Brain white matter changes in CPAP-treated obstructive sleep apnea patients with residual sleepiness

Altered fornix integrity is associated with sleep apnea-related hypoxemia in mild cognitive impairment

INTRODUCTION

The limbic system is critical for memory function and degenerates early in the Alzheimer's disease continuum. Whether obstructive sleep apnea (OSA) is associated with alterations in the limbic white matter tracts remains understudied.

METHODS

Polysomnography, neurocognitive assessment, and brain magnetic resonance imaging (MRI) were performed in 126 individuals aged 55-86 years, including 70 cognitively unimpaired participants and 56 participants with mild cognitive impairment (MCI). OSA measures of interest were the apnea-hypopnea index and composite variables of sleep fragmentation and hypoxemia. Microstructural properties of the cingulum, fornix, and uncinate fasciculus were estimated using free water-corrected diffusion tensor imaging.

RESULTS

Higher levels of OSA-related hypoxemia were associated with higher left fornix diffusivities only in participants with MCI. Microstructure of the other white matter tracts was not associated with OSA measures. Higher left fornix diffusivities correlated with poorer episodic verbal memory.

DISCUSSION

OSA may contribute to fornix damage and memory dysfunction in MCI.

HIGHLIGHTS

Sleep apnea-related hypoxemia was associated with altered fornix integrity in MCI. Altered fornix integrity correlated with poorer memory function. Sleep apnea may contribute to fornix damage and memory dysfunction in MCI.

Microstructural Changes in the Cerebral White Matter After 12 Months of CPAP Treatment for Moderate to Severe Obstructive Sleep Apnoea: A TBSS Study

Introduction

Continuous positive airway pressure (CPAP) therapy improves clinical symptoms in patients with obstructive sleep apnea (OSA); however, the mechanism of this clinical improvement and how it may be associated with the restoration of white matter (WM) structures in the brain is unclear. Therefore, this study investigated the relationship between the structural recovery of brain WM and improvements in cognitive function and emotion after long-term (12 months) CPAP treatment in patients with OSA.

Methods

We collected data from 17 patients with OSA before and 12 months after CPAP treatment, including sleep monitoring, clinical assessment, and diffusion tensor imaging (DTI) magnetic resonance imaging.

Results

We observed a partial reversible recovery of brain WM (mean and radial diffusion coefficients) after treatment. This recovery involved the commissural fibers (cingulum, body of corpus callosum), projection fibers (retrolenticular part of the internal capsule, posterior thalamic radiation, posterior limb of the internal capsule, superior corona radiata, posterior corona radiata), association fibers (external capsule, superior longitudinal fasciculus, inferior longitudinal fasciculus), and other regions. In addition, the improvements in WM fibers in one part of the brain significantly were correlated with the Hamilton Anxiety Scale and Hamilton Depression Scale scores.

Discussion

Our results suggest that reversible recovery of reduced brain WM integrity due to OSA may require longer CPAP treatment. Moreover, changes in the integrity of the commissural fibers were associated with emotion regulation. These restored WM areas may explain the cognitive and mood improvements observed after OSA treatment.

Guidelines for the assessment and management of residual sleepiness in obstructive apnea-hypopnea syndrome: Endorsed by the French Sleep Research and Medicine Society (SFRMS) and the French Speaking Society of Respiratory Diseases (SPLF)

Excessive daytime sleepiness (EDS) is frequent among patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and can persist despite the optimal correction of respiratory events (apnea, hypopnea and respiratory efforts), using continuous positive airway pressure (CPAP) or mandibular advancement device. Symptoms like apathy and fatigue may be mistaken for EDS. In addition, EDS has multi-factorial origin, which makes its evaluation complex. The marketing authorization [Autorisation de Mise sur le Marché (AMM)] for two wake-promoting agents (solriamfetol and pitolisant) raises several practical issues for clinicians. This consensus paper presents recommendations of good clinical practice to identify and evaluate EDS in this context, and to manage and follow-up the patients. It was conducted under the mandate of the French Societies for sleep medicine and for pneumology [Société Française de Recherche et de Médecine du Sommeil (SFRMS) and Société de Pneumologie de Langue Française (SPLF)]. A management algorithm is suggested, as well as a list of conditions during which the patient should be referred to a sleep center or a sleep specialist. The benefit/risk balance of a wake-promoting drug in residual EDS in OSAHS patients must be regularly reevaluated, especially in elderly patients with increased cardiovascular and psychiatric disorders risks. This consensus is based on the scientific knowledge at the time of the publication and may be revised according to their evolution.

Obstructive sleep apnea and attention deficits: A systematic review of magnetic resonance imaging biomarkers and neuropsychological assessments

BACKGROUND AND OBJECTIVE

Obstructive sleep apnea (OSA) is a common sleep disorder that causes intermittent hypoxia and sleep fragmentation, leading to attention impairment and other cognitive deficits. Magnetic resonance imaging (MRI) is a powerful modality that can reveal the structural and functional brain alterations associated with attention impairment in OSA patients. The objective of this systematic review is to identify and synthesize the evidence on MRI biomarkers and neuropsychological assessments of attention deficits in OSA patients.

METHODS

We searched the Scopus and PubMed databases for studies that used MRI to measure biomarkers related to attention alteration in OSA patients and reported qualitative and quantitative data on the association between MRI biomarkers and attention outcomes. We also included studies that found an association between neuropsychological assessments and MRI findings in OSA patients with attention deficits.

RESULTS

We included 19 studies that met our inclusion criteria and extracted the relevant data from each study. We categorized the studies into three groups based on the MRI modality and the cognitive domain they used: structural and diffusion tensor imaging MRI findings, functional, perfusion, and metabolic MRI findings, and neuropsychological assessment findings.

CONCLUSIONS

We found that OSA is associated with structural, functional, and metabolic brain alterations in multiple regions and networks that are involved in attention processing. Treatment with continuous positive airway pressure can partially reverse some of the brain changes and improve cognitive function in some domains and in some studies. This review suggests that MRI techniques and neuropsychological assessments can be useful tools for monitoring the progression and response to treatment of OSA patients.

