Publications by authors named "Julie Carrier"

192 Publications

Sleeping at the Switch.

Elife 2021 Aug 27;10. Epub 2021 Aug 27.

Psychology, Université de Montréal, Montreal, Canada.

Sleep slow waves are studied for their role in brain plasticity, homeostatic regulation and their changes during aging. Here, we address the possibility that two types of slow waves co-exist in humans. Thirty young and 29 older adults underwent a night of polysomnographic recordings. Using the slow waves with a slow transition (slow switchers) and with a fast transition (fast switchers) were discovered. Slow switchers had a high EEG connectivity along their depolarization transition while fast switchers had a lower connectivity dynamic and dissipated faster during the night. Aging was associated with lower temporal dissipation of sleep pressure in slow and fast switchers and lower EEG connectivity at the microscale of the oscillations, suggesting a decreased flexibility in the connectivity network of older individuals. Our findings show that two different types of slow waves with possible distinct underlying functions, coexist in the slow wave spectrum.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7554/eLife.64337DOI Listing
August 2021

Autonomic Modulation During Baseline and Recovery Sleep in Adult Sleepwalkers.

Front Neurol 2021 24;12:680596. Epub 2021 Jun 24.

Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur Montréal, Centre intégré universitaire de santé et de services sociaux du Nord-de-l'Île-de-Montréal (CIUSSS-NIM), Montreal, QC, Canada.

Sleepwalking has been conceptualized as deregulation between slow-wave sleep and arousal, with its occurrence in predisposed patients increasing following sleep deprivation. Recent evidence showed autonomic changes before arousals and somnambulistic episodes, suggesting that autonomic dysfunctions may contribute to the pathophysiology of sleepwalking. We investigated cardiac autonomic modulation during slow-wave sleep in sleepwalkers and controls during normal and recovery sleep following sleep deprivation. Fourteen adult sleepwalkers (5M; 28.1 ± 5.8 years) and 14 sex- and age-matched normal controls were evaluated by video-polysomnography for one baseline night and during recovery sleep following 25 h of sleep deprivation. Autonomic modulation was investigated with heart rate variability during participants' slow-wave sleep in their first and second sleep cycles. 5-min electrocardiographic segments from slow-wave sleep were analyzed to investigate low-frequency (LF) and high-frequency (HF) components of heart rate spectral decomposition. Group (sleepwalkers, controls) X condition (baseline, recovery) ANOVAs were performed to compare LF and HF in absolute and normalized units (nLF and nHF), and LF/HF ratio. When compared to controls, sleepwalkers' recovery slow-wave sleep showed lower LF/HF ratio and higher nHF during the first sleep cycle. In fact, compared to baseline recordings, sleepwalkers, but not controls, showed a significant decrease in nLF and LF/HF ratio as well as increased nHF during recovery slow-wave sleep during the first cycle. Although non-significant, similar findings with medium effect sizes were observed for absolute values (LF, HF). Patterns of autonomic modulation during sleepwalkers' recovery slow-wave sleep suggest parasympathetic dominance as compared to baseline sleep values and to controls. This parasympathetic predominance may be a marker of abnormal neural mechanisms underlying, or interfere with, the arousal processes and contribute to the pathophysiology of sleepwalking.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fneur.2021.680596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8263899PMC
June 2021

Variability of sleep stage scoring in late midlife and early old age.

J Sleep Res 2021 Jun 24:e13424. Epub 2021 Jun 24.

GIGA-Cyclotron Research Centre-In Vivo Imaging (CRC-IVI), University of Liège, Liège, Belgium.

Sleep stage scoring can lead to important inter-expert variability. Although likely, whether this issue is amplified in older populations, which show alterations of sleep electrophysiology, has not been thoroughly assessed. Algorithms for automatic sleep stage scoring may appear ideal to eliminate inter-expert variability. Yet, variability between human experts and algorithm sleep stage scoring in healthy older individuals has not been investigated. Here, we aimed to compare stage scoring of older individuals and hypothesized that variability, whether between experts or considering the algorithm, would be higher than usually reported in the literature. Twenty cognitively normal and healthy late midlife individuals' (61 ± 5 years; 10 women) night-time sleep recordings were scored by two experts from different research centres and one algorithm. We computed agreements for the entire night (percentage and Cohen's κ) and each sleep stage. Whole-night pairwise agreements were relatively low and ranged from 67% to 78% (κ, 0.54-0.67). Sensitivity across pairs of scorers proved lowest for stages N1 (8.2%-63.4%) and N3 (44.8%-99.3%). Significant differences between experts and/or algorithm were found for total sleep time, sleep efficiency, time spent in N1/N2/N3 and wake after sleep onset (p ≤ 0.005), but not for sleep onset latency, rapid eye movement (REM) and slow-wave sleep (SWS) duration (N2 + N3). Our results confirm high inter-expert variability in healthy aging. Consensus appears good for REM and SWS, considered as a whole. It seems more difficult for N3, potentially because human raters adapt their interpretation according to overall changes in sleep characteristics. Although the algorithm does not substantially reduce variability, it would favour time-efficient standardization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jsr.13424DOI Listing
June 2021

Obstructive Sleep Apnea and Cognitive Decline: A Review of Potential Vulnerability and Protective Factors.

Brain Sci 2021 May 27;11(6). Epub 2021 May 27.

Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Recherche CIUSSS NIM, Montreal, QC H4J 1C5, Canada.

