Cognition and daytime functioning in sleep-related breathing disorders

Role of Oxidative Stress in the Occurrence and Development of Cognitive Dysfunction in Patients with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) causes recurrent apnea and intermittent hypoxia at night, leading to several complications such as cognitive dysfunction. However, the molecular mechanisms underlying cognitive dysfunction in OSAS are unclear, and oxidative stress mediated by intermittent hypoxia is an important mechanism. In addition, the improvement of cognitive dysfunction in patients with OSAS varies by different treatment regimens; among them, continuous positive airway pressure therapy (CPAP) is mostly recognized for improving cognitive dysfunction. In this review, we discuss the potential mechanisms of oxidative stress in OSAS, the common factors of affecting oxidative stress and the Links between oxidative stress and inflammation in OSAS, focusing on the potential links between oxidative stress and cognitive dysfunction in OSAS and the potential therapies for neurocognitive dysfunction in patients with OSAS mediated by oxidative stress. Therefore, further analysis on the relationship between oxidative stress and cognitive dysfunction in patients with OSAS will help to clarify the etiology and discover new treatment options, which will be of great significance for early clinical intervention.

Cytosolic Escape of Mitochondrial DNA Triggers cGAS-STING Pathway-Dependent Neuronal PANoptosis in Response to Intermittent Hypoxia

Intermittent hypoxia (IH) is the predominant pathophysiological disturbance in obstructive sleep apnea (OSA), characterized by neuronal cell death and neurocognitive impairment. We focus on the accumulated mitochondrial DNA (mtDNA) in the cytosol, which acts as a damage-associated molecular pattern (DAMP) and activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, a known trigger for immune responses and neuronal death in degenerative diseases. However, the specific role and mechanism of the mtDNA-cGAS-STING axis in IH-induced neural damage remain largely unexplored. Here, we investigated the involvement of PANoptosis, a novel type of programmed cell death linked to cytosolic mtDNA accumulation and the cGAS-STING pathway activation, in neuronal cell death induced by IH. Our study found that PANoptosis occurred in primary cultures of hippocampal neurons and HT22 cell lines exposed to IH. In addition, we discovered that during IH, mtDNA released into the cytoplasm via the mitochondrial permeability transition pore (mPTP) activates the cGAS-STING pathway, exacerbating PANoptosis-associated neuronal death. Pharmacologically inhibiting mPTP opening or depleting mtDNA significantly reduced cGAS-STING pathway activation and PANoptosis in HT22 cells under IH. Moreover, our findings indicated that the cGAS-STING pathway primarily promotes PANoptosis by modulating endoplasmic reticulum (ER) stress. Inhibiting or silencing the cGAS-STING pathway substantially reduced ER stress-mediated neuronal death and PANoptosis, while lentivirus-mediated STING overexpression exacerbated these effects. In summary, our study elucidates that cytosolic escape of mtDNA triggers cGAS-STING pathway-dependent neuronal PANoptosis in response to IH, mainly through regulating ER stress. The discovery of the novel mechanism provides theoretical support for the prevention and treatment of neuronal damage and cognitive impairment in patients with OSA.

Association between sleep apnoea and risk of cognitive impairment and Alzheimer's disease: a meta-analysis of cohort-based studies

PURPOSE

To provide updated evidence on the association of obstructive sleep apnoea (OSA)/sleep-disordered breathing (SDB) with risk of all-cause cognitive impairment/dementia and Alzheimer's disease (AD).

METHODS

A systematic literature search was done in PubMed, EMBASE and Scopus databases for cohort studies (retrospective or prospective) that documented the association of SDB/OSA with the risk of cognitive impairment or all-cause dementia or AD. Only studies that were published in the year 2000 and onwards were included. The random-effects model was used for all the analyses and effect sizes were reported as hazards ratio (HR) with 95% confidence intervals.

RESULTS

Of 15 studies were included in the meta-analysis, SDB/OSA was diagnosed with at-home polysomnography in six studies, while five studies relied on self-report or questionnaires. In the remaining studies, International Classification of Diseases (ICD) codes determined the diagnosis of SDB. The overall pooled analysis showed that patients with SDB/OSA had higher risk of cognitive impairment and/or all-cause dementia (HR 1.52, 95% CI: 1.32, 1.74), when compared to patients without SDB/OSA. However, when studies with diagnosis of SDB based on polysomnography were pooled together, the strength of association for all-cause cognitive impairment was weaker (HR 1.32, 95% CI: 1.00, 1.74).

CONCLUSION

Findings suggest a possible association of SDB/OSA with risk of all-cause cognitive impairment and/or dementia. However, careful interpretation is warranted as the majority of the studies did not rely on objective assessment based on polysomnography.

Evolution of adherence and self-reported symptoms over 36 months with mandibular advancement device therapy for obstructive sleep apnea: a retrospective study

STUDY OBJECTIVES

Mandibular advancement devices (MAD) constitute a feasible option for management of mild-to-moderate obstructive sleep apnea (OSA) and in severe cases, when indicated. As a chronic condition, the management of OSA with MAD requires long-term patient adherence to treatment. The aim of the study was to investigate adherence to MAD therapy during a 36-month observation period in relation to changes in self-reported symptoms and objective response to therapy.

METHODS

Retrospective chart review of patients referred to the Orofacial Pain Clinic (University of Kentucky) between 2016 and 2021 for management of OSA with MAD was performed. Based on a posttreatment sleep study with MAD in situ, participants were subdivided into optimal response (> 50% reduction of baseline apnea-hypopnea index) and suboptimal response (< 50% reduction of baseline apnea-hypopnea index) groups. Outcomes included self-reported adherence to MAD use, self-reported OSA symptoms including snoring, apneic episodes, tiredness upon awakening, fatigue, and sleep quality (on a 100-mm numerical rating scale), and daytime sleepiness (0-24 on the Epworth Sleepiness Scale). Intragroup and intergroup differences at different time points over a 36-month observation period were assessed with one-way and repeated-measures analysis of variance.

RESULTS

Of 54 participants included (46.3% female, age 64.4 ± 10.71 years), 30 (55.6%) achieved optimal response and 24 (44.4%) achieved suboptimal response. At baseline, participants with optimal response differed from those with suboptimal response in apnea-hypopnea index (P = .007), snoring (P = .026), and sleep quality (P = .042). Although fluctuating in both groups, no difference was found over time in adherence (7 nights/wk, 7 h/night) and in OSA symptoms (all P > .05).

CONCLUSIONS

Adherence to MAD was maintained over 36 months regardless of fluctuation in self-reported OSA symptoms and effectiveness of MAD therapy.

CITATION

Sangalli L, Yanez-Regonesi F, Moreno-Hay I. Evolution of adherence and self-reported symptoms over 36 months with mandibular advancement device therapy for obstructive sleep apnea: a retrospective study. J Clin Sleep Med. 2024;20(4):487-496.

A review of obstructive sleep apnea and lung cancer: epidemiology, pathogenesis, and therapeutic options

Despite undeniable advances in modern medicine, lung cancer still has high morbidity and mortality rates. Lung cancer is preventable and treatable, and it is important to identify new risk factors for lung cancer, especially those that can be treated or reversed. Obstructive sleep apnea (OSA) is a very common sleep-breathing disorder that is grossly underestimated in clinical practice. It can cause, exacerbate, and worsen adverse outcomes, including death and various diseases, but its relationship with lung cancer is unclear. A possible causal relationship between OSA and the onset and progression of lung cancer has been established biologically. The pathophysiological processes associated with OSA, such as sleep fragmentation, intermittent hypoxia, and increased sympathetic nervous excitation, may affect normal neuroendocrine regulation, impair immune function (especially innate and cellular immunity), and ultimately contribute to the occurrence of lung cancer, accelerate progression, and induce treatment resistance. OSA may be a contributor to but a preventable cause of the progression of lung cancer. However, whether this effect exists independently of other risk factors is unclear. Therefore, by reviewing the literature on the epidemiology, pathogenesis, and treatment of lung cancer and OSA, we hope to understand the relationships between the two and promote the interdisciplinary exchange of ideas between basic medicine, clinical medicine, respiratory medicine, sleep medicine, and oncology.

[The effect of insomnia on mild cognitive impairment in patients with vascular risks: results of a three-year longitudinal study]

OBJECTIVE

To assess the dynamics of sleep parameters based on the analysis of three items of HDRS-17, designed to measure the severity of insomnia, during 36 months of follow-up and their relationship with indicators of the cognitive phenotype in patients with vascular risk factors.

MATERIAL AND METHODS

The longitudinal study included 51 patients (mean age 57.7±6.2 years, 19 (37.3%) men)) who met the inclusion criteria. All participants underwent a general clinical examination with assessment of vascular risks and neuropsychological testing using the Montreal Cognitive Assessment (MoCA) and HDRS-17 at baseline and after 36 months. During the study, patients received stable basic therapy to prevent modifiable vascular risk factors. Sleeping pills were taken sporadically when there were complaints of problems falling asleep.

