Insular cortex metabolite changes in obstructive sleep apnea

The effect of hypoxia on interoception in patient with obstructive sleep apnea

PURPOSE

Obstructive Sleep Apnea (OSA) is the most common sleep-related disorder. Interoception is the collection of sensory and cognitive processes that involve receiving and interpreting physiological signals from internal body structures and conveying the perception of inner sensations. In this study, it was hypothesized that the impairment in cognitive functions associated with chronic hypoxemia and the insular effects due to OSA would negatively affect interoceptive functions. The aim of this study was to evaluate whether interoception in OSA changes consistent with the hypothesis.

METHODS

A total of 102 patients diagnosed with OSA were included in this study. All participants were divided into groups based on their T90 values: desaturated OSA (T90 ≥ 20%) and non-desaturated OSA (T90 < 20%). The Heartbeat Counting Task was used to assess interoceptive accuracy, while the Interoceptive Sense Questionnaire (ISQ) was employed to identify subjective challenges in evaluating interoception.

RESULTS

Interoceptive accuracy was lower in the desaturated OSA group than in the non-desaturated OSA group (Z = -2.463; p = 0.014). Interoceptive accuracy was negatively correlated with the body mass index (r = -0.228; p = 0.021), T90 (r = -0.269; p = 0.006), and positively correlated with the average SaO2 (r = 0.377; p < 0.001) and SaO2 nadir (r = 0.243; p = 0.014).

CONCLUSION

This study examined interoceptive functions in patients with OSA. It was concluded that interoceptive accuracy is affected by the severity of hypoxia as hypothesized.

Neurometabolic and structural alterations of medial septum and hippocampal CA1 in a model of post-operative sleep fragmentation in aged mice: a study combining 1H-MRS and DTI

Post-operative sleep disturbance is a common feature of elderly surgical patients, and sleep fragmentation (SF) is closely related to post-operative cognitive dysfunction (POCD). SF is characterized by sleep interruption, increased number of awakenings and sleep structure destruction, similar to obstructive sleep apnea (OSA). Research shows that sleep interruption can change neurotransmitter metabolism and structural connectivity in sleep and cognitive brain regions, of which the medial septum and hippocampal CA1 are key brain regions connecting sleep and cognitive processes. Proton magnetic resonance spectroscopy (1H-MRS) is a non-invasive method for the evaluation of neurometabolic abnormalities. Diffusion tensor imaging (DTI) realizes the observation of structural integrity and connectivity of brain regions of interest in vivo. However, it is unclear whether post-operative SF induces harmful changes in neurotransmitters and structures of the key brain regions and their contribution to POCD. In this study, we evaluated the effects of post-operative SF on neurotransmitter metabolism and structural integrity of medial septum and hippocampal CA1 in aged C57BL/6J male mice. The animals received a 24-h SF procedure after isoflurane anesthesia and right carotid artery exposure surgery. 1H-MRS results showed after post-operative SF, the glutamate (Glu)/creatine (Cr) and glutamate + glutamine (Glx)/Cr ratios increased in the medial septum and hippocampal CA1, while the NAA/Cr ratio decreased in the hippocampal CA1. DTI results showed post-operative SF decreased the fractional anisotropy (FA) of white matter fibers in the hippocampal CA1, while the medial septum was not affected. Moreover, post-operative SF aggravated subsequent Y-maze and novel object recognition performances accompanied by abnormal enhancement of glutamatergic metabolism signal. This study suggests that 24-h SF induces hyperglutamate metabolism level and microstructural connectivity damage in sleep and cognitive brain regions in aged mice, which may be involved in the pathophysiological process of POCD.

Functional Connectivity Changes in the Insular Subregions of Patients with Obstructive Sleep Apnea after 6 Months of Continuous Positive Airway Pressure Treatment

This study was aimed at investigating the functional connectivity (FC) changes between the insular subregions and whole brain in patients with obstructive sleep apnea (OSA) after 6 months of continuous positive airway pressure (CPAP) treatment and at exploring the relationship between resting-state FC changes and cognitive impairment in OSA patients. Data from 15 patients with OSA before and after 6 months of CPAP treatment were included in this study. The FC between the insular subregions and whole brain was compared between baseline and after 6 months of CPAP treatment in OSA. After 6 months of treatment, OSA patients had increased FC from the right ventral anterior insula to the bilateral superior frontal gyrus and bilateral middle frontal gyrus and increased FC from the left posterior insula to the left middle temporal gyrus and left inferior temporal gyrus. Hyperconnectivity was found from the right posterior insula to the right middle temporal gyrus, bilateral precuneus, and bilateral posterior cingulate cortex, which mainly involved the default mode network. There are changes in functional connectivity patterns between the insular subregions and whole brain in OSA patients after 6 months of CPAP treatment. These changes provide a better understanding of the neuroimaging mechanisms underlying the improvement in cognitive function and emotional impairment in OSA patients and can be used as potential biomarkers for clinical CPAP treatment.

Exploring the brain with sleep-related injuries, and fixing it

The focus of my research efforts rests with determining dysfunctional neural systems underlying disorders of sleep, and identifying interventions to overcome those disorders. Aberrant central and physiological control during sleep exerts serious consequences, including disruptions in breathing, motor control, blood pressure, mood, and cognition, and plays a major role in sudden infant death syndrome, congenital central hypoventilation, and sudden unexpected death in epilepsy, among other concerns. The disruptions can be traced to brain structural injury, leading to inappropriate outcomes. Identification of failing systems arose from the assessment of single neuron discharge in intact, freely moving and state-changing human and animal preparations within multiple systems, including serotonergic action and motor control sites. Optical imaging of chemosensitive, blood pressure and other breathing regulatory areas, especially during development, were useful to show integration of regional cellular action in modifying neural output. Identification of damaged neural sites in control and afflicted humans through structural and functional magnetic resonance imaging procedures helped to identify the sources of injury, and the nature of interactions between brain sites that compromise physiological systems and lead to failure. Interventions to overcome flawed regulatory processes were developed, and incorporate noninvasive neuromodulatory means to recruit ancient reflexes or provide peripheral sensory stimulation to assist breathing drive to overcome apnea, reduce the frequency of seizures, and support blood pressure in conditions where a failure to perfuse can lead to death.

