Obstructive sleep apnea, cognition and Alzheimer's disease: A systematic review integrating three decades of multidisciplinary research

Association of Hypoxemia Due to Obstructive Sleep Apnea With White Matter Hyperintensities and Temporal Lobe Changes in Older Adults

BACKGROUND AND OBJECTIVES

Cerebral small vessel disease (CSVD) is a leading cause of cognitive decline and functional loss in older adults. Obstructive sleep apnea (OSA) is common in older adults, can increase cerebrovascular disease risk, and is linked to medial temporal lobe (MTL) degeneration and cognitive impairment. However, the interaction between OSA features and CSVD burden and their combined effect on MTL structure and function are not well understood. This study tested the hypothesis that CSVD burden is a candidate mechanism linking OSA to MTL degeneration and impaired memory in older adults.

METHODS

Cognitively unimpaired older adults from the Biomarker Exploration in Aging, Cognition, and Neurodegeneration cohort were recruited for an observational, in-lab overnight polysomnography (PSG) study with emotional mnemonic discrimination ability assessed before and after sleep. Participants had no neurologic or psychiatric disorders and were not on sleep-affecting medications. PSG-derived OSA variables included apnea-hypopnea index (AHI), total arousal index, and minimum SpO2. MRI was used to assess global and lobar white matter hyperintensity (WMH) volumes and MTL structure (hippocampal volume; entorhinal cortex [ERC] thickness) at an earlier time point. Regressions were implemented while adjusting for age, sex, and concurrent use of antihyperlipidemic and/or antihypertensive medication. Minimum SpO2 was transformed into a Hypoxemia Severity Index for normality, in which lower SpO2 values indicated more severe hypoxemia.

RESULTS

Thirty-seven older adults were included in the study (age 72.5 ± 5.6 years, 23 women, AHI = 13.8 ± 18.0 [range 0-80]). Hypoxemia measures significantly predicted global WMH volume (bminSpO2 = 0.141 [0.001-0.282], bduration <90% = 0.008 [0.000-0.016]). This relationship was driven by hypoxemia severity during REM sleep (bREMminSpO2 = 0.143 [0.003-0.284]), which also predicted frontal (bREMminSpO2 = 0.101 [0.004-0.198]) and parietal (bREMminSpO2 = 0.121 [0.024-0.219]) WMH burden. Greater frontal WMH burden indirectly mediated the relationship between REM sleep hypoxemia and ERC thickness (indirect effect = -0.043, 95% CI -0.1174 to -0.00015). Reduced ERC thickness was, in turn, associated with worse overnight mnemonic discrimination ability (bleftERCthickness = 0.112 [0.014-0.211]).

DISCUSSION

These findings identify CSVD as a candidate mechanism linking OSA-related hypoxemia to MTL degeneration and impaired sleep-dependent memory in older adults, specifically implicating hypoxic events during REM sleep.

Sex differences in sleep apnea and Alzheimer's Disease: role of cerebrovascular dysfunction

Obstructive sleep apnea (OSA) significantly impacts cardiovascular health in post-menopausal females. Given that cardiovascular and cerebrovascular diseases are tightly linked, OSA-mediated impacts on cerebrovascular function and Alzheimer's Disease (AD) risk are also likely more manifest in females. This review will: summarize sex differences in cerebrovascular function, review the vascular hypothesis of AD, characterize sex differences in the OSA phenotype and implications for cerebrovascular control, and highlight OSA-mediated AD risk.

Decoupling of global signal and cerebrospinal fluid inflow is associated with cognitive decline in patients with obstructive sleep apnoea

OBJECTIVES

The role of cortical glymphatic dysfunction in the cognitive impairment of the obstructive sleep apnea (OSA) requires further study. To compare the coupling between the resting-state blood-oxygen-level-dependent (BOLD) signals and cerebrospinal fluid (CSF) signals (BOLD-CSF coupling), a proxy for the cortical glymphatic function, across patients with differing severities of OSA and relate them with disease characteristics and treatment.

METHODS

A total of 153 participants (89 OSA patients and 64 matched controls) were prospectively included. OSA patients were classified into three groups (mild, moderate, and severe OSA) according to the apnea-hypopnea index (AHI). All participants underwent neuropsychological assessment and BOLD functional magnetic resonance imaging. BOLD-CSF coupling was assessed at global and regional levels and correlated with the cognitive impairment. Alterations in BOLD-CSF coupling and cognitive performance after treatment were assessed in OSA patients.

RESULT

Severe OSA patients exhibited weaker global and anterior BOLD-CSF coupling than mild OSA patients, moderate OSA patients, and healthy controls (HCs). Furthermore, the weaker global and anterior BOLD-CSF coupling was associated with poor cognitive performance in all OSA patients. Notably, cognitive performance and cortical glymphatic function improved significantly in patients with OSA after treatment.

CONCLUSION

Our findings demonstrated cortical glymphatic dysfunction in severe OSA patients, especially in the anterior region of the brain. Cortical glymphatic dysfunction may underlie the cognitive impairment in OSA patients, both of which would improve in OSA patients after treatment.

Neuroregulation of histamine of circadian rhythm disorder induced by chronic intermittent hypoxia

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxemia, sleep fragmentation, and excessive daytime sleepiness. OSA patients are at an elevated risk for circadian rhythm disturbances. Histamine is known to regulate the sleep-wake cycle predominantly via histamine H1 receptors. We utilized a C57BL/6 mouse model exposed to chronic intermittent hypoxia (CIH) for three weeks to assess alterations in circadian rhythmicity. Sleep architecture and voluntary wheel-running activity were evaluated. Additionally, c-fos expression and mPer2 levels in the frontal cortex (FC) and the suprachiasmatic nucleus (SCN) were examined. BV-2 microglial cells were subjected to intermittent hypoxia (IH) for 12 h to explore the underlying signaling pathways. CIH exposure led to a significant prolongation of the wake phase and a reduction in the Non-rapid eye movement (NREM) phase, accompanied by increased sleep fragmentation and disruption of circadian rhythms. Treatment with mepyramine, an H1 receptor antagonist, mitigated these effects by reducing arousal duration, extending NREM phase, and decreasing sleep fragmentation. CIH also resulted in increased c-fos expression and elevated mPer2 levels in the FC and SCN, both of which were reversed following mepyramine administration. In vitro studies on BV-2 cells demonstrated that histamine exerts its modulatory effects through the activation of the PLC and PKA signaling pathways, influencing mPer2 expression via the regulation of K+, Na + -Ca2+, and Ca2+ ion channels. In conclusion, CIH disrupts circadian rhythms through histamine-mediated mechanisms, and mepyramine effectively ameliorates these disruptions. These findings highlight histamine as a promising therapeutic target for addressing circadian rhythm disorders associated with OSA.

Association Between Sleep Duration and Cognitive Frailty in Older Chinese Adults: Prospective Cohort Study

Background

Disturbed sleep patterns are common among older adults and may contribute to cognitive and physical declines. However, evidence for the relationship between sleep duration and cognitive frailty, a concept combining physical frailty and cognitive impairment in older adults, is lacking.

Objective

This study aimed to examine the associations of sleep duration and its changes with cognitive frailty.

Methods

We analyzed data from the 2008-2018 waves of the Chinese Longitudinal Healthy Longevity Survey. Cognitive frailty was rendered based on the modified Fried frailty phenotype and Mini-Mental State Examination. Sleep duration was categorized as short (<6 h), moderate (6-9 h), and long (>9 h). We examined the association of sleep duration with cognitive frailty status at baseline using logistic regressions and with the future incidence of cognitive frailty using Cox proportional hazards models. Restricted cubic splines were used to explore potential nonlinear associations.

Results

Among 11,303 participants, 1298 (11.5%) had cognitive frailty at baseline. Compared to participants who had moderate sleep duration, the odds of having cognitive frailty were higher in those with long sleep duration (odds ratio 1.71, 95% CI 1.48-1.97; P<.001). A J-shaped association between sleep duration and cognitive frailty was also observed (P<.001). Additionally, during a mean follow-up of 6.7 (SD 2.6) years among 5201 participants who were not cognitively frail at baseline, 521 (10%) participants developed cognitive frailty. A higher risk of cognitive frailty was observed in participants with long sleep duration (hazard ratio 1.32, 95% CI 1.07-1.62; P=.008).

Conclusions

Long sleep duration was associated with cognitive frailly in older Chinese adults. These findings provide insights into the relationship between sleep duration and cognitive frailty, with potential implications for public health policies and clinical practice.

Sleep disorders in rheumatoid arthritis: Incidence, risk factors and association with dementia

BACKGROUND/OBJECTIVE

We aimed to examine the incidence of sleep disorders (SD) in individuals with rheumatoid arthritis (RA) vs. non-RA comparators, evaluate risk factors for SD, and assess the association between incident SD and dementia in RA.

METHODS

This retrospective cohort study included residents aged ≥50 years within an 8-county region of Minnesota who first met the 1987 ACR criteria for RA in 1980-2014. Individuals with RA were matched 1:1 with non-RA individuals on age, sex, and calendar year of RA incidence. Data on SD, cardiovascular disease (CVD) risk factors, CVD and other comorbidities were collected from the medical records.

RESULTS

Nine hundred thirteen individuals with RA and 913 non-RA comparators were included (mean age: 65 years, 65 % female in both cohorts). During the median follow-up of 10.4 years in RA and 11.0 years in non-RA cohort, SD developed in 234 and 206 individuals, respectively. RA patients experienced an increased risk for any incident SD (HR 1.34; 95 % CI:1.11-1.61) and insomnia (HR 1.34; 95 % CI:1.03-1.73). Obesity, dyslipidemia, presence of CVD, depression, anxiety, and more recent calendar year of RA incidence were associated with increased risk of any SD in RA. There were no significant association between SD overall and by subtype with dementia in RA.

CONCLUSION

Individuals with RA (vs non-RA) experienced a significantly increased risk for any SD, particularly insomnia. CVD and CVD risk factors, as well as depression and anxiety increased the risk for incident SD in RA. There was no significant association between SD and dementia in RA.

