28 research outputs found
Regional cerebral blood flow during wakeful rest in older subjects with mild to severe obstructive sleep apnea
Objectives: To evaluate changes in regional cerebral blood flow (rCBF) during wakeful rest in older
subjects with mild to severe obstructive sleep apnea (OSA) and healthy controls, and to identify
markers of OSA severity that predict altered rCBF.
Design: High-resolution 99mTc-HMPAO SPECT images during wakeful rest.
Setting: Research sleep laboratory affiliated with a University hospital.
Participants: Fifty untreated OSA patients aged between 55 and 85 years divided into mild, moderate
and severe OSA and 20 age-matched healthy controls.
Interventions: N/A
Measurements: Using statistical parametrical mapping, rCBF was compared between groups and
correlated with clinical, respiratory and sleep variables.
Results: Whereas no rCBF change was observed in mild and moderate groups, participants with severe
OSA had reduced rCBF compared to controls in the left parietal lobules, precentral gyrus, bilateral
postcentral gyri, and right precuneus. Reduced rCBF in these regions and in areas of the bilateral
frontal and left temporal cortex was associated with more hypopneas, snoring, hypoxemia, and
sleepiness. Higher apnea, micro-arousal, and body mass indexes were correlated to increased rCBF in
the basal ganglia, insula, and limbic system.
Conclusions: While older individuals with severe OSA had hypoperfusions in the sensorimotor and
parietal areas, respiratory variables and subjective sleepiness were correlated with extended regions of
hypoperfusion in the lateral cortex. Interestingly, OSA severity, sleep fragmentation and obesity
correlated with increased perfusion in subcortical and medial cortical regions. Anomalies with such a
distribution could result in cognitive deficits and reflect impaired vascular regulation, altered neuronal
integrity, and/or undergoing neurodegenerative processes
Consultations sur l'enseignement supérieur : projet de création du Conseil des collÚges du Québec et de la Commission mixte de l'enseignement supérieur et suggestions de modifications au RÚglement sur le régime des études collégiales
Comprend des références bibliographique
Gray matter hypertrophy and thickening with obstructive sleep apnea in middle-aged and older adults
Rationale: Obstructive sleep apnea causes intermittent hypoxemia, hemodynamic fluctuations,
and sleep fragmentation, all of which could damage cerebral gray matter that can be indirectly
assessed with neuroimaging.
Objectives: To investigate whether markers of obstructive sleep apnea severity are associated
with gray matter changes among middle-aged and older individuals.
Methods: Seventy-one subjects (ages: 55 to 76; apneaâhypopnea index: 0.2 to 96.6 events/h)
were evaluated with magnetic resonance imaging. Two techniques were used: 1) voxel-based
morphometry, which measures gray matter volume and concentration; 2) FreeSurfer automated
segmentation, which estimates the volume of predefined cortical/subcortical regions and cortical
thickness. Regression analyses were performed between gray matter characteristics and markers
of obstructive sleep apnea severity (hypoxemia, respiratory disturbances, sleep fragmentation).
Measurements and Main Results: Subjects had few symptoms, i.e. sleepiness, depression,
anxiety and cognitive deficits. While no association was found with voxel-based morphometry,
FreeSurfer revealed increased gray matter with obstructive sleep apnea. Higher levels of
hypoxemia correlated with increased volume and thickness of the left lateral prefrontal cortex as
well as increased thickness of the right frontal pole, the right lateral parietal lobules, and the left
posterior cingulate cortex. Respiratory disturbances positively correlated with right amygdala
volume while more severe sleep fragmentation was associated with increased thickness of the
inferior frontal gyrus.