The Relationship Between Sleep and Brain Function in Older Adults With Chronic Kidney Disease and Self-Identified Cognitive Impairment

Older adults with chronic kidney disease (CKD) are at risk for cognitive impairment and sleep disturbances. The purpose of the current study was to investigate the relationship between sleep and brain structure/function in older adults with CKD and self-identified cognitive impairment. The sample (N = 37) had a mean age of 68 years (SD = 4.9 years), estimated glomerular filtration rate of 43.7 mL/min/1.73m2 (SD = 10.98), median sleep time of 7.4 hours, and was 70% female. Sleeping <7.4 hours, compared to ≥7.4 hours, was associated with better attention/information processing (β = 11.46, 95% confidence interval [CI] [3.85, 19.06]) and better learning/memory (β = 2.06, 95% CI [0.37, 3.75]). Better sleep efficiency was associated with better global cerebral blood flow (β = 3.30, 95% CI [0.65, 5.95]). Longer awake length after sleep onset was associated with worse fractional anisotropy of the cingulum (β = -0.01, 95% CI [-0.02, -0.003]). Sleep duration and continuity may be related to brain function in older adults with CKD and self-identified cognitive impairment. [Journal of Gerontological Nursing, 49(7), 31-39.].

Changes in Functional Connectivity of Hippocampal Subregions in Patients with Obstructive Sleep Apnea after Six Months of Continuous Positive Airway Pressure Treatment

Previous studies have shown that the structural and functional impairments of hippocampal subregions in patients with obstructive sleep apnea (OSA) are related to cognitive impairment. Continuous positive airway pressure (CPAP) treatment can improve the clinical symptoms of OSA. Therefore, this study aimed to investigate functional connectivity (FC) changes in hippocampal subregions of patients with OSA after six months of CPAP treatment (post-CPAP) and its relationship with neurocognitive function. We collected and analyzed baseline (pre-CPAP) and post-CPAP data from 20 patients with OSA, including sleep monitoring, clinical evaluation, and resting-state functional magnetic resonance imaging. The results showed that compared with pre-CPAP OSA patients, the FC between the right anterior hippocampal gyrus and multiple brain regions, and between the left anterior hippocampal gyrus and posterior central gyrus were reduced in post-CPAP OSA patients. By contrast, the FC between the left middle hippocampus and the left precentral gyrus was increased. The changes in FC in these brain regions were closely related to cognitive dysfunction. Therefore, our findings suggest that CPAP treatment can effectively change the FC patterns of hippocampal subregions in patients with OSA, facilitating a better understanding of the neural mechanisms of cognitive function improvement, and emphasizing the importance of early diagnosis and timely treatment of OSA.

Obstructive Sleep Apnea - Influence on the Cardiovascular System and Cognition

Kardiovaskuläre und kognitive Erkrankungen sind ebenso wie die obstruktive Schlafapnoe sehr häufige Krankheiten mit einer erheblichen Beeinträchtigung der Lebensqualität und einer deutlichen sozioökonomischen Bedeutung. Die Auswirkungen einer unbehandelten obstruktiven Schlafapnoe (OSA) auf das kardiovaskuläre und kognitive Erkrankungsrisiko und die Therapieeffekte einer OSA sind für die meisten kardiovaskulären und kognitiven Folgeerkrankungen wissenschaftlich nachgewiesen. Für die klinische Praxis besteht ein deutlicher Bedarf nach mehr Interdisziplinarität. Aus schlafmedizinischer Sicht müssen bei der Therapieindikation das individuelle kardiovaskuläre und kognitive Risiko berücksichtigt und kognitive Erkrankungen bei der Beurteilung der Therapieintoleranz und residuellen Symptomatik beachtet werden. Aus internistischer Sicht sollte bei Patienten mit schlecht einstellbarem Hypertonus, Vorhofflimmern, koronarer Herzkrankheit und Schlaganfall die Abklärung einer OSA in die Diagnostik integriert werden. Bei Patienten mit milder kognitiver Beeinträchtigung, Alzheimer-Krankheit und Depression können sich die typischen Symptome wie Fatigue, Tagesmüdigkeit und Reduktion der kognitiven Leistungen mit OSA-Symptomen überschneiden. Die Diagnostik einer OSA sollte in die Abklärung dieser Krankheitsbilder integriert werden, da eine Therapie der OSA die kognitiven Beeinträchtigungen reduzieren und die Lebensqualität verbessern kann.

Machine learning approach for obstructive sleep apnea screening using brain diffusion tensor imaging

Patients with obstructive sleep apnea (OSA) show autonomic, mood, cognitive, and breathing dysfunctions that are linked to increased morbidity and mortality, which can be improved with early screening and intervention. The gold standard and other available methods for OSA diagnosis are complex, require whole-night data, and have significant wait periods that potentially delay intervention. Our aim was to examine whether using faster and less complicated machine learning models, including support vector machine (SVM) and random forest (RF), with brain diffusion tensor imaging (DTI) data can classify OSA from healthy controls. We collected two DTI series from 59 patients with OSA [age: 50.2 ± 9.9 years; body mass index (BMI): 31.5 ± 5.6 kg/m2 ; apnea-hypopnea index (AHI): 34.1 ± 21.2 events/h 23 female] and 96 controls (age: 51.8 ± 9.7 years; BMI: 26.2 ± 4.1 kg/m2 ; 51 female) using a 3.0-T magnetic resonance imaging scanner. Using DTI data, mean diffusivity maps were calculated from each series, realigned and averaged, normalised to a common space, and used to conduct cross-validation for model training and selection and to predict OSA. The RF model showed 0.73 OSA and controls classification accuracy and 0.85 area under the curve (AUC) value on the receiver-operator curve. Cross-validation showed the RF model with comparable fitting over SVM for OSA and control data (SVM; accuracy, 0.77; AUC, 0.84). The RF ML model performs similar to SVM, indicating the comparable statistical fitness to DTI data. The findings indicate that RF model has similar AUC and accuracy over SVM, and either model can be used as a faster OSA screening tool for subjects having brain DTI data.

Louis EK, Przybelski SA, Morgenthaler TI, Machulda MM, Boeve BF, Petersen RC, Jack CR, Graff-Radford J, Vemuri P, Mielke MM. Sleepiness in Cognitively Unimpaired Older Adults Is Associated With CSF Biomarkers of Inflammation and Axonal Integrity

Introduction

Sleepiness has been associated with cognitive decline and dementia in the elderly. Older adults with excessive daytime sleepiness appear to be more vulnerable to longitudinal amyloid PET accumulation before the onset of the dementia. However, it remains unclear whether sleepiness is similarly associated with other biomarkers of Alzheimer's disease (AD), axonal integrity, and inflammation, which may also contribute to neurodegeneration and cognitive decline.

