title: Epigenetic alterations in the suprachiasmatic nucleus and hippocampus contribute to age-related cognitive decline.
abstract: Circadian rhythm dysfunction and cognitive decline, specifically memory loss, frequently accompany natural aging. Circadian rhythms and memory are intertwined, as circadian rhythms influence memory formation and recall in young and old rodents. Although, the precise relationship between circadian rhythms and memory is still largely unknown, it is hypothesized that circadian rhythm disruption, which occurs during aging, contributes to age-associated cognitive decline, specifically memory loss. While there are a variety of mechanisms that could mediate this effect, changes in the epigenome that occur during aging has been proposed as a potential candidate. Interestingly, epigenetic mechanisms, such as DNA methylation and sirtuin1 (SIRT1) are necessary for both circadian rhythms and memory. During aging, similar alterations of epigenetic mechanisms occur in the suprachiasmatic nucleus (SCN) and hippocampus, which are necessary for circadian rhythm generation and memory, respectively. Recently, circadian rhythms have been linked to epigenetic function in the hippocampus, as some of these epigenetic mechanisms oscillate in the hippocampus and are disrupted by clock gene deletion. The current paper will review how circadian rhythms and memory change with age, and will suggest how epigenetic changes in these processes might contribute to age-related cognitive decline.
authors.affiliation: Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
authors.forename: Scott H
authors.initials: SH
authors.lastname: Deibel
authors.affiliation: Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
authors.forename: Erin L
authors.initials: EL
authors.lastname: Zelinski
authors.affiliation: Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Keeley
authors.affiliation: Department of Biological Sciences, University of Lethbridge, Lethbridge, AB, Canada.
authors.forename: Olga
authors.initials: O
authors.lastname: Kovalchuk
authors.affiliation: Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McDonald
mesh_terms: D000368:Aged; D000375:Aging / Q000235:genetics*; D000818:Animals; D002940:Circadian Rhythm; D003072:Cognition Disorders / Q000235:genetics* / Q000503:physiopathology*; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D017353:Gene Deletion; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D008568:Memory; D051379:Mice; D056564:Sirtuin 1 / Q000235:genetics; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*
chemical_list: C447939:SIRT1 protein, human; D056564:Sirtuin 1
keywords: Gerotarget; aging; brain; circadian rhythms; memory