Conclusions: Gray matter hypertrophy and thickening were associated with hypoxemia,
respiratory disturbances, and sleep fragmentation. These structural changes in a group of middle-aged and older individuals may represent adaptive/reactive brain mechanisms attributed to a
presymptomatic stage of obstructive sleep apnea
BDNF Val66Met polymorphism interacts with sleep consolidation to predict ability to create new declarative memories
It is hypothesized that a fundamental function of sleep is to restore an individual's day-to-day ability to learn and to constantly adapt to a changing environment through brain plasticity. Brain-derived neurotrophic factor (BDNF) is among the key regulators that shape brain plasticity. However, advancing age and carrying the BDNF Met allele were both identified as factors that potentially reduce BDNF secretion, brain plasticity, and memory. Here, we investigated the moderating role of BDNF polymorphism on sleep and next-morning learning ability in 107 nondemented individuals who were between 55 and 84 years of age. All subjects were tested with 1 night of in-laboratory polysomnography followed by a cognitive evaluation the next morning. We found that in subjects carrying the BDNF Val66Val polymorphism, consolidated sleep was associated with significantly better performance on hippocampus-dependent episodic memory tasks the next morning (ÎČ-values from 0.290 to 0.434, p †0.01). In subjects carrying at least one copy of the BDNF Met allele, a more consolidated sleep was not associated with better memory performance in most memory tests (ÎČ-values from -0.309 to -0.392, p values from 0.06 to 0.15). Strikingly, increased sleep consolidation was associated with poorer performance in learning a short story presented verbally in Met allele carriers (ÎČ = -0.585, p = 0.005). This study provides new evidence regarding the interacting roles of consolidated sleep and BDNF polymorphism in the ability to learn and stresses the importance of considering BDNF polymorphism when studying how sleep affects cognition
Obstructive sleep apnea during REM sleep and daytime cerebral functioning : a regional cerebral blood flow study using high-resolution SPECT
Obstructive sleep apnea (OSA) predominantly during rapid eye movement (REM) sleep may have impacts on brain health, even in milder OSA cases. Here, we evaluated whether REM sleep OSA is associated with abnormal daytime cerebral functioning using high-resolution single-photon emission computed tomography (SPECT). We tested 96 subjects (25 F, age: 65.2â±â6.4) with a wide range of OSA severity from no OSA to severe OSA (apneaâhypopnea index: 0â97 events/h). More respiratory events during REM sleep were associated with reduced daytime regional cerebral blood flow (rCBF) in the bilateral ventromedial prefrontal cortex and in the right insula extending to the frontal cortex. More respiratory events during non-REM (NREM) sleep were associated with reduced daytime rCBF in the left sensorimotor and temporal cortex. In subjects with a lower overall OSA severity (apneaâhypopnea index<15), more respiratory events during REM sleep were also associated with reduced daytime rCBF in the insula and extending to the frontal cortex. Respiratory events that characterized OSA during NREM versus REM sleep are associated with distinct patterns of daytime cerebral perfusion. REM sleep OSA could be more detrimental to brain health, as evidenced by reduced daytime rCBF in milder forms of OSA
Waking EEG functional connectivity in middle-aged and older adults with obstructive sleep apnea
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 OSA. We also explored whether changes in spectral power or functional
connectivity are associated with polysomnographic characteristics and/or neuropsychological
performance.
Methods: 19 OSA subjects (apnea-hypopnea index ℠20, age: 63.6 ± 6.4) and 22 controls (apneahypopnea index †10, age: 63.6 ± 6.7) underwent a full night of in-laboratory polysomnography
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
Cerebral white matter diffusion properties and freeâwater with obstructive sleep apnea severity in older adults
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. Sixtyâfive adults aged 55 to 85 were recruited and divided into three groups: control (apneaâhypopnea index â€5/hr; n = 18; 65.2â±â7.2âyears old), mild (>5 to â€15 hr; n = 27; 64.2â±â5.3âyears old) and moderate to severe OSA (>15/hr; n = 20; 65.2â±â5.5âyears old). Diffusion tensor imaging metrics (fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity, and mean diffusivity) were compared between groups with TractâBased Spatial Statistics within the white matter skeleton created by the technique. Groups were also compared for white matter hyperintensities volume and the freeâwater (FW) fraction. Compared with controls, mild OSA participants showed widespread areas of lower diffusivity (pâ<â.05 corrected) and lower FW fraction (pâ<â.05). Participants with moderate to severe OSA showed lower AD in the corpus callosum compared with controls (pâ<â.05 corrected). No betweenâgroup 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
Organizational Knowledge Translation Strategies for Allied Health Professionals in Traumatology Settings: A Realist Review Protocol.
Background
Knowledge translation (KT) is an important means of improving the health service quality. Most research on the effectiveness of KT strategies has focused on individual strategies, i.e., those directly targeting the modification of allied health professionalsâ knowledge, attitudes, and behaviors, for example. In general, these strategies are moderately effective in changing practices (maximum 10% change). Effecting change in organizational contexts (e.g., change readiness, general and specific organizational capacity, organizational routines) is part of a promising new avenue to service quality improvement through the implementation of evidence-based practices. The objective of this study will be to identify why, how, and under what conditions organizational KT strategies have been shown to be effective or ineffective in changing the (a) knowledge, (b) attitudes, and (c) clinical behaviors of allied health professionals in traumatology settings.
Methods
This is a realist review protocol involving four iterative steps: (1) Initial theory formulation, (2) search for Evidence search, (3) knowledge extraction and synthesis, and (4) recommendations. We will search electronic databases such as PubMed, Embase, CINHAL, Cochrane Library, and Conference Proceedings Citation Index - Science. The studies included will be those relating to the use of organizational KT strategies in trauma settings, regardless of study designs, published between January 1990 and October 2020, and presenting objective measures that demonstrate change in allied health professionalsâ knowledge, attitudes, and clinical behaviors. Two independent reviewers will select, screen, and extract the data related to all relevant sources in order to refine or refute the context-mechanism-outcome (CMO) configurations developed in the initial theory and identify new CMO configurations.
Discussion
Using a systematic and rigorous method, this review will help guide decision-makers and researchers in choosing the best organizational strategies to optimize the implementation of evidence-based practices