Prevalence and Misperception: Exploring the Gap Between Objective and Subjective Assessment of Sleep Apnea in a Population at Increased Risk for Dementia

Background: Aging is a well-established independent risk factor for both cognitive impairment and sleep disorders, including obstructive sleep apnea (OSA), a modifiable yet underrecognized condition. OSA has been implicated in biological mechanisms contributing to Alzheimer's disease, including amyloid-β accumulation, tau phosphorylation, and neuroinflammation. This underscores the need to optimize OSA diagnosis in individuals with an increased risk of dementia. Methods: This cross-sectional observational study enrolled adults aged 60-85 years with a CAIDE dementia risk score ≥6. Subjective sleep was evaluated using validated questionnaires (Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and the Oviedo Sleep Questionnaire), while objective sleep data were obtained through a single-night peripheral arterial tonometry (PAT)-based wearable device, complemented by a 7-day sleep diary. Participants also completed the STOP-BANG and Berlin questionnaires, with clinically relevant findings communicated to participants. Results: Among 322 participants (48.8% women; mean age 71.4 ± 6.4 years), moderate-to-severe OSA (apnea-hypopnea index [AHI] ≥ 15) was identified in 48.49%, despite the absence of prior diagnoses. Subjective screening tools frequently underestimated OSA severity compared to objective assessments. While no significant sex-based differences were noted, higher AHI values correlated strongly with increased body mass index and elevated dementia risk scores. Conclusions: A marked discrepancy between subjective and objective sleep measurements complicates the accurate diagnosis and management of most sleep disorders, including OSA. Sleep disorders remain significantly underdiagnosed in individuals at increased risk for dementia. Integrating wearable technologies and structured tools such as sleep diaries into routine assessments can enhance diagnostic precision, enabling timely interventions for these modifiable risk factors of dementia.

Altered brain dynamic functional connectivity in patients with obstructive sleep apnea and its association with cognitive performance

OBJECTIVES

Obstructive sleep apnea (OSA) is associated with potential disruptions in brain function and structure. The aim was to investigate alterations in dynamic functional connectivity (dFC) in OSA patients utilizing resting-state functional magnetic resonance imaging (rs-fMRI) and multiplication of temporal derivatives (MTD) to better understand the neurological implications of OSA.

METHODS

This cross-sectional study eventually recruited 111 patients, aged 25-65 years. We categorized participants based on the apnea-hypopnea index (AHI) assessed via polysomnography (PSG), 43 patients were groupAHI <15 and 68 patients were group AHI ≥15. Rs-fMRI and neuropsychological assessments were conducted to assess the brain function and visual-spatial memory, respectively. We evaluated the intergroup differences in dFC as well as its correlation with clinical parameters.

RESULTS

The dFC analysis identified five distinct connectivity states, comprising four hyperconnected states (State 1, 2, 3, and 5) and one hypoconnected state (State 4). Group AHI≥ 15 showed altered fraction time (FT) and mean dwell time (MDT) in States 1, 3, and 4. The partial correlation showed that the FT/MDT of State 1 negatively correlated with hypoxia parameters, while the FT/MDT of State 3 positively correlated with total sleep time in Group AHI≥ 15. Group AHI≥ 15 exhibited a negative association between FT of state 3 and Visuospatial/Executive score in MoCA (r = -0.297, p = 0.033).

CONCLUSIONS

Untreated male moderate to severe OSA patients exhibited altered in dFC, which significantly correlated with hypoxia parameters and cognitive performance, high lighting that dFC changes may be an indicator of the neurological consequence of OSA, especially moderate to severe OSA.

Review on pathogenesis and treatment of Alzheimer's disease

The rising incidence of Alzheimer's disease (AD) and the associated economic impacts has prompted a global focus in the field. In recent years, there has been a growing understanding of the pathogenic mechanisms of AD, including the aggregation of β-amyloid, hyperphosphorylated tau, and neuroinflammation. These processes collectively lead to neurodegeneration and cognitive decline, which ultimately results in the loss of autonomy in patients. Currently, there are three main types of AD treatments: clinical tools, pharmacological treatment, and material interventions. This review provides a comprehensive analysis of the underlying etiology and pathogenesis of AD, as well as an overview of the current prevalence of AD treatments. We believe this article can help deepen our understanding of the AD mechanism, and facilitate the clinical translation of scientific research or therapies, to address this global problem of AD.

Weather-Associated Variations of Device-Detected Severe Sleep Apnea in Cardiac Pacemaker Patients

Using continuous thoracic impedance measurements, sleep apnea can be long-time monitored via an electronic device sensor. In the ACaSA trial, 233 patients implanted with a cardiac pacemaker (MicroPort CRM, Clamart, France) were prospectively observed between March 2022 and July 2024. For each night of follow-up, the burden of device-detected sleep apnea (DDSA) was measured via transthoracic impedance, defined by a respiratory disturbance index (RDI) ≥ 20 events per sleeping hour. Local meteorological data including maximum ambient diurnal temperature, humidity, precipitation and air pressure change were extracted from the national weather system and linked to the individual patient's place of residence. The association between these weather conditions and RDI in the following night was estimated using a generalised linear mixed effects model. Overall, 74,031 patient-nights of 210 individuals (median age 75.7 years [IQR 69.9-81.3], 77 [36.7%] female) with a median follow up of 593 nights (IQR 348-755) were analysed. In a multivariate regression analysis, ambient maximum diurnal temperature was independently associated with presence of DDSA. Following days with a maximum of 30°C, the odds of experiencing severe DDSA increased by 1.34 (95% CI: 1.17-1.54, p < 0.001) compared to days with only 10°C. Higher relative humidity increased the odds for suffering from severe DDSA as well (OR 1.19 [1.07-1.33] in 90% relative humidity vs. 65% humidity; p = 0.007). These associations of ambient maximum diurnal temperature and relative humidity with severe DDSA the following night need further investigations, in particular in view of upcoming global climate changes.

Obstructive sleep apnea and cerebral small vessel disease in community-based older people: an aspirin in reducing events in the elderly imaging substudy

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) may increase the risk of dementia. A potential pathway for this risk is through cerebral small vessel disease (CSVD). In the context of an existing randomized trial of aspirin for primary prevention, we aimed to investigate OSA's impact on CSVD imaging measures and explore whether aspirin effects these measures over 3 years that differ in the presence or absence of OSA.

METHODS

A substudy of the aspirin in reducing events in the elderly (ASPREE) randomized placebo-controlled trial of low-dose aspirin. Community-dwelling participants aged 70 years and above, without cognitive impairment, cardiovascular disease, or known OSA completed an unattended limited-channel sleep study that calculated the oxygen desaturation index and apnea-hypopnea index. At baseline and 3 years later, volumes of white matter hyperintensities (WMH) and silent brain infarctions (SBI) were measured on 1.5 Tesla brain magnetic resonance imaging, and retinal vessel calibers were calculated from retinal vascular imaging.

RESULTS

Mild and moderate/severe OSA was detected in 48.9% and 29.9%, respectively, of the 311 participants, who had a mean age of 73.7 years (SD 3.4 years), 38.6% female. OSA of any severity was not associated with WMH volumes, SBI, nor retinal vessel calibers at baseline, nor with change in these measures in the 277 participants with repeated measures acquired after 3 years. OSA of any severity did not interact with aspirin on change in these measures over 3 years.

CONCLUSIONS

In healthy older adults undiagnosed OSA was not associated with retinal vascular calibers and neuroimaging measures of CSVD.

CLINICAL TRIAL INFORMATION

ASPREE trial has registration with the International Standard Randomized Controlled Trial Number (ISRCTN) www.isrctn.com, ISRCTN83772183 and with www.clinicaltrials.gov, NCT01038583. SNORE-ASA has registration with the Australian New Zealand Clinical Trials Registry (ANZCTR) at www.anzctr.org.au, ACTRN12612000891820.

Epileptic activity on foramen ovale electrodes is associated with sleep and tau pathology in Alzheimer's disease

Both sleep alterations and epileptiform activity are associated with the accumulation of amyloid-β and tau pathology and are currently investigated for potential therapeutic interventions in Alzheimer's disease. However, a bidirectional intertwining relationship between sleep and neuronal hyperexcitability might modulate the effects of Alzheimer's disease pathology on the corresponding associations. To investigate this, we performed multiple day simultaneous foramen ovale (FO) plus scalp EEG and polysomnography recordings and acquired 18F-MK6240 tau PET-MR in three patients in the prodromal stage of Alzheimer's disease and in two patients with mild and moderate dementia due to Alzheimer's disease, respectively. As an eligibility criterion for the present study, subjects either had a history of a recent seizure (n = 2) or subclinical epileptiform activity (SEA) on a previous scalp EEG taken in a research context (n = 3). The 18F-MK6240 standard uptake value ratio (SUVR) and asymmetry index (AI) were calculated in a priori-defined volumes of interest. Linear mixed-effects models were used to study associations between interictal epileptiform discharges (IEDs), polysomnography parameters and 18F-MK6240 SUVR. Epileptiform activity was bilateral but asymmetrically present on FO electrodes in all patients and ≥95% of IEDs were not visible on scalp EEG. In one patient, two focal seizures were detected on FO electrodes, both without visual scalp EEG correlate. We observed lateralized periodic discharges, brief potentially ictal rhythmic discharges and lateralized rhythmic delta activity on FO electrodes in four patients. Unlike scalp EEG, intracranial electrodes showed a lateralization of epileptiform activity. Although the amount of IEDs on intracranial electrodes was not associated to the 18F-MK6240 SUVR binding in different volumes of interest, there was a congruent asymmetry of the 18F-MK6240 binding towards the most epileptic hemisphere for the mesial (P = 0.007) and lateral temporal cortex (P = 0.006). IEDs on intracranial electrodes were most abundant during slow wave sleep (SWS) (92/h) and non-REM sleep 2 (N2, 81/h), followed by non-REM sleep 1 (N1, 33/h) and least frequent during wakefulness (17/h) and REM sleep (9/h). The extent of IEDs during sleep was not reflected in the relative time in each sleep stage spent [REM% (P = 0.415), N1% (P = 0.668), N2% (P = 0.442), SWS% (P = 0.988)], and not associated with the arousal index (P = 0.317), apnoea-hypopnoea index (P = 0.846) or oxygen desaturation index (P = 0.746). Together, our observations suggest a multi-directional interaction between sleep, epileptiform activity and tau pathology in Alzheimer's disease.