RESULTS

During the 36-month study, as vascular cognitive impairment progressed from 23.7±2.6 to 22.1±2.4 points on the MoCA scale (p=0.01), mainly due to decreased attention (p=0.01), executive functions (EF) (p=0.01), memory (p=0.02), speech (p=0.02), an increase in sleep disturbances was observed (item 4: 0.8±0.02 to 1.9±0.1 points, p=0.01; point 5: 0.6±0.02 to 1.7±0.1 points, p=0.01) and depression (7.5±0.5 to 13.7±3.0 points, p=0.01) in patients with vascular risks. A strong inverse correlation was revealed between the values of items 4, 5, 6 on the HDRS-17 and the average MoCA-total scores (r=-0.85; r=-0.87; r=-0.8 (p<0.05)), memory index (r=-0.8; r=-0.75; r=-0.81 (p<0.05)), attention index (r=-0.88; r=-0.86; r=-0.83 (p<0.05)), index of executive functions (r=-0.87; r=-0.85; r=-0.8 (p<0.05)), respectively.

CONCLUSION

The progression of cognitive impairment is associated with worsening insomnia disorders and depression in patients with vascular risks.

Effects of smoking on sleep architecture and ventilatory parameters including apneas: Results of the Tab-OSA study

Background

The interaction between smoking and sleep seems appears to be bidirectional, but few studies evaluated the impact of smoking and its cessation on objective sleep parameters. In this context, this new study aimed to assess the impact of smoking and its cessation on sleep architecture and on ventilatory sleep parameters, particularly the presence of sleep apnea syndrome (apnea-hypopnea index (AHI)≥15). Methods: Patients hospitalized for polysomnographic sleep exploration were compared according to their smoking status: active smokers (AS), former smokers (FS), non-smokers (NoNi). Psychiatric and non-psychiatric co-morbidities and treatment or substance use were taken into account in the analyses.

Results

A total of 170 participants were included (N = 37 FS, 39 AS, 86 NoNi). A significant decrease in the mean nocturnal O2 saturation was observed for FS and AS compared to NoNi. No differences were found regarding AHI. Regarding sleep architecture, we observed a significant decrease in the slow wave sleep duration for AS compared to NoNi, and interestingly not between FS and NoNi.

Conclusion

This study suggests that current smokers suffer from alterations in both sleep architecture and ventilatory parameters, the later appears to persist even after smoking cessation.

The Sleepiness-Depression Link in Obstructive Sleep Apnea: Preliminary Results on the Mediation of Impulsivity

BACKGROUND

Emotional impulsivity has been found to be relevant in explaining the association between sleep problems and depressive symptoms, suggesting the potential role of impulsivity as a key underlying mechanism of this link. The objective of this study was to take a preliminary step in understanding the mediating role of impulsivity in the relation between excessive daytime sleepiness (EDS) and depression in patients with obstructive sleep apnea syndrome (OSAS) and to compare psychological and demographic characteristics between different levels of daytime sleepiness.

METHODS

A total of 138 patients with OSAS underwent polygraphic cardiorespiratory monitoring and completed a series of questionnaires investigating perceived sleepiness, depression, impulsivity, and other psychological characteristics. A mediational model was tested in order to assess whether impulsivity mediated the relation between sleepiness and depressive symptoms while controlling for the effects of age, sex, BMI, and oxygen saturation parameters.

RESULTS

the mediation model showed that there was a significant indirect effect of impulsivity in the sleepiness-depression link (αβ = 0.084 [0.0243-0.1617]).

CONCLUSIONS

The here-presented results showed that the sleepiness-depression link is not direct as previous studies asserted, but instead it may be better explained by impulsivity. Research and practical implications are discussed.

A narrative review of the mechanisms and consequences of intermittent hypoxia and the role of advanced analytic techniques in pediatric autonomic disorders

Disorders of autonomic functions are typically characterized by disturbances in multiple organ systems. These disturbances are often comorbidities of common and rare diseases, such as epilepsy, sleep apnea, Rett syndrome, congenital heart disease or mitochondrial diseases. Characteristic of many autonomic disorders is the association with intermittent hypoxia and oxidative stress, which can cause or exaggerate a variety of other autonomic dysfunctions, making the treatment and management of these syndromes very complex. In this review we discuss the cellular mechanisms by which intermittent hypoxia can trigger a cascade of molecular, cellular and network events that result in the dysregulation of multiple organ systems. We also describe the importance of computational approaches, artificial intelligence and the analysis of big data to better characterize and recognize the interconnectedness of the various autonomic and non-autonomic symptoms. These techniques can lead to a better understanding of the progression of autonomic disorders, ultimately resulting in better care and management.

Prevalence of temporomandibular disorders in adult obstructive sleep apnoea patients: A cross-sectional controlled study

BACKGROUND

Obstructive sleep apnoea (OSA) is characterised by partial or complete obstruction of the upper airways during sleep and it has been associated with temporomandibular disorders (TMDs) on the basis of several pathophysiological hypotheses.

OBJECTIVES

To assess the prevalence of TMDs in a population of patients affected by OSA compared to a control group of subjects not affected by OSA.

METHODS

A cross-sectional controlled study was conducted on a group subjects studied by polygraphy (PG) at the snoring section of the ENT department, Sant'Orsola-Malpighi Hospital - University of Bologna. Patients who received a diagnosis of OSA were included in the study group and subjects with a negative PG diagnosis for Sleep Disordered Breathing and PG respiratory pattern that did not suggest the occurrence of sleep disorders were enrolled in the control group. Both the subjects included in the study group and the control group underwent an examination following the Diagnostic Criteria for Temporomandibular Disorders Axis I and II.

RESULTS

Forty-three OSA patients (29 M, 16 F, mean age 52.26 ± 11.40) and 43 healthy controls (25 M, 18 F, mean age 49.95 ± 7.59) were included in the study. No significant differences were found between groups in demographic data. TMD prevalence and Axis II results did not differ between groups.

CONCLUSIONS

This paper does not highlight a higher prevalence of TMDs in adults with OSA compared to healthy controls. Further high-quality studies are needed to confirm the results and to give possible pathophysiological explanations, providing reliable evidence.

Adherence to CPAP therapy in Down syndrome: the population-based DISCOVERY study

STUDY OBJECTIVES

Persons with Down syndrome (DS) have an increased risk of obstructive sleep apnea (OSA) needing continuous positive airway pressure (CPAP), but data on the therapy and outcomes in this population are scarce. We aimed to compare patient characteristics and outcomes of CPAP treatment for patients with OSA with and without DS.

METHODS

This was a population-based, longitudinal study on patients initiating CPAP therapy between July 2010 and March 2018 in Sweden and a population-based sex- and age-matched control group (control:case ratio 5:1), with linked data from the Swedish National Patient Registry and the Prescribed Drug Registry (DISCOVERY study cohort).

RESULTS

Patients with DS (n = 64) had a higher apnea-hypopnea index (51.7 ± 30.3 vs 36.8 ± 29.1 events/h, P < .001), Epworth Sleepiness Scale score (13.7 ± 5.9 vs 11.0 ± 4.9, P = .001), rate of previous surgery of tonsils and/or adenoids (21.9% vs 8.2%, P = .001), and more thyroid replacement hormone therapy (45.3% vs 7.8%, P < .001), but lower use of cardiovascular drugs (7.8% vs 22.3%, P = .003) compared with controls. At follow-up after 1.3 ± 0.9 years, there were no differences in nocturnal CPAP usage time (5.6 ± 2.4 vs 5.5 ± 2.0 hours, P = .77), CPAP adherence ≥ 4 hours/night (62% vs 65%, P = .93), or improvement in Epworth Sleepiness Scale score (-5.4 ± 6.8 vs -5.0 ± 2.0, P = .84) between DS and non-DS patients.

CONCLUSIONS

OSA severity was substantially higher in patients with DS despite an increased rate of tonsil surgery. Treatment outcomes in terms of adherence and improved daytime sleepiness were comparable between groups, underlining the importance of both OSA diagnosis and treatment in patients with DS.

CITATION

Svensson M, Ekström M, Sundh J, Ljunggren M, Grote L, Palm A. Adherence to CPAP therapy in Down syndrome: the population-based DISCOVERY study. J Clin Sleep Med. 2023;19(3):453-458.

The Role of Inflammation in Cognitive Impairment of Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) has become a major worldwide public health concern, given its global prevalence. It has clear links with multiple comorbidities and mortality. Cognitive impairment is one related comorbidity causing great pressure on individuals and society. The clinical manifestations of cognitive impairment in OSAS include decline in attention/vigilance, verbal–visual memory loss, visuospatial/structural ability impairment, and executive dysfunction. It has been proven that chronic intermittent hypoxia (CIH) may be a main cause of cognitive impairment in OSAS. Inflammation plays important roles in CIH-induced cognitive dysfunction. Furthermore, the nuclear factor kappa B and hypoxia-inducible factor 1 alpha pathways play significant roles in this inflammatory mechanism. Continuous positive airway pressure is an effective therapy for OSAS; however, its effect on cognitive impairment is suboptimal. Therefore, in this review, we address the role inflammation plays in the development of neuro-impairment in OSAS and the association between OSAS and cognitive impairment to provide an overview of its pathophysiology. We believe that furthering the understanding of the inflammatory mechanisms involved in OSAS-associated cognitive impairment could lead to the development of appropriate and effective therapy.

