Memory and Executive Screening for the Detection of Cognitive Impairment in Obstructive Sleep Apnea

Evaluation of nocturnal apnea and airflow limitation as indicators for cognitive dysfunction in patients with chronic obstructive pulmonary disease/obstructive sleep apnea hypopnea syndrome overlap syndrome

OBJECTIVE

The aim of this study is to investigate how much intermittent hypoxemia and airflow limitation contribute to cognitive impairment in overlap syndrome (OS), which is the coexistence of two common diseases, obstructive sleep apnea hypopnea syndrome (OSAHS) and chronic obstructive pulmonary disease (COPD).

METHODS

We conducted a cross-sectional study of patients with OSAHS, COPD or OS, compared with normal controls, to determine the association between sleep apnea/pulmonary function-related indicators and cognitive dysfunction in individuals with OSAHS, COPD or OS.

RESULTS

A total of 157 participants were recruited. Both OSAHS and OS presented lower adjusted Montreal cognitive assessment (MoCA) scores compared with COPD group. In addition, the MoCA score was significantly lower in COPD group compared with control group. The incidence of cognitive impairment was 57.4% in OSAHS group, and 78% in OS group, which were significantly higher than COPD group (29%) and control group (8.8%). Furthermore, a broader range of cognitive domains were affected in OS group compared with OSAHS group. Elevated levels of oxygen desaturation index (ODI) and/or apnea hypopnea index (AHI) were positively correlated with increased Epworth sleeping scale (ESS) in OSAHS and OS. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) were positively correlated with cognitive scores in OSAHS but not in OS. Serum level of hypoxia-inducible factor-1α (HIF-1α) was significantly higher in OS. Logistic regression identified ODI as an independent risk factor for cognitive impairment in OS, while severity of snoring and PEF were independent risk factors in OSAHS.

DISCUSSION

This study revealed significant cognitive impairment in OS, OSAHS and COPD. Sleep-related indicators are warranted in OS patients for detection, differentiation and grading of cognitive impairment, whereas pulmonary functions are warranted in OSAHS patients for detection and early intervention of cognitive impairment.

Mentation Tracks Severity but not Oxygenation in Obstructive Sleep Apnea

There is a rough consensus, after decades of research, that obstructive sleep apnea (OSA) is associated with mild cognitive impairments, especially in areas of executive functioning (EF), attention/working memory (A/WM), episodic memory (EM), and speed of speed of information processing (SIP). However, there is less consensus as to whether apnea severity matters for these impairments, which sleep variables matter most to which cognitive domains, whether common OSA comorbidities contribute to these determinations, or whether the apparent associations are really artifacts of these comorbidities. In this study, 40 participants with OSA submitted to polysomnography and to neuropsychological assessment with an expanded Halstead-Reitan Test Battery. Aggregates of tests to cover the four cognitive domains mentioned above were linearly regressed on the apnea-hypopnea index (AHI), the nadir of oxygen saturation (NOS), and hypertension and diabetes mellitus (scored present or absent). The AHI predicted both EF (p = .015; sr2 = .13) and A/WM (p = .023; sr2 = 11) in the primary analyses, and EM (p = .027; sr2 = .10) in the secondary analyses. Thus, AHI may affect EF, A/WM and perhaps EM beyond NOS and beyond two of OSA's most common comorbidities. Implications of these findings are discussed here.

MoCA-T como herramienta de evaluación remota para precisar deterioro cognitivo en pacientes con SAHOS moderado a severo

La pandemia de COVID-19 ha dado lugar al surgimiento de herramientas tecnológicas que permiten la valoración de pacientes de forma remota. La prueba de evaluación cognitiva de Montreal, versión telefónica (MoCA-T), es una de ellas. Se considera como un recurso de la telemedicina que permite la tamización cognitiva a distancia en épocas de pandemia y en la población con dificultades en el acceso a los centros de salud. El deterioro cognitivo leve (DCL) es un hallazgo usual en pacientes con síndrome de apnea-hipopnea obstructiva del sueño (SAHOS); sin embargo, no se ha estudiado la aplicación de pruebas telefónicas para su tamización cognitiva. El objetivo principal de este trabajo es determinar la frecuencia de deterioro cognoscitivo mediante la aplicación de MoCA-T como prueba de tamización remota en pacientes con SAHOS moderado y severo. Para ello, se aplicó la prueba de MoCA-T en 104 pacientes entre 18 y 65 años con diagnóstico polisomnográfico de SAHOS moderado y severo, excluyéndose a pacientes con comorbilidades que afectasen las capacidades cognoscitivas. Se obtuvieron resultados anormales de MoCA-T en el 43% de los pacientes, siendo los dominios cognitivos de la memoria y la atención los más comúnmente afectados. Finalmente, los resultados anormales de MoCA-T se correlacionaron con la autopercepción de las dificultades en la memoria, estando más frecuentemente alterada en quienes manifestaron quejas cognitivas. La prueba MoCA-T podría ser una herramienta tecnológica breve, validada y factible para realizar el tamizaje cognitivo de pacientes con SAHOS en épocas de pandemia y en pacientes con barreras asistenciales.