Mediating role of obstructive sleep apnea in altering slow-wave activity and elevating Alzheimer's disease risk: Pilot study from a northern Taiwan cohort

OBJECTIVES

Obstructive sleep apnea is associated with alterations in slow-wave activity during sleep, potentially increasing the risk of Alzheimer's disease. This study investigated the associations between obstructive sleep apnea manifestations such as respiratory events, hypoxia, arousal, slow-wave patterns, and neurochemical biomarker levels.

METHODS

Individuals with suspected obstructive sleep apnea underwent polysomnography. Sleep disorder indices, oxygen metrics, and slow-wave activity data were obtained from the polysomnography, and blood samples were taken the following morning to determine the plasma levels of total tau (T-Tau) and amyloid beta-peptide 42 (Aβ42) by using an ultrasensitive immunomagnetic reduction assay. Subsequently, the participants were categorized into groups with low and high Alzheimer's disease risk on the basis of their computed product Aβ42 × T-Tau. Intergroup differences and the associations and mediation effects between sleep-related parameters and neurochemical biomarkers were analyzed.

RESULTS

Forty-two participants were enrolled, with 21 assigned to each of the low- and high-risk groups. High-risk individuals had a higher apnea-hypopnea index, oxygen desaturation index (≥3%, ODI-3%), fraction of total sleep time with oxygen desaturation (SpO2-90% TST), and arousal index and greater peak-to-peak amplitude and slope in slow-wave activity, with a correspondingly shorter duration, than did low-risk individuals. Furthermore, indices such as the apnea-hypopnea index, ODI-3% and SpO2-90% TST were found to indirectly affect slow-wave activity, thereby raising the Aβ42 × T-Tau level.

CONCLUSIONS

Obstructive sleep apnea manifestations, such as respiratory events and hypoxia, may influence slow-wave sleep activity (functioning as intermediaries) and may be linked to elevated neurochemical biomarker levels. However, a longitudinal study is necessary to determine causal relationships among these factors.

STATEMENT OF SIGNIFICANCE

This research aims to bridge gaps in understanding how obstructive sleep apnea is associated with an elevated risk of Alzheimer's disease, providing valuable knowledge for sleep and cognitive health.

Changes in sleep-disordered breathing severity and post-stroke outcomes in the first year after stroke

BACKGROUND

Sleep-disordered breathing (SDB) is common among stroke survivors and is associated with worse functional, cognitive, and neurologic outcomes after stroke. Little is known about the association between changes in SDB and changes in these outcomes over time.

METHODS

Ischemic stroke (IS) patients identified through the Brain Attack Surveillance in Corpus Christi project were offered SDB testing with a portable respiratory monitor (ApneaLink Plus) shortly after stroke, and at 3-, 6-, and 12-months post-stroke. SDB was quantified using the respiratory event index (REI; apneas plus hypopneas per hour of recording). At 3-, 6-, and 12-months post-stroke, functional outcomes, cognitive outcomes, and neurologic outcomes were measured. Linear mixed models were fitted to obtain random slopes reflecting individual changes in REI and each of outcome over time, adjusted for multiple covariates. Associations between the resulting individual slopes for REI and each outcome were then evaluated using linear regression models.

RESULTS

Of 482 IS patients with at least one REI measurement, in fully adjusted models, faster reduction in REI was not associated with faster improvement in functional (β = -0.06; 95 % CI: -0.15, 0.03, p = 0.16), cognitive (β = -0.03; 95 % CI: -0.12, 0.06, p = 0.51), or neurologic outcomes (β = -0.04; 95 % CI: -0.13, 0.05, p = 0.41).

CONCLUSIONS

In this observational study of stroke survivors, there was no clear association between the rate of improvement in SDB and improvement in functional, cognitive, or neurologic outcomes. It remains to be seen whether treatment of SDB might lead to improved outcomes among stroke survivors.

Automated remote sleep monitoring needs uncertainty quantification

Wearable electroencephalography devices emerge as a cost-effective and ergonomic alternative to gold-standard polysomnography, paving the way for better health monitoring and sleep disorder screening. Machine learning allows to automate sleep stage classification, but trust and reliability issues have hampered its adoption in clinical applications. Estimating uncertainty is a crucial factor in enhancing reliability by identifying regions of heightened and diminished confidence. In this study, we used an uncertainty-centred machine learning pipeline, U-PASS, to automate sleep staging in a challenging real-world dataset of single-channel electroencephalography and accelerometry collected with a wearable device from an elderly population. We were able to effectively limit the uncertainty of our machine learning model and to reliably inform clinical experts of which predictions were uncertain to improve the machine learning model's reliability. This increased the five-stage sleep-scoring accuracy of a state-of-the-art machine learning model from 63.9% to 71.2% on our dataset. Remarkably, the machine learning approach outperformed the human expert in interpreting these wearable data. Manual review by sleep specialists, without specific training for sleep staging on wearable electroencephalography, proved ineffective. The clinical utility of this automated remote monitoring system was also demonstrated, establishing a strong correlation between the predicted sleep parameters and the reference polysomnography parameters, and reproducing known correlations with the apnea-hypopnea index. In essence, this work presents a promising avenue to revolutionize remote patient care through the power of machine learning by the use of an automated data-processing pipeline enhanced with uncertainty estimation.

Health outcomes of former division I college athletes

BACKGROUND

Former professional collision sport (CS) athletes, particularly American football players, are at risk of developing chronic health conditions; however, little is known about the health outcomes of amateur athletes.

METHODS

A 60-item health survey examined self-reported symptoms and diagnoses among former Division 1 Collegiate CS athletes and non- or limited-contact sport (non-CS) athletes. Binary logistic regressions tested the association between playing CS and health outcomes.

RESULTS

Five hundred and two (6.2%) participants completed the survey: 160 CS athletes (mean age: 59.2, SD = 16.0) and 303 non-CS athletes (mean age: 54.0, SD = 16.9). CS athletes had increased odds of reported cognitive complaints and neuropsychiatric symptoms including memory (Padj < 0.01), attention/concentration (Padj = 0.01), problem solving/multi-tasking (Padj = 0.05), language (Padj = 0.02), anxiety (Padj = 0.04), impulsivity (Padj = 0.02), short-fuse/rage/explosivity (Padj < 0.001), and violence/aggression (Padj = 0.02). CS athletes also reported higher rates of sleep apnea (Padj = 0.02). There were no group differences in cardiovascular and physical health outcomes.

CONCLUSIONS

Former CS athletes reported more cognitive and neuropsychiatric complaints. The low response rate is a limitation of this study; however, over 500,000 athletes play college sports each year, thus research on long-term health outcomes in this population is critical.

Obstructive sleep apnea and structural and functional brain alterations: a brain-wide investigation from clinical association to genetic causality

BACKGROUND

Obstructive sleep apnea (OSA) is linked to brain alterations, but the specific regions affected and the causal associations between these changes remain unclear.

METHODS

We studied 20 pairs of age-, sex-, BMI-, and education- matched OSA patients and healthy controls using multimodal magnetic resonance imaging (MRI) from August 2019 to February 2020. Additionally, large-scale Mendelian randomization analyses were performed using genome-wide association study (GWAS) data on OSA and 3935 brain imaging-derived phenotypes (IDPs), assessed in up to 33,224 individuals between December 2023 and March 2024, to explore potential genetic causality between OSA and alterations in whole brain structure and function.

RESULTS

In the cohort study, OSA patients exhibited significantly lower fractional amplitude of low-frequency fluctuation and regional homogeneity in the right posterior cerebellar lobe and bilateral superior and middle frontal gyrus, while showing higher levels in the left occipital lobe and left posterior central gyrus. Decreased fractional anisotropy (FA) but increased apparent diffusion coefficient (ADC) was shown in the bilateral superior longitudinal fasciculus. According to the results of Affiliation file 2: table s6, it is the ADC value of right superior longitudinal fasciculus was shown a positive correlation with the lowest oxygen saturation. In the Mendelian randomization analyses, the area of left inferior temporal sulcus (OR: 0.89; 95% CI: 0.82-0.96), rfMRI connectivity ICA100 edge 893 (OR: 0.88; 95% CI: 0.82-0.96), ICA100 edge 951 (OR: 0.89; 95% CI: 0.82-0.97), and ICA100 edge 1213 (OR: 0.89; 95% CI: 0.82-0.96) were significantly decreased in OSA. Conversely, mean thickness of G-front-inf-Triangul in right hemisphere (OR: 1.14; 95% CI: 1.05-1.23), mean orientation dispersion index in right tapetum (OR: 1.13; 95% CI: 1.04-1.23), and rfMRI connectivity ICA100 edge 258 (OR: 1.13; 95% CI: 1.04-1.22) showed opposite results.

CONCLUSIONS

Nerve fiber damage and imbalances in neuronal activity across multiple brain regions caused by hypoxia, particularly the frontal lobe, underlie the structural and the functional connectivity impairments in OSA.

Sleep Disordered Breathing and Subsequent Neuroimaging Markers of Brain Health in Hispanic/Latino Adults

BACKGROUND AND OBJECTIVES

Sleep disordered breathing (SDB) is a risk factor of stroke and Alzheimer disease and related dementias (ADRDs). Hispanic/Latino adults have higher risk of SDB and ADRDs, which emphasizes the need to better understand the association between SDB and brain health. Furthermore, results on SDB and brain aging are mixed, and there are limited data for Hispanic/Latino adults. The main goal of this study is to assess the association between SDB and brain MRI measures in a diverse Hispanic/Latino population.

METHODS

The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) is a community-based prospective cohort multisite (Bronx, Chicago, Miami, San Diego) study of diverse Hispanic/Latino adults in the United States. Participants underwent 1 night of unsupervised home testing with a sleep apnea test device at baseline. The SOL-Investigation of Neurocognitive Aging MRI, an ancillary study, recruited 2,667 HCHS/SOL participants (35-85 years) who underwent neuroimaging approximately 10 years after baseline sleep assessment. The main exposure was the respiratory event index (REI, 3% desaturation). Secondary exposures encompassed measures of oxygen saturation. Main outcomes included total brain, gray matter, white matter hyperintensity (WMH), and hippocampal volumes. Survey linear regression models were used to determine associations between SDB and brain MRI measures.