Continuous positive airway pressure improved daytime sleepiness and memory function in patients with obstructive sleep apnea

Objectives

Obstructive sleep apnea (OSA) is a sleep disorder which results in daytime sleepiness and impaired memory function. The aim of this study was to investigate the effect of continuous positive airway pressure (CPAP) on daytime sleepiness and memory function in OSA patients. We also investigated whether CPAP compliance impacted the effect of this treatment.

Materials and Methods

The nonrandomized, nonblinded clinical trial enrolled 66 patients with moderate-to-severe OSA subjects. All subjects completed a polysomnographic study, daytime sleepiness questionnaires (the Epworth Sleepiness Scale and the Pittsburgh Sleep Quality Index), and four memory function tests (working memory; processing speed [PS]; logical memory [LM]; face memory [FM]).

Results

Before CPAP treatment, no significant differences (P < 0.05) were noted in the demographic data, daytime sleepiness, or memory function between two groups (with/without CPAP). However, OSA patients treated with CPAP for 2 months showed significant improvements in daytime sleepiness, PS, mostly of LM, and FM comparing to 2 months ago. As compared to those who did not receive CPAP treatment, CPAP can improve only parts of LM (delayed LM [DLM] and LM percentage [LMP]). In addition, compared to control group, a significant improvement of daytime sleepiness and LM (LM learning, DLM, and LMP) in good compliance with CPAP treatment group and of DLM and LMP in the low compliance with CPAP treatment group was found.

Conclusion

CPAP treatment for 2 months could improve some of LM in OSA patients, especially in patients exhibiting good CPAP compliance.

Improvements in cognitive function and quantitative sleep electroencephalogram in obstructive sleep apnea after six months of continuous positive airway pressure treatment

STUDY OBJECTIVES

Untreated obstructive sleep apnea (OSA) is associated with cognitive deficits and altered brain electrophysiology. We evaluated the effect of continuous positive airway pressure (CPAP) treatment on quantitative sleep electroencephalogram (EEG) measures and cognitive function.

METHODS

We studied 167 patients with OSA (age 50 ± 13, AHI 35.0 ± 26.8) before and after 6 months of CPAP. Cognitive tests assessed working memory, sustained attention, visuospatial scanning, and executive function. All participants underwent overnight polysomnography at baseline and after CPAP. Power spectral analysis was performed on EEG data (C3-M2) in a sub-set of 90 participants. Relative delta EEG power and sigma power in NREM and EEG slowing in REM were calculated. Spindle densities (events/min) in N2 were also derived using automated spindle event detection. All outcomes were analysed as change from baseline.

RESULTS

Cognitive function across all cognitive domains improved after six months of CPAP. In our sub-set, increased relative delta power (p < .0001) and reduced sigma power (p = .001) during NREM were observed after the 6-month treatment period. Overall, fast and slow sleep spindle densities during N2 were increased after treatment.

CONCLUSIONS

Cognitive performance was improved and sleep EEG features were enhanced when assessing the effects of CPAP. These findings suggest the reversibility of cognitive deficits and altered brain electrophysiology observed in untreated OSA following six months of treatment.

Sleep and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery, and Mental Health: An Update

Sleep health is an important consideration for athletic performance. Athletes are at high risk of insufficient sleep duration, poor sleep quality, daytime sleepiness and fatigue, suboptimal sleep schedules, irregular sleep schedules, and sleep and circadian disorders. These issues likely have an impact on athletic performance via several domains. Sleep loss and/or poor sleep quality can impair muscular strength, speed, and other aspects of physical performance. Sleep issues can also increase risk of concussions and other injuries and impair recovery after injury. Cognitive performance is also impacted in several domains, including vigilance, learning and memory, decision making, and creativity.

Correlation of Medical Comorbidities and Upper Airway Measurements among Dental Patients at Risk of Developing Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a partial or total upper airway collapse resulting in sleep-breathing disturbances. There are many medical comorbidities associated with OSA; hence, this study is important as the prevalence of patients with medical comorbidities associated with OSA is increasing. The study aimed to correlate medical comorbidities and OSA symptoms of the patients along with their upper airway dimensions using Cone Beam Computed Tomography (CBCT) scans to identify patients at risk of developing OSA. This cross-sectional study included patients who had CBCT imaging taken between 2014 and 2020. A questionnaire was used to gather information on patients’ medical history and OSA symptoms. The upper airway dimensions of the CBCT scans were evaluated before logistic regression and Fisher’s exact test were carried out to determine the relationships between the variables. p ≤ 0.05 was considered statistically significant. Logistic regression revealed an association of longer length (p = 0.016), smaller total volume (p = 0.017) and width (p = 0.010) of upper airways with hypertension. Furthermore, loud snoring was seen in patients with hypertension, heart disease and obesity whereas difficulty concentrating during the day was present in subjects with deviated nasal septum, tonsillitis and depression. For upper airway dimensions, a smaller average volume was associated with loud snoring (p = 0.037), difficulty concentrating during the day (p = 0.002) and mood changes (p = 0.036). A larger anterior-posterior dimension was also associated with excessive daytime sleepiness (p = 0.042), difficulty concentrating during the day (p < 0.001) and mood changes (p = 0.009). Longer airway length was additionally found to be associated with loud snoring (p = 0.021). CBCT taken for dental investigations could be correlated with patients’ medical history and OSA symptoms to screen patients at risk of OSA.

Pulmonary Function in Midlife as a Predictor of Later-Life Cognition: The Coronary Artery Risk Development in Adults (CARDIA) Study

BACKGROUND

Studies found associations between pulmonary function (PF) and cognition, but these are limited by mostly cross-sectional design and a single measure of PF (typically forced expiratory volume in 1 second [FEV1]). Our objective was to prospectively analyze the association of repeatedly measured PF with cognition.

METHODS

We studied 3 499 participants in the Coronary Artery Risk Development in Young Adults cohort with cognition measured at year 25 (Y25) and Y30, and PF (FEV1 and forced vital capacity [FVC], reflecting better PF) measured up to 6 times from Y0 to Y20. Cognition was measured via Stroop test, Rey-Auditory Verbal Learning Test [RAVLT], and digit symbol substitution test [DSST], which capture executive function, verbal learning and memory, and attention and psychomotor speed, respectively; lower Stroop, and higher RAVLT and DSST scores indicate better cognition. We modeled linear, cross-sectional associations between cognition and PF at Y30 (mean age 55), and mixed models to examine associations between cognition at Y25-Y30 and longitudinal PF (both annual rate of change, and cumulative PF from Y0 to Y20).

RESULTS

At Y30, FEV1 and FVC were cross-sectionally associated with all 3 measures of cognition (β = 0.08-0.12, p < .01-.02). Annual change from peak FEV1/FVC ratio was associated with Stroop and DSST (β = 18.06, 95% CI = 7.71-28.40; β = 10.30, 95% CI = 0.26-20.34, respectively), but not RAVLT. Cumulative FEV1 and FVC were associated with Stroop and DSST (β = 0.07-0.12, p < .01-.02), but only cumulative FEV1 was associated with RAVLT (β = 0.07, 95% CI = 0.00-0.14).

CONCLUSIONS

We identified prospective associations between measures of PF and cognition even at middle ages, adding evidence of a prospective association between reduced PF and cognitive decline.

Glymphatic system dysfunction in obstructive sleep apnea evidenced by DTI-ALPS

OBJECTIVES

This study aimed to evaluate the glymphatic system function in patients with obstructive sleep apnea (OSA) compared to healthy controls using diffusion tensor imaging (DTI) with the perivascular space (DTI-ALPS) method. Our hypothesis is that patients with OSA may have glymphatic system dysfunction, which is correlated with OSA severity.

METHODS

We enrolled 24 patients with OSA and 24 healthy controls. All participants underwent DTI magnetic resonance imaging (MRI) using the same 3T MRI scanner, and we calculated the DTI-ALPS index from the DTI. We evaluated the differences in the DTI-ALPS index between patients with OSA and healthy controls. In addition, we conducted a correlation analysis between the DTI-ALPS index and clinical characteristics.

RESULTS

The DTI-ALPS index was significantly different between the groups. The DTI-ALPS in patients with OSA was significantly lower than in healthy controls (1.30450 vs. 1.61600, p = 0.0006). Furthermore, the DTI-ALPS index was significantly negatively correlated with the apnea-hypopnea index in sleep stage N (r = -0.427, p = 0.042) and oxygen desaturation index during sleep N (r = -0.497, p = 0.036).

CONCLUSION

We successfully demonstrated glymphatic system dysfunction in patients with OSA. In addition, glymphatic system dysfunction is well correlated with OSA severity, especially during sleep stage N. Thus, these findings can explain the effects of OSA on increased risk of developing dementia and highlight the importance of OSA treatment.

Dropout and adherence of obstructive sleep apnoea patients to mandibular advancement device therapy: A systematic review of randomised controlled trials with meta-analysis and meta-regression

BACKGROUND

Mandibular advancement devices (MADs) are used as an alternative to continuous positive airways pressure to treat obstructive sleep apnoea (OSA) patients, but to date, specific data on the adherence to MAD therapy are lacking.