Methods

In this cross-sectional analysis, we identified 260 cognitively unimpaired adults (>60 years) from the Mayo Clinic Study of Aging, a population-based cohort from Olmsted County (MN), who underwent CSF quantification of AD biomarkers (Aβ42, p-tau, p-tau/Aβ42) in addition to at least one of the following biomarkers [neurofilament light chain (NfL) interleukin-6 (IL-6), IL-10, and tumor necrosis factor-α (TNF-α)]. We fit linear regression models to assess associations between sleepiness, as measured by the Epworth Sleepiness Scale (ESS), and CSF biomarkers, controlling for age, sex, APOε4 status, body mass index, hypertension, dyslipidemia, and prior diagnosis of obstructive sleep apnea.

Results

Higher ESS scores were associated with higher CSF IL-6 and NfL, but not with the other CSF biomarkers. For every ESS score point increase, there was a 0.009 ([95% CI 0.001-0.016], p = 0.033) increase in the log of IL-6 and 0.01 ([95% CI 0.002-0.018], p = 0.016) increase in the log of NfL. A sensitivity analysis showed an association between ESS scores and log of p-tau/Aβ42 only in participants with an abnormal ratio (>0.023), highly predictive of amyloid positivity. For every ESS score point increase, there was a 0.006 ([95% CI 0.001-0.012], p = 0.021) increase in the log of CSF p-tau/Aβ42.

Conclusion

Sleepiness was associated with greater CSF IL-6 and NfL levels, which could contribute to neurodegeneration or alternatively cause sleepiness. Higher NfL levels may result from sleep disruption and/or contribute to sleepiness via disturbed connectivity or damage to wake-promoting centers. Associations between sleepiness and p-tau/Aβ42 in participants with abnormal ratio suggest that amyloid positivity contributes to vulnerability to sleep disturbance, which may further amyloid accumulation in a feed-forward loop process. Prospective studies of these markers are needed to determine cause-effect relationships between these associations.

Residual sleepiness in veterans with post-traumatic stress disorder and obstructive sleep apnea

PURPOSE

The causes of residual excessive sleepiness (RES) in patients with post-traumatic stress disorder (PTSD) and obstructive sleep apnea (OSA) are multifactorial and modulated by comorbid conditions. The aim of the present study was to elucidate clinical and polysomnographic determinants of RES in continuous positive airway pressure (CPAP)-adherent OSA veterans with PTSD.

METHODS

The study protocol consisted of a retrospective analysis of consecutive cases of patients with PTSD who presented to the Veterans Affairs sleep clinics with adequately treated OSA between June 1, 2017 and October 15, 2021. Based on the Epworth Sleepiness Scale (ESS), patients were categorized into RES (ESS ≥ 11) and no RES (ESS < 11) groups. Demographic and PSG data were subjected to univariate and multivariate analyses to ascertain predictive factors of RES.

RESULTS

Out of 171 veterans with PTSD who were adherent to CPAP, 59 (35%) continued to experience RES. The RES group had a decrease in mean ESS score of 1.2 ± 4.5 after CPAP treatment compared with 4.6 ± 4.9 for the no RES group (< 0.001). A dose-response was observed between CPAP use and RES (p = 0.003). Multivariate regression analysis identified higher baseline ESS (OR 1.30; 95% CI 1.16-1.44), greater percentage of time spent in REM sleep (OR 0.91; 95% CI 0.85-0.96), CPAP use less than 6 h (OR 2.82; 95% CI 1.13-7.01), and a positive screen for depression (OR 1.69; 95% CI 1.03-4.72) as independent predictors of RES in patients with PTSD and OSA.

CONCLUSION

RES is highly prevalent in patients with PTSD and OSA despite adherence to CPAP and is independently associated with percentage time spent in REM, duration of CPAP utilization, and symptoms of depression.

Investigation and management of residual sleepiness in CPAP-treated patients with obstructive sleep apnoea: the European view

Excessive daytime sleepiness (EDS) is a major symptom of obstructive sleep apnoea (OSA), defined as the inability to stay awake during the day. Its clinical descriptors remain elusive, and the pathogenesis is complex, with disorders such as insufficient sleep and depression commonly associated. Subjective EDS can be evaluated using the Epworth Sleepiness Scale, in which the patient reports the probability of dozing in certain situations; however, its reliability has been challenged. Objective tests such as the multiple sleep latency test or the maintenance of wakefulness test are not commonly used in patients with OSA, since they require nocturnal polysomnography, daytime testing and are expensive. Drugs for EDS are available in the United States but were discontinued in Europe some time ago. For European respiratory physicians, treatment of EDS with medication is new and they may lack experience in pharmacological treatment of EDS, while novel wake-promoting drugs have been recently developed and approved for clinical use in OSA patients in the USA and Europe. This review will discuss 1) the potential prognostic significance of EDS in OSA patients at diagnosis, 2) the prevalence and predictors of residual EDS in treated OSA patients, and 3) the evolution of therapy for EDS specifically for Europe.

Deep Learning Analyses of Brain MRI to Identify Sustained Attention Deficit in Treated Obstructive Sleep Apnea: A Pilot Study

Purpose

Persistent sustained attention deficit (SAD) after continuous positive airway pressure (CPAP) treatment is a source of quality of life and occupational impairment in obstructive sleep apnea (OSA). However, persistent SAD is difficult to predict in patients initiated on CPAP treatment. We performed secondary analyses of brain magnetic resonance (MR) images in treated OSA participants, using deep learning, to predict SAD.

Methods

26 middle-aged men with CPAP use of more than 6 hours daily and MR imaging were included. SAD was defined by psychomotor vigilance task lapses of more than 2. 17 participants had SAD and 9 were without SAD. A Convolutional Neural Network (CNN) model was used for classifying the MR images into +SAD and -SAD categories.