RESULTS

The mean age was 67.6 years, with a body mass index of 29.7, and 58.3% were female. We found that increased REI was associated with larger hippocampal volumes (bhippocampus = 0.006 [0.001-0.012]). These results were consistent with oxygen levels (minimum SpO2%) during sleep (bhippocampus = -0.013 [-0.021 to -0.004]). Lower oxygen levels (mean SpO2) during sleep were associated with enlarged WMH volumes (bWMH = -0.095 [-0.164 to -0.025]).

DISCUSSION

We found that SDB and worse oxygenation during sleep were linked to larger hippocampal volumes. These results underscore the complex relationships between sleep health and brain aging and warrant longitudinal follow-up, starting in middle age or earlier.

Snoring and risk of dementia: a prospective cohort and Mendelian randomization study

STUDY OBJECTIVES

The association between snoring, a very common condition that increases with age, and dementia risk is controversial. We aimed to investigate the observational and causal relationship between snoring and dementia, and to elucidate the role of body mass index (BMI).

METHODS

Using data from 451 250 participants who were dementia-free at baseline, we examined the association between self-reported snoring and incident dementia using Cox proportional-hazards models. Causal relationship between snoring and Alzheimer's disease (AD) was examined using bidirectional two-sample Mendelian randomization (MR) analysis.

RESULTS

During a median follow-up of 13.6 years, 8325 individuals developed dementia. Snoring was associated with a lower risk of all-cause dementia (hazard ratio [HR] 0.93; 95% confidence interval [CI] 0.89 to 0.98) and AD (HR 0.91; 95% CI 0.84 to 0.97). The association was slightly attenuated after adjusting for BMI, and was stronger in older individuals, APOE ε4 allele carriers, and during shorter follow-up periods. MR analyses suggested no causal effect of snoring on AD; however, genetic liability to AD was associated with a lower risk of snoring. Multivariable MR indicated that the effect of AD on snoring was primarily driven by BMI.

CONCLUSIONS

The phenotypic association between snoring and lower dementia risk likely stems from reverse causation, with genetic predisposition to AD associated with reduced snoring. This may be driven by weight loss in prodromal AD. Increased attention should be paid to reduced snoring and weight loss in older adults as potential early indicators of dementia risk.

Sleep disturbances and their correlation with memory impairment in patients with Alzheimer's disease and amnestic mild cognitive impairment

Background

Episodic memory impairment is the core clinical feature of patients with typical Alzheimer's disease (AD) at an early stage. Since sleep plays a very important role in memory consolidation, the relationship between memory impairment and sleep disorders in AD patients is worthy of investigation.

Objective

To investigate sleep disturbances and their correlations with memory impairment in patients with AD and amnestic mild cognitive impairment (aMCI).

Methods

Forty-three patients with AD, 43 patients with aMCI, and 43 cognitively unimpaired controls (CUCs) were recruited and subjected to memory assessment via the Hopkins Verbal Learning Test-Revised and objective sleep evaluation via polysomnography (PSG).

Results

The total sleep time and the percentages of nonrapid eye movement (NREM) sleep stage 3 (N3) and the rapid eye movement (REM) were lower, while the percentages of NREM sleep stage 2 (N2) were greater in the AD and aMCI groups than in the CUC group (all p < 0.01). Compared with the CUC group, the AD group also presented a longer sleep latency and higher NREM sleep stage 1 (N1) percentage, apnea-hypopnea index (AHI), periodic limb movements during sleep index (PLMSI), and arousal index (AI). Both total learning scores and delayed recall scores were positively correlated with the N3 sleep percentage and negatively correlated with the AHI and PLMSI (all p < 0.01). Recognition scores were positively correlated with the N3 sleep percentage and negatively correlated with the AI (all p < 0.01).

Conclusions

Our results suggest that sleep disturbance is correlated with learning and memory disability in AD and aMCI patients. PSG is useful for screening and monitoring AD.

Sleep apnoea, cognition and aspirin's effects in healthy older people: an ASPREE substudy

Importance

Obstructive sleep apnoea (OSA) may increase the risk of dementia; however, studies have reported variable findings. We investigated if undiagnosed OSA in healthy older adults is associated with cognitive decline, and whether low-dose aspirin could attenuate this.

Methods

This was conducted as a substudy of the ASPirin in Reducing Events in the Elderly study. Participants were aged 70 years and above, free of dementia, cardiovascular disease and known OSA. A limited channel home sleep study calculated the oxygen desaturation index. Participants were randomised to daily aspirin 100 mg or placebo. Outcomes were the association of OSA, and the interaction of aspirin with OSA, with change in the Modified Mini-Mental State examination (3MS), a test of global cognition, over 3 years. Secondary outcomes were changes in domain-specific cognitive tests. Analyses were adjusted for relevant demographic, lifestyle and cardiometabolic factors.

Results

Mild OSA, detected in 630 (49.0%) participants, and moderate/severe OSA, detected in 405 (31.5%) participants, were associated with lower 3MS scores over 3 years (mild OSA: β -0.58, 95% CI -1.15 to -0.00, p=0.049; moderate/severe OSA: β -0.69, 95% CI -1.32 to -0.05, p=0.035), compared to the 250 (19.5%) participants without OSA. No associations of OSA with decline in domain-specific cognitive tests were observed. Interaction terms were not significant for the effects of aspirin with OSA on change in any cognitive test score.

Conclusions

OSA was associated with a small decline in global cognition over 3 years in this healthy older cohort. This decline was not attenuated by aspirin.

Engagement in moderate-intensity physical activity supports overnight memory retention in older adults

Preserving the ability to vividly recall emotionally rich experiences contributes to quality of life in older adulthood. While prior works suggest that moderate-intensity physical activity (MPA) may bolster memory, it is unclear whether this extends to emotionally salient memories consolidated during sleep. In the current study, older adults (mean age = 72.3 ± 5.8) completed an overnight polysomnography assessment with emotional memory tested before and after sleep and a self-report questionnaire assessing habitual PA. Results show that better negative emotional memory consolidation was associated with the frequency and duration of MPA. Statistically replacing 30 min of lower-intensity activity with MPA was associated with better negative emotional memory consolidation. MPA may enhance sleep-dependent consolidation of negative memories in older adults, with modest increases in MPA yielding significant consolidation benefits. Findings may guide interventions and inform public health recommendations by demonstrating that substituting even short durations of low-intensity activity for MPA could produce significant cognitive gains in older adulthood.

Challenges in Obstructive Sleep Apnea Management in Elderly Patients

With the aging of the population, obstructive sleep apnea (OSA) in elderly patients is now more commonly seen in clinical practice. In older people, sleepiness is less marked than in younger patients, but insomnia symptoms are more common. Comorbidities are numerous and related to cardiometabolic and cognitive conditions. Polygraphy can be used to establish the diagnosis in the vast majority of cases, but polysomnography is indicated in cases of comorbid sleep disorders. Continuous positive airway pressure (CPAP) remains the cornerstone of treatment, but compliance decreases with age, especially in those over 80, and when cognitive disorders are also present. In these patients, CPAP can be beneficial in terms of nighttime symptoms, sleepiness, mood, and cognition but can also prevent cardiovascular and cerebrovascular disorders, especially in severeOSA patients. For this reason, we should offer this treatment to elderly patients and devise strategies to support them with treatment difficulties (e.g., therapeutic education, adapted masks, and telemonitoring). In the future, we need prospective studies to help identify elderly patients who will gain the greatest long-term benefit from treatment. Dedicated sleep testing, OSA severity markers, and specific questionnaires need to be developed in this older, but large, OSA population.

Clinical correlates of obstructive sleep apnoea in idiopathic normal pressure hydrocephalus

BACKGROUND AND PURPOSE

The pathogenesis of idiopathic normal pressure hydrocephalus (iNPH) remains controversial. Limited studies have indicated a high prevalence of obstructive sleep apnoea (OSA) amongst iNPH patients. The aim was to investigate the clinical correlates of OSA in iNPH patients.

METHODS

In this cross-sectional observational study, consecutive iNPH patients were prospectively enrolled. Evaluations included the iNPH Rating Scale, the Movement Disorder Society Unified Parkinson's Disease Rating Scale part III, the time and number of steps to walk 10 m, the Epworth Sleepiness Scale, the Pittsburgh Sleep Quality Index, a complete neuropsychological evaluation, 3-T brain MRI, full-night video-polysomnography, tap test and cerebrospinal fluid (CSF) neurodegeneration biomarkers.

RESULTS

Fifty-one patients were screened, of whom 38 met the inclusion criteria. Amongst the recruited patients, 19/38 (50%) exhibited OSA, with 12/19 (63.2%) presenting moderate to severe disorder. OSA+ iNPH patients required more time (p = 0.02) and more steps (p = 0.04) to complete the 10-m walking test, had lower scores on the gait subitem of the iNPH Rating Scale (p = 0.04) and demonstrated poorer performance on specific neuropsychological tests (Rey Auditory Verbal Learning Test immediate recall, p = 0.03, and Rey-Osterrieth Complex Figure, p = 0.01). Additionally, OSA+ iNPH patients had higher levels of total tau (p = 0.02) and phospho-tau (p = 0.03) in their CSF but no statistically significant differences in beta-amyloid (1-42) levels compared to OSA- iNPH patients.

CONCLUSION

Obstructive sleep apnoea is highly prevalent in iNPH patients, particularly at moderate to severe levels. OSA is associated with worse motor and cognitive performance in iNPH. The CSF neurodegeneration biomarker profile observed in OSA+ iNPH patients may reflect OSA-induced impairment of cerebral fluid dynamics.

Associations between quantitative susceptibility mapping with male obstructive sleep apnea clinical and imaging markers

PURPOSE

To quantitatively measure and compare whole-brain iron deposition between OSA patients and a healthy control group, we initially utilized QSM and evaluated its correlation with PSG results and cognitive function.