Machine learning approach for obstructive sleep apnea screening using brain diffusion tensor imaging

Patients with obstructive sleep apnea (OSA) show autonomic, mood, cognitive, and breathing dysfunctions that are linked to increased morbidity and mortality, which can be improved with early screening and intervention. The gold standard and other available methods for OSA diagnosis are complex, require whole-night data, and have significant wait periods that potentially delay intervention. Our aim was to examine whether using faster and less complicated machine learning models, including support vector machine (SVM) and random forest (RF), with brain diffusion tensor imaging (DTI) data can classify OSA from healthy controls. We collected two DTI series from 59 patients with OSA [age: 50.2 ± 9.9 years; body mass index (BMI): 31.5 ± 5.6 kg/m2 ; apnea-hypopnea index (AHI): 34.1 ± 21.2 events/h 23 female] and 96 controls (age: 51.8 ± 9.7 years; BMI: 26.2 ± 4.1 kg/m2 ; 51 female) using a 3.0-T magnetic resonance imaging scanner. Using DTI data, mean diffusivity maps were calculated from each series, realigned and averaged, normalised to a common space, and used to conduct cross-validation for model training and selection and to predict OSA. The RF model showed 0.73 OSA and controls classification accuracy and 0.85 area under the curve (AUC) value on the receiver-operator curve. Cross-validation showed the RF model with comparable fitting over SVM for OSA and control data (SVM; accuracy, 0.77; AUC, 0.84). The RF ML model performs similar to SVM, indicating the comparable statistical fitness to DTI data. The findings indicate that RF model has similar AUC and accuracy over SVM, and either model can be used as a faster OSA screening tool for subjects having brain DTI data.

Relationships between brain tissue damage, oxygen desaturation, and disease severity in obstructive sleep apnea evaluated by diffusion tensor imaging

STUDY OBJECTIVES

Patients with obstructive sleep apnea (OSA) show brain injury in sites responsible for autonomic, cognitive, and respiratory functions. Brain changes in OSA may vary with disease severity as assessed by the apnea-hypopnea index (AHI), which does not provide information about the apnea depth and length in contrast to oxygen desaturation. Although significant associations with brain injury and AHI are known in OSA, it is unclear whether AHI or the extent of oxygen desaturations better correlate with brain damage. We evaluated associations between brain changes, AHI, and oxygen desaturation using diffusion tensor imaging-based measures.

METHODS

We acquired diffusion tensor imaging data from 19 patients with OSA using a 3.0-Tesla MRI scanner and calculated, normalized, and smoothed mean, axial, and radial diffusivity maps that were used for correlations between brain changes, oxygen desaturation, and AHI values.

RESULTS

Positive correlations with extent of injury (mean, axial, and radial diffusivity values) and AHI appeared in the frontal areas, cingulate and insula, amygdala, hippocampus, and basal pons, and negative associations emerged in the putamen, internal-capsule, globus-pallidus, and cerebellar cortices. Regional diffusivity values and oxygen desaturation showed positive correlations in the cingulate, frontal, putamen, and cerebellar sites, and negative relationships in several areas, including the occipital cortex.

CONCLUSIONS

Patients with OSA show negative and positive correlations, indicated by increased and decreased diffusivity values, resulting from chronic and acute changes in those areas. The extent of injury in OSA partially depends on the extent of AHI and oxygen desaturation, with the effects representing continued development from acute to chronic processes.

CITATION

Sahib A, Roy B, Kang D, Aysola RS, Wen E, Kumar R. Relationships between brain tissue damage, oxygen desaturation, and disease severity in obstructive sleep apnea evaluated by diffusion tensor imaging. J Clin Sleep Med. 2022;18(12):2713-2721.

Brain tissue integrity mapping in adults with obstructive sleep apnea using T1-weighted and T2-weighted images

BACKGROUND

Obstructive sleep apnea (OSA) is accompanied by both gray and white matter differences in brain areas that regulate autonomic, cognitive, and mood functions, which are deficient in the condition. Such tissue changes have been examined through diffusion tensor and diffusion kurtosis imaging-based procedures. However, poor in-plane spatial resolution of these techniques precludes precise determination of the extent of tissue injury. Tissue texture maps derived from the ratio of T1-weighted and T2-weighted images can provide more adequate in-plane assessment of brain tissue differences.

OBJECTIVES

To examine brain tissue integrity in recently diagnosed, treatment-naïve OSA subjects, relative to age- and sex-comparable control subjects using T1-weighted and T2-weighted images.

DESIGN

A cross-sectional study.

METHODS

We examined the extent of tissue changes in 106 OSA over 115 control subjects using high-resolution T1- and T2-weighted images collected from a 3.0-Tesla scanner (analysis of covariance; covariates: age, sex, body-mass-index, Pittsburgh sleep quality index, Epworth sleepiness scale, Beck Anxiety Inventory, and Beck Depression Inventory II; false discovery rate corrected; p < 0.01).

RESULTS

OSA subjects showed significantly lowered tissue integrity in several brain regions, including the frontal, cingulate and insular cortices, cingulum bundle, thalamus, corpus callosum, caudate and putamen, pons, temporal, occipital, and parietal sites, cerebellar peduncles, and medial medullary sites, compared with controls.

CONCLUSION

OSA subjects show widespread lowered tissue integrity in autonomic, mood, and cognitive control sites over healthy controls. The pathological processes contributing to the alterations may include repetitive hypoxic and hypercarbic processes and excitotoxic injury, leading to altered brain tissue integrity in OSA.

Prevalence of depression and anxiety in obstructive sleep apnea

INTRODUCTION

Organic comorbidities of obstructive sleep apnea (OSA) have been widely studied. However, psychiatric disorders, especially depression and anxiety, have not attracted so much attention.

AIM

The primary aim was to determine the prevalence and the predictive factors of depression and anxiety in OSA patients. The secondary aim was to investigate the association between OSA severity and these psychiatric disorders.

METHODS

A cross-sectional study including untreated OSA patients without mental illness history was conducted. Patients were administered the Hospital Anxiety (HADS-A) and Depression Scale (HADS-D). Depression and anxiety were diagnosed for HAD-D and HAD-A scores ≥ 8.

RESULTS

Eighty patients were included (mean age: 54.83 ± 13.12 yr; female: 52 (65%); mean Body mass index (BMI) :34.7±6.14 kg/m2). The prevalence of depression and anxiety was 35 % and 43.8% of patients respectively. Both depressive and anxious OSA patients had more libido disorder ( p=0.011, p=0.0007 ;respectively), anhedonia (p= 10-4, p= 10-4respectively ) and suicidal ideas(p= 0.002 ,p=0.019 respectively). Moreover, depressed OSA patients had lower socio-economic condition (p= 0.019), more coronary artery diseases (CAD) (p=0.019) and less cognitive disorder (p= 0.005). The HADS-D (r=0,095; p=0,404) and the HADS-A (r=0,212; p=0,059) were not correlated with the Apnea/Hyponea Index. The determinants of depressive and anxious mood were female-sex (p= 0.035, p=0.004 respectively) and libido disorder (p=0.040, p=0.02 respectively). Anhedonia (p=10-4) and CAD (p=0.010) were also identified as a predictive factors of depression.