Results

The CNN model achieved an accuracy of 97.02±0.80% in classifying MR images into +SAD and -SAD categories. Assuming a threshold of 90% probability for the MR image being correctly classified, the model provided a participant-level accuracy of 99.11±0.55% and a stable image level accuracy of 97.45±0.63%.

Conclusion

Deep learning methods, such as the proposed CNN model, can accurately predict persistent SAD based on MR images. Further replication of these findings will allow early initiation of adjunctive pharmacologic treatment in high-risk patients, along with CPAP, to improve quality of life and occupational fitness. Future augmentation of this approach with explainable artificial intelligence methods may elucidate the neuroanatomical areas underlying persistent SAD to provide mechanistic insights and novel therapeutic targets.

Brain regional homogeneity changes after short-term positive airway pressure treatment in patients with obstructive sleep apnea

Patients with obstructive sleep apnea (OSA) reveal functional changes in brain sites involved in autonomic, cognitive, and mood regulations. However, it is unclear whether these brain changes reverse with short-term positive airway pressure (PAP) treatment. Our aim was to examine brain functional changes in response to 3-months of PAP treatment using regional homogeneity (ReHo) measures, where increased and decreased ReHo value indicates hyper- and hypo-local neural activities, respectively, and considered as functional deficits. We collected brain magnetic resonance imaging data as well as mood, cognitive, and sleep variables from 17 treatment-naïve OSA at baseline and after 3-months of PAP treatment and 25 age- and gender-matched healthy controls. Whole-brain ReHo maps were calculated and compared between OSA and controls and OSA subjects before and after PAP treatment. At baseline, treatment-naïve OSA subjects showed higher ReHo in the bilateral thalamus, putamen, postcentral gyrus, paracentral lobule, supplementary motor area, and right insula, and lower ReHo in the frontal and parietal cortices, compared to controls. After 3-months of PAP treatment, abnormal sleep and mood scores decreased significantly to normal levels. ReHo decreased in the autonomic and somatosensory control areas, including the thalamus, putamen, postcentral gyrus, and insula, and increased in the cognitive and affective regulatory parietal regions. The normalized ReHo was correlated with improved sleep quality and reduced anxiety symptoms. These findings suggest that 3-months of PAP use can improve sleep, mood issues, and partly recover brain activities, however, longer PAP treatment may be required to fully and permanently reverse brain functional deficits.

Pharmacotherapy of residual excessive sleepiness among continuous positive airway pressure (CPAP) treated patients with sleep apnea

INTRODUCTION

Patients with persistent sleepiness after adequate treatment of obstructive sleep apnea (OSA) with nasal continuous positive airway pressure (nCPAP) experience impaired cognition, reduced productivity, and worse quality of life. Although the mechanisms responsible for this phenomenon are not completely understood, neuroimaging studies have identified reduced gray matter in the frontal cortex and alterations in white matter integrity suggestive of axonal and myelin damage. The intermittent hypoxia with resulting oxidative injury is considered a prime culprit behind the loss of wake-promoting catecholaminergic neurons.

AREAS COVERED

This narrative review gives an overview of the pathophysiology and approaches to managing patients with residual sleepiness. The authors explore different targeted strategies aimed at improving selection of appropriate pharmacotherapy.

EXPERT OPINION

Wake-stimulant medications (modafinil and armodafinil) have demonstrated efficacy in reducing sleepiness in adequately treated OSA. The recent FDA approval of pitolisant and solriamfetol complements the use of modafinil by substituting for direct sympathomimetic agents. The distinctive pharmacologic profile and mode of action of each of these agents offer the opportunity of a personalized approach to the management of this disorder. Further studies should be conducted on the long-term effect of these agents alone or in combination on brain structural and functional changes.

Current Management of Residual Excessive Daytime Sleepiness Due to Obstructive Sleep Apnea: Insights for Optimizing Patient Outcomes

Although excessive daytime sleepiness (EDS) attributable to obstructive sleep apnea (OSA) can be resolved by consistent usage of and effective treatment (often with the use of continuous positive airway pressure therapy), 12–58% of patients report residual EDS (REDS). While REDS is difficult to treat, a proportion of cases are possibly due to reversible issues, and wake-promoting medications can prove useful for the remaining cases. Given the challenges associated with effective management of REDS and its relationship to multiple comorbidities, multidisciplinary management of patients with REDS is often recommended. Here we aim to bridge the knowledge gap on the burden, risk factors, prevalence, and potential pathophysiologic mechanisms of REDS in patients with OSA after first-line treatment. The roles of primary care physicians and sleep specialists, as well as the importance of the use of objective assessment tools for the evaluation of REDS and the effective management of comorbidities, are discussed. An update of approved treatments and emerging candidate treatments is also presented.

Long-term effects of solriamfetol on quality of life and work productivity in participants with excessive daytime sleepiness associated with narcolepsy or obstructive sleep apnea

STUDY OBJECTIVES

Solriamfetol, a dopamine/norepinephrine reuptake inhibitor, is approved in the United States and European Union for excessive daytime sleepiness in adults with narcolepsy (75-150 mg/day) or obstructive sleep apnea (OSA; 37.5-150 mg/day). In 12-week studies, solriamfetol was associated with improvements in quality of life in participants with narcolepsy or OSA. These analyses evaluated the long-term effects of solriamfetol on quality of life.

METHODS

Participants with narcolepsy or OSA who completed previous solriamfetol studies were eligible. A 2-week titration was followed by a maintenance phase ≤ 50 weeks (stable doses: 75, 150, or 300 mg/day). Quality of life assessments included Functional Outcomes of Sleep Questionnaire short version, Work Productivity and Activity Impairment Questionnaire: Specific Health Problem, and 36-Item Short Form Health Survey version 2. Mean (standard deviation) changes from baseline to end of study were evaluated. Data were summarized descriptively. Adverse events were assessed.

RESULTS

Safety population comprised 643 participants (417 OSA, 226 narcolepsy). Solriamfetol improved Functional Outcomes of Sleep Questionnaire short version Total scores (mean change [standard deviation], 3.7 [3.0]) and 36-Item Short Form Health Survey version 2 Physical and Mental Component Summary scores (3.1 [6.9] and 4.3 [8.4], respectively); improvements were sustained throughout treatment. On Work Productivity and Activity Impairment Questionnaire: Specific Health Problem, solriamfetol reduced (improved) % presenteeism, % overall work impairment, and % activity impairment by a minimum of 25%. Common adverse events (≥ 5%): headache, nausea, nasopharyngitis, insomnia, dry mouth, anxiety, decreased appetite, and upper respiratory tract infection.

