The Associations between Polysomnographic Parameters and Memory Impairment among Patients with Obstructive Sleep Apnea: A 10-Year Hospital-Based Longitudinal Study

Systematic bibliometric and visualized analysis of research hotspots and trends in obstructive sleep apnea neuroimaging

BACKGROUND

Obstructive sleep apnea (OSA) patients exhibit neurological symptoms, driving research in sleep medicine and clinical neurology. Neurologists and radiologists explore detection methods to identify unique neural features associated with OSA in the atypical nervous system. Neuroimaging research in OSA encompasses studying the structural, functional connectivity (FC), and neurometabolic aspects of the brain. Limited resources and OSA's heterogeneity pose challenges to effective neuroimaging research. This study aims to conduct a bibliometric analysis of OSA neuroimaging research to identify key trends and emerging themes.

METHODS

This research utilizes various techniques, including functional MRI, structural MRI, diffusion tensor imaging, magnetic resonance spectroscopy, and electroencephalography, among others. Publications from 1993 to 2023 were retrieved from Web of Science on neuroimaging. Analysis tools included Bibliometric.com, CiteSpace, VOSviewer, and R4.3.2.

RESULTS

A total of 714 papers were published in 47 countries, with 651 articles, 55 reviews, and 8 meeting abstracts. The USA led in publications, with the University of California System contributing most, primarily in "Sleep" journal. The study identified 2916 authors, with Macey PM having the highest publication count. Recent years highlighted burst keywords such as network, classification, sleep staging, FC, and brain activity. Analysis of keyword clusters revealed "electroencephalography" with the longest temporal duration.

CONCLUSIONS

Neuroimaging in OSA research has gained increased attention. Incorporating behavioral sleep medicine insights could enhance understanding of OSA's impact on brain function and behavior. This study aims to assist researchers in identifying potential collaborators, institutions, and key themes, providing a comprehensive perspective on OSA neuroimaging research and related sleep disorders.

The association between hypoxic burden and the risk of cognitive impairment in patients with obstructive sleep apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with an increasing risk of cognitive impairment, but traditional hypoxic indicators can not accurately identify cognitive impairment. This study aimed to assess a new indicator, hypoxic burden, in cognitive impairment in OSA.

METHODS

A total of 116 patients with OSA were enrolled in this study. Daytime sleepiness and cognition were assessed using the Epworth Sleepiness Scales and Montreal Cognitive Assessment (MoCA), respectively. All participants underwent polysomnography (PSG). The hypoxic burden was derived from PSG and calculated according to a specific algorithm. All the participants were divided into two groups. Seventy-seven were OSA with mild cognitive impairment (OSA + MCI), and 39 were OSA without mild cognitive impairment (OSA-MCI). The relationship between hypoxic burden and cognitive impairment was analyzed by establishing a series of logistic regression models.

RESULTS

Hypoxic burden was higher in OSA + MCI group compared with OSA-MCI group, while there was no significance found for the apnea-hypopnea index between the two groups. After adjusting for various confounders, patients with OSA who had a higher total hypoxic burden and rapid eye movement-hypoxic burden in the fourth quartile were found to have an increased risk of MCI compared to those in the first quartile. The adjusted ORs were 7.69 (95% CI, 1.15 to 51.55) and 8.87 (95% CI, 1.22 to 64.34), respectively. However, There was no significant association between the other traditional hypoxic parameters and cognitive function after adjusting for various confounders.

CONCLUSIONS

Compared to the conventional hypoxic parameter, a higher hypoxic burden is associated with cognition and may be an important indicator for assessing MCI in OSA.

Obstructive Sleep Apnea: The Effect of Bariatric Surgery After Five Years-A Prospective Multicenter Trial

BACKGROUND

The prevalence of obstructive sleep apnea (OSA) is high among the bariatric surgery candidates. Obesity is the most important individual risk factor for OSA. The aim of this study was to investigate the effect of a laparoscopic Roux-en-Y gastric bypass (LRYGB) on OSA 5 years after the surgery.

PATIENTS AND METHODS

In this prospective multicenter study, standard overnight cardiorespiratory recording was conducted to 150 patients at baseline prior to bariatric surgery. A total of 111 (73.3%) patients of those had OSA. Cardiorespiratory recordings at 5 years after surgery were available for 70 OSA patients. The changes in anthropometric and demographic measurements including age, weight, body mass index (BMI), and waist and neck circumference were evaluated. Also, a quality of life (QoL) questionnaire 15D administered in a baseline was controlled at 5-year follow-up visit.

RESULTS

At 5-year OSA was cured in 55% of patients, but moderate or severe OSA still persisted in 20% of patients after operation. Mean total AHI decreased from 27.8 events/h to 8.8 events/h (p < 0.001) at 5-year follow-up. A clinically significant difference in QoL was seen in mobility, breathing, sleeping, usual activities, discomfort and symptoms, vitality and sexual activity. The QoL total score improved more in OSA patient at 5-year follow-up.

CONCLUSIONS

LRYGB is an effective treatment of OSA in obese patients and the achieved beneficial outcomes are maintained at 5-year follow-up.

Respiratory Dysfunction in Alzheimer's Disease-Consequence or Underlying Cause? Applying Animal Models to the Study of Respiratory Malfunctions

Alzheimer's disease (AD) is a neurodegenerative brain disease that is the most common cause of dementia among the elderly. In addition to dementia, which is the loss of cognitive function, including thinking, remembering, and reasoning, and behavioral abilities, AD patients also experience respiratory disturbances. The most common respiratory problems observed in AD patients are pneumonia, shortness of breath, respiratory muscle weakness, and obstructive sleep apnea (OSA). The latter is considered an outcome of Alzheimer's disease and is suggested to be a causative factor. While this narrative review addresses the bidirectional relationship between obstructive sleep apnea and Alzheimer's disease and reports on existing studies describing the most common respiratory disorders found in patients with Alzheimer's disease, its main purpose is to review all currently available studies using animal models of Alzheimer's disease to study respiratory impairments. These studies on animal models of AD are few in number but are crucial for establishing mechanisms, causation, implementing potential therapies for respiratory disorders, and ultimately applying these findings to clinical practice. This review summarizes what is already known in the context of research on respiratory disorders in animal models, while pointing out directions for future research.