OBJECTIVES

The aim of the present systematic review was to investigate the dropout rate and adherence of OSA patients to different custom-made (CM) and non-custom-made (NCM) MAD therapies.

SEARCH METHODS

An electronic search was performed in MEDLINE, Cochrane Database of Systematic Reviews, Scopus, LILACS and Web of Science.

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing the compliance to customised and not customised MADs in the treatment of adult OSA patients were included.

DATA COLLECTION AND ANALYSIS

The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and the risk of bias by the Cochrane Collaboration's tool for assessing risk of bias in RCT. The dropout rate of each study was computed and the adherence to MAD therapy in terms of hours per night and nights per week was extracted from each study.

RESULTS

Thirty-two RCTs were included. The risk of bias resulted low in most of the studies. The GRADE scores indicated that the quality of evidence was from very low to moderate. The meta-analyses showed that the mean dropout rate did not significantly differ between CM and NCM MADs: The overall mean dropout rate was 0.171 [0.128-0.213] with a mean follow-up of 4.1 months. The hours per night adherence was significantly higher for CM MADs (6.418 [6.033-6.803]) compared to NCM MADs (5.107 [4.324-5.890]. The meta-regression showed that the dropout rate increases significantly during time (p < .05).

CONCLUSIONS

There is a very low to moderate quality of evidence that the dropout rate of MAD therapy is similar among CM and NCM MADs, that the dropout rate increases significantly during time and that CM MADs have higher hours per night adherence compared with NCM MAD.

REGISTRATION

The study protocol was registered on PROSPERO (n. CRD42020199866).

Different components of excessive daytime sleepiness and the change with positive airway pressure treatment in patients with obstructive sleep apnea: Results from the Icelandic Sleep Apnea Cohort (ISAC)

Excessive daytime sleepiness includes both an inability to stay awake during the day and a general feeling of sleepiness. We describe different dimensions of daytime sleepiness in adults with moderate-severe obstructive sleep apnea (OSA) before and after 2 years of positive airway pressure (PAP) treatment. Using the Epworth Sleepiness Scale (score >10 defined as "risk of dozing") and Basic Nordic Sleep Questionnaire (feeling sleepy ≥3 times/week defined as "feeling sleepy"), participants were categorised into sleepiness phenotypes labelled non-sleepy, risk of dozing only, feeling sleepy only, or both symptoms. Participants repeated baseline assessments and PAP adherence was evaluated after 2 years. PAP-adherent subjects with sleepiness symptoms at both baseline and follow-up were considered persistently sleepy. Of the 810 participants, 722 (89%) returned for follow-up. At baseline, 17.7% were non-sleepy, 7.7% were at risk of dozing only, 24.7% were feeling sleepy only, and 49.9% had both symptoms. PAP adherence did not differ by baseline sleepiness phenotype. Patients with risk of dozing demonstrated greater PAP benefits for sleepiness symptoms than non-sleepy and feeling sleepy only phenotypes. Using these phenotypes, 42.3% of PAP users had persistent sleepiness; they had less severe OSA (p < 0.001), more persistent OSA symptoms and more often had symptoms of insomnia than patients in whom sleepiness resolved. Our present results, therefore, suggest that measuring the risk of dozing and the feeling of sleepiness reflect different sleepiness components and may respond differently to PAP. Patients feeling sleepy without risk of dozing may need more thorough evaluation for factors contributing to sleepiness before initiating treatment.

Alzheimer's Disease, Sleep Disordered Breathing, and Microglia: Puzzling out a Common Link

Sleep Disordered Breathing (SDB) and Alzheimer's Disease (AD) are strongly associated clinically, but it is unknown if they are mechanistically associated. Here, we review data covering both the cellular and molecular responses in SDB and AD with an emphasis on the overlapping neuroimmune responses in both diseases. We extensively discuss the use of animal models of both diseases and their relative utilities in modeling human disease. Data presented here from mice exposed to intermittent hypoxia indicate that microglia become more activated following exposure to hypoxia. This also supports the idea that intermittent hypoxia can activate the neuroimmune system in a manner like that seen in AD. Finally, we highlight similarities in the cellular and neuroimmune responses between SDB and AD and propose that these similarities may lead to a pathological synergy between SDB and AD.

[The role of biomarkers in the detection of the OSA syndrome. A narrative review of the literature]

INTRODUCTION

Obstructive sleep apnoea (OSA) is a common sleep-related breath disorder associated with cardiovascular and cerebrovascular complications, such as hypertension, arrhythmia, coronary artery disease and stroke. Unfortunately, OSA is underdiagnosed.

BACKGROUND

Because of its clinical and therapeutic variability, OSA could benefit a personalized medicine approach. Diagnosis with polysomnography is expensive and access is limited. Clinical scoring systems allow screening of OSA, but many limitations exist. Because of this, biomarkers could be useful for the detection of OSA.

OUTLOOK

Biomarkers specific to OSA would allow for better mass screening and more personalized treatment of the disease. This narrative review of the literature aims to summarize the biomarkers already described for the diagnosis of OSA and clarify both their advantages and limitations in daily practice.

CONCLUSIONS

Our review of the literature did not actually identify an ideal biomarker even if promising research is ongoing.

Hypoxia-inducible factors and obstructive sleep apnea

Intermittent hypoxia (IH) is a hallmark manifestation of obstructive sleep apnea (OSA), a widespread disorder of breathing. This Review focuses on the role of hypoxia-inducible factors (HIFs) in hypertension, type 2 diabetes (T2D), and cognitive decline in experimental models of IH patterned after O2 profiles seen in OSA. IH increases HIF-1α and decreases HIF-2α protein levels. Dysregulated HIFs increase reactive oxygen species (ROS) through HIF-1-dependent activation of pro-oxidant enzyme genes in addition to reduced transcription of antioxidant genes by HIF-2. ROS in turn activate chemoreflex and suppress baroreflex, thereby stimulating the sympathetic nervous system and causing hypertension. We also discuss how increased ROS generation by HIF-1 contributes to IH-induced insulin resistance and T2D as well as disrupted NMDA receptor signaling in the hippocampus, resulting in cognitive decline.

Salivary Inflammatory Molecules as Biomarkers of Sleep Alterations: A Scoping Review

Poor sleep quality and sleep disorders are the most common problems in people, affecting health-related quality of life. Various studies show an association between sleep disorders and altered levels of stress hormones and inflammatory cytokines measured in saliva. The main objective of this article is to provide an analysis of the current evidence related to changes in inflammatory markers in the saliva and their associations with sleep quality measurement (both objective and subjective methods) in healthy subjects and in sleep-related disorders. To that end, a scoping review was carried out, following the PRISMA criteria in the bibliographic search in several databases: PubMed, EBSCO, and SCOPUS. Eleven of the articles are from the adult population and two from the child-youth population. They mainly measure the relationship between sleep and interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFα) alpha, as well as other inflammatory markers such as myeloperoxidase (MPO) and prostaglandin-endoperoxide synthase 2. An analysis shows the relationship between these salivary biomarkers and sleep quality, especially in the case of IL-6 in both healthy subjects and several pathologies associated with sleep-disorders. The results for TNFα and IL-1β measurements are still inconclusive and the difference with IL-6 was assessed. Two studies reported interventions that result in sleep improvement and are accompanied by the normalization of inflammatory changes detected in the saliva. As it is an easy-to-apply and non-invasive method, the measurement of salivary cytokines can be very useful in chronobiology studies. Further studies are required to determine the sensitivity of salivary inflammatory markers in monitoring biological rhythms and acting as biomarkers in the detection of sleep disorders and sleep interventions.

Neurocognitive and Synaptic Potentiation Deficits Are Mitigated by Inhibition of HIF1a Signaling following Intermittent Hypoxia in Rodents

Highlighted Research Paper:A HIF1a-Dependent Pro-Oxidant State Disrupts Synaptic Plasticity and Impairs Spatial Memory in Response to Intermittent Hypoxia. Alejandra Arias-Cavieres, Maggie A. Khuu, Chinwendu U. Nwakudu, Jasmine E. Barnard, Gokhan Dalgin and Alfredo J. Garcia III

Effectiveness of different mandibular advancement device designs in obstructive sleep apnoea therapy: A systematic review of randomised controlled trials with meta-analysis

Mandibular advancement devices (MADs) are used to treat patients with obstructive sleep apnoea (OSA). To date, there are no data that identify the most effective MAD design for apnoea-hypopnea index (AHI) reduction. The purpose of this systematic review is to investigate the effectiveness of different MAD designs in AHI reduction and oxygen saturation improvement in OSA patients. An electronic search was performed in MEDLINE, Cochrane Database, Scopus, Web of Knowledge and LILACS. Randomised controlled trials (RCTs) investigating the reduction of AHI on adult patients wearing MAD for OSA were included. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and the risk of bias by the Cochrane Collaboration's tool for assessing risk of bias in randomised controlled trial. The success rate of each study was computed: [(mean baseline AHI - mean AHI after treatment)/mean baseline AHI]. Fifty RCTs were included. The risk of bias resulted with some concerns in most of the studies. The GRADE scores indicated that the quality of evidence was very low. The meta-analysis showed a success rate with mono-bloc and duo-bloc MADs respectively of 0.821 [0.722-0.887] and 0.547 [0.443-0.637]. The mono-bloc compared with duo-bloc better improved the minimum oxygen saturation (10.048 [7.733-12.363] and 3.357 [2.290-4.423], respectively). There is a very low quality body of evidence that mono-bloc MADs are more effective in reducing AHI and improving minimum oxygen saturation compared with duo-bloc MADs. The study protocol was registered on PROSPERO (n. CRD42019118084).