CONCLUSIONS

Long-term solriamfetol treatment was associated with clinically meaningful, sustained improvements in functional status, work productivity, and quality of life for up to 52 weeks. Adverse events were similar between narcolepsy and OSA.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: A Long-Term Safety Study of JZP-110 in the Treatment of Excessive Sleepiness in Subjects with Narcolepsy or OSA; Identifier: NCT02348632; URL: https://clinicaltrials.gov/ct2/show/NCT02348632.

CITATION

Weaver TE, Pepin J-L, Schwab R, et al. Long-term effects of solriamfetol on quality of life and work productivity in participants with excessive daytime sleepiness associated with narcolepsy or obstructive sleep apnea. J Clin Sleep Med. 2021;17(10):1995-2007.

Deep Learning-Based Assessment of Brain Connectivity Related to Obstructive Sleep Apnea and Daytime Sleepiness

PURPOSE

Obstructive sleep apnea (OSA) is associated with altered pairwise connections between brain regions, which might explain cognitive impairment and daytime sleepiness. By adopting a deep learning method, we investigated brain connectivity related to the severity of OSA and daytime sleepiness.

PATIENTS AND METHODS

A cross-sectional design applied a deep learning model on structural brain networks obtained from 553 subjects (age, 59.2 ± 7.4 years; men, 35.6%). The model performance was evaluated with the Pearson's correlation coefficient (R) and probability of absolute error less than standard deviation (PAE

RESULTS

We achieved a meaningful R (up to 0.74) and PAE

CONCLUSION

A deep learning method can assess the association of brain network characteristics with OSA severity and daytime sleepiness and specify the relevant brain connectivity.

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Key Words

• convolutional neural network
• daytime sleepiness
• diffusion tensor imaging
• obstructive sleep apnea
• structural brain network

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Affiliation(s)

Min-Hee Lee Institute of Human Genomic Study, College of Medicine, Korea University Ansan Hospital, Ansan, Republic of Korea
Seung Ku Lee Institute of Human Genomic Study, College of Medicine, Korea University Ansan Hospital, Ansan, Republic of Korea
Robert J Thomas Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA
Jee-Eun Yoon Department of Neurology, Uijeongbu Eulji Medical Center, Uijeongbu, Republic of Korea
Chang-Ho Yun Department of Neurology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
Chol Shin Institute of Human Genomic Study, College of Medicine, Korea University Ansan Hospital, Ansan, Republic of Korea Department of Pulmonary Sleep and Critical Care Medicine Disorder Center, College of Medicine, Korea University, Ansan, Republic of Korea

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Microstructural changes in normal-appearing white matter in male sleep apnea patients are reversible after treatment: A pilot study

Visually appreciable white matter (WM) changes have been described in obstructive sleep apnea (OSA). However, few data exist on the involvement of silent WM abnormalities. This prospective study investigated the microstructural integrity of normal-appearing white matter (NAWM) in male OSA patients before and after continuous positive airway pressure (CPAP) treatment, using a neuroimaging approach. Magnetic resonance imaging (MRI) was acquired from 32 participants (16 severe never-treated OSA and 16 controls). Diffusion tensor imaging (DTI) and Tract-Based Spatial Statistics (TBSS) were used to assess the microstructural NAWM changes in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). In order to evaluate the efficacy of the therapy, OSA patients underwent MRI evaluations at baseline and after 3 months of treatment (follow-up). CPAP treatment significantly increased the FA in NAWM of the brain stem, corpus callosum and bilateral internal capsule of OSA patients at follow-up compared to baseline (p < 0.05, TFCE-corrected). OSA patients also showed increases in AD in the corpus callosum, superior corona radiata, and internal capsule of the right hemisphere (p < 0.05, TFCE-corrected) after CPAP treatment. A significant negative correlation was found between the FA of the corona radiata, corpus callosum, internal capsule, limbic structures, and neuropsychological scores at follow-up evaluation. No significant differences were found in MD and RD of NAWM in our patients after treatment. Our results demonstrate that FA and AD of NAWM in major tracts such as the corpus callosum and the internal capsule increased significantly after CPAP treatment, as a potential beneficial effect of ventilatory therapy. The recovery of NAWM alterations might also be related to the improvement in the neurocognitive profile, suggesting that nonclearly visible WM alterations may contribute to the physiopathology of OSA-related cognitive impairment.

Digital sleep measures and white matter health in the Framingham Heart Study

AIM

Impaired sleep quality and sleep oxygenation are common sleep pathologies. This study assessed the impact of these abnormalities on white matter (WM) integrity in an epidemiological cohort.

METHODS

The target population was the Framingham Heart Study Generation-2/Omni-1 Cohorts. Magnetic resonance imaging (diffusion tensor imaging) was used to assess WM integrity. Wearable digital devices were used to assess sleep quality: the (M1-SleepImage™ system) and the Nonin WristOx for nocturnal oxygenation. The M1 device collects trunk actigraphy and the electrocardiogram (ECG); sleep stability indices were computed using cardiopulmonary coupling using the ECG. Two nights of recording were averaged.

RESULTS

Stable sleep was positively associated with WM health. Actigraphic periods of wake during the sleep period were associated with increased mean diffusivity. One marker of sleep fragmentation which covaries with respiratory chemoreflex activation was associated with reduced fractional anisotropy and increased mean diffusivity. Both oxygen desaturation index and oxygen saturation time under 90% were associated with pathological directions of diffusion tensor imaging signals. Gender differences were noted across most variables, with female sex showing the larger and significant impact.

CONCLUSIONS

Sleep quality assessed by a novel digital analysis and sleep hypoxia was associated with WM injury, especially in women.

Characterization of the abnormal cortical effective connectivity in patients with sleep apnea hypopnea syndrome during sleep

BACKGROUND AND OBJECTIVES

Sleep apnea hypopnea syndrome (SAHS) is a prevalent sleep breathing disorder that can lead to brain damage and is also a risk factor for cognitive impairment and some common diseases. Studies on cortical effective connectivity (EC) during sleep may provide more direct and pathological information and shed new light on brain dysfunction due to SAHS. However, the EC is rarely explored in SAHS patients, especially during different sleep stages.