Around 40% of dementia risk is attributable to modifiable risk factors such as physical inactivity, hypertension, diabetes and obesity. Recently, sleep disorders, including obstructive sleep apnea (OSA), have also been considered among these factors. However, despite several epidemiological studies investigating the link between OSA and cognitive decline, there is still no consensus on whether OSA increases the risk of dementia or not. Part of the heterogeneity observed in previous studies might be related to some individual characteristics that modulate the association between OSA and cognitive decline. In this narrative review, we present these individual characteristics, namely, age, sex, menopause, obesity, diabetes mellitus, hypertension, cardiovascular diseases, smoking, excessive alcohol consumption, depression, air pollution, allele, physical activity, and cognitive reserve. To date, large cohort studies of OSA and cognitive decline tended to statistically control for the effects of these variables, but whether they interact with OSA to predict cognitive decline remains to be elucidated. Being able to better predict who is at risk of cognitive decline when they have OSA would improve clinical management and treatment decisions, particularly when patients present relatively mild OSA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/brainsci11060706DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8226698PMC
May 2021

Somatosensory Targeted Memory Reactivation Modulates Oscillatory Brain Activity but not Motor Memory Consolidation.

Neuroscience 2021 06 3;465:203-218. Epub 2021 Apr 3.

KU Leuven, Department of Movement Sciences, Movement Control and Neuroplasticity Research Group, Leuven, Belgium; KU Leuven Brain Institute (LBI), Leuven, Belgium.

Previous research has shown that targeted memory reactivation (TMR) protocols using acoustic or olfactory stimuli can boost motor memory consolidation. While somatosensory information is crucial for motor control and learning, the effects of somatosensory TMR on motor memory consolidation remain elusive. Here, healthy young adults (n = 28) were trained on a sequential serial reaction time task and received, during the offline consolidation period that followed, sequential electrical stimulation of the fingers involved in the task. This somatosensory TMR procedure was applied during either a 90-minute diurnal sleep (NAP) or wake (NONAP) interval that was monitored with electroencephalography. Consolidation was assessed with a retest following the NAP/NONAP episode. Behavioral results revealed no effect of TMR on motor performance in either of the groups. At the brain level, somatosensory stimulation elicited changes in oscillatory activity in both groups. Specifically, TMR induced an increase in power in the mu band in the NONAP group and in the beta band in both the NAP and NONAP groups. Additionally, TMR elicited an increase in sigma power and a decrease in delta oscillations in the NAP group. None of these TMR-induced modulations of oscillatory activity, however, were correlated with measures of motor memory consolidation. The present results collectively suggest that while somatosensory TMR modulates oscillatory brain activity during post-learning sleep and wakefulness, it does not influence motor performance in an immediate retest.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neuroscience.2021.03.027DOI Listing
June 2021

Cerebral functional networks during sleep in young and older individuals.

Sci Rep 2021 Mar 1;11(1):4905. Epub 2021 Mar 1.

Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada.

Even though sleep modification is a hallmark of the aging process, age-related changes in functional connectivity using functional Magnetic Resonance Imaging (fMRI) during sleep, remain unknown. Here, we combined electroencephalography and fMRI to examine functional connectivity differences between wakefulness and light sleep stages (N1 and N2 stages) in 16 young (23.1 ± 3.3y; 7 women), and 14 older individuals (59.6 ± 5.7y; 8 women). Results revealed extended, distributed (inter-between) and local (intra-within) decreases in network connectivity during sleep both in young and older individuals. However, compared to the young participants, older individuals showed lower decreases in connectivity or even increases in connectivity between thalamus/basal ganglia and several cerebral regions as well as between frontal regions of various networks. These findings reflect a reduced ability of the older brain to disconnect during sleep that may impede optimal disengagement for loss of responsiveness, enhanced lighter and fragmented sleep, and contribute to age effects on sleep-dependent brain plasticity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-021-84417-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7921592PMC
March 2021

First sleep health guidelines for Canadian adults: implications for clinicians.

Sleep Med 2021 03 12;79:117-118. Epub 2021 Jan 12.

Département de psychologie, Université de Montréal, Montréal, Québec, Canada; Centre d'étude avancée en médecine du sommeil, Hôpital du Sacré-Cœur de Montréal, Montréal, Québec, Canada.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.sleep.2021.01.012DOI Listing
March 2021

Pandémie COVID-19, sommeil et séquelles psychologiques: au nom du Réseau canadien du sommeil et des rythmes circadiens* et de la Société canadienne du sommeil*.

Can J Psychiatry 2020 Dec 23:706743720980262. Epub 2020 Dec 23.

École de psychologie, 204255Université Laval, Québec, Canada.

Les données recueillies lors de crises et tragédies passées prouvent que les problèmes de sommeil survenant durant ou peu de temps après un événement traumatique sont reliés à une probabilité accrue de développer des symptômes psychiatriques durables. Or la pandémie COVID-19 et ses conséquences à moyen et long-terme combinent plusieurs facteurs de risque pour le sommeil, tant pour les intervenants de la santé que la population générale. Notre relevé mensuel des publications scientifiques qui combinent COVID-19 et sommeil/insomnie entre janvier et juillet 2020 révèle un taux de croissance comparable pour les articles qui portent plus précisément sur la santé mentale mais aucune ne porte sur les résultats d'une intervention. Nous proposons qu'il faille agir rapidement sur les difficultés de sommeil en cette période de pandémie afin de protéger l'équilibre psychologique individuel à moyen et long terme, d'autant plus que les outils nécessaires à la prévention de l'insomnie, sa détection et son traitement sont à la portée de tous les professionnels de la santé mentale.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/0706743720980262DOI Listing
December 2020

A Prodromal Brain-Clinical Pattern of Cognition in Synucleinopathies.