Olfactory function in patients with obstructive sleep apnea: a meta-analysis study

PURPOSE

This meta-analysis study was designed to analyze the olfactory function in obstructive sleep apnea patients (OSA).

METHODS

A comprehensive review of the English language literature regarding OSA patients and olfactory function/dysfunction was performed. The papers assessing olfactory dysfunction with Sniffin' Sticks test were taken into consideration.

RESULTS

A total of 420 OSA patients were judged eligible for the study. The average TDI score was found to be 24.3 ± 5.6. The olfactory identification (OD), the olfactory discrimination (OD), and the olfactory threshold (OT) average values were calculated resulting 9.9 ± 2.1, 9.8 ± 1.5, and 5.3 ± 2, respectively. There were 161 healthy control subjects in this meta-analysis. The average TDI of the control group was 30.7 ± 6.0 showing a statistical difference with the group of OSA patients (p = 0.03). A linear correlation between Apnea-Hypopnea Index (AHI) increase and TDI decrease (R² = 0.1, p = 0.05) was detected. Finally, the average values of TDI of 151 patients classified as mild-moderate OSA and 159 patients considered as severe OSA were calculated. The difference between these two groups resulted not statistically significant (p = 0.3).

CONCLUSION

The comparison between OSA patients and healthy subjects using Sniffin' Sticks test showed lower values of the various olfactory parameters. Although a linear correlation between AHI increase and olfactory dysfunction was observed, no statistical difference between mild-moderate and severe OSA patients in terms of the severity of olfactory dysfunction could be proved.

Sleep EEG microstructure is associated with neurobehavioural impairment after extended wakefulness in obstructive sleep apnea

PURPOSE

Using quantitative EEG (qEEG) analysis, we investigated sleep EEG microstructure as correlates of neurobehavioural performance after 24 h of extended wakefulness in untreated OSA.

METHODS

Eight male OSA patients underwent overnight polysomnography (PSG) at baseline followed by 40 h awake with repeated performance testing (psychomotor vigilance task [PVT] and AusEd driving simulator). EEG slowing during REM and spindle density during NREM sleep were calculated using power spectral analysis and a spindle detection algorithm at frontal and central electrode sites. Correlations between sleep EEG microstructure measures and performance after 24-h awake were assessed.

RESULTS

Greater EEG slowing during REM sleep was associated with slower PVT reaction times (rho = - 0.79, p = 0.02), more PVT lapses (rho = 0.87, p = 0.005) and more AusEd crashes (rho = 0.73, p = 0.04). Decreased spindle density in NREM sleep was also associated with slower PVT reaction times (rho = 0.89, p = 0.007). Traditional PSG measures of disease severity were not consistent correlates of neurobehavioural performance in OSA.

CONCLUSIONS

Sleep EEG microstructure measures recorded during routine PSG are associated with impaired vigilance in OSA patients after sleep deprivation.

SIGNIFICANCE

Quantitative brain oscillatory (or EEG)-based measures of sleep may better reflect the deleterious effects of untreated OSA than traditional PSG metrics in at-risk individuals. Trial Registration ACTRN12606000066583.

Integrity of Multiple Memory Systems in Individuals With Untreated Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is associated with working- and autobiographical-memory impairments, and high rates of mood disorder. This study aimed to examine (i) behavioral responses and (ii) neural activation patterns elicited by autobiographical and working memory tasks in moderate-severe untreated OSA patients and healthy controls, and (iii) whether variability in autobiographical and working memory activation are associated with task performance, OSA severity and psychological symptomatology (depression, anxiety). In order to control for the potential confounding effect of elevated rates of clinical depression in OSA, we excluded individuals with a current psychiatric condition. Seventeen untreated OSA participants and 16 healthy controls were comparable with regards to both activation and behavioral performance. OSA was associated with worse subclinical mood symptoms and poorer personal semantic memory. Higher levels of nocturnal hypoxia were associated with increased activation in the occipital cortex and right cerebellum during the working memory task in OSA participants, however, no significant relationships between activation and task performance or depressive/anxiety symptomatology were observed. The neurocognitive substrates supporting autobiographical recall of recent events and working memory in younger, recently diagnosed individuals with OSA appear to be indistinguishable from healthy age-matched individuals. These findings point to the importance of early diagnosis and treatment of OSA in order to preserve cognitive function.

Performance of brief ICF-sleep disorders and obesity core set in obstructive sleep apnea patients

BACKGROUND

Clinical questionnaires are mainly applied as screening tools for identification of the Obstructive sleep apnea (OSA) patients. Little attention has been paid to assess the body functions and health status of the patients. International Classification of Functioning, Disability and Health (ICF) was designed for better understanding and describing functioning and disability of patients. This study adopted the Brief ICF-Sleep Disorders and Obesity Core Set to evaluate the impairment of functioning and health status of OSA patients.

METHODS

Five hundred ninety-two participants were enrolled in this cross-sectional study. Data were collected using Brief ICF-Sleep Disorders and Obesity Core Set Polysomnography was performed and basic characteristics of the patients were recorded.

RESULTS

The scores for the component Body Functions and Code b130, b134, b140, b440, b530, s330, d160, d240, d450 of the two core sets were significantly different among the patients divided by apnea-hypopnea index (AHI) or oxygen saturation (SaO2) nadir, but the frequency of code s330, d160, d240, d450 was low. The Body Functions component of the both sets were closely related to neck circumference (NC), body mass index (BMI), apnea-hypopnea index (AHI) of the OSA patients. Body Functions of the Brief ICF-Sleep Disorders performed better with a threshold of 4 with sensitivity, specificity and area under the receiver operating characteristic curve (AUC) as 0.62, 0.74, 0.68(AHI ≥ 5), 0.69, 0.63, 0.66 (AHI ≥ 15), 0.75, 0.56, 0.66 (AHI ≥ 30), 0.56, 0.70, 0.63 (SaO2 nadir≤90%), 0.67, 0.66, 0.66 (SaO2 nadir<85%), 0.71, 0.59, 0.65 (SaO2 nadir<80%), separately.

CONCLUSION

The Body Functions component of both two sets could be an evaluation tool of impairment of body functions for OSA patients. The Brief ICF-Sleep Disorders Body Functions component performed better with a threshold of 4 and might provide a new insight for physicians to assess OSA patients.

The Drives for Driving Simulation: A Scientometric Analysis and a Selective Review of Reviews on Simulated Driving Research

Driving behaviors and fitness to drive have been assessed over time using different tools: standardized neuropsychological, on-road and driving simulation testing. Nowadays, the great variability of topics related to driving simulation has elicited a high number of reviews. The present work aims to perform a scientometric analysis on driving simulation reviews and to propose a selective review of reviews focusing on relevant aspects related to validity and fidelity. A scientometric analysis of driving simulation reviews published from 1988 to 2019 was conducted. Bibliographic data from 298 reviews were extracted from Scopus and WoS. Performance analysis was conducted to investigate most prolific Countries, Journals, Institutes and Authors. A cluster analysis on authors' keywords was performed to identify relevant associations between different research topics. Based on the reviews extracted from cluster analysis, a selective review of reviews was conducted to answer questions regarding validity, fidelity and critical issues. United States and Germany are the first two Countries for number of driving simulation reviews. United States is the leading Country with 5 Institutes in the top-ten. Top Authors wrote from 3 to 7 reviews each and belong to Institutes located in North America and Europe. Cluster analysis identified three clusters and eight keywords. The selective review of reviews showed a substantial agreement for supporting validity of driving simulation with respect to neuropsychological and on-road testing, while for fidelity with respect to real-world driving experience a blurred representation emerged. The most relevant critical issues were the a) lack of a common set of standards, b) phenomenon of simulation sickness, c) need for psychometric properties, lack of studies investigating d) predictive validity with respect to collision rates and e) ecological validity. Driving simulation represents a cross-cutting topic in scientific literature on driving, and there are several evidences for considering it as a valid alternative to neuropsychological and on-road testing. Further research efforts could be aimed at establishing a consensus statement for protocols assessing fitness to drive, in order to (a) use standardized systems, (b) compare systematically driving simulators with regard to their validity and fidelity, and (c) employ shared criteria for conducting studies in a given sub-topic.

Sleep and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery, and Mental Health

Research has characterized the sleep of elite athletes and attempted to identify factors associated with athletic performance, cognition, health, and mental well-being. Sleep is a fundamental component of performance optimization among elite athletes, yet only recently embraced by sport organizations as an important part of training and recovery. Sleep plays a crucial role in physical and cognitive performance and is an important factor in reducing risk of injury. This article aims to highlight the prevalence of poor sleep, describe its impacts, and address the issue of sport culture surrounding healthy sleep.