CONCLUSIONS

In our study, the high prevalence of depression and axiety in apneic patients demonstrates the importance of the psychiatric component in the management of this disease. A collaboration between pneumologists and psychiatrists is necessary in order to improve the quality of life of these patients.

[Effects of continuous positive airway pressure on depression, anxiety and quality of life in obstructive sleep apnea hypopnea syndrome patients]

INTRODUCTION

The obstructive sleep apnea hypopnea syndrome (OSAHS) is a chronic stressor that may alter the emotional state and quality of life (QOL) of patients suffering from it. In this work, we proposed to estimate the prevalence of depression and anxiety, to assess the QOL in a Tunisian population of apneic patients, and to assess their evolution under continuous positive airway pressure (CPAP).

METHODS

We conducted a prospective study, involving 33 apneic patients followed for SAHOS with moderate or severe class disease in the pneumology department at Hedi Chaker university hospital in Sfax, Tunisia. They received CPAP treatment for three months. We used an epidemiological record. Two scales, the Hospital Anxiety and Depression Scale (HADS) and the 36-item Short-Form Health Survey (SF-36), were completed before and after treatment to evaluate the effect of three months of treatment with CPAP.

RESULTS

The prevalence of depression in the study's patients, according to the HADS, was 45.5% and that of anxiety was 21.2%. After 3months of CPAP, the prevalence of depression and anxiety had become 18.2% and 6.1%, respectively. QOL was impaired in 81.8% of cases before treatment, according to the SF-36. This figure had decreased to 69.7% after 3months of treatment with CPAP. Apart from the third dimension (physical pain), all other dimensions were significantly improved after 3months of CPAP treatment. The treatment with CPAP induced a significant improvement in the average scores of depression (P<0.001), anxiety (P=0.002) and QOL (P<0.001).

CONCLUSIONS

These results attest to the importance of the frequency of anxio-depressive disorders as well as an altered QOL in patients with OSAHS. CPAP treatment was shown to be effective in improving these parameters, but this efficacy was partial. Specialized care may be needed in cases of residual anxio-depressive symptoms.

Functional organization of the insula in men and women with obstructive sleep apnea during Valsalva

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) patients show impaired autonomic regulation, perhaps related to functional reorganization of the insula, which in healthy individuals shows sex-specific anterior and right dominance during sympathetic activation. We examined insular organization of responses to a Valsalva maneuver in OSA with functional magnetic resonance imaging (fMRI).

METHODS

We studied 43 newly diagnosed OSA (age mean ± SD: 46.8 ± 8.7 years; apnea-hypopnea index (AHI) ± SD: 32.1 ± 20.1 events/hour; 34 males) and 63 healthy (47.2 ± 8.8 years; 40 males) participants. Participants performed four 18-second Valsalva maneuvers (1-minute intervals, pressure ≥ 30 mmHg) during scanning. fMRI time trends from five insular gyri-anterior short (ASG); mid short (MSG); posterior short (PSG); anterior long (ALG); and posterior long (PLG)-were assessed for within-group responses and between-group differences with repeated measures ANOVA (p < 0.05); age and resting heart rate (HR) influences were also assessed.

RESULTS

Right and anterior fMRI signal dominance appeared in OSA and controls, with no between-group differences. Separation by sex revealed group differences. Left ASG anterior signal dominance was lower in OSA versus control males. Left ASG and ALG anterior dominance was higher in OSA versus control females. In all right gyri, only OSA females showed greater anterior dominance than controls. Right dominance was apparent in PSG and ALG in all groups; females showed right dominance in MSG and PLG. OSA males did not show PLG right dominance. Responses were influenced substantially by HR but modestly by age.

CONCLUSIONS

Anterior and right insular fMRI dominance appears similar in OSA versus control participants during the sympathetic phase of the Valsalva maneuver. OSA and control similarities were present in just males, but not necessarily females, which may reflect sex-specific neural injury.

Decoding Causal Links Between Sleep Apnea and Alzheimer’s Disease

Obstructive sleep apnea (OSA) and Alzheimer’s disease (AD) are two common chronic diseases with a well-documented association. Whether the association is causal has been highlighted by recent evidence reporting a neurobiological link between these disorders. This narrative review discusses the brain regions and networks involved in OSA as potential vulnerable areas for the development of AD neuropathology with a particular focus on gender-related implications. Using a neuroimaging perspective supported by neuropathological investigations, we provide a new model of neurodegeneration common to OSA and AD, that we have called OSA-AD neurodegeneration in order to decode the causal links between these two chronic conditions.

Insular functional organization during handgrip in females and males with obstructive sleep apnea

STUDY OBJECTIVES

Brain regulation of autonomic function in obstructive sleep apnea (OSA) is disrupted in a sex-specific manner, including in the insula, which may contribute to several comorbidities. The insular gyri have anatomically distinct functions with respect to autonomic nervous system regulation; yet, OSA exerts little effect on the organization of insular gyral responses to sympathetic components of an autonomic challenge, the Valsalva. We further assessed neural responses of insular gyri in people with OSA to a static handgrip task, which principally involves parasympathetic withdrawal.

METHODS

We measured insular function with blood oxygen level dependent functional MRI. We studied 48 newly-diagnosed OSA (age mean±std:46.5±9 years; AHI±std:32.6±21.1 events/hour; 36 male) and 63 healthy (47.2±8.8 years;40 male) participants. Subjects performed four 16s handgrips (1 min intervals, 80% subjective maximum strength) during scanning. fMRI time trends from five insular gyri-anterior short (ASG); mid short (MSG); posterior short (PSG); anterior long (ALG); and posterior long (PLG)-were assessed for within-group responses and between-group differences with repeated measures ANOVA (p<0.05) in combined and separate female-male models; age and resting heart-rate (HR) influences were also assessed.

RESULTS

Females showed greater right anterior dominance at the ASG, but no differences emerged between OSA and controls in relation to functional organization of the insula in response to handgrip. Males showed greater left anterior dominance at the ASG, but there were also no differences between OSA and controls. The males showed a group difference between OSA and controls only in the ALG. OSA males had lower left activation at the ALG compared to control males. Responses were mostly influenced by HR and age; however, age did not impact the response for right anterior dominance in females.