Ann Neurol 2021 02 7;89(2):341-357. Epub 2020 Dec 7.

Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada.

Objective: Isolated (or idiopathic) rapid eye movement sleep behavior disorder (iRBD) is associated with dementia with Lewy bodies (DLB) and Parkinson's disease (PD). Biomarkers are lacking to predict conversion to a dementia or a motor-first phenotype. Here, we aimed at identifying a brain-clinical signature that predicts dementia in iRBD.

Methods: A brain-clinical signature was identified in 48 patients with polysomnography-confirmed iRBD using partial least squares between brain deformation and 27 clinical variables. The resulting variable was applied to 78 patients with iRBD followed longitudinally to predict conversion to a synucleinopathy, specifically DLB. The deformation scores from patients with iRBD were compared with 207 patients with PD, DLB, or prodromal DLB to assess if scores were higher in DLB compared to PD.

Results: One latent variable explained 31% of the brain-clinical covariance in iRBD, combining cortical and subcortical deformation and subarachnoid/ventricular expansion to cognitive and motor variables. The deformation score of this signature predicted conversion to a synucleinopathy in iRBD (p = 0.036, odds ratio [OR] = 2.249; 95% confidence interval [CI] = 1.053-4.803), specifically to DLB (OR = 4.754; 95% CI = 1.283-17.618, p = 0.020) and not PD (p = 0.286). Patients with iRBD who developed dementia had scores similar to clinical and prodromal patients with DLB but higher scores compared with patients with PD. The deformation score also predicted cognitive performance over 1, 2, and 4 years in patients with PD.

Interpretation: We identified a brain-clinical signature that predicts conversion in iRBD to more severe/dementing forms of synucleinopathy. This pattern may serve as a new biomarker to optimize patient care, target risk reduction strategies, and administer neuroprotective trials. ANN NEUROL 2021;89:341-357.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ana.25962DOI Listing
February 2021

Slow wave activity moderates the association between new learning and traumatic brain injury severity.

Sleep 2021 04;44(4)

Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Centre de Recherche du CIUSSS NIM, Montreal, Quebec, Canada.

Study Objectives: Sleep-wake complaints and difficulties in making new learning are among the most persistent and challenging long-term sequelea following moderate to severe traumatic brain injury (TBI). Yet, it is unclear whether, and to what extent, sleep characteristics during the chronic stage of TBI contribute to sleep-wake and cognitive complaints. We aimed to characterize sleep architecture in chronic moderate to severe TBI adults and assess whether non-rapid eye movement slow wave activity (SWA) is associated to next day performance in episodic memory tasks according to TBI severity.

Methods: Forty-two moderate to severe TBI participants, 12-47 months post-injury, and 38 healthy controls were tested with one night of in-laboratory polysomnography, followed the next morning by questionnaires (sleep quality, fatigue, and sleepiness) and neuropsychological assessment. We used multiple regression analyses to assess the moderator effect of SWA power on TBI severity and next-day memory performance.

Results: We found that TBI participants reported worse sleep quality and fatigue, and had worse cognitive performance than controls. No between group differences were found on macro- and micro-architecture of sleep. However, SWA significantly interacted with TBI severity to explain next-day memory performance: higher SWA was more strongly associated to better memory performance in more severe TBI compared to milder TBI.

Conclusions: This study provides evidence that the injured brain is able to produce macro- and micro-architecture of sleep comparable to what is seen in healthy controls. However, with increasing TBI severity, lower non-rapid eye movement SWA power is associated with reduced ability to learn and memorise new information the following day.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/sleep/zsaa242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8033458PMC
April 2021

Sleep timing, sleep consistency, and health in adults: a systematic review.

Appl Physiol Nutr Metab 2020 Oct;45(10 (Suppl. 2)):S232-S247

Départment de psychologie, Université de Montréal, Montreal, QC H2V 2S9, Canada.

The objective of this systematic review was to examine the associations between sleep timing (e.g., bedtime/wake-up time, midpoint of sleep), sleep consistency/regularity (e.g., intra-individual variability in sleep duration, social jetlag, catch-up sleep), and health outcomes in adults aged 18 years and older. Four electronic databases were searched in December 2018 for articles published in the previous 10 years. Fourteen health outcomes were examined. A total of 41 articles, including 92 340 unique participants from 14 countries, met inclusion criteria. Sleep was assessed objectively in 37% of studies and subjectively in 63% of studies. Findings suggest that later sleep timing and greater sleep variability were generally associated with adverse health outcomes. However, because most studies reported linear associations, it was not possible to identify thresholds for "late sleep timing" or "large sleep variability". In addition, social jetlag was associated with adverse health outcomes, while weekend catch-up sleep was associated with better health outcomes. The quality of evidence ranged from "very low" to "moderate" across study designs and health outcomes using GRADE. In conclusion, the available evidence supports that earlier sleep timing and regularity in sleep patterns with consistent bedtimes and wake-up times are favourably associated with health. (PROSPERO registration no.: CRD42019119534.) This is the first systematic review to examine the influence of sleep timing and sleep consistency on health outcomes. Later sleep timing and greater variability in sleep are both associated with adverse health outcomes in adults. Regularity in sleep patterns with consistent bedtimes and wake-up times should be encouraged.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1139/apnm-2020-0032DOI Listing
October 2020

Sleep duration and health in adults: an overview of systematic reviews.

Appl Physiol Nutr Metab 2020 Oct;45(10 (Suppl. 2)):S218-S231

Départment de psychologie, Université de Montréal, Montreal, QC H2V 2S9, Canada.

