Intricate relationship between obstructive sleep apnea and dementia in older adults

The Interaction of Hypertension and Obstructive Sleep Apnea Risk on Cognitive Function in Healthy Older Adults

PURPOSE

To preliminarily examine the individual and interaction effects of hypertension and obstructive sleep apnea (OSA) risk on cognitive functions (i.e., global cognition, memory, attention, and executive function).

METHOD

The current study was a secondary data analysis. Forty older adults were retrieved from a descriptive study. OSA risk was measured by the STOP-BANG questionnaire, and hypertension by self-report and medications used. Spearman rho correlation and two-way analysis of covariance were used in the data analysis.

RESULTS

After controlling for covariates (i.e., age, educational years, health conditions, body mass index, and depressive symptoms), older adults with hypertension had poorer memory and attention; older adults with high OSA risk had poorer memory and better executive function. This interaction effect of hypertension and OSA risk on executive function was significant.

CONCLUSION

The association between hypertension and memory and attention and between OSA risk and memory in older adults was supported. The interaction effect was found in executive function but unexpected. Future studies are needed to recruit older adults with hypertension and diagnosed OSA to explore these interaction effects. [Research in Gerontological Nursing, xx(x), xx-xx.].

Glymphatic pathway dysfunction in severe obstructive sleep apnea: A meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA), a sleep disorder, is associated with cognitive decline and is potentially linked to glymphatic system dysfunction. This meta-analysis investigates glymphatic function in severe OSA (apnea-hypopnea index ≥30) using the Diffusion Tensor Imaging Analysis along the Perivascular Space (DTI-ALPS) index.

METHODS

This study followed PRISMA guidelines for systematic reviews and meta-analyses. A comprehensive search of PubMed, Web of Science, Scopus, and Embase was conducted from inception to January 20, 2024. Studies investigating the ALPS index in OSA using DTI were included. Analyses included a random-effects meta-analysis, sensitivity analysis, meta-regression, publication bias evaluation (funnel plot, Egger's test, and Begg's test), and risk of bias assessment.

RESULTS

Systematic review identified four studies (137 patients with severe OSA and 170 healthy controls (HCs)). Pooled analysis revealed a significant reduction in the DTI-ALPS index in severe OSA patients compared to HCs (standardized mean difference: -0.95, 95 % CI: -1.46 to -0.44, p < 0.001), indicating impaired glymphatic function. Heterogeneity was moderate to high (I2 = 76.07 %), but sensitivity analyses confirmed robustness. Meta-regression analyses identified the sources of heterogeneity as the apnea-hypopnea index (β = -0.039, p = 0.009) and the Epworth Sleepiness Scale (β = -0.150, p = 0.032), with no effects observed for age or male ratio. Qualitative (funnel plot) and quantitative publication bias assessments (Egger's and Begg's tests) showed no significant bias, and risk of bias evaluations using the Newcastle-Ottawa Scale indicated high methodological quality across studies.

CONCLUSIONS

These findings suggest that severe OSA disrupts glymphatic activity. The DTI-ALPS index emerges as a promising tool for assessing glymphatic dysfunction in OSA.

Age at diagnosis of obstructive sleep apnea and subsequent risk of dementia

BACKGROUND

Epidemiological evidence regarding the association between Obstructive sleep apnea (OSA) onset age and risk of incident dementia remains unexplored. The study sought to examine whether younger onset age of OSA is associated with a higher risk of incident dementia.

METHODS

This cohort study, based on the UK Biobank's prospective population data, excluded 445,023 participants due to baseline dementia diagnoses, incomplete covariate information, or pre-OSA onset dementia over a 12.6-year median follow-up. The research applied Cox regression and propensity score matching to explore the relationship between sleep apnea onset age and later development of all-cause dementia, Alzheimer's, and vascular dementia.

RESULTS

In a controlled study contrasting those without obstructive sleep apnea (OSA), those suffering from OSA showed markedly higher risks for developing all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VD), with hazard ratios (HR) of 4.243 (95% CI: 3.678-4.897), 5.668 (95% CI: 4.380-7.336), and 6.064 (95% CI: 4.008-9.175) respectively. Following adjustment with propensity score matching, OSA patients younger than 52 presented the highest risk of all-cause dementia, with an adjusted HR of 2.256 (95% CI: 1.901-3.747). This trend was consistent for early-onset AD and VD in the same age group.

CONCLUSION

Younger age at OSA onset was associated with increased risk of dementia. Individuals with an onset age of OSA before 52 years of age may represent a particularly vulnerable population for dementia irrespective of subtypes and need careful monitoring and timely intervention to attenuate subsequent risk of incident dementia.

