Relationship between Memory Performance and β-Amyloid Deposition at Different Stages of Alzheimer's Disease

Background: Postmortem studies have suggested that beta-amyloid (A beta) deposition was only weakly related to the degree of cognitive impairment in Alzheimer's disease (AD). The development of A beta ligands for in vivo PET imaging has greatly facilitated the assessment of this question. Objective: The objective of the present study was to provide an overview of our current knowledge regarding the relationship between A beta deposition and episodic memory deficits in nondemented elderly and in patients with mild cognitive impairment or AD. Methods: Information was obtained both from studies comparing memory performance in individuals with high Pittsburgh compound B (PiB) and those with low PiB and from studies performing correlation analyses between memory performance and PiB retention considered as a continuous variable. Results: Previous studies assessing the relationship between memory and global neocortical PiB reported conflicting findings, and overall suggest that this link is weak, probably indirect, and detectable only in early stages. Assessing the relationship with regional instead of global neocortical PiB, we found a specific relationship between episodic memory deficits and neocortical temporal PiB, independent from hippocampal atrophy, in the predementia stage of the disease. Conclusion: There is a relationship between regional A beta deposition and episodic memory deficits in the presymptomatic stage of AD. Copyright (C) 2012 S. Karger AG, Basel