The objective of this overview of systematic reviews was to examine the associations between sleep duration and health outcomes in adults. Four electronic databases were searched in December 2018 for systematic reviews published in the previous 10 years. Included reviews met the a priori determined population (community-dwelling adults aged 18 years and older), intervention/exposure/comparator (various levels of sleep duration), and outcome criteria (14 outcomes examined). To avoid overlap in primary studies, we used a priority list to choose a single review per outcome; reviews that examined the effect of age and those that looked at dose-response were prioritized. A total of 36 systematic reviews were eligible and 11 were included. Reviews included comprised 4 437 101 unique participants from 30 countries. Sleep duration was assessed subjectively in 96% of studies and 78% of studies in the reviews were prospective cohort studies. The dose-response curves showed that the sleep duration that was most favourably associated with health was 7-8 h per day. Modification of the effect by age was not apparent. The quality of the evidence ranged from low to high across health outcomes. In conclusion, the available evidence suggests that a sleep duration of 7-8 h per day is the one most favourably associated with health among adults and older adults. (PROSPERO registration no.: CRD42019119529.) This is the first overview of reviews that examines the influence of sleep duration on a wide range of health outcomes in adults. Seven to 8 h of sleep per day was most favourably associated with health. Effect modification by age was not evident.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1139/apnm-2020-0034DOI Listing
October 2020

Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older: an integration of physical activity, sedentary behaviour, and sleep.

Appl Physiol Nutr Metab 2020 Oct;45(10 (Suppl. 2)):S57-S102

Canadian Public Health Association, Ottawa, ON K1Z 8R9, Canada.

The Canadian Society for Exercise Physiology assembled a Consensus Panel representing national organizations, content experts, methodologists, stakeholders, and end-users and followed an established guideline development procedure to create the . These guidelines underscore the importance of movement behaviours across the whole 24-h day. The development process followed the strategy outlined in the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. A large body of evidence was used to inform the guidelines including 2 de novo systematic reviews and 4 overviews of reviews examining the relationships among movement behaviours (physical activity, sedentary behaviour, sleep, and all behaviours together) and several health outcomes. Draft guideline recommendations were discussed at a 4-day in-person Consensus Panel meeting. Feedback from stakeholders was obtained by survey ( = 877) and the draft guidelines were revised accordingly. The final guidelines provide evidence-based recommendations for a healthy day (24-h), comprising a combination of sleep, sedentary behaviours, and light-intensity and moderate-to-vigorous-intensity physical activity. Dissemination and implementation efforts with corresponding evaluation plans are in place to help ensure that guideline awareness and use are optimized. First ever 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older with consideration of a balanced approach to physical activity, sedentary behaviour, and sleep Finalizes the suite of 24-Hour Movement Guidelines for Canadians across the lifespan.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1139/apnm-2020-0467DOI Listing
October 2020

Knowledge translation of the Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older: a collaborative movement guideline knowledge translation process.

Appl Physiol Nutr Metab 2020 Oct;45(10 (Suppl. 2)):S103-S124

School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, ON K1G 5Z3, Canada.

Establishing a step-by-step process that provides practitioners with a blueprint for translating movement guidelines into action stands to optimize the investment in guideline development, improve guideline promotion and uptake, and ultimately enhance population health. The purpose of this paper is to describe how the Knowledge-to-Action framework and integrated knowledge translation were operationalized to systematically inform our knowledge translation (KT) efforts for the Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older. In October 2018, the need for a KT Process, operating in tandem with the Guideline Development Process, led to the establishment of a KT team with a specific structure and terms of reference. The KT team collaboratively agreed on decision-making principles prior to selecting target audiences to focus their efforts. We undertook formative research to assess the local context and determinants of guideline dissemination and implementation efforts among target audiences. Plans for the subsequent steps and research are outlined. We highlight recommendations and lessons learned for applying the process in other settings. We outline a collaborative and systematic process and research program for the knowledge translation of movement guidelines. This paper provides an innovative and replicable blueprint to optimize future movement guideline knowledge translation efforts.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1139/apnm-2020-0601DOI Listing
October 2020

The effects of exercise on sleep quality in persons with Parkinson's disease: A systematic review with meta-analysis.

Sleep Med Rev 2021 Feb 8;55:101384. Epub 2020 Sep 8.

Memory and Motor Rehabilitation Laboratory (MEMORY-LAB), Feil and Oberfeld Research Centre, Jewish Rehabilitation Hospital, Montreal Center for Interdisciplinary Research in Rehabilitation (CRIR), Laval, Quebec, Canada; School of Physical and Occupational Therapy, Faculty of Medicine, McGill University, Montreal, Quebec, Canada. Electronic address: https://memorylab.ca/.

We conducted a systematic review with meta-analysis to determine the evidence in support of exercise to improve sleep quality assessed subjectively and objectively in Parkinson's Disease (PD). Standardized mean differences (SMD) comparing the effects of exercise and control interventions on sleep quality with 95% confidence intervals (CI) were calculated. Data from 10 randomized and 2 non-randomized controlled trials, including a total of 690 persons with PD were included. Exercise had a significant positive effect on sleep quality assessed subjectively (SMD = 0.53; 95% CI = 0.16-0.90; p = 0.005). However, the methodological quality of the studies showing positive effects on sleep quality was significantly poorer than the studies showing no effects. Only one study assessed the impact of exercise on objective sleep quality, showing improvements in sleep efficiency assessed with polysomnography (SMD = 0.94; 95% CI = 0.38-1.50; p = 0.001). Exercise performed at moderate to maximal intensities (SMD = 0.46; 95% CI = 0.05-0.87; p = 0.03) had significant effects on subjective sleep quality. In contrast, exercise performed at mild to moderate intensities showed non-significant effects (SMD = 0.76; 95% CI = -0.24-1.76; p = 0.14). These results support the use of exercise to improve sleep quality in persons with PD and reinforce the importance of achieving vigorous exercise intensities. Biases, limitations, practice points and directions for future research are discussed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.smrv.2020.101384DOI Listing
February 2021

Sleep spindles are resilient to extensive white matter deterioration.

