable atrophy patterns, with similar degrees of medial temporal volume loss compared with controls. Specifically assessing the primacy effect might complement global memory scores in identifying beta amyloid-positive patients with aMCI.

Keywords: Alzheimer's disease; Amnestic mild cognitive impairment; Beta amyloid; Hippocampus; Memory; Positron emission tomography.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / etiology
  • Amyloid beta-Peptides / metabolism*
  • Atrophy
  • Cognitive Dysfunction / diagnostic imaging
  • Cognitive Dysfunction / metabolism*
  • Cognitive Dysfunction / psychology*
  • Female
  • Hippocampus / diagnostic imaging
  • Hippocampus / metabolism
  • Hippocampus / pathology
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Memory*
  • Positron-Emission Tomography
  • Temporal Lobe / diagnostic imaging
  • Temporal Lobe / pathology

Substances

  • Amyloid beta-Peptides