CONCLUSIONS

Insular gyri functional responses to handgrip differ in OSA vs controls in a sex-based manner, but only in laterality of one gyrus, suggesting anterior and right-side insular dominance during sympathetic activation but parasympathetic withdrawal is largely intact, despite morphologic injury to the overall structure.

Association of Obstructive Sleep Apnea With the Risk of Affective Disorders

Importance

Obstructive sleep apnea (OSA) is a common subtype of sleep breathing disorder; however, the association between OSA and the psychological health of affected individuals has not been fully evaluated.

Objective

To investigate the association between OSA and development of affective disorders.

Design, Setting, and Participants

This study used a nationwide representative cohort sample from the Korea National Health Insurance Service-National Sample Cohort database comprising data from 1 025 340 patients. The study included 197 patients with OSA diagnosed between January 2004 and December 2006 and 780 individuals without OSA who were matched using propensity score matching. Data were analyzed from September 28, 2018, to March 30, 2019.

Main Outcomes and Measures

Affective disorder events over a 9-year follow-up period. Kaplan-Meier survival curves with log-rank tests and Cox proportional hazards regression models were used to calculate cumulative incidence and hazard ratios (HRs) of affective disorders for each group.

Results

Of the total population of 985 (860 male [87.3%], 540 [54.8%] were aged <45 years), the incidences per 1000 person-years of affective disorders were 49.57 and 27.18 in the OSA and comparison groups, respectively. A total of 1371.7 person-years in the OSA group and 6328.6 person-years in the comparison group were evaluated for affective disorder events. After adjustment for sociodemographic factors (age, residential area, and household income), disability, and comorbidities, the adjusted HRs for patients with OSA developing affective disorders in patients with OSA during the 9-year follow-up period was 2.04 (95% CI, 1.53-2.70). In a subgroup analysis, the adjusted HRs for patients with OSA who developed depressive and anxiety disorders were 2.90 (95% CI, 1.98-4.24) and 1.75 (95% CI, 1.26-2.44), respectively. Moreover, female patients with OSA had a significant likelihood of prospective development of depression and anxiety (adjusted HR for depression, 3.97 [95% CI, 1.54-10.19]; adjusted HR for anxiety, 2.42 [95% CI, 1.17-5.02]) compared with male patients with OSA (adjusted HR for depression, 2.74 [95% CI, 1.80-4.17]; adjusted HR for anxiety, 1.64 [95% CI, 1.13-2.39]).

Conclusions and Relevance

This observational study using nationwide data suggests that OSA is associated with an increased incidence of affective disorder, such as depression and anxiety. Further studies appear to be needed to confirm our findings and, if validated, then studies are needed to explore the nature of the observed association, including potential causality, between OSA and affective symptoms.

Changes in insular cortex metabolites in patients with obstructive sleep apnea syndrome

The aim of this study was to investigate the changes in insular cortex metabolites and the correlation with clinical manifestations in patients with obstructive sleep apnea syndrome (OSA). Lateral insular metabolite levels were measured and relevant ratios were calculated in OSA patients and healthy individuals, including N-acetyl aspartate/creatine (NAA/Cr), choline/creatine (Cho/Cr), inositol/creatine (Ins/Cr), glutamate compound/creatine (Glx/Cr), N-acetyl aspartate/choline (NAA/Cho), and lactic acid (Lac). Participants' scores on the Hamilton Anxiety Scale (HAMA), the Hamilton Depression Scale (HAMD), the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale (ESS) were also evaluated. Apnea-Hypopnea Index, the lowest arterial oxygen saturation, and the mean arterial oxygen saturation (MSaO2) values were monitored by polysomnography. NAA/Cr, Glx/Cr, and NAA/Cho values in the insular cortex were significantly decreased, whereas HAMA, HAMD, PSQI, and ESS scores were significantly higher in OSA patients compared with the control participants. HAMA and HAMD scores showed a significant negative correlation with the NAA/Cho value in the insular cortex and a positive correlation with PSQI and ESS scores. PSQI scores were correlated positively with the Cho/Cr and Ins/Cr ratios in the left insular cortex, but correlated negatively with the NAA/Cho ratio. The symptoms of anxiety and depression in OSA patients may be associated with insular neuron damage or dysfunction; proton magnetic resonance spectroscopy can provide an objective imaging basis for the early diagnosis and treatment of OSA in clinical practice.

A Pilot Study About the Dysfunction of Adipose Tissue in Male, Sleep Apneic Patients in Relation to Psychological Symptoms

Introduction: Obstructive sleep apnea (OSA) and its cardiometabolic alterations are closely associated with visceral obesity. Patients with OSA frequently present with symptoms of depression and anxiety. Although these subjective symptoms of OSA are the result of complex biological dysregulation, it remains unclear if they have a direct effect on the dysfunction of adipose tissue. Methods: In a pilot, prospective, randomized study, we evaluated 10 recently diagnosed male patients with severe OSA by full polysomnography (PSG) and 4 male non-apneic subjects matched for age and body mass index (BMI) with abdomen adipose tissue biopsies. Subjects with diabetes/prediabetes and cardiovascular and psychiatric diseases and who are current smokers were excluded. All patients underwent anthropometric measurements and completed the following questionnaires: Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and Hospital Anxiety and Depression Scale (HADS-A and HADS-D). Fasting venous blood samples were collected on the day after PSG, between 8:00 and 9:00 a.m., after an overnight fast. Fat biopsies were performed at the same time periods and adipose tissue samples of 300 mg were obtained from abdominal fat. Fat cell size, extent of fibrosis, vascularity, leukocyte common antigen inflammatory infiltration, and tissue macrophage accumulation were microscopically evaluated. Results: The mean age of the group was 47.4 ± 13.8 years, with mean BMI of 35.8 ± 4.8 kg/m² and mean apnea-hypopnea index of 79.4 ± 46.1 events per hour of sleep (severe OSA). HADS-A and HADS-D scores were 5.8 ± 2.3 (3.0-8.0) and 4.7 ± 2.3 (2.0-8.0), respectively. HADS-A score correlated positively with macrophage accumulation in fat biopsy (r = 0.82, p = 0.047), whereas ESS, FSS, and HADS-D did not. Severity of fibrosis correlated largely with waist circumference (r = -0.66, p = 0.038) and neck circumference (r = -0.790, p = 0.006). Respiratory events correlated negatively with the extent of vascularization of adipose tissue (r = -0.614, p = 0.05). Conclusions: In the preliminary results of our pilot study, we assessed that the symptoms of anxiety mainly contribute to macrophage accumulation, whereas the increased number of respiratory events reduces the extent of vascularization in visceral fat in OSA. Based on this observation, further larger studies are required to verify if anxious OSA patients are more vulnerable to the metabolic manifestations of the syndrome.