Cross-sectional study of the association between triglyceride glucose-body mass index and obstructive sleep apnea risk

BACKGROUND

The triglyceride glucose-body mass index (TyG-BMI) is a novel indicator of insulin resistance (IR). Obstructive sleep apnea (OSA) is a prevalent disorder characterized by recurrent complete or partial collapse of the pharyngeal airway during sleep; however, the relationship between these two conditions remains unexplored. We hypothesized that a higher TyG-BMI is associated with the occurrence of OSA.

AIM

To assess the association between TyG-BMI and OSA in adults in the United States.

METHODS

A cross-sectional study was conducted utilizing data from the National Health and Nutrition Examination Surveys spanning from 2005-2008 to 2015-2018. TyG-BMI was calculated as Ln [triglyceride (mg/dL) × fasting blood glucose (mg/dL)/2] × BMI. Restricted cubic splines were used to analyze the risk of TyG-BMI and OSA occurrence. To identify potential nonlinear relationships, we combined Cox proportional hazard regression with smooth curve fitting. We also conducted sensitivity and subgroup analyses to verify the robustness of our findings.

RESULTS

We included 16794 participants in the final analysis. Multivariate regression analysis showed that participants with a higher TyG-BMI had a higher OSA incidence. After adjusting for all covariates, TyG-BMI was positively correlated with the prevalence of OSA (odds ratio: 1.28; 95% confidence interval: 1.17, 1.40; P < 0.001); no significant nonlinear relationship was observed. Subgroup analysis showed no strong correlation between TyG-BMI and OSA in patients with diabetes. The correlation between TyG-BMI and OSA was influenced by age, sex, smoking status, marital status, hypertensive stratification, and obesity; these subgroups played a moderating role between TyG-BMI and OSA. Even after adjusting for all covariates, there was a positive association between TYG-BMI and OSA prevalence.

CONCLUSION

A higher TyG-BMI index is linked to higher chances of developing OSA. As TyG-BMI is an indicator of IR, managing IR may help reduce the risk of OSA.

Exploring the Association Between Triglyceride-Glucose Indices and Their Derivatives With Obstructive Sleep Apnea: Insights From the National Health and Nutrition Examination Survey

Background

Simple and affordable methods for evaluating Insulin Resistance (IR) have been suggested, such as the Triglyceride-Glucose (TyG) index and its variants, including the TyG-Body Mass Index (TyG-BMI), TyG-Waist Circumference (TyG-WC), and TyG-Waist-to-Height Ratio (TyG-WHtR). The aim of this study is to investigate the relationship between these TyG-related indices, which measure IR, and Obstructive Sleep Apnea (OSA).

Methods

This study analyzed NHANES data from 2007-2008, 2015-2016, and 2017-2020. TyG and its derivatives were evaluated as continuous and categorical variables in relation to OSA using multivariable logistic regression models. Subgroup analyses, dose-response relationships, and threshold effects were explored, and the diagnostic performance of TyG-related indices was assessed using AUC curves.

Results

The study included 8,374 participants. The fully adjusted Model 3 analysis (Note: Body Mass Index was not adjusted for TyG-BMI) of continuous variables showed a positive correlation between OSA and all four indices. All four TyG-related indicators showed statistically significant relationships with OSA when grouped into quartiles (TyG: AOR = 1.448, 95% CI: 1.260-1.663; TyG-BMI: AOR = 3.785, 95% CI: 3.319-4.317; TyG-WC: AOR = 2.089, 95% CI: 1.629-2.677; TyG-WHtR: AOR = 1.913, 95% CI: 1.548-2.363). Subgroup analysis revealed a stronger association of TyG-WHtR with OSA in the 41-59 age group (AOR = 1.459, 95% CI: 1.254-1.698) and the low-income group (AOR = 1.451, 95% CI: 1.241-1.698). TyG showed a linear relationship with OSA, while TyG-BMI, TyG-WC, and TyG-WHtR exhibited nonlinear relationships. The diagnostic capability was highest for TyG-WC, with an AUC of 0.647.

Conclusion

The study confirms strong associations between OSA and the TyG indices, particularly TyG-WC, which demonstrates significant predictive power for OSA risk. Future longitudinal studies are recommended to further investigate these associations and enhance OSA management in resource-constrained environments.

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.

Phase-Amplitude Coupling in Theta and Beta Bands: A Potential Electrophysiological Marker for Obstructive Sleep Apnea

Background

Phase-amplitude coupling (PAC) between the phase of low-frequency signals and the amplitude of high-frequency activities plays many physiological roles and is involved in the pathological processed of various neurological disorders. However, how low-frequency and high-frequency neural oscillations or information synchronization activities change under chronic central hypoxia in OSA patients and whether these changes are closely associated with OSA remains largely unexplored. This study arm to elucidate the long-term consequences of OSA-related oxygen deprivation on central nervous system function.