Brain Commun 2020 13;2(2):fcaa071. Epub 2020 Jun 13.

Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.

Sleep spindles are an essential part of non-rapid eye movement sleep, notably involved in sleep consolidation, cognition, learning and memory. These oscillatory waves depend on an interaction loop between the thalamus and the cortex, which relies on a structural backbone of thalamo-cortical white matter tracts. It is still largely unknown if the brain can properly produce sleep spindles when it underwent extensive white matter deterioration in these tracts, and we hypothesized that it would affect sleep spindle generation and morphology. We tested this hypothesis with chronic moderate to severe traumatic brain injury ( = 23; 30.5 ± 11.1 years old; 17 m/6f), a unique human model of extensive white matter deterioration, and a healthy control group ( = 27; 30.3 ± 13.4 years old; 21m/6f). Sleep spindles were analysed on a full night of polysomnography over the frontal, central and parietal brain regions, and we measured their density, morphology and sigma-band power. White matter deterioration was quantified using diffusion-weighted MRI, with which we performed both whole-brain voxel-wise analysis (Tract-Based Spatial Statistics) and probabilistic tractography (with High Angular Resolution Diffusion Imaging) to target the thalamo-cortical tracts. Group differences were assessed for all variables and correlations were performed separately in each group, corrected for age and multiple comparisons. Surprisingly, although extensive white matter damage across the brain including all thalamo-cortical tracts was evident in the brain-injured group, sleep spindles remained completely undisrupted when compared to a healthy control group. In addition, almost all sleep spindle characteristics were not associated with the degree of white matter deterioration in the brain-injured group, except that more white matter deterioration correlated with lower spindle frequency over the frontal regions. This study highlights the resilience of sleep spindles to the deterioration of all white matter tracts critical to their existence, as they conserve normal density during non-rapid eye movement sleep with mostly unaltered morphology. We show that even with such a severe traumatic event, the brain has the ability to adapt or to withstand alterations in order to conserve normal sleep spindles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/braincomms/fcaa071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7472897PMC
June 2020

Are age and sex effects on sleep slow waves only a matter of electroencephalogram amplitude?

Sleep 2021 03;44(3)

Center for Advanced Research in Sleep Medicine, CIUSSS-NÎM-Hôpital du Sacré-Coeur de Montréal, Montreal, Quebec, Canada.

Aging is associated with reduced slow wave (SW) density (number SW/min in nonrapid-eye movement sleep) and amplitude. It has been proposed that an age-related decrease in SW density may be due to a reduction in electroencephalogram (EEG) amplitude instead of a decline in the capacity to generate SW. Here, we propose a data-driven approach to adapt SW amplitude criteria to age and sex. We predicted that the adapted criteria would reduce age and sex differences in SW density and SW characteristics but would not abolish them. A total of 284 healthy younger and older adults participated in one night of sleep EEG recording. We defined age- and sex-adapted SW criteria in a first cohort of younger (n = 97) and older (n = 110) individuals using a signal-to-noise ratio approach. We then used these age- and sex-specific criteria in an independent second cohort (n = 77, 38 younger and 39 older adults) to evaluate age and sex differences on SW density and SW characteristics. After adapting SW amplitude criteria, we showed maintenance of an age-related difference for SW density whereas the sex-related difference vanished. Indeed, older adults produced less SW compared with younger adults. Specifically, the adapted SW amplitude criteria increased the probability of occurrence of low amplitude SW (<80 µV) for older men especially. Our results thereby confirm an age-related decline in SW generation rather than an artifact in the detection amplitude criteria. As for the SW characteristics, the age- and sex-adapted criteria display reproducible effects across the two independent cohorts suggesting a more reliable inventory of the SW.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/sleep/zsaa186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7953219PMC
March 2021

Spindles insufficiency in sleepwalkers' deep sleep.

Neurophysiol Clin 2020 Oct 4;50(5):339-343. Epub 2020 Sep 4.

Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur, Montréal, Canada; Department of Neurosciences, Université de Montréal, Montréal, Canada.

Objectives: Sleepwalkers have consistently shown N3 sleep discontinuity, especially after sleep deprivation. In healthy subjects, sleep spindles activity has been positively correlated to sleep stability. We aimed to compare spindles density during N3 sleep between sleepwalkers and healthy controls.

Methods: Two cohorts of 10 and 21 adult sleepwalkers respectively controlled with 10 and 18 healthy volunteers underwent one baseline and one recovery sleep recording after 38h (cohort 1) and 25h (cohort 2) of sleep deprivation. For the two recordings, we performed an automatic detection of spindles (11-16Hz) from EEG signal during N3 sleep, restricted to the first sleep cycle and repeated for all cycles. For better interpretation of results, we extended the analysis to N2 sleep and we also measured the density of slow waves oscillation (SWO) (0.5-4Hz) during the same periods.

Results: Compared to controls, sleepwalkers showed significantly lower spindle densities during N3 sleep considering the first sleep cycle (both cohorts) or all cycles (cohort 1). SWO densities did not differ (cohort 1) or were lower (cohort 2) for sleepwalkers. The effect of sleep deprivation did not interact with the effect of group on spindles and SWO densities.