MATERIALS AND METHODS

A total of 28 OSA patients and 22 healthy control subjects matched in age, education level, and BMI were enrolled in our study. Each participant underwent scanning with 3D T1 and multi-echo GRE sequences. Additionally, PSG results were collected from OSA patients, and they underwent simple cognitive assessments. Finally, we analyzed the relationship between iron content in different brain regions, PSG results, and cognitive ability.

RESULTS

In OSA patients, iron content increased in the left temporal-pole-sup and right putamen, while it decreased in the left fusiform gyrus, left middle temporal gyrus, right inferior occipital gyrus, and right superior temporal gyrus. The correlation analysis between brain iron content and PSG results/cognitive scales is as follows: left fusiform gyrus and MMSE (r = -0.416, p = 0.028); right superior temporal gyrus and MMSE (r = 0.422, p = 0.025); left middle temporal gyrus and average oxygen saturation (r = -0.418, p = 0.027); left temporal-pole-sup and REM stage (rs = 0.466, p = 0.012); the right putamen and N1 stage (rs = 0.393. p = 0.039). Moreover, both MoCA (r = 0.598, p = 0.001) and MMSE (r = 0.456, p = 0.015) show a positive correlation with average oxygen saturation.

CONCLUSION

This study is the first to use QSM technology to show abnormal brain iron levels in OSA. Correlations between brain iron content, PSG, and cognition in OSA may reveal neuropathological mechanisms, aiding OSA diagnosis.

The association between small vessel disease and obstructive sleep apnea: a peak width of skeletonized mean diffusivity-based study

PURPOSE

Peak width of skeletonized mean diffusivity (PSMD) is a novel marker of small vessel disease in the brain. This study aimed to investigate the association between small vessel disease and obstructive sleep apnea (OSA) using PSMD.

METHODS

We enrolled patients with OSA and age- and sex-matched healthy controls, and performed diffusion tensor imaging (DTI) using a 3-tesla MRI scanner in them. We calculated the PSMD based on DTI in several steps, including preprocessing, skeletonization, application of a custom mask, and histogram analysis using the FSL program. We compared the PSMD between patients with OSA and healthy controls and investigated the correlation between PSMD and clinical factors.

RESULTS

Thirty-nine patients with OSA (apnea-hypopnea index > 5; mean = 20.5) and 48 healthy controls were enrolled. The PSMD was significantly higher in patients with OSA than that in the healthy controls (2.521 vs. 2.320 × 10- 4 mm2/s, p = 0.013). In addition, PSMD positively correlated with age (r = 0.512, p < 0.001) and body mass index (r = 0.472, p = 0.002). However, PSMD was not associated with polysomnographic measurements.

CONCLUSIONS

The mean PSMD is higher in patients with OSA than that in healthy controls, indicating a white matter injury due to small-vessel disease in patients with OSA. Our study highlights the importance of actively diagnosing and treating OSA. In addition, PSMD can be used to determine the relationship between sleep disorders and small vessel disease.

Sex-specific dementia risk in known or suspected obstructive sleep apnea: a 10-year longitudinal population-based study

Study Objectives

To evaluate sex-specific associations between known or suspected obstructive sleep apnea (OSA) and dementia risk over 10 years among older women and men.

Methods

This study included 18 815 women and men age 50+ years (dementia-free at baseline) who participated in the Health and Retirement Study (HRS), a nationally representative cohort of US adults. Presence of OSA was defined by self-reported diagnosis or key HRS items that correspond to elements of a validated OSA screening tool (STOP-Bang). Incident dementia cases were identified using a validated, HRS-based algorithm derived from objective cognitive assessments. Survey-weighted regression models based on pseudo-values were utilized to estimate sex- and age-specific differences in cumulative incidence of dementia by OSA status.

Results

Data from 18 815 adults were analyzed, of which 9% of women and 8% of men (weighted proportions) met criteria for incident dementia. Known/suspected OSA was more prevalent in men than in women (weighted proportions 68% vs. 31%). Unadjusted sex-stratified analyses showed that known/suspected OSA was associated with higher cumulative incidence of dementia across ages 60-84 years for women and men. By age 80, relative to adults without known/suspected OSA, the cumulative incidence of dementia was 4.7% higher (CI 2.8%, 6.7%) for women with known/suspected OSA, and 2.5% (CI 0.5%, 4.5%) for men with known/suspected OSA, respectively. Adjusted associations between age-specific OSA and cumulative incidence of dementia attenuated for both women and men but remained statistically significant.

Conclusions

OSA contributes to dementia risk in older adults, particularly women. This study illuminates the impact of a potentially modifiable yet frequently overlooked risk factor for dementia onset.

Louis EK, McCarter SJ, Bukartyk J, Przybelski SA, Kamykowski MG, Spychalla AJ, Machulda MM, Boeve BF, Petersen RC, Jack CR, Lowe VJ, Graff-Radford J, Worrell GA, Somers VK, Varga AW, Vemuri P. Non-rapid eye movement sleep slow-wave activity features are associated with amyloid accumulation in older adults with obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is associated with an increased risk for cognitive impairment and dementia, which likely involves Alzheimer's disease pathology. Non-rapid eye movement slow-wave activity (SWA) has been implicated in amyloid clearance, but it has not been studied in the context of longitudinal amyloid accumulation in OSA. This longitudinal retrospective study aims to investigate the relationship between polysomnographic and electrophysiological SWA features and amyloid accumulation. From the Mayo Clinic Study of Aging cohort, we identified 71 participants ≥60 years old with OSA (mean baseline age = 72.9 ± 7.5 years, 60.6% male, 93% cognitively unimpaired) who had at least 2 consecutive Amyloid Pittsburgh Compound B (PiB)-PET scans and a polysomnographic study within 5 years of the baseline scan and before the second scan. Annualized PiB-PET accumulation [global ΔPiB(log)/year] was estimated by the difference between the second and first log-transformed global PiB-PET uptake estimations divided by the interval between scans (years). Sixty-four participants were included in SWA analysis. SWA was characterized by the mean relative spectral power density (%) in slow oscillation (SO: 0.5-0.9 Hz) and delta (1-3.9 Hz) frequency bands and by their downslopes (SO-slope and delta-slope, respectively) during the diagnostic portion of polysomnography. We fit linear regression models to test for associations among global ΔPiB(log)/year, SWA features (mean SO% and delta% or mean SO-slope and delta-slope), and OSA severity markers, after adjusting for age at baseline PiB-PET, APOE ɛ4 and baseline amyloid positivity. For 1 SD increase in SO% and SO-slope, global ΔPiB(log)/year increased by 0.0033 (95% CI: 0.0001; 0.0064, P = 0.042) and 0.0069 (95% CI: 0.0009; 0.0129, P = 0.026), which were comparable to 32% and 59% of the effect size associated with baseline amyloid positivity, respectively. Delta-slope was associated with a reduction in global ΔPiB(log)/year by -0.0082 (95% CI: -0.0143; -0.0021, P = 0.009). Sleep apnoea severity was not associated with amyloid accumulation. Regional associations were stronger in the pre-frontal region. Both slow-wave slopes had more significant and widespread regional associations. Annualized PiB-PET accumulation was positively associated with SO and SO-slope, which may reflect altered sleep homeostasis due to increased homeostatic pressure in the setting of unmet sleep needs, increased synaptic strength, and/or hyper-excitability in OSA. Delta-slope was inversely associated with PiB-PET accumulation, suggesting it may represent residual physiological activity. Further investigation of SWA dynamics in the presence of sleep disorders before and after treatment is necessary for understanding the relationship between amyloid accumulation and SWA physiology.

Sleep apnea evokes right hemisphere dominance and psychological disorders: An exploratory study

BACKGROUND

Obstructive sleep apnea (OSA) is considered one of the major causes of sleep disorders and psychological disorders in individuals. Brain asymmetry (BA) demonstrates individual hemispheric activity and psychological disorders. This study aimed to explore the characteristics of BA and psychology in OSA.

METHODS

Enrolment of patients for sleep assessment at the Sleep Medicine Center. Clinical characteristics, handedness, and psychological scales were prospectively collected from subjects. Subsequently, EEG power in alpha, beta, and theta bilaterally was calculated for the rest and sleep phases.

RESULTS

A total of 152 OSA and 21 non-OSA subjects were included in the study. In the frontal, central and occipital regions, OSA exhibited increased interhemispheric asymmetry with increasing apnea-hypopnea index (AHI) during rest and sleep. Simultaneously, the results showed that greater activity in the right hemisphere was positively associated with anxiety and extraversion, while inversely with positive and lie scale. In addition, the results show that OSA contributes to abnormal BA fluctuations during sleep.

CONCLUSIONS

Our results suggest that sleep disorders associated with apnea-hypopnea and arousal may contribute to increased BA during sleep. Such changes may persist into wakefulness with psychological traits.

Microstructural brain abnormalities and associated neurocognitive dysfunction in obstructive sleep apnea: a pilot study with diffusion kurtosis imaging

STUDY OBJECTIVES

We assessed possible brain abnormalities in adult patients with moderate and severe obstructive sleep apnea using the mean kurtosis (MK) from diffusion kurtosis imaging and analyzed the correlation between MK and cognitive function.

METHODS

A total of 30 patients with moderate or severe obstructive sleep apnea and 30 healthy controls evaluated by the Montreal Cognitive Assessment scale were enrolled. All participants underwent diffusion kurtosis imaging and 3-dimensional T1-weighted imaging on a 3.0T magnetic resonance scanner. The MK values of gray and white matter brain regions were compared. Partial correlation analysis was used to analyze the correlation between respiratory sleep parameters/cognitive score and MK values in different brain regions.

RESULTS

Compared with the healthy controls, the MK of 20 brain regions (13 after false discovery rate correction) and cognitive scores in the obstructive sleep apnea group were significantly lower. In the obstructive sleep apnea group, apnea-hypopnea index was negatively correlated with the MK in the white matter of the right occipital lobe; lowest oxygen saturation was positively correlated with the MK in the bilateral parietal, precentral, and right postcentral cortex; total score on the Montreal Cognitive Assessment scale was positively correlated with MK in the left hippocampus; language function was positively correlated with MK in the white matter of the left parietal lobe; and delayed recall was positively correlated with the MK in right insula cortex and bilateral cingulate. After false discovery rate correction, only the correlations of lowest oxygen saturation with right precentral gyrus cortex and bilateral parietal cortex were significant.