METHODS

To this end, six-channel EEG signals of 43 SAHS patients and 41 healthy participants were recorded by whole-night polysomnography (PSG). The symbolic transfer entropy (STE) was applied to measure the EC between cortical regions in different frequency bands. Posterior-anterior ratio (PA) was employed to evaluate the posterior-to-anterior pattern of information flow based on overall cortical EC. The statistical characteristics of the STE and PA and of the intra-individual normalized parameters (STE* and PA*) were served as different feature sets for classifying the severity of SAHS.

RESULTS

Although the patterns of STE across electrodes were similar, significant differences were found between the patient and the control groups. The variation trends across stages in the PA were also different in multiple frequency bands between groups. Important features extracted from the STE* and PA* were distributed in multiple rhythms, mainly in δ, α, and γ. The PA* feature set gave the best results, with accuracies of 98.8% and 83.3% for SAHS diagnosis (binary) and severity classification (four-way).

CONCLUSIONS

These results suggest that modifications in cortical EC were existed in SAHS patients during sleep, which may help characterize cortical abnormality in patients.

Excessive Daytime Sleepiness in Obstructive Sleep Apnea. Mechanisms and Clinical Management

Many patients with obstructive sleep apnea (OSA) experience excessive daytime sleepiness (EDS), which can negatively affect daily functioning, cognition, mood, and other aspects of well-being. Although EDS can be reduced with primary OSA treatment, such as continuous positive airway pressure (CPAP) therapy, a significant proportion of patients continue to experience EDS despite receiving optimized therapy for OSA. This article reviews the pathophysiology and clinical evaluation and management of EDS in patients with OSA. The mechanisms underlying EDS in CPAP-treated patients remain unclear. Experimental risk factors include chronic intermittent hypoxia and sleep fragmentation, which lead to oxidative injury and changes in neurons and brain circuit connectedness involving noradrenergic and dopaminergic neurotransmission in wake-promoting regions of the brain. In addition, neuroimaging studies have shown alterations in the brain's white matter and gray matter in patients with OSA and EDS. Clinical management of EDS begins with ruling out other potential causes of EDS and evaluating its severity. Tools to evaluate EDS include objective and self-reported assessments of sleepiness, as well as cognitive assessments. Patients who experience residual EDS despite primary OSA therapy may benefit from wake-promoting pharmacotherapy. Agents that inhibit reuptake of dopamine or of dopamine and norepinephrine (modafinil/armodafinil and solriamfetol, respectively) have demonstrated efficacy in reducing EDS and improving quality of life in patients with OSA. Additional research is needed on the effects of wake-promoting treatments on cognition in these patients and to identify individual or disorder-specific responses.

Obstructive Sleep Apnea and the Brain: a Focus on Gray and White Matter Structure

PURPOSE OF REVIEW

Obstructive sleep apnea is extremely prevalent in the elderly and may precipitate dementia. We review recent advances on gray and white matter structure in obstructive sleep apnea, the impact of treatment, and potential pathological and neurodegenerative processes underlying brain structural changes.

RECENT FINDINGS

Two opposite patterns are observed in neuroimaging studies of obstructive sleep apnea. One may indicate cellular damage (gray matter atrophy, higher white matter hyperintensity burden, lower white matter fractional anisotropy, higher water diffusivities), while the other (gray matter hypertrophy, restricted white matter diffusivities) may reflect transitory responses, such as intracellular edema, reactive gliosis or compensatory structural changes. Treating obstructive sleep apnea could partly reverse these structural changes. Structural alterations related to obstructive sleep apnea may follow a multi-determined biphasic pattern depending on numerous factors (e.g. severity, symptomatology, age) that could tip the scale toward neurodegeneration and need to be investigated by longitudinal studies.

A Prospective Clinical Trial of Prolonged Fasting in Healthy Young Males and Females-Effect on Fatigue, Sleepiness, Mood and Body Composition

Fasting during a long period (17–18 h/day) may affect daily performance. Fatigue is one of important parameters to observe for this effect. This study aimed to determine the effect of Ramadan fasting (RF)—particularly on fatigue in both young males and females. Sleepiness, mood-related symptoms (MRSs) and body composition (BC) were determined, too. Thirty-four young males and females were recruited and performed RF. They were assessed for fatigue, sleepiness, MRS and BC at T1 (one week before RF), T2 (mid of RF), T3 (last days of RF), T4 (one week after RF) and T5 (one month after RF). The assessments were done in the morning, except for fatigue and sleepiness, which were also assessed in the afternoon and evening of T1 to T5. This study observed numerous positive effects to RF. After they began fasting and compared to T1, participants experienced (1) significantly less fatigue; (2) small to large improvement of MRSs; and (3) positive changes relating to BC. RF did not appear to have a significant effect on participants’ sleepiness scores. Ultimately, this study illustrates how prolonged fasting, like RF, benefits the youth, particularly by decreasing fatigue, improving MRSs and positively impacting BC.

Traumatic Brain Injury: Imaging Patterns and Complications

While the diagnosis of traumatic brain injury (TBI) is a clinical decision, neuroimaging remains vital for guiding management on the basis of identification of intracranial pathologic conditions. CT is the mainstay of imaging of acute TBI for both initial triage and follow-up, as it is fast and accurate in detecting both primary and secondary injuries that require neurosurgical intervention. MRI is more sensitive for the detection of certain intracranial injuries (eg, axonal injuries) and blood products 24-48 hours after injury, but it has limitations (eg, speed, accessibility, sensitivity to motion, and cost). The evidence primarily supports the use of MRI when CT findings are normal and there are persistent unexplained neurologic findings or at subacute and chronic periods. Radiologists should understand the role and optimal imaging modality to use, in addition to patterns of primary brain injury and their influence on the risk of developing secondary brain injuries related to herniation. ^©RSNA, 2019 See discussion on this article by Mathur and Nicolaou.