Sleep and libido in men with obstructive sleep apnea syndrome

OBJECTIVES

The objectives of this study were to investigate the relationship between a low libido and objective sleep parameters as well as mood disturbances in patients with obstructive sleep apnea syndrome (OSA).

METHODS

We enrolled 436 untreated patients who were newly diagnosed with OSA (all male, mean age 42.8 years). Patients completed the Symptom checklist-90-Revised (SCL-90-R), Epworth Sleepiness Scale (ESS), Beck Depression Inventory-II (BDI), and Beck Anxiety Inventory (BAI). Patients were divided into low-libido and normal-libido groups according to their response to the statement "Loss of sexual interest or pleasure" on the SCL-90-R.

RESULTS

Approximately 23% of patients reported a low libido. Patients with a low libido were older (47.5 ± 9.0 vs. 41.4 ± 11.1 years; p < 0.001), had more nocturia (33.3% vs. 16.6%; p < 0.001), higher BDI (9.0 (5.0-14.0) vs. 5.0 (2.0-9.0); p < 0.001) and BAI score (11.0 (6.3-16.8) vs. 5.0 (2.0-10.0); p < 0.001). These patients had a lower non-REM sleep stage 3 (N3) % (0.1 (0-4.0) vs. 2.3 (0.1-7.9); p < 0.001). Multivariate analysis revealed that older age and higher BDI score were independent factors associated with a low libido.

CONCLUSIONS

Men with untreated OSA suffered from a low libido. Older age and depressed mood were the most important factors of low libido in middle-aged men with OSA.

Effects of Habenular Stimulation Frequencies on Obstructive Sleep Apnea Induced by Stimulation of Insular Cortex

Objective

To investigate the effects of high-frequency stimulation of the habenula (Hb) on obstructive sleep apnea (OSA) induced by stimulation of the insular cortex Method. After OSA was induced by stimulating the insular cortex (Ic) with concentric stimulating electrodes at 100 Hz in rats, the Hb was stimulated at different frequencies (50 Hz, 120 Hz, 130 Hz, and 280 Hz). The changes of apnea events and electromyography (EMG) of the genioglossus were compared before and after stimulation of the Hb.

Results

With stimulation of the Ic at 100 Hz, apnea events were successfully induced with disappearance of EMG of the genioglossus. After stimulation of the Hb at 130 Hz, apnea events disappeared with significantly increased genioglossal EMG. However, such a change failed to be found at the stimulation frequencies of 50 Hz, 120 Hz, and 280 Hz.

Conclusion

Stimulation of the Hb at the frequency of 130 Hz could effectively inhibit OSA events induced by stimulation of the Ic.

Aberrant brain functional connectome in patients with obstructive sleep apnea

OBJECTIVE

Obstructive sleep apnea (OSA) is accompanied by widespread abnormal spontaneous regional activity related to cognitive deficits. However, little is known about the topological properties of the functional brain connectome of patients with OSA. This study aimed to use the graph theory approaches to investigate the topological properties and functional connectivity (FC) of the functional connectome in patients with OSA, based on resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

Forty-five male patients with newly diagnosed untreated severe OSA and 45 male good sleepers (GSs) underwent a polysomnography (PSG), clinical evaluations, and rs-fMRI scans. The automated anatomical labeling (AAL) atlas was used to construct the functional brain connectome. The topological organization and FC of brain functional networks in patients with OSA were characterized using graph theory methods and investigated the relationship between functional network topology and clinical variables.

RESULTS

Both the patients with OSA and the GSs exhibited high-efficiency "small-world" network attributes. However, the patients with OSA exhibited decreased σ, γ, Eglob; increased Lp, λ; and abnormal nodal centralities in several default-mode network (DMN), salience network (SN), and central executive network (CEN) regions. However, the patients with OSA exhibited abnormal functional connections between the DMN, SN, and CEN. The disrupted FC was significantly positive correlations with the global network metrics γ and σ. The global network metrics were significantly correlated with the Epworth Sleepiness Scale (ESS) score, Montreal Cognitive Assessment (MoCA) score, and oxygen desaturation index.

CONCLUSION

The findings suggest that the functional connectome of patients with OSA exhibited disrupted functional integration and segregation, and functional disconnections of the DMN, SN, and CEN. The aberrant topological attributes may be associated with disrupted FC and cognitive functions. These topological abnormalities and disconnections might be potential biomarkers of cognitive impairments in patients with OSA.

Relationships between obstructive sleep apnea and anxiety

PURPOSE OF REVIEW

To summarize recent research investigating the interaction between obstructive sleep apnea (OSA) and anxiety, and contextualize their bidirectional relationship.

RECENT FINDINGS

Recent investigations corroborate the bidirectional relationship between sleep-disordered breathing (SDB) and anxiety, evaluate the etiological and clinical manifestations through different mechanisms, and provide insight into clinical implications of this interaction. Much of the literature about anxiety as it relates to SDB is from small samples, using different tools of symptom measurement that are often subjectively quantified. The objective severity of OSA does not appear to be associated with subjectively reported sleepiness and fatigue, whereas physiological manifestations of anxiety are associated with the severity of subjective symptoms reported. Recent findings support that women are more likely to have comorbid SDB and anxiety than men. SDB may precipitate and perpetuate anxiety, whereas anxiety in OSA negatively impacts quality-of-life. Treating SDB may improve anxiety symptoms, whereas anxiety symptoms can be an obstacle and deterrent to appropriate treatment.

SUMMARY

The interaction between anxiety and SDB is still poorly elucidated. Being aware of the clinical associations, risk factors, and treatment implications for SDB as related to anxiety disorders in different populations can help clinicians with the diagnosis and management of both SDB and anxiety.

Altered Regional Brain Cortical Thickness in Pediatric Obstructive Sleep Apnea

Rationale

Obstructive sleep apnea (OSA) affects 2–5% of all children and is associated with cognitive and behavioral deficits, resulting in poor school performance. These psychological deficits may arise from brain injury, as seen in preliminary findings of lower gray matter volume among pediatric OSA patients. However, the psychological deficits in OSA are closely related to functions in the cortex, and such brain areas have not been specifically assessed. The objective was to determine whether cortical thickness, a marker of possible brain injury, is altered in children with OSA.