Coping Processes, Self-Efficacy, and CPAP Use in Adults With Obstructive Sleep Apnea

Background: Coping strategies are predictive of 1 week CPAP use. Coping strategies may predict longer-term CPAP use among adults with obstructive sleep apnea (OSA). Objectives: To investigate the influence of two coping styles (active and passive) and individual coping processes on CPAP use at 1 week and 1 month; and explore the association between self-efficacy and coping on CPAP use. Participants: CPAP-naïve adults (52.3% male, 90.9% White) newly diagnosed with OSA (AHI ≥ 5 events/hr) from two U.S. clinical sleep centers (n = 66). Methods: A post-hoc analysis from a prospective, longitudinal study that examined influential factors on CPAP use among CPAP-naïve patients with newly diagnosed OSA. The Ways of Coping Questionnaire and the Self-Efficacy Measure for Sleep Apnea were completed immediately after CPAP titration polysomnography. Objective 1 week and 1 month CPAP use (mean hr/night) were the primary outcomes. Descriptive analyses and stepwise multiple linear regression analyses modeling for CPAP use (mean hr/night). Results: Active coping was significantly associated with greater CPAP use (mean hr/night) at 1 week, but not at 1 month (p = 0.0397; p = 0.0556, respectively). Higher Planful Problem Solving was significantly associated with greater average CPAP use at 1 week and 1 month (p = 0.0117, p = 0.0378, respectively). Self-efficacy was significantly associated with greater average CPAP use at 1 week (p = 0.0056) and 1 month (p = 0.0056). Conclusions: Self-efficacy and Planful Problem Solving coping are promising behavioral intervention targets to promote CPAP use in newly diagnosed OSA.

Dysfunction in Automatic Processing of Emotional Facial Expressions in Patients with Obstructive Sleep Apnea Syndrome: An Event-Related Potential Study

AIM

Obstructive sleep apnea syndrome (OSAS) is a prevalent chronic disease characterized by sleep fragmentation and intermittent hypoxemia. Several studies suggested that electrophysiological changes and neurocognitive abnormalities occurred in OSAS patients. In this study, we compared automatic processing of emotional facial expressions schematic in OSAS patients and matched healthy controls via assessing expression-related mismatch negativity (EMMN).

METHODS

Twenty-two OSAS patients (mean age 44.59 years) and twenty-one healthy controls (mean age 42.71 years) were enrolled in this study. All participants underwent Montreal Cognitive Assessment (MoCA) scale test and polysomnographic recording. An expression-related oddball paradigm was used to elicit EMMN and the electroencephalogram was recorded and analyzed. Furthermore, Pearson's correlations were calculated to discuss the correlation between neuropsychological test scores, clinical variables and electrophysiological data.

RESULTS

Compared with healthy controls, OSAS sufferers demonstrated significantly reduced EMMN mean amplitudes within corresponding time intervals, regardless of happy or sad conditions. Meanwhile, we observed that amplitude of sad EMMN was larger (more negative) than happy EMNN in healthy controls, while not in patients. Moderate correlations were found between MoCA test scores, sleep parameters and EMMN amplitudes.

CONCLUSION

Our findings suggested pre-attentive dysfunction of processing emotional facial expressions in patients with OSAS, without the existence of negative bias effect. Moreover, correlation analysis showed that clinical characteristics of OSAS patients could affect EMMN amplitudes. Further studies on the advantages of EMMN as clinical and electrophysiological indicators of OSAS are warranted.

Effects of CPAP for patients with OSA on visual sensitivity and retinal thickness

OBJECTIVE

Obstructive sleep apnea/hypopnea syndrome (OSA) could compromise oxygenation of the optic nerve and cause glaucomatous optic neuropathy; there has been no study to investigate the microstructure changes of the optic nerve and retina in OSA patients before and after continuous positive airway pressure (CPAP) therapy. In this study, we assess whether treatment with CPAP might improve visual sensitivity and retinal thickness in patients with OSA.

METHODS

Patients with OSA were prospectively recruited and referred for ophthalmologic evaluation at baseline and three months after CPAP treatment. Each patient underwent an ophthalmological exam, standard automated perimetry (SAP), and optical coherence tomography (OCT) exam. Peripapillary retinal nerve fiber layer (RNFL) and macular layer (ML) thickness parameters were measured. The SAP, RNFL, and ML thickness parameters before and after treatment were compared.

RESULTS

A total of 32 OSA patients were consecutively enrolled. At baseline, the mean deviation (MD) of SAP was -2.15 ± 1.90 dB (dB). After CPAP treatment, the MD was -1.38 ± 1.37 dB (p = 0.017). Regarding the OCT parameters, the inferior quadrant and nasal-inferior sector of RNFL thickness significantly improved after treatment (p = 0.025 and 0.004, respectively). The ML thickness in the superior-inner sector, inferior-outer sector, nasal-outer sector, superior hemisphere, and inferior hemisphere were also significantly improved after treatment. Improvement of ML thickness in the superior-inner sector positively correlated with the apnea/hypopnea index (r = 0.405, p = 0.022) and desaturation index (r = 0.473, p = 0.006) on pre-treatment polysomnography.

CONCLUSION

The treatment of CPAP could improve visual sensitivity and increase retinal thickness in patients with OSA.

Role of Obstructive Sleep Apnea in Cognitive Impairment

Obstructive sleep apnea (OSA) is a prevalent sleep related breathing disorder characterized by repetitive collapse of the upper airways leading to intermittent hypoxia and sleep disruption. Clinically relevant neurocognitive, metabolic and cardiovascular disease often occurs in OSA. Systemic hypertension, coronary artery disease, type 2 diabetes mellitus, cerebral vascular infarctions and atrial fibrillation are among the most often cited conditions with causal connections to OSA. Emerging science suggest that untreated and undertreated OSA increases the risk of developing cognitive impairment, including vascular dementia and neurodegenerative disorders, like Alzheimer’s disease. As with OSA, cardiovascular disease and type 2 diabetes mellitus, the incidence of dementia increases with age. Given our rapidly aging population, dementia prevalence will significantly increase. The aim of this treatise is to review current literature linking OSA to dementia and explore putative mechanisms by which OSA might facilitate the development and progression of dementia.

Sleep-Disordered Breathing and Idiopathic Normal-Pressure Hydrocephalus: Recent Pathophysiological Advances

Purpose of Review

Idiopathic normal-pressure hydrocephalus (iNPH) is characterized clinically by ventriculomegaly, abnormal gait, falls, incontinence, and cognitive decline. This article reviews recent advances in the pathophysiology of iNPH concerning sleep-disordered breathing (SDB) and glymphatic circulation during deep sleep.

Recent Findings

The authors found iNPH frequently associated with obstructive sleep apnea (OSA). A critical factor in iNPH is intracranial venous hypertension delaying drainage of cerebrospinal fluid (CSF) into the cerebral venous sinuses. CSF-venous blood circulates in the jugular veins and finally drains into the heart. During SDB, repeated reflex attempts to breathe induce strong respiratory efforts against a closed glottis thereby increasing the negative intrathoracic pressure. This causes atrial distortion and decreases venous return to the heart resulting in retrograde intracranial venous hypertension. Additionally, repeated awakenings from OSA impede sleep-associated circulation of interstitial CSF into the glymphatic circulation contributing to hydrocephalus.

Summary

Sleep has become a critical element in the cognitive changes of aging including iNPH.

Definition of excessive daytime sleepiness in the general population: Feeling sleepy relates better to sleep-related symptoms and quality of life than the Epworth Sleepiness Scale score. Results from an epidemiological study

Many different subjective tools are being used to measure excessive daytime sleepiness (EDS) but the most widely used is the Epworth Sleepiness Scale (ESS). However, it is unclear if using the ESS is adequate on its own when assessing EDS. The aim of this study was to estimate the characteristics and prevalence of EDS using the ESS and the Basic Nordic Sleep Questionnaire (BNSQ) in general population samples. Participants aged 40 years and older answered questions about sleepiness, health, sleep-related symptoms and quality of life. Two groups were defined as suffering from EDS: those who scored >10 on the ESS (with increased risk of dozing off) and those reporting feeling sleepy during the day ≥3 times per week on the BNSQ. In total, 1,338 subjects (53% male, 74.1% response rate) participated, 13.1% reported an increased risk of dozing off, 23.2% reported feeling sleepy and 6.4% reported both. The prevalence of restless leg syndrome, nocturnal gastroesophageal reflux, difficulties initiating and maintaining sleep and nocturnal sweating was higher among subjects reporting feeling sleepy compared to non-sleepy subjects. Also, subjects reporting feeling sleepy had poorer quality of life and reported more often feeling unrested during the day than non-sleepy subjects. However, subjects reporting increased risk of dozing off (ESS > 10) without feeling sleepy had a similar symptom profile as the non-sleepy subjects. Therefore, reporting only risk of dozing off without feeling sleepy may not reflect problematic sleepiness and more instruments in addition to ESS are needed when evaluating daytime sleepiness.