CONCLUSIONS

MK values of diffusion kurtosis imaging may provide valuable information in assessing the neurological impacts of obstructive sleep apnea.

CITATION

Zhang N, Peng K, Guo J-X, Liu Q, Xiao A-L, Jing H. Microstructural brain abnormalities and associated neurocognitive dysfunction in obstructive sleep apnea: a pilot study with diffusion kurtosis imaging. J Clin Sleep Med. 2024;20(10):1571-1578.

Impact of excessive daytime sleepiness on attention impairment in obstructive sleep apnea: a cross-sectional observational study

PURPOSE

This study aims to examine the relationship between excessive daytime sleepiness (EDS) and attention impairment in Chinese individuals with obstructive sleep apnea (OSA).

METHODS

A total of 1996 OSA patients with an apnea-hypopnea index (AHI) of ≥ 5 events per hour were included in this study. EDS was measured using the Epworth Sleepiness Scale (ESS), while cognitive function was assessed using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA).

RESULTS

OSA patients with EDS demonstrated higher body mass index (BMI), comorbidities of hypertension and diabetes, decreased N3 sleep, increased AHI and ODI, as well as lower minimum oxygen saturation. Despite no significant differences in total cognitive scores assessed by MMSE and MoCA, individuals with comorbid sleepiness exhibited more evident attention deficits in the subdomains of MoCA. Stratified analysis indicated that regardless of age, educational level was the primary factor influencing attention in the AHI < =20 group. In the AHI > 20 group, attention impairment in patients younger than 40 remained significantly associated with education level, whereas for individuals aged 40 and above, attention deficits were associated with education level, age, and daytime sleepiness. The interaction analysis indicated that OSA severity modulated the impact of sleepiness on attention in patients aged 40 and above.

CONCLUSION

A significant correlation was observed between EDS and attention deficits in Chinese individuals diagnosed with OSA, with a particular emphasis on patients aged 40 and above. The severity of OSA modulates the impact of sleepiness on attention in patients aged 40 and above.

Cortical activation during the verbal fluency task for obstructive sleep apnea patients with depressive symptoms: A multi-channel fNIRS study

STUDY OBJECTIVE

The aim of our study was to elucidate differences in brain activity patterns among obstructive sleep apnea (OSA) patients, OSA patients with depressive symptoms, and healthy controls (HCs). We also investigated the relationship between brain function and depression in OSA patients.

METHODS

A total of 95 subjects were included in the study, including 34 OSA patients without depressive symptoms, 31 OSA patients with depressive symptoms, and 30 HCs. The 53-channel functional near-infrared spectroscopy (fNIRS) was used to monitor the concentration of oxy-hemoglobin (Oxy-Hb) in the brain, whereas the participants performed the verbal fluency task, and the degree of depression was scored using the 17-item Hamilton Rating Scale for Depression (HAMD-17). Hierarchical regression models were conducted to analyze the association of fNIRS features with depressive symptom.

RESULTS

The Oxy-Hb changes of the three groups were significantly different in Channels 25 (H = 9.878, p = .007) and 43 (H = 6.957, p = .031). Inter-group comparisons showed that the Oxy-Hb change of Channel 25 (located in the dorsolateral prefrontal cortex [DLPFC]) in OSA group was less than that in HC group (p = .006), and the Oxy-Hb change of Channel 43 (located in the right frontal polar region) in OSA group with depression was less than that in OSA group (p = .025). Spearman's test showed that there was a significant negative correlation between HAMD-17 scores and mean Oxy-Hb changes in Channel 43 (r = -.319, p < .05) in the OSA patients. Using hierarchical regression, Oxy-Hb changes in Channel 43 accounted for a significant proportion of the variation in outcome variables, even when accounting for other polysomnography features.

CONCLUSIONS

Changes in the hemodynamic response of DLPFC may be a potential mechanism of executive dysfunction in OSA patients. And the right frontal polar region may be significant in assessing depressive symptoms in patients with OSA.

Sleep apnea in schizophrenia: Estimating prevalence and impact on cognition

Undertreated medical illnesses can compound the disabling cognitive deficits of schizophrenia. Obstructive sleep apnea (OSA) impairs cognitive domains also affected by schizophrenia, is common, and is treatable. The effects of sleep apnea on cognition in schizophrenia, however, are not well understood. We estimated the prevalence of OSA in a previously characterized sample of 3942 Veterans with schizophrenia by self-report and with a predictive model to identify individuals at high risk for OSA. We then compared neuropsychological and functional capacity assessment results between those who reported OSA versus those who did not, and between those predicted to have OSA versus predicted to not have OSA. We expected that many Veterans not reporting sleep apnea would be predicted to have it, and that both reported and predicted sleep apnea would be associated with lower cognitive and functional performance. The reported prevalence of OSA in the sample was 14%, whereas 72% were predicted to be at high risk of OSA. Interestingly, participants who reported having OSA had better cognitive and functional capacity performance (p's < 0.001) compared to those who did not report OSA, particularly on speed of processing assessments (p < 0.001). Predicted OSA, by contrast, was associated with lower speed of processing, verbal learning and working memory test scores (p's < 0.001). One possible interpretation of these results is that people with higher cognitive capacity may be more likely to seek medical care, while those with cognitive impairments are at greater risk for having untreated co-occurring medical conditions that further compromise cognition.

Evaluating practice effects across learning trials - ceiling effects or something more?

BACKGROUND

Practice effects (PE) are traditionally considered improvements in performance observed resulting from repeated exposure to test materials across multiple testing sessions. While PE are commonly observed for memory tests, this effect has only been considered in summary total scores. The current objective was to consider PE in summary total scores, individual learning trials, and learning slopes.

METHOD

One-week PE for individual trial and learning slope performance was examined on the BVMT-R and HVLT-R in 151 cognitively intact participants and 131 participants with Mild Cognitive Impairment (MCI) aged 65 years and older.

RESULTS

One-week PE were observed across all trials and summary total scores for both memory measures and diagnostic classifications, despite the potential for ceiling effects to limit improvement on retesting. PE were largest on the first trial relative to subsequent learning trials. This effect was diminished - but not eliminated - in participants with MCI. Conversely, no PE were observed for learning slope scores, which was counter to expectations and likely confounded by ceiling effects.

CONCLUSIONS

PE were present across learning trials but not learning slopes, and the initial learning trial at follow-up tended to benefit most from PE relative to subsequent learning trials. Ceiling effects appeared to influence PE for learning slopes more than learning trials. These results highlight the potential diagnostic utility of PE across individual learning trials and inform how they are distributed at follow-up, while also suggesting that learning slopes may be generally stable during longitudinal assessment.

Amyloid profile is associated with sleep quality in preclinical but not in prodromal Alzheimer's disease older adults

BACKGROUND

Few studies have assessed whether neuropathological markers of AD in the preclinical and prodromal stages are associated with polysomnographic changes and obstructive sleep apnea (OSA).

METHODS

This was a cross-sectional, case-control study of older adults (≥60 years) without relevant clinical and psychiatric comorbidities selected randomly from a cohort of individuals without dementia in a tertiary university hospital in São Paulo, Brazil. They underwent neuropsychological evaluation for clinical diagnosis and were allocated into two samples: cognitively unimpaired (CU) and mild cognitive impairment (MCI). Also, they underwent PET-PiB to determine the amyloid profile and all-night in-lab polysomnography. For each sample, we compared polysomnographic parameters according to the amyloid profile (A+ vs A-).

RESULTS

We allocated 67 participants (mean age 73 years, SD 10,1), 70 % females, 14 ± 5 years of education, into two samples: CU (n = 28, 42.4 %) and MCI (n = 39, 57.6 %). In the CU sample, the group A+ (n = 9) showed worse sleep parameters than A- (n = 19) (lower total sleep time (p = 0.007), and sleep efficiency (p = 0.005); higher sleep onset latency (p = 0.025), wake time after sleep onset (p = 0.011), and arousal index (AI) (p = 0.007)), and changes in sleep structure: higher %N1 (p = 0.005), and lower %REM (p = 0.006). In the MCI sample, MCI A-had higher AI (p = 0.013), respiratory disturbance index (p = 0.025, controlled for age), and higher rates of severe OSA than A+.

DISCUSSION

The amyloid profile was associated with polysomnographic markers of worse sleep quality in individuals with preclinical AD but not with prodromal AD, probably due to the higher frequencies of severe OSA.

Development of a diagnostic model for detecting mild cognitive impairment in young and middle-aged patients with obstructive sleep apnea: a prospective observational study

Objectives

Obstructive sleep apnea (OSA) is a common sleep-disordered breathing condition linked to the accelerated onset of mild cognitive impairment (MCI). However, the prevalence of undiagnosed MCI among OSA patients is high and attributable to the complexity and specialized nature of MCI diagnosis. Timely identification and intervention for MCI can potentially prevent or delay the onset of dementia. This study aimed to develop screening models for MCI in OSA patients that will be suitable for healthcare professionals in diverse settings and can be effectively utilized without specialized neurological training.

Methods

A prospective observational study was conducted at a specialized sleep medicine center from April 2021 to September 2022. Three hundred and fifty consecutive patients (age: 18-60 years) suspected OSA, underwent the Montreal Cognitive Assessment (MoCA) and polysomnography overnight. Demographic and clinical data, including polysomnographic sleep parameters and additional cognitive function assessments were collected from OSA patients. The data were divided into training (70%) and validation (30%) sets, and predictors of MCI were identified using univariate and multivariate logistic regression analyses. Models were evaluated for predictive accuracy and calibration, with nomograms for application.

Results

Two hundred and thirty-three patients with newly diagnosed OSA were enrolled. The proportion of patients with MCI was 38.2%. Three diagnostic models, each with an accompanying nomogram, were developed. Model 1 utilized body mass index (BMI) and years of education as predictors. Model 2 incorporated N1 and the score of backward task of the digital span test (DST_B) into the base of Model 1. Model 3 expanded upon Model 1 by including the total score of digital span test (DST). Each of these models exhibited robust discriminatory power and calibration. The C-statistics for Model 1, 2, and 3 were 0.803 [95% confidence interval (CI): 0.735-0.872], 0.849 (95% CI: 0.788-0.910), and 0.83 (95% CI: 0.763-0.896), respectively.