Methods

We examined regional brain cortical thicknesses using high-resolution T1-weighted magnetic resonance images in 16 pediatric OSA patients (8 males; mean age ± SD = 8.4 ± 1.2 years; mean apnea/hypopnea index ± SD = 11 ± 6 events/h) and 138 controls (8.3 ± 1.1 years; 62 male; 138 subjects from the NIH Pediatric MRI database) to identify cortical thickness differences in pediatric OSA subjects.

Results

Cortical thinning occurred in multiple regions including the superior frontal, ventral medial prefrontal, and superior parietal cortices. The left side showed greater thinning in the superior frontal cortex. Cortical thickening was observed in bilateral precentral gyrus, mid-to-posterior insular cortices, and left central gyrus, as well as right anterior insula cortex.

Conclusion

Changes in cortical thickness are present in children with OSA and likely indicate disruption to neural developmental processes, including maturational patterns of cortical volume increases and synaptic pruning. Regions with thicker cortices may reflect inflammation or astrocyte activation. Both the thinning and thickening associated with OSA in children may contribute to the cognitive and behavioral dysfunction frequently found in the condition.

Obstructive sleep apnea is associated with altered midbrain chemical concentrations

Obstructive sleep apnea (OSA) is accompanied by altered structure and function in cortical, limbic, brainstem, and cerebellar regions. The midbrain is relatively unexamined, but contains many integrative nuclei which mediate physiological functions that are disrupted in OSA. We therefore assessed the chemistry of the midbrain in OSA in this exploratory study. We used a recently developed accelerated 2D magnetic resonance spectroscopy (2D-MRS) technique, compressed sensing-based 4D echo-planar J-resolved spectroscopic imaging (4D-EP-JRESI), to measure metabolites in the midbrain of 14 OSA (mean age±SD:54.6±10.6years; AHI:35.0±19.4; SAO2 min:83±7%) and 26 healthy control (50.7±8.5years) subjects. High-resolution T1-weighted scans allowed voxel localization. MRS data were processed with custom MATLAB-based software, and metabolite ratios calculated with respect to the creatine peak using a prior knowledge fitting (ProFit) algorithm. The midbrain in OSA showed decreased N-acetylaspartate (NAA; OSA:1.24±0.43, Control:1.47±0.41; p=0.03; independent samples t-test), a marker of neuronal viability. Increased levels in OSA over control subjects appeared in glutamate (Glu; OSA:1.23±0.57, Control:0.98±0.33; p=0.03), ascorbate (Asc; OSA:0.56±0.28, Control:0.42±0.20; (50.7±8.5years; p=0.03), and myo-inositol (mI; OSA:0.96±0.48, Control:0.72±0.35; p=0.03). No differences between groups appeared in γ-aminobutyric acid (GABA) or taurine. The midbrain in OSA patients shows decreased NAA, indicating neuronal injury or dysfunction. Higher Glu levels may reflect excitotoxic processes and astrocyte activation, and higher mI is also consistent with glial activation. Higher Asc levels may result from oxidative stress induced by intermittent hypoxia in OSA. Additionally, Asc and Glu are involved with glutamatergic processes, which are likely upregulated in the midbrain nuclei of OSA patients. The altered metabolite levels help explain dysfunction and structural deficits in the midbrain of OSA patients.

Non-Gaussian Diffusion Imaging Shows Brain Myelin and Axonal Changes in Obstructive Sleep Apnea

OBJECTIVE

Obstructive sleep apnea (OSA) is accompanied by brain changes in areas that regulate autonomic, cognitive, and mood functions, which were initially examined by Gaussian-based diffusion tensor imaging measures, but can be better assessed with non-Gaussian measures. We aimed to evaluate axonal and myelin changes in OSA using axial (AK) and radial kurtosis (RK) measures.

MATERIALS AND METHODS

We acquired diffusion kurtosis imaging data from 22 OSA and 26 controls; AK and RK maps were calculated, normalized, smoothed, and compared between groups using analysis of covariance.

RESULTS

Increased AK, indicating axonal changes, emerged in the insula, hippocampus, amygdala, dorsolateral pons, and cerebellar peduncles and showed more axonal injury over previously identified damage. Higher RK, showing myelin changes, appeared in the hippocampus, amygdala, temporal and frontal lobes, insula, midline pons, and cerebellar peduncles and showed more widespread myelin damage over previously identified injury.

CONCLUSIONS

Axial kurtosis and RK measures showed widespread changes over Gaussian-based techniques, suggesting a more sensitive nature of kurtoses to injury.

Accelerated Echo Planer J-resolved Spectroscopic Imaging of Putamen and Thalamus in Obstructive Sleep Apnea

Obstructive sleep apnea syndrome (OSAS) leads to neurocognitive and autonomic deficits that are partially mediated by thalamic and putamen pathology. We examined the underlying neurochemistry of those structures using compressed sensing-based 4D echo-planar J-resolved spectroscopic imaging (JRESI), and quantified values with prior knowledge fitting. Bilaterally increased thalamic mI/Cr, putamen Glx/Cr, and Glu/Cr, and bilaterally decreased thalamic and putamen tCho/Cr and GABA/Cr occurred in OSAS vs healthy subjects (p < 0.05). Increased right thalamic Glx/Cr, Glu/Cr, Gln/Cr, Asc/Cr, and decreased GPC/Cr and decreased left thalamic tNAA/Cr, NAA/Cr were detected. The right putamen showed increased mI/Cr and decreased tCho/Cr, and the left, decreased PE/Cr ratio. ROC curve analyses demonstrated 60–100% sensitivity and specificity for the metabolite ratios in differentiating OSAS vs. controls. Positive correlations were found between: left thalamus mI/Cr and baseline oxygen saturation (SaO₂); right putamen tCho/Cr and apnea hypopnea index; right putamen GABA/Cr and baseline SaO₂; left putamen PE/Cr and baseline SaO₂; and left putamen NAA/Cr and SaO₂ nadir (all p < 0.05). Negative correlations were found between left putamen PE/Cr and SaO₂ nadir. These findings suggest underlying inflammation or glial activation, with greater alterations accompanying lower oxygen saturation. These metabolite levels may provide biomarkers for future neurochemical interventions by pharmacologic or other means.