The relationships between obstructive sleep apnea and psychiatric disorders: a narrative review

Introduction: Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder. Its prevalence tends to increase worldwide. Untreated sleep apnea is associated with a higher risk of metabolic diseases, cardiovascular diseases, stroke, road accidents, and death, but also it is suggested that it increases the risk of mental disorders.

Method: The literature review was based on a search of articles on Medline, Pubmed, and Google Scholar from 2003 to 2021 using the keywords: obstructive sleep apnea; mental disorders; cognitive functions; affective disorders; depression; bipolar disorder; schizophrenia; psychotic disorders. The analysis included original studies, meta-analysis, and review articles.

Discussion: The result obtained from researches published so far does not allow for drawing unequivocal conclusions. There is a lot of bias present in study protocols and inclusion/exclusion criteria. Nonetheless, it seems that some disorders have a better proven correlation with OSA. Cognitive impairment, depression, and anxiety disorders are linked to OSA not only in terms of the overlapping of symptoms but also of a causal relationship. Psychotic disorders and bipolar disorders connections with OSA are confirmed, but they are not yet well understood. All correlations are found to be possibly bidirectional.

Conclusion: 1. Multiple lines of evidence increasingly point towards a bidirectional connection between OSA and mental disorders, and the cause and effect relationship between these two groups of disorders requires further research.

2. Due to reports of an increased risk of OSA with antipsychotic drugs, caution should be exercised when initiating therapy with this type of drug in patients with known risk factors for it.

3. Screening for OSA in psychiatric patients should be introduced as OSA can increase cognitive impairment, affective, and psychotic symptoms.

The relationship between inflammation and neurocognitive dysfunction in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS), a state of sleep disorder, is characterized by repetitive apnea, chronic hypoxia, oxygen desaturation, and hypercapnia. Previous studies have revealed that intermittent hypoxia (IH) conditions in OSAS patients elicited neuron injury (especially in the hippocampus and cortex), leading to cognitive dysfunction, a significant and extraordinary complication of OSAS patients. The repeated courses of airway collapse and obstruction in OSAS patients resulted in apnea and arousal during sleep, leading to IH and excessive daytime sleepiness (EDS) and subsequently contributing to the development of inflammation. IH-mediated inflammation could further trigger various types of cognitive dysfunction. Many researchers have found that, besides continuous positive airway pressure (CPAP) treatment and surgery, anti-inflammatory substances might alleviate IH-induced neurocognitive dysfunction. Clarifying the role of inflammation in IH-mediated cognitive impairment is crucial for potentially valuable therapies and future research in the related domain. The objective of this article was to critically review the relationship between inflammation and cognitive deficits in OSAS.

A contemporary review of obstructive sleep apnea

PURPOSE OF REVIEW

This review provides a contemporary review of sleep apnea with emphasis on definitions, epidemiology, and consequences.

RECENT FINDINGS

Amyloid β-42 is one of the main peptides forming amyloid plaques in the brains of Alzheimer patients. Poorer sleep quality and shorter sleep duration have been associated with a higher amyloid burden. Decreased sleep time in the elderly is a precipitating factor in amyloid retention. Studies have shown that the dysregulation of the homeostatic balance of the major inhibitory and excitatory amino acid neurotransmitter systems of gamma-aminobutyric acid (GABA) and glutamate play a role in sleep disordered breathing (SDB).

SUMMARY

Untreated sleep disordered breathing (obstructive sleep apnea and/or central sleep apnea) are an important cause of medical mortality and morbidity. OSA is characterized by recurrent episodes of partial or complete collapse of the upper airway during sleep followed by hypoxia and sympathetic activation. Apneic events are terminated by arousal, followed by increases in pulse and blood pressure, and re-oxygenation and the release of inflammatory factors. Individuals with OSA have an increased risk of developing atrial fibrillation. Hypoxemia and poor sleep quality because of OSA increase the risk of cognitive decline in the elderly.