Methods

: We screened 521 patients who were clinically suspected of having OSA at our neurology and sleep centers. Through polysomnography (PSG) and other clinical examinations, 103 patients were ultimately included in the study and classified into mild, moderate, and severe OSA groups based on the severity of hypoxia determined by PSG. We utilized the phase-amplitude coupling (PAC) method to analyze the modulation index (MI) trends between different frequency bands during NREM (N1/N2/N3), REM, and wakefulness stages in OSA patients with varying severity levels. We also examined the correlation between the MI index and OSA hypoxia indices.

Results

Apart from reduced N2 sleep duration and increased microarousal index, the sleep architecture remained largely unchanged among OSA patients with varying severity levels. Compared to the mild OSA group, patients with moderate and severe OSA exhibited higher MI values of PAC in the low-frequency theta phase and high-frequency beta amplitude in the frontal and occipital regions during N1 sleep and wakefulness. No significant differences in the MI of phase-amplitude coupling were observed during N2/3 and REM sleep. Moreover, the MI of phase-amplitude coupling in theta and beta bands positively correlated with hypoxia-related indices, including the apnea-hypopnea index (AHI) and oxygenation desaturation index (ODI), and the percentage of oxygen saturation below 90% (SaO2<90%).

Conclusion

OSA patients demonstrated increased MI values of theta phase and beta amplitude in the frontal and occipital regions during N1 sleep and wakefulness. This suggests that cortical coupling is prevalent and exhibits sleep-stage-specific patterns in OSA. Theta-beta PAC during N1 and wakefulness was positively correlated with hypoxia-related indices, suggesting a potential relationship between these neural oscillations and OSA severity. The present study provides new insights into the relationship between neural oscillations and respiratory hypoxia in OSA patients.

Exploring the Influence of Gut-Brain Axis Modulation on Cognitive Health: A Comprehensive Review of Prebiotics, Probiotics, and Symbiotics

Recent research exploring the relationship between the gut and the brain suggests that the condition of the gut microbiota can influence cognitive health. A well-balanced gut microbiota may help reduce inflammation, which is linked to neurodegenerative conditions. Prebiotics, probiotics, and symbiotics are nutritional supplements and functional food components associated with gastrointestinal well-being. The bidirectional communication of the gut-brain axis is essential for maintaining homeostasis, with pre-, pro-, and symbiotics potentially affecting various cognitive functions such as attention, perception, and memory. Numerous studies have consistently shown that incorporating pre-, pro-, and symbiotics into a healthy diet can lead to improvements in cognitive functions and mood. Maintaining a healthy gut microbiota can support optimal cognitive function, which is crucial for disease prevention in our fast-paced, Westernized society. Our results indicate cognitive benefits in healthy older individuals with probiotic supplementation but not in healthy older individuals who have good and adequate levels of physical activity. Additionally, it appears that there are cognitive benefits in patients with mild cognitive impairment and Alzheimer's disease, while mixed results seem to arise in younger and healthier individuals. However, it is important to acknowledge that individual responses may vary, and the use of these dietary supplements should be tailored to each individual's unique health circumstances and needs.

Triglyceride-glucose index and obstructive sleep apnea: a systematic review and meta-analysis

BACKGROUND

Obstructive sleep apnea (OSA) has a bidirectional association with metabolic syndrome, and insulin resistance (IR). The triglyceride-glucose (TyG) index could be a simply calculated marker of IR in OSA. However, its clinical application appears still limited. Hence, this systematic review and meta-analysis aimed to respond to this question by analyzing all the existing studies showing an association between OSA and the TyG index.

METHODS

Four online databases, including PubMed, Scopus, the Web of Science, and Embase were searched for studies evaluating the TyG index in OSA. After screening and data extraction, a random-effect meta-analysis was performed to compare the TyG index in OSA patients vs. healthy controls by calculating standardized mean difference (SMD) and 95% confidence interval (CI) and pooling the area under the curves (AUCs) for diagnosis of OSA based on this index.

RESULTS

Ten studies involving 16,726 individuals were included in the current systematic review. Meta-analysis indicated that there was a significantly higher TyG index in patients with OSA, compared with the healthy controls (SMD 0.856, 95% CI 0.579 to 1.132, P < 0.001). Also, TyG had a diagnostic ability for OSA representing a pooled AUC of 0.681 (95% CI 0.627 to 0.735). However, based on the two studies' findings, no difference between different severities of OSA was observed. Finally, our data showed that the TyG index is a good potential predictor of adverse outcomes in these patients.

CONCLUSION

Our study revealed that the TyG index is an easy-to-measure marker of IR for assessing OSA, both in diagnosis and prognosis. Our study supports its implementation in routine practice to help clinicians in decision-making and patient stratification.