Changes in cerebral metabolites in obstructive sleep apnea: a systemic review and meta-analysis

Cognitive impairment is associated with changes in cerebral metabolites in patients with obstructive sleep apnea (OSA). Several studies have used magnetic resonance spectroscopy (MRS) to detect variations in cerebral metabolites; however, the results have been inconsistent. This meta-analysis summarizes the differences in cerebral metabolites between patients with OSA and controls. Two electronic databases, PubMed and Embase, were searched for articles (published before March 31, 2016) describing studies that used MRS to evaluate the cerebral metabolite changes. The overall effects were measured using the weighted mean difference with a 95% confidence interval. Subgroup analysis and sensitivity analysis were used to explore the sources of between-study heterogeneity and the stability of the results. Publication bias was also evaluated. Thirteen studies were ultimately included. In the hippocampus, the N-acetylaspartate (NAA)/creatine ratio was lower in patients with OSA. In the frontal lobe, only the NAA/choline ratio was lower in patients with OSA. Cerebral metabolites are significantly altered in the hippocampus in patients with OSA. Further clinical studies are needed to explore the underlying mechanisms between OSA and the changes in cerebral metabolites in the brain.

Aberrant Insular Functional Network Integrity in Patients with Obstructive Sleep Apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is accompanied by tissue injury to the insular cortices, areas that regulate autonomic pain, dyspnea, and mood, all of which are affected in the syndrome. Presumably, the dysregulation of insular-related functions are mediated by aberrant functional connections with other brain regions; however, the integrity of the functional connectivity (FC) to other sites is undescribed. Our aim was to examine resting-state FC of the insular cortices to other brain areas in OSA, relative to control subjects.

METHODS

We collected resting-state functional magnetic resonance imaging (MRI) data from 67 newly diagnosed, treatment-naïve OSA and 75 control subjects using a 3.0-Tesla MRI scanner. After standard processing, data were analyzed for the left and right insular FC.

RESULTS

OSA subjects showed complex aberrant insular FC to several brain regions, including frontal, parietal, cingulate, temporal, limbic, basal ganglia, thalamus, occipital, cerebellar, and brainstem regions. Areas of altered FC in OSA showed linear relationships with magnitudes of sleep related and neuropsychologic-related variables, whereas control subjects showed no such relationships with those measures.

CONCLUSIONS

Brain functional connections from insular sites to other brain regions in OSA subjects represent abnormal autonomic, affective, sensorimotor, and cognitive control networks that may affect both impaired parasympathetic and sympathetic interactions, as well as abnormal sensorimotor integration, affected in the condition. The functional changes likely result from the previously reported structural changes in OSA subjects, as demonstrated by diverse neuroimaging studies.

Structural and functional neural adaptations in obstructive sleep apnea: An activation likelihood estimation meta-analysis

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The right basolateral amygdala, the hippocampus and the right insular cortex are important nodes in obstructive sleep apnea (OSA).

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Functional characterization of these regions suggested associated dysfunction of emotional, sensory, and limbic processes in OSA.

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Connectivity analysis demonstrated that these regions are part of a joint network comprising the anterior insula, posterior-medial frontal cortex and thalamus.

Obstructive sleep apnea (OSA) is a common multisystem chronic disorder. Functional and structural neuroimaging has been widely applied in patients with OSA, but these studies have often yielded diverse results. The present quantitative meta-analysis aims to identify consistent patterns of abnormal activation and grey matter loss in OSA across studies. We used PubMed to retrieve task/resting-state functional magnetic resonance imaging and voxel-based morphometry studies. Stereotactic data were extracted from fifteen studies, and subsequently tested for convergence using activation likelihood estimation. We found convergent evidence for structural atrophy and functional disturbances in the right basolateral amygdala/hippocampus and the right central insula. Functional characterization of these regions using the BrainMap database suggested associated dysfunction of emotional, sensory, and limbic processes. Assessment of task-based co-activation patterns furthermore indicated that the two regions obtained from the meta-analysis are part of a joint network comprising the anterior insula, posterior-medial frontal cortex and thalamus. Taken together, our findings highlight the role of right amygdala, hippocampus and insula in the abnormal emotional and sensory processing in OSA.

Obstructive sleep apnea is associated with low GABA and high glutamate in the insular cortex

The insular cortex is injured in obstructive sleep apnea (OSA) and responds inappropriately to autonomic challenges, suggesting neural reorganization. The objective of this study was to assess whether the neural changes might result from γ-aminobutyric acid (GABA) and glutamate alterations. We studied 14 OSA patients [mean age ± standard deviation (SD): 47.5 ± 10.5 years; nine male; apnea-hypopnea index (AHI): 29.5 ± 15.6 events h(-1) ] and 22 healthy participants (47.5 ± 10.1 years; 11 male), using magnetic resonance spectroscopy to detect GABA and glutamate levels in insular cortices. We localized the cortices with anatomical scans, and measured neurochemical levels from anterior to mid-regions. Left and right anterior insular cortices showed lower GABA and higher glutamate in OSA versus healthy subjects [GABA left: OSA n = 6: 0.36 ± 0.10 (mean ± SD), healthy n = 5: 0.62 ± 0.18; P < 0.05), right: OSA n = 11: 0.27 ± 0.09, healthy n = 14: 0.45 ± 0.16; P < 0.05; glutamate left: OSA n = 6: 1.61 ± 0.32, healthy n = 8: 0.94 ± 0.34; P < 0.05, right: OSA n = 14: 1.26 ± 0.28, healthy n = 19: 1.02 ± 0.28; P < 0.05]. GABA and glutamate levels were correlated only within the healthy group in the left insula (r: -0.9, P < 0.05). The altered anterior insular levels of GABA and glutamate may modify integration and projections to autonomic areas, contributing to the impaired cardiovascular regulation in OSA.

Global and Regional Brain Non-Gaussian Diffusion Changes in Newly Diagnosed Patients with Obstructive Sleep Apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) patients show brain structural injury and functional deficits in autonomic, affective, and cognitive regulatory sites, as revealed by mean diffusivity (MD) and other imaging procedures. The time course and nature of gray and white matter injury can be revealed in more detail with mean kurtosis (MK) procedures, which can differentiate acute from chronic injury, and better show extent of damage over MD procedures. Our objective was to examine global and regional MK changes in newly diagnosed OSA, relative to control subjects.

METHODS

Two diffusion kurtosis image series were collected from 22 recently-diagnosed, treatment-naïve OSA and 26 control subjects using a 3.0-Tesla MRI scanner. MK maps were generated, normalized to a common space, smoothed, and compared voxel-by-voxel between groups using analysis of covariance (covariates; age, sex).

RESULTS

No age or sex differences appeared, but body mass index, sleep, neuropsychologic, and cognitive scores significantly differed between groups. MK values were significantly increased globally in OSA over controls, and in multiple localized sites, including the basal forebrain, extending to the hypothalamus, hippocampus, thalamus, insular cortices, basal ganglia, limbic regions, cerebellar areas, parietal cortices, ventral temporal lobe, ventrolateral medulla, and midline pons. Multiple sites, including the insular cortices, ventrolateral medulla, and midline pons showed more injury over previously identified damage with MD procedures, with damage often lateralized.