Update on Research and Practices in Major Sleep Disorders: Part I. Obstructive Sleep Apnea Syndrome

PURPOSE

The purpose of this first of two review articles providing an update on sleep disorders was to examine the pathophysiology, epidemiology, and treatment of obstructive sleep apnea (OSA). OSA is a common sleep disorder whose prevalence is similar to asthma. As with other sleep disorders, OSA has a broad impact on individuals, affecting their daily behaviors, cognitive abilities, and performance, and putting them at increased risk for accidents, mood disorders, cancer, cardiovascular disease, and hypertension. Thus, early recognition and management, much of which can be implemented by nurses, can reduce health and accident risks and improve daily functioning.

METHODS

This narrative review utilized medical databases such as PubMed to identify relevant English language original and systematic review articles predominantly from peer-reviewed journals from 2012 to 2018. However, as background, findings from classic articles prior to 2012 were also included.

CLINICAL RELEVANCE

OSA is a common condition with considerable impact on daily functioning and potential for accidents and serious comorbidities such as hypertension, cardiovascular disease, diabetes, and depressed mood. The impairments and comorbidities associated with OSA can be reduced through early detection, encouraging treatment, providing education about sleep and OSA, and, importantly, promoting adherence to the predominant therapy, positive airway pressure.

Selective microstructural integrity impairments of the anterior corpus callosum are associated with cognitive deficits in obstructive sleep apnea

BACKGROUND

There is some evidence that obstructive sleep apnea (OSA) patients have white matter integrity abnormality in the corpus callosum (CC). However, whether the CC subregions are differentially affected in OSA is largely unknown.

METHODS

Twenty patients with OSA and 24 well-matched healthy controls were enrolled and underwent diffusion tensor imaging (DTI) and clinical and cognitive assessments. DTI tractography was used to reconstruct the CC which was divided into five subregions. Intergroup differences in multiple diffusion metrics of each CC subregion and their correlations with clinical and cognitive parameters were tested.

RESULTS

In comparison with healthy controls, OSA patients exhibited white matter integrity alterations in the anterior CC, characterized by increased radial diffusivity (RD) in the subregion 1 and decreased fractional anisotropy (FA) along with increased mean diffusivity (MD) and RD in the subregion 2. Moreover, we found that the lower microstructural integrity in the anterior CC was correlated with worse prospective memory and sustained attention in OSA patients.

CONCLUSIONS

These findings indicate that the selective impairments of the anterior CC may help clarify the neural correlates of cognitive impairments in OSA.

Continuous positive airway pressure alters brain microstructure and perfusion patterns in patients with obstructive sleep apnea

OBJECTIVES

To assess the effects of continuous positive airway pressure (CPAP) treatment on brain structure and function in patients with obstructive sleep apnea (OSA).

METHODS

A prospective study of seven OSA patients recruited from the sleep center at our institution was carried out. Patients were treated with six weeks of CPAP treatment. Pre-treatment and post-treatment magnetic resonance imaging (MRI) perfusion scans were obtained and compared to assess for treatment-induced changes. Microstructural changes were quantified using functional anistrophy (FA) and mean diffusivity (MD), and brain perfusion was quantified using cerebral blood flow (CBF) and cerebral blood volume (CBV).

RESULTS

Of the seven patients included the in study, six (85.7%) were male, and the mean age was 51 years (standard deviation = 13.14). Increased FA and decreased MD were found in the hippocampus, temporal lobes, fusiform gyrus, and occipital lobes. Decreased FA and increased MD were found in frontal regions for all patients (p < 0.05). Increased CBF and CBV were also observed following treatment (p < 0.05).

CONCLUSION

In addition to symptom resolution, CPAP treatment may allow for healing of OSA-induced brain damage as seen by restoration of brain structure and perfusion.

White matter structural differences in OSA patients experiencing residual daytime sleepiness with high CPAP use: a non-Gaussian diffusion MRI study

OBJECTIVES

To investigate factors associated with residual sleepiness in patients who were highly adherent to continuous positive airway pressure (CPAP). Nocturnal inactivity, comorbidities, concomitant medications, and, in particular, white matter (WM) differences using diffusion magnetic resonance imaging (MRI) were explored using a continuous-time random-walk (CTRW) model.

METHODS

Twenty-seven male patients (30-55 years of age) with obstructive sleep apnea (OSA) received CPAP as the only treatment (CPAP ≥ 6 h/night) for at least 30 days. Based on the Psychomotor Vigilance Task (PVT) results, participants were divided into a non-sleepy group (lapses ≤ 5; n = 18) and a sleepy group (lapses > 5; n = 9). Mean nocturnal inactivity (sleep proxy) was measured using actigraphy for one week. Diffusion-weighted imaging (DWI) with high b-values, as well as diffusion tensor imaging (DTI), was performed on a 3 T MRI scanner. The DWI dataset was analyzed using the CTRW model that yielded three parameters: temporal diffusion heterogeneity α, spatial diffusion heterogeneity β, and an anomalous diffusion coefficient D_m. The differences in α, β, and D_m between the two groups were investigated by a whole-brain analysis using tract-based spatial statistics (TBSS), followed by a regional analysis on individual fiber tracts using a standard parcellation template. Results from the CTRW model were compared with those obtained from DTI. The three CTRW parameters were also correlated with the clinical assessment scores, Epworth Sleepiness Scale (ESS), PVT lapses, and PVT mean reaction time (MRT) in specific fiber tracts.

RESULTS

There were no differences between groups in mean sleep duration, comorbidities, and the number or type of medications, including alerting and sedating medications. In the whole-brain DWI analysis, the sleepy group showed higher α (17.27% of the WM voxels) and D_m (17.14%) when compared to the non-sleepy group (P < 0.05), whereas no significant difference in β was observed. In the regional fiber analysis, the sleepy and non-sleepy groups showed significant differences in α, β, or their combinations in a total of 12 fiber tracts; whereas similar differences were not observed in DTI parameters, when age was used as a covariate. Additionally, moderate to strong correlations between the CTRW parameters (α, β, or D_m) and the sleepiness assessment scores (ESS, PVT lapses, or PVT MRT) were observed in specific fiber tracts (|R| = 0.448-0.654, P = 0.0003-0.019).

CONCLUSIONS

The observed differences in the CTRW parameters between the two groups indicate that WM alterations can be a possible mechanism to explain reversible versus residual sleepiness observed in OSA patients with identical high level of CPAP use. The moderate to strong correlations between the CTRW parameters and the clinical scores suggest the possibility of developing objective and quantitative imaging markers to complement clinical assessment of OSA patients.