Autobiographical Memory From Different Life Stages in Individuals With Obstructive Sleep Apnea

OBJECTIVES

Autobiographical memory dysfunction is a marker of vulnerability to depression. Patients with obstructive sleep apnea (OSA) experience high rates of depression and memory impairment, and autobiographical memory impairments have been observed compared to healthy controls; however, these groups were not age-matched. This study aimed to determine whether individuals with untreated OSA have impaired autobiographical memory when compared to age-matched controls, and to assess the quality of autobiographical memories from three broad time points.

METHODS

A total of 44 participants with OSA (M age=49.4±13.0) and 44 age-matched controls (M age=50.0±13.1) completed the Autobiographical Memory Interview (AMI) to assess semantic and episodic memories from three different life stages, and 44 OSA participants and 37 controls completed the Autobiographical Memory Test (AMT) to assess overgeneral memory recall (an inability to retrieve specific memories).

RESULTS

OSA participants had significantly poorer semantic recall of early adult life on the AMI (p&lt;.001), and more overgeneral autobiographical memories recalled on the AMT (=.001), than controls. Poor semantic recall from early adult life was significantly correlated with more depressive symptoms (p=0.006) and lower education (p&lt;0.02), while higher overgeneral memory recall was significantly associated with older age (p=.001).

CONCLUSIONS

A specific deficit in semantic autobiographical recall was observed in individuals with OSA. OSA patients recalled more overgeneral memories, suggesting that aspects of the sleep disorder affect their ability to recollect specific details of events from their life. These cognitive features of OSA may contribute to the high incidence of depression in this population. (JINS 2019, 25, 266-274).

Distance to Specialist Medical Care and Diagnosis of Obstructive Sleep Apnea in Rural Saskatchewan

Obstructive sleep apnea (OSA) is the most common sleep-disordered breathing condition. Patients with OSA symptoms are often not diagnosed clinically, which is a concern, given the health and safety risks associated with unmanaged OSA. The availability of fewer practicing medical specialists combined with longer travel distances to access health care services results in barriers to diagnosis and treatment in rural communities. This study aimed to (1) determine whether the proportion of adults reporting OSA symptoms in the absence of a sleep apnea diagnosis in rural populations varied by travel distance to specialist medical care and (2) assess whether any distance-related patterns were attributable to differences in the frequency of diagnosis among adults who likely required this specialist medical care. We used a cross-sectional epidemiologic study design, augmented by analysis of follow-up survey data. Our study base included adults who completed a 2010 baseline questionnaire for the Saskatchewan Rural Health Study. Follow-up occurred until 2015. 6525 adults from 3731 households constituted our sample. Statistical models used log-binomial regression. Rural adults who reported the largest travel distances (≥250 km) to specialist medical care were 1.17 (95% CI: 1.07, 1.29) times more likely to report OSA symptoms in the absence of a sleep apnea diagnosis than those who reported the smallest (<100 km; referent) distances. However, the proportion of sleep apnea diagnoses was low and unaffected by reported travel distance among adults who likely required this specialist medical care. Our findings suggest factors other than travel distance may be contributing to the low sleep apnea diagnostic rate. This remains important as undiagnosed and untreated OSA has serious implications on the health of people and populations, but effective treatments are available. Health care access barriers to the diagnosis and treatment of OSA require evaluation to inform health care planning and delivery.

Intermittent Hypoxia Disrupts Adult Neurogenesis and Synaptic Plasticity in the Dentate Gyrus

Individuals with sleep apnea often exhibit changes in cognitive behaviors consistent with alterations in the hippocampus. It is hypothesized that adult neurogenesis in the dentate gyrus is an ongoing process that maintains normal hippocampal function in many mammalian species, including humans. However, the impact of chronic intermittent hypoxia (IH), a principal consequence of sleep apnea, on hippocampal adult neurogenesis remains unclear. Using a murine model, we examined the impact of 30 d of IH (IH₃₀) on adult neurogenesis and synaptic plasticity in the dentate gyrus. Although IH₃₀ did not affect paired-pulse facilitation, IH₃₀ suppressed long-term potentiation (LTP). Immunohistochemical experiments also indicate that IH perturbs multiple aspects of adult neurogenesis. IH₃₀ increased the number of proliferating Sox2⁺ neural progenitor cells in the subgranular zone yet reduced the number of doublecortin-positive neurons. Consistent with these findings, cell lineage tracing revealed that IH₃₀ increased the proportion of radial glial cells in the subgranular zone, yet decreased the proportion of adult-born neurons in the dentate gyrus. While administration of a superoxide anion scavenger during IH did not prevent neural progenitor cell proliferation, it mitigated the IH-dependent suppression of LTP and prevented adult-born neuron loss. These data demonstrate that IH causes both reactive oxygen species-dependent and reactive oxygen species-independent effects on adult neurogenesis and synaptic plasticity in the dentate gyrus. Our findings identify cellular and neurophysiological changes in the hippocampus that may contribute to cognitive and behavioral deficits occurring in sleep apnea.SIGNIFICANCE STATEMENT Individuals with sleep apnea experience periods of intermittent hypoxia (IH) that can negatively impact many aspects of brain function. Neurons are continually generated throughout adulthood to support hippocampal physiology and behavior. This study demonstrates that IH exposure attenuates hippocampal long-term potentiation and reduces adult neurogenesis. Antioxidant treatment mitigates these effects indicating that oxidative signaling caused by IH is a significant factor that impairs synaptic plasticity and reduces adult neurogenesis in the hippocampus.

Hypercapnia impaired cognitive and memory functions in obese patients with obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is a sleep disorder involving repeated nocturnal desaturation and sleep fragmentation. OSA can result in decreased daytime alertness and neurocognitive dysfunction. Hypercapnia status is also related to neurocognitive dysfunction in patients with pulmonary diseases. We evaluated the effects of hypercapnia on cognitive performance and memory function in a prospective case-controlled study. We enrolled thirty-nine obese patients with OSA and collected their arterial blood samples. All the participants provided arterial blood samples, and completed two questionnaires (the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale) and six cognitive tasks (the psychomotor vigilance task [PVT], the Stroop task, the Eriksen flanker task, processing speed [DSST], and verbal and visual memory [LM&FM]), which were used to evaluate daytime sleepiness, cognitive function, and memory function within one week of a polysomnographic study. When compared to the OSA without diurnal hypoventilation, the patients with stable hypercapnia (OHS) had increased reaction times in the PVT, Stroop task, and flanker task. Hypercapnic obese patients with OSA also had comparatively significantly lower scores in the processing speed and logical memory tests. OHS had increased reaction times in the attention and cognitive function assessments, and deficits in the logical memory, when compared to those with OSA without diurnal hypoventilation.

MiRNA expression profiles in healthy OSAHS and OSAHS with arterial hypertension: potential diagnostic and early warning markers

Background

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is prone to being complicated with various cardiovascular, cerebrovascular and metabolic conditions. OSAHS, due to its multifactorial nature, entails individualized and comprehensive treatment. So far, no well-established diagnostic criteria for the disease are available. In recent years, miRNA has been shown to be a sensitive biomarker suggestive of the progression and prognosis of many diseases. In this study, we examined some serum miRNAs in healthy OSAHS (OSAHS patients without complication) and OSAHS with arterial hypertension, with an attempt to understand the potential effects on the disease, improve the diagnosis of OSAHS and find OSAHS-related diagnostic markers.

Methods

Against various diagnostic criteria, participants were divided into three groups: healthy OSAHS, OSAHS with arterial hypertension and healthy controls. Their serum miRNA profiles were assessed by microarray technology, and then differentially expressed miRNAs were verified by quantitative real-time PCR (qRT-PCR). The receiver operating characteristic (ROC) curves of miRNAs were constructed and the areas under the curve (AUC) were calculated. Meanwhile, the miRNAs were subjected to logistic regression analysis. The target genes were bioinformatically assessed, their functions and signaling pathways further determined and eventually an miRNA-gene network was established.

Results

Analysis with the miRNA array exhibited that, compared with the control group, 12 differentially expressed miRNAs were found in healthy OSAHS, and 33 were found in OSAHS with arterial hypertension. The expression of miR-126-3p, let-7d-5p, miR-7641 and miR-1233-5p, miR-320b, miR-145-5p, miR-107, miR-26a-5p were validated by using qRT-PCR. Bioinformatics analysis predicted that the potential target genes of these miRNAs might be involved in metabolism, and the regulation of endothelial cells and nervous system. Moreover, the ROC analysis showed that the using miR-145-5p and let-7d-5p in combination can identify the healthy OSAHS, presence of miR-126-3p, miR-26a-5p and miR-107 was well indicative of OSAHS with arterial hypertension.

Conclusions

A cluster of dysregulation miRNAs have been found to be involved in the development of OSAHS patients. Moreover, these miRNAs might be used to be potential diagnostic and early warning markers.

Prevalence and correlates of obstructive sleep apnea among African Americans: the Jackson Heart Sleep Study

Study Objectives

African Americans have been under-represented in obstructive sleep apnea (OSA) research. This study determined the prevalence and correlates of OSA overall and by sex among African Americans in the Jackson Heart Sleep Study.