CONCLUSIONS

Global mean kurtosis values are significantly increased in obstructive sleep apnea (OSA), suggesting acute tissue injury, and these changes are principally localized in critical sites mediating deficient functions in the condition. The mechanisms for injury likely include altered perfusion and hypoxemia-induced processes, leading to acute tissue changes in recently diagnosed OSA.

Forebrain neurocircuitry associated with human reflex cardiovascular control

Physiological homeostasis depends upon adequate integration and responsiveness of sensory information with the autonomic nervous system to affect rapid and effective adjustments in end organ control. Dysregulation of the autonomic nervous system leads to cardiovascular disability with consequences as severe as sudden death. The neural pathways involved in reflexive autonomic control are dependent upon brainstem nuclei but these receive modulatory inputs from higher centers in the midbrain and cortex. Neuroimaging technologies have allowed closer study of the cortical circuitry related to autonomic cardiovascular adjustments to many stressors in awake humans and have exposed many forebrain sites that associate strongly with cardiovascular arousal during stress including the medial prefrontal cortex, insula cortex, anterior cingulate, amygdala and hippocampus. Using a comparative approach, this review will consider the cortical autonomic circuitry in rodents and primates with a major emphasis on more recent neuroimaging studies in awake humans. A challenge with neuroimaging studies is their interpretation in view of multiple sensory, perceptual, emotive and/or reflexive components of autonomic responses. This review will focus on those responses related to non-volitional baroreflex control of blood pressure and also on the coordinated responses to non-fatiguing, non-painful volitional exercise with particular emphasis on the medial prefrontal cortex and the insula cortex.

Water Exchange across the Blood-Brain Barrier in Obstructive Sleep Apnea: An MRI Diffusion-Weighted Pseudo-Continuous Arterial Spin Labeling Study

BACKGROUND AND PURPOSE

Obstructive sleep apnea (OSA) subjects show brain injury in sites that control autonomic, cognitive, and mood functions that are deficient in the condition. The processes contributing to injury may include altered blood-brain barrier (BBB) actions. Our aim was to examine BBB function, based on diffusion-weighted pseudo-continuous arterial spin labeling (DW-pCASL) procedures, in OSA compared to controls.

METHODS

We performed DW-pCASL imaging in nine OSA and nine controls on a 3.0-Tesla MRI scanner. Global mean gray and white matter arterial transient time (ATT, an index of large artery integrity), water exchange rate across the BBB (Kw, BBB function), DW-pCASL ratio, and cerebral blood flow (CBF) values were compared between OSA and control subjects.

RESULTS

Global mean gray and white matter ATT (OSA vs. controls; gray matter, 1.691 ± .120 vs. 1.658 ± .109 second, P = .49; white matter, 1.700 ± .115 vs. 1.650 ± .114 second, P = .44), and CBF values (gray matter, 57.4 ± 15.8 vs. 58.2 ± 10.7 ml/100 g/min, P = .67; white matter, 24.2 ± 7.0 vs. 24.6 ± 6.7 ml/100 g/min, P = .91) did not differ significantly, but global gray and white matter Kw (gray matter, 158.0 ± 28.9 vs. 220.8 ± 40.6 min(-1) , P = .002; white matter, 177.5 ± 57.2 vs. 261.1 ± 51.0 min(-1) , P = .006), and DW-pCASL ratio (gray matter, .727 ± .076 vs. .823 ± .069, P = .011; white matter, .722 ± .144 vs. .888 ± .100, P = .004) values were significantly reduced in OSA over controls.

CONCLUSIONS

OSA subjects show compromised BBB function, but intact large artery integrity. The BBB alterations may introduce neural damage contributing to abnormal functions in OSA, and suggest a need to repair BBB function with strategies commonly used in other fields.

Anxiety and its relationship to quality of life independent of depression in patients with obstructive sleep apnea

OBJECTIVES

The relationship between anxiety and obstructive sleep apnea (OSA) has not been well studied. We evaluated the factors associated with anxiety and whether anxiety is related to quality of life (QoL) independently of depression in OSA patients.

METHODS

Data were collected from adults with newly diagnosed, untreated OSA. The State-Trait Anxiety Inventory-State Scale (STAI-S), the Beck Depression Inventory (BDI), the Epworth Sleepiness Scale (ESS), and the Short Form 36 Health survey (SF-36) were used. Anxiety and depression were defined as high levels of anxiety symptoms (STAI-S score≥40) and depressive symptoms (BDI≥10), respectively. Associations between anxiety and OSA were analyzed using multiple linear regression analysis.

RESULTS

Of 655 OSA subjects included, the prevalence of anxiety and depression was 48.4% and 46.4%, respectively. The scores of STAI-S had strong correlations with BDI (r=0.676, p<0.001). Female sex (p<0.05), excessive daytime sleepiness (ESS≥10) (p<0.05), and a lower educational level (p<0.05) were identified as independent factors for predicting the presence of anxiety in OSA patients. The severity of OSA measured by the apnea-hypopnea index or respiratory distress index was not related to comorbid anxiety. In linear regression analysis, both anxiety (ß=-10.196, p<0.001) and depression (ß=-16.317, p<0.001) were independently associated with lower SF-36 scores in OSA patients.

CONCLUSIONS

The presence of anxiety can be predicted by female sex, daytime sleepiness, and a lower educational level. Both anxiety and depression were independently associated with a lower QoL in OSA patients.

The Utility of Magnetic Resonance Spectroscopy for Understanding Substance Use Disorders: A Systematic Review of the Literature

The aim of this article is to present a systematic review of magnetic resonance spectroscopy (MRS) studies of substance use disorders. As a noninvasive and nonionizing imaging technique, MRS is being widely used in substance abuse research to evaluate the effects substances of abuse have on brain chemistry. Nearly 40 peer-reviewed research articles that focused on the utility of MRS in alcohol, methamphetamine, 3,4-methylenedioxymethamphetamine, cocaine, opiates, opioids, marijuana, and nicotine use disorders were reviewed. Findings indicate inconsistencies with respect to alterations in brain chemistry within each substance of abuse, and the most consistent finding across substances was decreased N-acetylaspartate and choline levels with chronic alcohol, methamphetamine, and nicotine use. Variation in the brain regions studied, imaging technique, as well as small sample sizes might explain the discrepancies in findings within each substance. Future well-designed MRS studies offer promise in examining novel treatment approaches in substance use disorders.