Sleep and episodic memory: A review of the literature in young healthy subjects and potential links between sleep changes and memory impairment observed during aging and Alzheimer's disease

Introduction. - A large body of evidence indicates that sleep favors memory consolidation. State of the art. - This process would occur, mainly during slow-wave sleep, by means of a dialogue between the hippocampus and neocortical areas. Low levels of acetylcholine and cortisol are also needed to favor the transfer of memory traces toward the neocortex, where they will be stored for the long-term. Perspectives. - The aim of this article is, first, to give an overview of studies conducted in young healthy subjects and underpinning the hypothesis that sleep is involved in memory consolidation. Then, we will investigate the potential links between changes in sleep architecture and episodic memory impairment in both aging and Alzheimer's disease. Finally, we will see how these results can affect clinical practice. Conclusion. - Sleep-dependent memory consolidation is impaired both in aging and Alzheimer's disease. These findings suggest the importance of taking into account sleep when assessing memory function in patients. (C) 2010 Elsevier Masson SAS. All rights reserved.