Methods

Participants (N = 852) underwent a type 3 in-home sleep apnea study, 7 day wrist actigraphy and completed standardized measurements and questionnaires. OSA was defined as an apnea-hypopnea index (AHI) of ≥15, where hypopneas were defined as ≥ 4% associated desaturation. Physician diagnosis of OSA was self-reported. Logistic regression models were fit to determine the associations of demographics, socioeconomic status, sleep symptoms, actigraphy-based sleep, body mass index (BMI), and comorbidities with OSA.

Results

Average age was 63.1 (standard deviation = 10.7), 66% were female, and mean BMI was 32.0 (6.9) kg/m2. Approximately 24% had an AHI ≥ 15; of those, 5% had a physician diagnosis of OSA. Prevalence of OSA increased across BMI categories, but not age groups. Men had a 12% higher prevalence of OSA compared with women, p < 0.01. Older age, male sex, higher BMI, larger neck circumference, and report of habitual snoring were independently associated with higher odds of OSA, all p < 0.05. Associations between sleep symptoms and OSA were similar for men and women. Sleepiness and waist circumference were not associated with OSA.

Conclusions

There was a high prevalence of objectively measured but undiagnosed OSA in this sample of African Americans. Snoring, BMI, and neck circumference were important markers of OSA for men and women. Our results suggest that screening tools that incorporate information on sleepiness and waist circumference may be suboptimal in this population.

Effects of continuous positive airway pressure on neurocognitive and neuropsychiatric function in obstructive sleep apnea

The aim of this study was to determine the neurocognitive and neuropsychiatric effects of continuous positive airway pressure treatment on patients with obstructive sleep apnea. This cross-sectional, prospective, observational study included 126 patients with sleep apnea. The following tests were performed: the Montreal Cognitive Assessment for the evaluation of cognitive impairment, the Beck Depression Inventory, and the State-Trait Anxiety Inventory, together with the Epworth Sleepiness Scale for the evaluation of neuropsychiatric symptoms and a person's general level of daytime sleepiness. The first measurement did not show neurocognitive impairment or a higher level of depressive and anxiety symptoms in 126 patients with obstructive sleep apnea in comparison to normative standards. After the 3-month treatment indicated for 43 patients with obstructive sleep apnea, we did not find any significant improvement in cognitive performance (p = .213). However, patients with sleep apnea with continuous positive airway pressure treatment did show significantly less daytime sleepiness, anxiety and depressive symptoms (all p < .001). In conclusion, short-term (3 months) treatment of patients with obstructive sleep apnea can substantially alleviate their daytime sleepiness, as well as depressive and anxiety symptoms.

Dysfunction of Nrf2-ARE Signaling Pathway: Potential Pathogenesis in the Development of Neurocognitive Impairment in Patients with Moderate to Severe Obstructive Sleep Apnea-Hypopnea Syndrome

The present study investigated the nuclear factor erythroid 2-related factor 2- (Nrf2-) antioxidant response element (ARE) signaling pathway in patients with moderate to severe obstructive sleep apnea-hypopnea syndrome (OSAHS). Their correlation with neurocognitive impairment metrics was investigated to explore potential pathogenesis in OSAHS. Forty-eight patients with OSAHS and 28 controls underwent testing with the Epworth Sleep Scale (ESS), MATRICS Consensus Cognitive Battery (MCCB), Stroop Color and Word Test, polysomnography (PSG), and measurements of the concentration of plasma superoxide dismutase (SOD) and thioredoxin (Trx). Further, 20 pairs of matched patients with OSAHS and controls were selected for measurement of the expression (protein and mRNA) of Nrf2 and of its downstream antioxidase, heme oxygenase-1 (HO-1), in peripheral mononuclear cells (PBMCs). Finally, correlations between neurocognitive impairment and the above metrics were analyzed. Expression of Nrf2 and HO-1 mRNA and protein in the PBMCs, as well as plasma SOD and Trx levels, were significantly reduced in patients with OSAHS. After adjusting for education, sex, age, and smoking index, the expression of Nrf2-ARE signaling pathway proteins (or mRNA) was closely correlated with sleep respiratory parameters. An inverse relationship was demonstrated between the expression of nuclear Nrf2 in PBMCs, concentration of plasma SOD and Trx, and apnea-hypopnea index (AHI) in patients with OSAHS. Trx, nuclear Nrf2 protein, and HO-1 protein were also negatively correlated with the percent of time that SaO₂ was less than 90% (TSat90). Total Nrf2 protein level was positively correlated with AHI and TSat90 and negatively correlated with minimum SaO₂ (LSaO₂), while nuclear Nrf2 protein and HO-1 protein were positively correlated with LSaO₂. Moreover, significant positive correlations were found between maze scores and expression of nuclear Nrf2 protein, HO-1 protein, and SOD and Trx levels. Furthermore, inverse relationships between total Nrf2 protein in PBMCs and HVLT-R and maze scores were found. Multiple linear regression showed plasma Trx concentration as a potential predictor of maze and BVMT-R scores. In conclusion, the expression of Nrf2-ARE molecules and related antioxidases is significantly decreased in patients with OSAHS and is correlated with neurocognitive dysfunction. The Nrf2-ARE signaling pathway may play a crucial role in neurocognitive impairment in patients with moderate to severe OSAHS. Further studies are needed to explore the exact mechanisms and potential treatment interventions.

Obstructive sleep apnea syndrome and olfactory perception: An OERP study

Obstructive Sleep Apnea Syndrome (OSA) is characterized by snoring associated with repeated apnea and/or obstructive hypopnea. The nasal airways of OSA patients, measured via acoustic rhinometry, could be significantly narrower than healthy subjects and this reduced nasal structure can impair olfactory function. The relationship between nasal structure and olfactory function, assessed via behavioral test results, indicates that there is a high prevalence of nasal airflow problems. Based on these assumptions, the purpose of this study was to carry out an assessment of olfactory perception in OSA patients through the Chemosensory Event-Related Potentials (CSERP), investigating the N1 component and the Late Positive Component (LPC). Twelve OSA patients, non-smokers, were recruited in the Pulmonary Rehabilitation Unit, scored with the Epworth Sleepiness Scales, after Polygraphic Recording, Apnea Hypopnea Index and Body Mass Index evaluation. The control group consisted of twelve healthy controls, non-smokers, recruited as volunteers. Subjects, during an EEG recording, performed an oddball olfactory recognition task based on two scents: rose and eucalyptus. Main results highlighted differences in N1 and LPC between OSA and controls. OSA patients presented faster N1 latencies and greater amplitude. The same trend was found in LPC, where OSA showed decreased latency and increased amplitude during rose stimulation, in the right inferior frontal cortex. and faster latencies in left centroparietal cortex OERP results can suggest an impairment in endogenous components. This result could be the consequence of the exogenous perceptual difficulty highlighted in N1 component. The increased arousal could also be related to the respiratory activity involved during the olfactory task.

Greater Cognitive Deficits with Sleep-disordered Breathing among Individuals with Genetic Susceptibility to Alzheimer Disease. The Multi-Ethnic Study of Atherosclerosis

RATIONALE

There are conflicting findings regarding the link between sleep apnea and cognitive dysfunction.

OBJECTIVES

Investigate associations between indicators of sleep-disordered breathing (SDB) and cognitive function in the Multi-Ethnic Study of Atherosclerosis and assess effect modification by the apolipoprotein ε-4 (APOE-ε4) allele.

METHODS

A diverse population (N = 1,752) underwent type 2 in-home polysomnography, which included measurement of percentage sleep time less than 90% oxyhemoglobin saturation (%Sat < 90%) and apnea-hypopnea index (AHI). Epworth Sleepiness Scale score (ESS) and sleep apnea syndrome (SAS; AHI ≥ 5 and ESS > 10) were also analyzed. Cognitive outcomes included the Cognitive Abilities Screening Instrument; Digit Symbol Coding (DSC) test; and Digit Span Tests (DST) Forward and Backward.

RESULTS

Participants were 45.4% men, aged 68.1 years (SD, 9.1 yr) with a median AHI of 9.0 and mean ESS of 6.0. Approximately 9.7% had SAS, and 26.8% had at least one copy of the APOE-ε4 allele. In adjusted analyses, a 1-SD increase in %Sat < 90% and ESS score were associated with a poorer attention and memory assessed by the DST Forward score (β = -0.12 [SE, 0.06] and β = -0.13 [SE, 0.06], respectively; P ≤ 0.05). SAS and higher ESS scores were also associated with poorer attention and processing speed as measured by the DSC (β = -0.69 [SE, 0.35] and β = -1.42 [SE, 0.35], respectively; P < 0.05). The presence of APOE-ε4 allele modified the associations of %Sat < 90% with DST forward and of ESS with DSC (P_interaction ≤ 0.05).

CONCLUSIONS

Overnight hypoxemia and sleepiness were associated with cognition. The average effect estimates were small, similar to effect estimates for several other individual dementia risk factors. Associations were strongest in APOE-ε4 risk allele carriers. Our results (1) suggest that SDB be considered among a group of modifiable dementia risk factors, and (2) highlight the potential vulnerability of APOE-ε4 risk allele carriers with SDB.