Epigenetic Regulation of BMAL1 with Sleep Disturbances and Alzheimer's Disease

BACKGROUND

An early symptom of Alzheimer's disease (AD) is a disturbance of the circadian rhythm that is associated with disrupted sleep/wake cycles.

OBJECTIVE

To investigate if BMAL1, a key gene that drives the circadian cycle, is epigenetically regulated in brains in relation to longitudinal changes in cognition, sleep quality, and AD neuropathology.

METHODS

Frontal cortex tissues were acquired from the Manchester Brain Bank (N = 96). DNA methylation at six CpG sites at the promoter of BMAL1, determined using bisulfite pyrosequencing, was tested for associations with Braak stage, CERAD score and Thal phase, longitudinal changes in cognition, sleep measurements and cross-section measures of depressive symptoms (BDI score).

RESULTS

Methylation across all the CpGs strongly correlated with each other. We found increased CpG2 methylation with higher Braak (t(92), p = 0.015) and CERAD (t(94), p = 0.044) stages. No significance was found between longitudinal fluid intelligence, processing speed and memory tests, but methylation at CpG1 (r = 0.20, p = 0.05) and CpG4 (r = 0.20, p = 0.05) positively correlated with vocabulary. CpG2 positively correlated with cross-sectional fluid intelligence (r = 0.20 p = 0.05) and vocabulary (r = 0.22 p = 0.03). Though longitudinal analysis revealed no significance between sleep duration, midsleep and efficiency for any of the CpG sites, CpG3 (B = 0.03, 95% CI, p = 0.03) and CpG5 (B = 0.04, 95% CI, p = 0.01) significantly correlated with night wake. CpG4 correlated with depressive symptoms (B = -0.27, 95% CI, p = 0.02).

CONCLUSION

Methylation of BMAL1 associated with tau pathology, changes in cognitive measures, a measure of sleep and depressive symptoms, suggesting an involvement of the circadian cycle.

Effects of somatotropic axis on cognitive dysfunction of obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is associated with a variety of neuroendocrine disorders and may lead to many complications, including cognitive dysfunction. The aim of this study was to assess the change of somatotropic axis and to detect the relation between somatotropic axis hormone and cognitive dysfunction.

METHODS

Sixty-six patients with OSA and 16 healthy controls were enrolled in this cross-sectional study. Cognitive function assessment using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) and polysomnography were performed on all individuals. Blood samples were taken the next morning following the polysomnography and the level of serum growth hormone-releasing hormone (GHRH) and growth hormone (GH) were analyzed by enzyme-linked immunosorbent assay.

RESULTS

Compared with the control group, OSA patients showed significantly lower serum GH level (p < 0.05), whereas no statistical significance of GHRH level was found. In addition, lower MMSE and MoCA scores were found only in the severe OSA patients when compared with the controls. Furthermore, in severe OSA patients with cognitive dysfunction (MMSE score < 27 and MoCA score < 26), serum GHRH and GH levels were significantly lower than those without cognitive dysfunction. Logistic analysis revealed that cognitive dysfunction in severe OSA patients was associated with micro-arousal index and the level of serum GHRH and GH.

CONCLUSION

Decreased serum GH and GHRH levels were found among severe OSA patients with cognitive dysfunction who were overweight, which might promote the occurrence of cognitive dysfunction.

Athletes with neurologic disease

Neurologic disease does not discriminate, even among athletes. Common neurologic diseases among athletes include multiple sclerosis, seizures, headaches, and sleep disorders. Although concrete guidelines for sport participation among athletes with neurologic diseases do not exist, evidence-based and consensus statements can aid healthcare providers in determining whether and to what extent such athletes should participate in sports. Moreover, sport participation is important, since multiple studies indicate that exercise improves disease-specific symptoms, manifestations, and overall quality of life. Although some risk is involved for athletes with neurologic disease, risk is mitigated with proper supervision and neurologic oversight, disease-specific accommodations, and counseling of the athletic staff and the athletes. Neurologic oversight entails an initial comprehensive neurologic assessment by a neurologist followed by regular follow-up. Preparation for environmental conditions encountered by athletes with neurologic disease will further improve safety during their participation in sport. With sound recommendations, neurologic oversight, and proper supervision, most athletes with neurologic disease can participate in athletics. The health benefits that they will gain from participation in athletics outweigh the risks.