title: Cortical thinning explains changes in sleep slow waves during adulthood.
abstract: Sleep slow waves (SWs) change considerably throughout normal aging. In humans, SWs are generated and propagate on a structural backbone of highly interconnected cortical regions that form most of the default mode network, such as the insula, cingulate cortices, temporal lobe, parietal lobe, and medial frontal lobe. Regions in this network undergo cortical thinning and breakdown in structural and functional connectivity over the course of normal aging. In this study, we investigated how changes in cortical thickness (CT), a measure of gray matter integrity, are involved in modifications of sleep SWs during adulthood in humans. Thirty young (mean age = 23.49 years; SD = 2.79) and 33 older (mean age = 60.35 years; SD = 5.71) healthy subjects underwent a nocturnal polysomnography and T1 MRI. We show that, when controlling for age, higher SW density (nb/min of nonrapid eye movement sleep) was associated with higher CT in cortical regions involved in SW generation surrounding the lateral fissure (insula, superior temporal, parietal, middle frontal), whereas higher SW amplitude was associated with higher CT in middle frontal, medial prefrontal, and medial posterior regions. Mediation analyses demonstrated that thinning in a network of cortical regions involved in SW generation and propagation, but also in cognitive functions, explained the age-related decrease in SW density and amplitude. Altogether, our results suggest that microstructural degradation of specific cortical regions compromise SW generation and propagation in older subjects, critically contributing to age-related changes in SW oscillations.
authors.affiliation: Department of Psychology, Université de Montréal, Montréal H2V 2S9, Canada, Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montréal H4J 1C5, Canada, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal H3W 1W4, Canada.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dubé
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montréal H4J 1C5, Canada.
authors.forename: Marjolaine
authors.initials: M
authors.lastname: Lafortune
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montréal H4J 1C5, Canada, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal H3W 1W4, Canada.
authors.forename: Christophe
authors.initials: C
authors.lastname: Bedetti
authors.affiliation: Department of Psychology, Université de Montréal, Montréal H2V 2S9, Canada, Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montréal H4J 1C5, Canada, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal H3W 1W4, Canada.
authors.forename: Maude
authors.initials: M
authors.lastname: Bouchard
authors.affiliation: Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montréal H4J 1C5, Canada, Department of Psychology, Université du Québec à Montréal, Montréal H2L 2C4, Canada.
authors.forename: Jean François
authors.initials: JF
authors.lastname: Gagnon
authors.affiliation: Department of Psychology, Université de Montréal, Montréal H2V 2S9, Canada, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal H3W 1W4, Canada.
authors.forename: Julien
authors.initials: J
authors.lastname: Doyon
authors.affiliation: Montreal Neurological Institute, McGill University, Montréal H3A 2B4, Canada.
authors.forename: Alan C
authors.initials: AC
authors.lastname: Evans
authors.affiliation: Department of Electrical Engineering, École de Technologie Supérieure, Montréal H3C 1K3, Canada, and Centre de Recherches Mathématiques, Université de Montréal, Montréal H3C 1K3, Canada.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Lina
authors.affiliation: Department of Psychology, Université de Montréal, Montréal H2V 2S9, Canada, Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montréal H4J 1C5, Canada, Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, Montréal H3W 1W4, Canada, julie.carrier.1@umontreal.ca.
authors.forename: Julie
authors.identifier: http://orcid.org/0000-0001-5311-2370
authors.initials: J
authors.lastname: Carrier
mesh_terms: D000328:Adult; D000368:Aged; D058256:Brain Waves; D002540:Cerebral Cortex / Q000254:growth & development / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012890:Sleep; D066127:White Matter / Q000254:growth & development / Q000502:physiology*
keywords: aging; cortical thickness; electroencephalography; humans; sleep; slow waves