Conclusion: This work suggests that the instability of N3 sleep inherent to sleepwalkers may be underpinned by a specific alteration of spindles activity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neucli.2020.08.003DOI Listing
October 2020

Prospective relations between sleep in preschool years and academic achievement at school entry.

J Sleep Res 2021 06 6;30(3):e13183. Epub 2020 Sep 6.

Laval University, Quebec, QC, Canada.

It is often assumed that adequate sleep is a key ingredient of children's school success. Research to date, however, suggests modest associations between child sleep and academic achievement. Adopting a developmental perspective, this report investigates the associations between age-related changes in sleep across the preschool period and academic achievement at school entry. Sleep was assessed by actigraphy at ages 2, 3 and 4 among 128 children from mostly White middle-class families, and their performance in reading and mathematics was tested in Grade 1. The results revealed that children whose sleep duration decreased more rapidly across the preschool period showed better performance in both reading and mathematics. These results suggest that age-related developments may be a key characteristic of sleep in the preschool years.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/jsr.13183DOI Listing
June 2021

Subtle long-term cognitive effects of a single mild traumatic brain injury and the impact of a three-month aerobic exercise intervention.

J Sports Med Phys Fitness 2021 Jan 2;61(1):87-95. Epub 2020 Sep 2.

Montreal Sacred Heart Hospital Research Center, Montreal, QC, Canada -

Background: Although there is a growing body of literature on the impact of multiple concussions on cognitive function with aging, less is known about the long-term impact of sustaining a single mild traumatic brain injury (mTBI). Additionally, very few interventions exist to treat mTBI patients and prevent a possible accelerated cognitive decline. This study aimed to: 1) examine the long-term effects of a single mTBI on cognition in patients aged between 55 and 70 years old; and 2) evaluate the cognitive effects of an aerobic exercise program for these patients.

Methods: Thirty-five participants (average age: 58.89, SD=4.14) were assessed using neuropsychological tests. Among them, 18 hadsustained a mTBI two to seven years earlier. Significant differences in information processing speed, executive function and visual memory were found between controls and mTBI patients. Sixteen of the mTBI patients then engaged in a 12-week physical exercise program. They were divided into equivalent groups: 1) aerobic training (cycle ergometers); or 2) stretching exercises. The participants' cardiopulmonary fitness (VO2max) was evaluated pre- and postintervention and neuropsychological tests were re-administered postintervention.

Results: Participants from the aerobic group significantly improved their fitness compared to the stretching group. However, no between-group difference was found on neuropsychological measures postintervention.

Conclusions: In summary, this study shows long-term cognitive effects of mTBI in late adulthood patients. Moreover, the controlled, 12-week aerobic exercise program did not lead to cognitive improvements in our small mTBI sample. Lastly, future directions in optimizing mTBI intervention are discussed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.23736/S0022-4707.20.10918-6DOI Listing
January 2021

Waking EEG functional connectivity in middle-aged and older adults with obstructive sleep apnea.

Sleep Med 2020 11 14;75:88-95. Epub 2020 Jun 14.

Center for Advanced Research in Sleep Medicine, CIUSSS du Nord de l'Île-de-Montréal, Hôpital du Sacré-Coeur de Montréal, 5400 Boulevard Gouin Ouest, Montréal, Québec, H4J 1C5, Canada; Département de Psychologie, Université de Montréal, Pavillon Marie-Victorin, C. P. 6128, Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada. Electronic address:

Objectives: The present study aimed at investigating changes in waking electroencephalography (EEG), most specifically regarding spectral power and functional connectivity, in middle-aged and older adults with obstructive sleep apnea (OSA). We also explored whether changes in spectral power or functional connectivity are associated with polysomnographic characteristics and/or neuropsychological performance.

Methods: In sum, 19 OSA subjects (apnea-hypopnea index ≥ 20, age: 63.6 ± 6.4) and 22 controls (apnea-hypopnea index ≤ 10, age: 63.6 ± 6.7) underwent a full night of in-laboratory polysomnography (PSG) followed by a waking EEG and a neuropsychological assessment. Waking EEG spectral power and imaginary coherence were compared between groups for all EEG frequency bands and scalp regions. Correlation analyses were performed between selected waking EEG variables, polysomnographic parameters and neuropsychological performance.

Results: No group difference was observed for EEG spectral power for any frequency band. Regarding the imaginary coherence, when compared to controls, OSA subjects showed decreased EEG connectivity between frontal and temporal regions in theta and alpha bands as well as increased connectivity between frontal and parietal regions in delta and beta 1 bands. In the OSA group, these changes in connectivity correlated with lower sleep efficiency, lower total sleep time and higher apnea-hypopnea index. No relationship was found with neuropsychological performance.

Conclusions: Contrary to spectral power, imaginary coherence was sensitive enough to detect changes in brain function in middle-aged and older subjects with OSA when compared to controls. Whether these changes in cerebral connectivity predict cognitive decline needs to be investigated longitudinally.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.sleep.2020.06.008DOI Listing
November 2020

Sleep and circadian rhythm in response to the COVID-19 pandemic.

Can J Public Health 2020 10 22;111(5):654-657. Epub 2020 Jul 22.

Université de Montréal, Montreal, QC, Canada.