Determinants of sleepiness in obstructive sleep apnea

STUDY OBJECTIVES

Significant interindividual variability in sleepiness is observed in clinical populations with obstructive sleep apnea (OSA). This phenomenon is only partially explained by the apnea-hypopnea index (AHI). Understanding factors that lead to sleepiness is critical to effective management of patients with OSA. We examined demographic and other factors associated with sleepiness in OSA.

METHODS

Prospective study of 283 patients with newly diagnosed OSA by polysomnography (AHI ≥ 5 per hour). Subjective sleepiness (Epworth Sleep Scale [ESS] ≥ 11) and objective sleepiness (psychomotor vigilance task [PVT] mean lapse ≥ 2) were assessed.

RESULTS

Participants were classified into four groups (1: sleepy by ESS and PVT, 2: sleepy by PVT only, 3: sleepy by ESS only, and 4: nonsleepy reference group) and compared by generalized logit model. Shorter daily sleep duration by actigraphy and less morningness were associated with higher risk of sleepiness (Odds ratio [OR] = 0.52, 95% confidence interval [CI] 0.33-0.82 and OR = 0.89, CI 0.80-0.98, respectively). African-American race was associated with sleepiness (group 1, OR = 8.8, CI 2.8-27.3; group 2, OR = 16.6, CI 3.3-83.6; and group 3, OR = 3.3, CI 1.0-10.1). IL-6 level was higher in groups 1 and 3 (OR = 1.9, CI 1.0-3.4 and OR 2.0, CI 1.1-3.7, respectively).

CONCLUSIONS

African-American race, short sleep duration, chronotype, and increased proinflammatory cytokine IL-6 level were associated with sleepiness in OSA. These findings will inform future investigations determining mechanisms of sleepiness in OSA.

Sleep-Disordered Breathing and Excessive Daytime Sleepiness

Sleep-related breathing disorders include obstructive sleep apnea (OSA), central sleep apnea, sleep-related hypoventilation, and sleep-related hypoxemia. Excessive daytime sleepiness (EDS) is frequently reported by patients with OSA but is not invariably present. The efficacy of positive airway pressure therapy in improving EDS is well established for OSA, but effectiveness is limited by suboptimal adherence. Non-OSA causes of sleepiness should be identified and treated before initiating pharmacotherapy for persistent sleepiness despite adequately treated OSA. Further research on the identification of factors that promote EDS in the setting of OSA is needed to aid in the development of better treatment options.

Disrupted small-world brain functional network topology in male patients with severe obstructive sleep apnea revealed by resting-state fMRI

PURPOSE

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder that can damage cognitive function. However, the functional network organization remains poorly understood. The aim of this study was to investigate the topological properties of OSA patients using a graph theoretical analysis.

PATIENTS AND METHODS

A total of 30 male patients with untreated severe OSA and 25 male education- and age-matched good sleepers (GSs) underwent functional magnetic resonance imaging (MRI) examinations. Clinical and cognitive evaluations were conducted by an experienced psychologist. GRETNA (a toolbox for topological analysis of imaging connectomics) was used to construct the brain functional network and calculate the small-world properties (γ, λ, σ, E_glob, and E_loc). Relationships between these small-world properties and clinical and neuropsychological assessments were investigated in OSA patients.

RESULTS

The networks of both OSA patients and GSs exhibited efficient small-world topology over the sparsity range of 0.05-0.40. Compared with GSs, the OSA group had significantly decreased γ, but significantly increased λ and σ. The OSA group's brain network showed significantly decreased E_glob (P<0.05) over the sparsity range of 0.09-0.15, but significantly increased E_loc over the sparsity range of 0.23-0.40. In OSA patients, γ was significantly negatively correlated with apnea-hypopnea index (AHI; r=-0.326, P=0.015) and Epworth Sleepiness Scale (ESS; r=-0.274, P=0.043), λ was significantly positively correlated with AHI (r=0.373, P=0.005) and ESS (r=0.269, P=0.047), and σ was significantly negatively correlated with AHI (r=-0.363, P=0.007) and ESS (r=-0.295, P=0.029).

CONCLUSION

Our results suggest that the high degree of local integration and integrity of the brain connections in OSA patients may be disrupted. The topological alterations of small-world properties may be the mechanism of cognitive impairment in OSA patients. In addition, σ, γ, and λ could be used as a quantitative physiological index for auxiliary clinical diagnoses.

Effect of Ramadan fasting on fatigue, mood, sleepiness, and health-related quality of life of healthy young men in summer time in Germany: A prospective controlled study

Muslims around the world fast during the lunar month of Ramadan. The month consists of 29 or 30 days, which vary in length depending on geographic location and the time of year. During this month, Muslims abstain from food, drink, smoking, and sex from dawn until sunset. In 2015, Ramadan fell during the summer. As a result, Muslims in Germany fasted 19 h a day. Previous research has shown associations between fasting and mood enhancement. This study aimed to determine the effect of fasting on young, healthy males who fasted in Germany during Ramadan 2015. In particular, this study examined the impact of fasting on mood, fatigue, and health-related Quality of Life (QoL). This study had 2 groups: fasting group (FG; n = 25), and non-fasting group (NFG; n = 25). In FG, participants were assessed at four different points: one week before Ramadan (T1), mid Ramadan (T2), the last days of Ramadan (T3), and one week after Ramadan (T4). In NFG, participants were assessed only at T1 and T3. The results revealed that there were no significant differences between the participants in the FG and the NFG at T1 or T3 for any of the outcomes. However, participants in the FG demonstrated significant improvement from T2 to T4 in fatigue (visual analogue scale p < 0.01; fatigue severity scale:p < 0.01), mood (Beck's Depression Index-II; ANOVA; p < 0.05), and sleepiness during day time (Epworth Sleepiness Scale: ANOVA; p < 0.01). Participants in the FG also experienced significant loss of body weight (ANOVA; p < 0.001), body mass index (ANOVA; p < 0.001), skeletal muscle mass (ANOVA; p < 0.01) and fat free mass (ANOVA; p < 0.01). Findings demonstrate that Ramadan fasting did not significantly influence mood, fatigue and QoL, when compared to NFG. Even, it gives benefit to fasting group with regard to these parameters.