Beta-amyloid burden predicts poorer mnemonic discrimination in cognitively normal older adults

• Published in: NeuroImage (Orlando, Fla.) Vol. 221; p. 117199
• Main Authors: Webb, Christina E., Foster, Chris M., Horn, Marci M., Kennedy, Kristen M., Rodrigue, Karen M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.2020; Elsevier Limited; Elsevier
• Subjects: Aged; Aged, 80 and over; Aging; Alzheimer's disease; Amyloid beta-Peptides - metabolism; Aniline Compounds - pharmacokinetics; Beta-amyloid; Cognitive ability; Cognitive aging; Cognitive Aging - physiology; Data collection; Ethylene Glycols - pharmacokinetics; Female; Hippocampus; Hippocampus - diagnostic imaging; Hippocampus - metabolism; Hippocampus - physiology; Humans; Male; Memory; Mental task performance; Middle age; Middle Aged; Mnemonic discrimination; Neurodegenerative diseases; Neuroimaging; Neuropathology; Older people; Pathology; Positron emission tomography; Preclinical Alzheimer's disease; Recognition, Psychology - physiology; Scanners; Spatial Memory - physiology; β-Amyloid; United States > US; Texas; Cognitive aging; Mnemonic discrimination; Memory; Preclinical Alzheimer's disease; Beta-amyloid
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2020.117199

One of the earliest indicators of Alzheimer's disease pathology is the presence of beta-amyloid (Αβ) protein deposition. Significant amyloid deposition is evident even in older adults who exhibit little or no overt cognitive or memory impairment. Hippocampal-based processes that help distinguish between highly similar memory representations may be the most susceptible to early disease pathology. Amyloid associations with memory have been difficult to establish, possibly because typical memory assessments do not tax hippocampal operations sufficiently. Thus, the present study utilized a spatial mnemonic discrimination task designed to tax hippocampal pattern separation/completion processes in a sample of cognitively normal middle-aged and older adults (53–98 years old) who underwent PET 18F-Florbetapir Αβ scanning. The degree of interference between studied and new information varied, allowing for an examination of mnemonic discrimination as a function of mnemonic similarity. Results indicated that greater beta-amyloid burden was associated with poorer discrimination across decreasing levels of interference, suggesting that even subtle elevation of beta-amyloid in cognitively normal adults is associated with impoverished performance on a hippocampally demanding memory task. The present study demonstrates that degree of amyloid burden negatively impacts the ability of aging adults to accurately distinguish old from increasingly distinct new information, providing novel insight into the cognitive expression of beta-amyloid neuropathology.