This commentary highlights the critical role of sleep as a public health issue, particularly during a stressful life period such as the COVID-19 pandemic, and provides evidence-based practical guidelines to manage sleep disturbances during this crisis. The COVID-19 pandemic and the imposed social confinement have produced significant stress, anxiety, and worries about health and the fear of being infected, jobs and financial problems, and uncertainty about the future. The incidence of sleep disturbances has also increased dramatically during this period. Aside from stress and anxiety, two other factors are likely to contribute to increased sleep disturbances during this crisis. First, alterations of our daily routines such as arising at a specific time, showing up at work, eating, exercising, and engaging in social and leisure activities at relatively fixed times are all important timekeepers for our sleep-wake cycles to remain synchronized with the day (light) and night (dark) cycles. Alterations of these timekeepers, combined with reduced daylight exposure, also essential to keep our biological clock synchronized, are likely to disrupt sleep and circadian rhythms. Sleep plays a fundamental role for mental and physical health, and adequate sleep duration and quality are essential for coping with major life events such as the COVID-19 pandemic. Public health education is warranted to keep the population well informed about the importance of sleep and healthy sleep practices in order to cope with the pandemic and prevent or minimize long-term adverse outcomes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.17269/s41997-020-00382-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7375451PMC
October 2020

The acute effects of the COVID-19 pandemic on insomnia and psychological symptoms.

Sleep Med 2021 01 6;77:346-347. Epub 2020 Jun 6.

Université de Montréal, Hôpital Du Sacré-Cœur de Montréal, Canada; Centre D'étude Avancée en Médecine Du Sommeil, Hôpital Du Sacré-Cœur de Montréal, Canada.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.sleep.2020.06.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7274952PMC
January 2021

Attempted induction of signalled lucid dreaming by transcranial alternating current stimulation.

Conscious Cogn 2020 08 10;83:102957. Epub 2020 Jun 10.

Department of Psychiatry, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, Québec H3C 3J7, Canada; Center for Advanced Research in Sleep Medicine, CIUSSS-NÎM - Hôpital du Sacré-Cœur de Montréal, 5400 Gouin Blvd West, Montréal, Québec H4J 1C5, Canada. Electronic address:

Neurophysiological correlates of self-awareness during sleep ('lucid dreaming') remain unclear despite their importance for clarifying the neural underpinnings of consciousness. Transcranial direct (tDC) and alternating (tAC) current stimulation during sleep have been shown to increase dream self-awareness, but these studies' methodological weaknesses prompted us to undertake additional study. tAC stimulation was associated with signal-verified and self-rated lucid dreams-but so was the sham procedure. Situational factors may be crucial to inducing self-awareness during sleep.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.concog.2020.102957DOI Listing
August 2020

Cerebral white matter diffusion properties and free-water with obstructive sleep apnea severity in older adults.

Hum Brain Mapp 2020 07 13;41(10):2686-2701. Epub 2020 Mar 13.

Research Centre, Hôpital du Sacré-Coeur de Montréal, Montréal, Québec, Canada.

Characterizing the effects of obstructive sleep apnea (OSA) on the aging brain could be key in our understanding of neurodegeneration in this population. Our objective was to assess white matter properties in newly diagnosed and untreated adults with mild to severe OSA. Sixty-five adults aged 55 to 85 were recruited and divided into three groups: control (apnea-hypopnea index ≤5/hr; n = 18; 65.2 ± 7.2 years old), mild (>5 to ≤15 hr; n = 27; 64.2 ± 5.3 years old) and moderate to severe OSA (>15/hr; n = 20; 65.2 ± 5.5 years old). Diffusion tensor imaging metrics (fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity, and mean diffusivity) were compared between groups with Tract-Based Spatial Statistics within the white matter skeleton created by the technique. Groups were also compared for white matter hyperintensities volume and the free-water (FW) fraction. Compared with controls, mild OSA participants showed widespread areas of lower diffusivity (p < .05 corrected) and lower FW fraction (p < .05). Participants with moderate to severe OSA showed lower AD in the corpus callosum compared with controls (p < .05 corrected). No between-group differences were observed for FA or white matter hyperintensities. Lower white matter diffusivity metrics is especially marked in mild OSA, suggesting that even the milder form may lead to detrimental outcomes. In moderate to severe OSA, competing pathological responses might have led to partial normalization of diffusion metrics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/hbm.24971DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7294053PMC
July 2020

Effects of menopause on sleep quality and sleep disorders: Canadian Longitudinal Study on Aging.

Menopause 2020 03;27(3):295-304

Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montréal, Québec, Canada.

Objectives: Sleep complaints are common during the menopause transition. However, it is difficult to disentangle changes in sleep related to aging from those directly due to menopause. We compared sleep disorders in 45 to 60-year-old women in a large population-based study, according to menopausal status.

Methods: Women aged between 45 and 60 years who self-reported menopausal status were selected from the Canadian Longitudinal Study of Aging, excluding those with prior hysterectomy. Participants completed assessments for overall sleep satisfaction, hours of daily sleep, sleep-onset insomnia, sleep-maintenance insomnia, daytime somnolence, rapid eye movement sleep behavior disorder (RBD), restless leg syndrome (RLS), and obstructive sleep apnea (OSA). Each sleep variable was compared between postmenopausal and pre/perimenopausal women using multivariate regression, adjusting for potential confounders.

Results: Among 6,179 women included, 3,713 (60.1%; age 55.7 ± 3.3 years) were postmenopausal and 2,466 (39.9%) were pre/perimenopausal (age 49.80 ± 3.1 years). Compared with pre/perimenopausal women, postmenopausal women were more often reported requiring ≥30 minutes to fall asleep (20.4% vs 15.5%; adjusted odds ratio [AOR] 1.24, 95% confidence interval [CI] 1.00-1.53) and were more likely to meet criteria for possible sleep-onset insomnia disorder (10.8% vs 7.3%; AOR 1.51, 95% CI 1.07-2.12). Postmenopausal women were also more likely to screen positive for OSA (14.6% vs 10.4%; AOR 1.48, 95% CI 1.14-1.92). The two groups did not differ on sleep dissatisfaction (32.4% vs 29%), daytime somnolence disorder (1.6% vs 1.3%), sleep-maintenance insomnia disorder (17% vs 14.5%), RLS (23.5% vs 20.9%), or RBD (3.9% vs 4.0%).