Conclusion

Three straightforward diagnostic models, each requiring only two to four easily accessible parameters, were developed that demonstrated high efficacy. These models offer a convenient diagnostic tool for healthcare professionals in diverse healthcare settings, facilitating timely and necessary further evaluation and intervention for OSA patients at an increased risk of MCI.

Tet1-mediated 5hmC regulates hippocampal neuroinflammation via wnt signaling as a novel mechanism in obstructive sleep apnoea leads to cognitive deficit

BACKGROUND

Obstructive sleep apnoea (OSA) is a sleep-disordered breathing characterized by intermittent hypoxia (IH) that may cause cognitive dysfunction. However, the impact of IH on molecular processes involved in cognitive function remains unclear.

METHODS

C57BL / 6 J mice were exposed to either normoxia (control) or IH for 6 weeks. DNA hydroxymethylation was quantified by hydroxymethylated DNA immunoprecipitation (hMeDIP) sequencing. ten-eleven translocation 1 (Tet1) was knocked down by lentivirus. Specifically, cognitive function was assessed by behavioral experiments, pathological features were assessed by HE staining, the hippocampal DNA hydroxymethylation was examined by DNA dot blot and immunohistochemical staining, while the Wnt signaling pathway and its downstream effects were studied using qRT-PCR, immunofluorescence staining, and Luminex liquid suspension chip analysis.

RESULTS

IH mice showed pathological changes and cognitive dysfunction in the hippocampus. Compared with the control group, IH mice exhibited global DNA hydroxylmethylation in the hippocampus, and the expression of three hydroxylmethylases increased significantly. The Wnt signaling pathway was activated, and the mRNA and 5hmC levels of Wnt3a, Ccnd2, and Prickle2 were significantly up-regulated. Further caused downstream neurogenesis abnormalities and neuroinflammatory activation, manifested as increased expression of IBA1 (a marker of microglia), GFAP (a marker of astrocytes), and DCX (a marker of immature neurons), as well as a range of inflammatory cytokines (e.g. TNFa, IL3, IL9, and IL17A). After Tet1 knocked down, the above indicators return to normal.

CONCLUSION

Activation of Wnt signaling pathway by hippocampal Tet1 is associated with cognitive dysfunction induced by IH.

Sex differences in the association of sleep spindle density and cognitive performance among community-dwelling middle-aged and older adults with obstructive sleep apnea

Recent studies have found associations between obstructive sleep apnea and cognitive decline. The underlying mechanisms are still unclear. Here, we investigate the associations between changes in micro-architecture, specifically sleep spindles, and cognitive function in community-dwelling middle-aged and older adults, some with obstructive sleep apnea, with a focus on sex differences. A total of 125 voluntary participants (mean age 66.0 ± 6.4 years, 64 females) from a larger cohort (participants of the Brain in Motion Studies I and II) underwent 1 night of in-home polysomnography and a neuropsychological battery (sleep and cognitive testing were conducted within 2 weeks of each other). A semi-automatic computerized algorithm was used to score polysomnography data and detect spindle characteristics in non-rapid eye movement Stages 2 and 3 in both frontal and central electrodes. Based on their apnea-hypopnea index, participants were divided into those with no obstructive sleep apnea (apnea-hypopnea index < 5 per hr, n = 21), mild obstructive sleep apnea (5 ≥ apnea-hypopnea index < 15, n = 47), moderate obstructive sleep apnea (15 ≥ apnea-hypopnea index < 30, n = 34) and severe obstructive sleep apnea (apnea-hypopnea index ≥ 30, n = 23). There were no significant differences in spindle characteristics between the four obstructive sleep apnea severity groups. Spindle density and percentage of fast spindles were positively associated with some verbal fluency measures on the cognitive testing. Sex might be linked with these associations. Biological sex could play a role in the associations between spindle characteristics and some verbal fluency measures. Obstructive sleep apnea severity was not found to be a contributing factor in this non-clinical community-dwelling cohort.

Biomarkers of sleep-wake disturbance as predictors of cognitive decline and accelerated disease progression

INTRODUCTION

In older adults, where sleep disturbances and cognitive impairment are common, mounting evidence suggests a potential connection between sleep and cognitive function, highlighting the significance of utilizing sleep as a biomarker for early detection of cognitive impairment to improve clinical outcomes in a noninvasive, cost-effective manner.

AREAS COVERED

This review describes the relationship between sleep and cognitive function in older adults, encompassing both subjective and objective measures of sleep quality, duration, architecture, and sleep-disordered breathing. The authors consider the directionality of the associations observed in prospective and cross-sectional studies, exploring whether sleep disturbances precede cognitive decline or vice versa. Furthermore, they discuss the potential bidirectional relationships between sleep and Alzheimer's disease (AD) risks in older adults while also examining the neurodegenerative pathways of this relationship.

EXPERT OPINION

Routine sleep monitoring in primary care settings has the potential to bolster early detection and treatment of sleep disturbance, and by extension, reduce the risk of dementia. Improving sleep assessment tools, such as wearables, provide scalable alternatives to traditional methods like polysomnography, potentially enabling widespread monitoring of sleep characteristics. Standardized measurement and inclusive participant recruitment are needed to enhance generalizability, while longitudinal studies are essential to understand the interaction between sleep and AD pathology.

Rural-Urban mild cognitive impairment comparison in West Michigan through EHR

INTRODUCTION

Mild cognitive impairment (MCI) is a significant public health concern and a potential precursor to Alzheimer's disease (AD). This study leverages electronic health record (EHR) data to explore rural-urban differences in MCI incidence, risk factors, and healthcare navigation in West Michigan.

METHODS

Analysis was conducted on 1,528,464 patients from Corewell Health West, using face-to-face encounters between 1/1/2015 and 7/31/2022. MCI cases were identified using International Classification of Diseases (ICD) codes, focusing on patients aged 45+ without prior MCI, dementia, or AD diagnoses. Incidence rates, cumulative incidences, primary care physicians (PCPs), and neuropsychology referral outcomes were examined across rural and urban areas. Risk factors were evaluated through univariate and multivariate Cox regression analyses. The geographic distribution of patient counts, hospital locations, and neurology department referrals were examined.

RESULTS

Among 423,592 patients, a higher MCI incidence rate was observed in urban settings compared to rural settings (3.83 vs. 3.22 per 1,000 person-years). However, sensitivity analysis revealed higher incidence rates in rural areas when including patients who progressed directly to dementia. Urban patients demonstrated higher rates of referrals to and completion of neurological services. While the risk factors for MCI were largely similar across urban and rural populations, urban-specific factors for incident MCI are hearing loss, inflammatory bowel disease, obstructive sleep apnea, insomnia, being African American, and being underweight. Common risk factors include diabetes, intracranial injury, cerebrovascular disease, coronary artery disease, stroke, Parkinson's disease, epilepsy, chronic obstructive pulmonary disease, depression, and increased age. Lower risk was associated with being female, having a higher body mass index, and having a higher diastolic blood pressure.

DISCUSSION

This study highlights rural-urban differences in MCI incidence and access to care, suggesting potential underdiagnosis in rural areas likely due to reduced access to specialists. Future research should explore socioeconomic, environmental, and lifestyle determinants of MCI to refine prevention and management strategies across geographic settings.

Highlights

Leveraged EHRs to explore rural-urban differences in MCI in West Michigan.Revealed a significant underdiagnosis of MCI, especially in rural areas.Observed lower rates of neurological referrals and completions for rural patients.Identified risk factors specific to rural and urban populations.

Precision Prevention in Obstructive Sleep Apnea

Sleep-related breathing disorders, encompassing snoring and obstructive sleep apnea (OSA), are highly prevalent worldwide, and there have been important advances in recent years regarding the understanding of underlying pathophysiology mechanisms, diagnosis, and improvement in therapeutic options. The precision medicine and person-centered approaches are based on the concept that every individual is unique and a myriad of elements influence the likelihood of developing the disease, the signs and symptoms expressed, the response to different treatment modalities, and the susceptibility to complications. Thus, health and disease are the result of phenotypic outcomes resulting from interactions between biological factors, environment, and lifestyle.

Sex and APOE genotype influence respiratory function under hypoxic and hypoxic-hypercapnic conditions

The apolipoprotein E (APOE) gene has been studied due to its influence on Alzheimer's disease (AD) development and work in an APOE mouse model recently demonstrated impaired respiratory motor plasticity following spinal cord injury (SCI). Individuals with AD often copresent with obstructive sleep apnea (OSA) characterized by cessations in breathing during sleep. Despite the prominence of APOE genotype and sex as factors in AD progression, little is known about the impact of these variables on respiratory control. Ventilation is tightly regulated across many systems, with respiratory rhythm formation occurring in the brainstem but modulated in response to chemoreception. Alterations within these modulatory systems may result in disruptions of appropriate respiratory control and ultimately, disease. Using mice expressing two different humanized APOE alleles, we characterized how sex and the presence of APOE3 or APOE4 influences ventilation during baseline breathing (normoxia) and during respiratory challenges. We show that sex and APOE genotype influence breathing during hypoxic challenge, which may have clinical implications in the context of AD and OSA. In addition, female mice, while responding robustly to hypoxia, were unable to recover to baseline respiratory levels, emphasizing sex differences in disordered breathing.NEW & NOTEWORTHY This study is the first to use whole body plethysmography (WBP) to measure the impact of APOE alleles on breathing under normoxia and during adverse respiratory challenges in a targeted replacement Alzheimer's model. Both sex and genotype were shown to affect breathing under normoxia, hypoxic challenge, and hypoxic-hypercapnic challenge. This work has important implications regarding the impact of genetics on respiratory control as well as applications pertaining to conditions of disordered breathing including sleep apnea and neurotrauma.