Conclusions: Menopause is associated with increased sleep-onset insomnia. Postmenopausal women also are more likely to screen positive for OSA. However, menopausal status is not associated with sleep maintenance, somnolence, or RLS, and RBD. : Video Summary:http://links.lww.com/MENO/A501.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/GME.0000000000001462DOI Listing
March 2020

EEG connectivity across sleep cycles and age.

Sleep 2020 03;43(3)

Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montréal, QC, Canada.

Study Objectives: In young adults, sleep is associated with important changes in cerebral connectivity during the first cycle of non-rapid eye movement (NREM) sleep. Our study aimed to evaluate how electroencephalography (EEG) connectivity during sleep differs between young and older individuals, and across the sleep cycles.

Methods: We used imaginary coherence to estimate EEG connectivity during NREM and rapid eye movement (REM) sleep in 30 young (14 women; 20-30 years) and 29 older (18 women; 50-70 years) individuals. We also explored the association between coherence and cognitive measures.

Results: Older individuals showed lower EEG connectivity in stage N2 but higher connectivity in REM and stage N3 compared to the younger cohort. Age-related differences in N3 were driven by the first sleep cycle. EEG connectivity was lower in REM than N3, especially in younger individuals. Exploratory analyses, controlling for the effects of age, indicated that higher EEG connectivity in delta during N2 was associated with higher processing speed, whereas, during REM sleep, lower EEG connectivity in delta and sigma was associated with higher verbal memory performance and a higher global averaged intelligence quotient score.

Conclusion: Our results indicated that age modifies sleep EEG connectivity but the direction and the magnitude of these effects differ between sleep stages and cycles. Results in N3 and REM point to a reduced ability of the older brains to disconnect as compared to the younger ones. Our results also support the notion that cerebral functional connectivity during sleep may be associated with cognitive functions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/sleep/zsz236DOI Listing
March 2020

Sleep-Wake Cycle in Young and Older Mice.

Front Syst Neurosci 2019 24;13:51. Epub 2019 Sep 24.

Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Québec, QC, Canada.

Sleep plays a key role in multiple cognitive functions and sleep pattern changes with aging. Human studies revealed that aging decreases sleep efficiency and reduces the total sleep time, the time spent in slow-wave sleep (SWS), and the delta power (1-4 Hz) during sleep; however, some studies of sleep and aging in mice reported opposing results. The aim of our work is to estimate how features of sleep-wake state in mice during aging could correspond to age-dependent changes observed in human. In this study, we investigated the sleep/wake cycle in young (3 months old) and older (12 months old) C57BL/6 mice using local-field potentials (LFPs). We found that older adult mice sleep more than young ones but only during the dark phase of sleep-wake cycle. Sleep fragmentation and sleep during the active phase (dark phase of cycle), homologous to naps, were higher in older mice. Older mice show a higher delta power in frontal cortex, which was accompanied with similar trend for age differences in slow wave density. We also investigated regional specificity of sleep-wake electrographic activities and found that globally posterior regions of the cortex show more rapid eye movement (REM) sleep whereas somatosensory cortex displays more often SWS patterns. Our results indicate that the effects of aging on the sleep-wake activities in mice occur mainly during the dark phase and the electrode location strongly influence the state detection. Despite some differences in sleep-wake cycle during aging between human and mice, some features of mice sleep share similarity with human sleep during aging.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnsys.2019.00051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6769075PMC
September 2019

G-quadruplex located in the 5'UTR of the BAG-1 mRNA affects both its cap-dependent and cap-independent translation through global secondary structure maintenance.

Nucleic Acids Res 2019 11;47(19):10247-10266

Département de Biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada.

The anti-apoptotic BAG-1 protein isoforms are known to be overexpressed in colorectal tumors and are considered to be potential therapeutic targets. The isoforms are derived from alternative translation initiations occuring at four in-frame start codons of a single mRNA transcript. Its 5'UTR also contains an internal ribosome entry site (IRES) regulating the cap-independent translation of the transcript. An RNA G-quadruplex (rG4) is located at the 5'end of the BAG-1 5'UTR, upstream of the known cis-regulatory elements. Herein, we observed that the expression of BAG-1 isoforms is post-transcriptionally regulated in colorectal cancer cells and tumors, and that stabilisation of the rG4 by small molecules ligands reduces the expression of endogenous BAG-1 isoforms. We demonstrated a critical role for the rG4 in the control of both cap-dependent and independent translation of the BAG-1 mRNA in colorectal cancer cells. Additionally, we found an upstream ORF that also represses BAG-1 mRNA translation. The structural probing of the complete 5'UTR showed that the rG4 acts as a steric block which controls the initiation of translation at each start codon of the transcript and also maintains the global 5'UTR secondary structure required for IRES-dependent translation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/nar/gkz777DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6821271PMC
November 2019

Loss of PTEN Signaling in Foxl1 Mesenchymal Telocytes Initiates Spontaneous Colonic Neoplasia in Mice.

Cell Mol Gastroenterol Hepatol 2019 27;8(3):530-533.e5. Epub 2019 May 27.

Département d'Anatomie et Biologie Cellulaire, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada. Electronic address:

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcmgh.2019.05.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6819895PMC
July 2020
-->