Worldwide prevalence of sleep problems in community-dwelling older adults: A systematic review and meta-analysis

The understanding of the prevalence of sleep problems in older adults can provide a broad and reliable perspective into the occurrence of such issues among older adults. This systematic review and meta-analysis aimed to estimate the worldwide prevalence of sleep problems in community-dwelling older adults. Studies that provide information on the prevalence of sleep problems in community-dwelling older adults (≥60 years) were screened between December 2022 and March 2023. A total of 20,379 studies were identified in database searches, from which 252 were included in this review. These studies covered the last 35 years (from 1988 to 2023) and pooled a sample of 995,544 participants from 36 countries. The most frequent sleep problem worldwide was obstructive sleep apnea (46.0%), followed by poor sleep quality (40.0%), other sleep problems (37.0%), insomnia (29.0%), and excessive daytime sleepiness (19.0%). No significant difference in the prevalence estimates of all sleep problems was observed between the sexes. This systematic review and meta-analysis showed a high prevalence of some sleep problems, mainly obstructive sleep apnea, poor sleep quality, and other sleep problems. Our estimates can be useful for managers and policymakers in planning healthcare strategies for sleep problems aimed at the older population.

Mitochondrial dysfunction is associated with cognitive impairment in adults with OSA without dementia

STUDY OBJECTIVES

Increased reactive oxygen species associated with loss of mitochondrial function affect synaptic activity, which is an important mechanism underlying cognitive decline. This study assesses the role of mitochondrial proteins in neuron-derived exosomes (NDEs) on cognitive impairment in patients with obstructive sleep apnea (OSA) without dementia.

METHODS

Analyses were conducted in 268 study participants with complete polysomnography data, cognitive tests, and important clinical data available. NDEs were isolated immunochemically for enzyme-linked immunosorbent assay quantification of mitochondrial proteins, i.e., humanin and mitochondrial open reading frame of the 12S rRNA-c (MOTS-c), and synaptic protein, i.e., neurogranin (NRGN). A mediation analysis of the relationship between sleep parameters and cognition was performed using humanin, MOTS-c, and NRGN values as a mediating factor. Twenty-two patients with moderate to severe OSA who received CPAP therapy were followed up, and humanin, MOTS-c and NRGN levels were reassessed after 1 year of treatment.

RESULTS

All participants were divided into the OSA + MCI group (n = 91), OSA-MCI group (n = 89), MCI group (MCI without OSA) (n = 38) and control group (normal cognitive state without OSA) (n = 50). The mean CD63-normalized NDE levels of humanin, MOTS-c, and NRGN in the OSA + MCI group were higher than those in the OSA-MCI and control groups. The NDE levels of humanin, MOTS-c, and NRGN in the MCI group were lower than those in controls. The odds of cognitive impairment in patients with OSA were higher with higher NDE levels of humanin, MOTS-c, and NRGN (odds ratio (OR): 2.100, 95 % confidence interval (CI): 1.646-2.679, P < 0.001; OR: 5.453, 95 % CI: 3.112-9.556, P < 0.001; OR: 3.115, 95 % CI: 2.163-4.484, P < 0.001). The impaired cognitive performance was associated with higher NDE levels of humanin (β: 0.505, SE: 0.048, P < 0.001), MOTS-c (β: 0.580, SE: 0.001, P < 0.001), and NRGN (β: 0.585, SE: 0.553, P < 0.001). The relationship between sleep parameters (mean SaO2 and T90) and MoCA scores was mediated by the NDE levels of humanin, MOTS-c, and NRGN with the proportion of mediation varying from 35.33 % to 149.07 %. Receiver operating characteristic curve revealed an area under the curve of 0.905 for humanin, 0.873 for MOTS-c, and 0.934 for NRGN to predict MCI in OSA patients without dementia. Increased humanin, MOTS-c, and NRGN levels significantly decreased after CPAP treatment.

CONCLUSIONS

Mitochondrial dysfunction is implicated in cognitive impairment in OSA patients without dementia, and mainly mediates the association between intermittent hypoxia and cognitive impairment in adults with OSA without dementia. Mitochondrial dysfunction can be partially reversible by CPAP treatment. Mitochondrial proteins can be used as markers of cognitive impairment in patients with OSA.

Could an increased risk of obstructive sleep apnoea be one of the determinants associated with disability in individuals with cardiovascular and cerebrovascular diseases?

PURPOSE

To investigate a possible association between the risk of obstructive sleep apnoea (OSA) and disability in individuals with cardiovascular or cerebrovascular diseases.

METHODS

Cross-sectional study was conducted with 373 individuals (313 with cardiovascular or cerebrovascular diseases and 60 healthy). Disability was assessed by the 12-item World Health Organization Disability Assessment Schedule (WHODAS), and the risk of OSA was assessed by STOP-BANG. Anxiety and depression symptoms, daytime sleepiness, and cognition were assessed by the Hospital Anxiety and Depression Scale (HADS), Epworth Sleepiness Scale (ESS), and Mini Mental State Examination (MMSE).

RESULTS

Greater disability was found in individuals with intermediate or high risk of OSA, considering healthy individuals (p=0.03), or individuals diagnosed with arrhythmia (p<0.01) or coronary artery disease (p=0.04). A high risk of OSA and higher WHODAS scores was significant among women as well as between OSA risk categories (p<0.01). Cognitive deficit and level of education also showed differences between OSA risk categories. Age, depression, and sleepiness were also associated with the subjects' disability (p<0.01). Gamma regression model showed higher WHODAS scores in female, in those with intermediate and high risk of OSA, and in those with depressive symptoms and cognitive deficit. Age also showed a correlation with higher WHODAS scores. The presence of all investigated cardio and cerebrovascular diseases showed an increase in the WHODAS score, implying a greater disability compared to healthy individuals.

CONCLUSION

Moderate and high risk of OSA is associated with disability, as well as gender, age, depressive symptoms, cognitive deficit, and cardiovascular diseases.

Altered cerebral white matter network topology and cognition in children with obstructive sleep apnea

OBJECTIVES

The study aimed to explore the underlying mechanisms of OSA-related cognitive impairment by investigating the altered topology of brain white matter networks in children with OSA.

METHODS

Graph theory was used to examine white matter networks' network topological properties in 46 OSA and 31 non-OSA children. All participants underwent MRI, polysomnography, and cognitive testing. The effects of the obstructive apnea-hypopnea index (OAHI) on topological properties of white matter networks and network properties on cognition were studied using hierarchical linear regression. Mediation analyses were used to explore whether white matter network properties mediated the effects of OAHI on cognition.

RESULTS

Children with OSA had significantly higher assortativity than non-OSA children. Furthermore, OAHI was associated with the nodal properties of several brain regions, primarily in the frontal and temporal lobes. The relationship between OAHI and verbal comprehension index was mediated through clustering coefficients in the right temporal pole of the superior temporal gyrus.

CONCLUSIONS

OSA affects the development of white matter networks in children's brains. Besides, the mediating role of white matter network properties between the OAHI and the verbal comprehension index provided neuroimaging evidence of impaired cognitive function in children with OSA.

Bioinformatics-based identification of key candidate genes and signaling pathways in patients with Parkinson's disease and obstructive sleep apnea

OBJECTIVES

Existing evidence exhibits that obstructive sleep apnea (OSA) is a potential consequence of Parkinson's disease (PD) or a contributor to PD progression. This investigation aimed to detect potential critical genes and molecular mechanisms underlying interactions between PD and OSA through bioinformatics analyses.

METHODS

The Gene Expression Omnibus (GEO) database was employed to obtain the expression profiles GSE20163 and GSE135917. The identification of common genes connected to PD and OSA was performed utilizing weighted gene co-expression network analysis and the R 4.0.4 program. The Cytoscape program was utilized to generate a network of protein-protein interactions (PPI), and the CytoHubba plugin was utilized to detect hub genes. Subsequently, functional enrichment analyses of the hub genes were conducted. Markers with increased diagnostic values for PD and OSA were confirmed using the GEO datasets GSE8397 and GSE38792.

RESULTS

Typically, 57 genes that are common were identified in PD and OSA. Among these common genes, the top 10 hub genes in the PPI network were chosen. The verified datasets confirmed the presence of three important genes: CADPS, CHGA, and SCG3. Functional enrichment analysis revealed that these hub genes mostly participate in GABAergic synapses.

CONCLUSION

Our findings suggest that CADPS, CHGA, and SCG3 are key genes involved in molecular mechanisms underlying interactions between OSA and PD. Functional enrichment of hub genes indicated a link between GABAergic synapses and the shared pathogenesis of PD and OSA. These candidate genes and corresponding pathways offer novel insights regarding biological targets that underlie the transcriptional connection between OSA and PD.

Continuous positive airway pressure compliance in patients with mild cognitive impairment

PURPOSE

Sleep apnoea (SA) is associated with accelerated cognitive decline in patients with mild cognitive impairment (MCI). Treatment of SA by continuous positive airway pressure (CPAP) may slow this decline if patients comply with the treatment. The aim of this study was to assess the rate of CPAP compliance in this population.

METHODS

In this single-centre retrospective study conducted in a tertiary care institution, patients with a diagnosis of MCI and SA initiating CPAP between January 2015 and August 2021 were included. Data from the initial sleep recording, the 3-month follow-up and compliance with at least 12 months of CPAP were analysed. Compliance was defined as an average CPAP use of at least 4 h per night.

RESULTS

55 patients were included (49% women, age 70.7 ± 8.9 years, body mass index 28.9 ± 6.5 kg/m2). Aetiology of MCI was vascular (45.5%), psychiatric (12.7%) and related to Alzheimer's disease (7.3%), with 47.3% of amnesic disorders and 45.5% of dysexecutive disorders. The MiniMentalState score was 26.7 ± 3.1. SA was mostly obstructive (81.8%) with a mean apnoea-hypopnoea index of 41.1 ± 16.4/h. At 3 months, 38 patients were compliant (69%) with a CPAP median use of 5.9 h per night and 83% of nights. Self-reported tolerance was better in compliant patients (75.7% vs 38.5% p = 0.017). Thirty-four patients remained compliant at 12 months (62%).

CONCLUSION

Our results suggest a high rate of CPAP compliance in patients suffering from MCI. Compliance was related to the device tolerance, emphasizing the need to closely monitor and improve this factor.