Sex-specific hippocampus volume changes in obstructive sleep apnea.

Introduction: Obstructive sleep apnea (OSA) patients show hippocampal-related autonomic and neurological symptoms, including impaired memory and depression, which differ by sex, and are mediated in distinct hippocampal subfields. Determining sites and extent of hippocampal sub-regional injury in OSA could reveal localized structural damage linked with OSA symptoms.

Methods: High-resolution T1-weighted images were collected from 66 newly-diagnosed, untreated OSA (mean age ± SD: 46.

Altered resting-state hippocampal and caudate functional networks in patients with obstructive sleep apnea.

Introduction: Brain structural injury and metabolic deficits in the hippocampus and caudate nuclei may contribute to cognitive and emotional deficits found in obstructive sleep apnea (OSA) patients. If such contributions exist, resting-state interactions of these subcortical sites with cortical areas mediating affective symptoms and cognition should be disturbed. Our aim was to examine resting-state functional connectivity (FC) of the hippocampus and caudate to other brain areas in OSA relative to control subjects, and to relate these changes to mood and neuropsychological scores.

Epiglottis cross-sectional area and oropharyngeal airway length in male and female obstructive sleep apnea patients.

Introduction: Obstructive sleep apnea (OSA) is a male-predominant condition, characterized by repeated upper-airway collapse with continued diaphragmatic efforts during sleep, and is accompanied by severe physiological consequences. Multiple morphological aspects, including epiglottis cross-sectional area (CSA) and oropharyngeal airway length (OPAL), can contribute to airway collapsibility in the condition. This study focused on the effects of OSA severity, sex, and race on OPA dimensions.

Disrupted functional brain network organization in patients with obstructive sleep apnea.

Introduction: Obstructive sleep apnea (OSA) subjects show impaired autonomic, affective, executive, sensorimotor, and cognitive functions. Brain injury in OSA subjects appears in multiple sites regulating these functions, but the integrity of functional networks within the regulatory sites remains unclear. Our aim was to examine the functional interactions and the complex network organization of these interactions across the whole brain in OSA, using regional functional connectivity (FC) and brain network topological properties.

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.

Abnormal myelin and axonal integrity in recently diagnosed patients with obstructive sleep apnea.

Study Objectives: Patients with obstructive sleep apnea (OSA) show significant white matter injury; whether that injury represents myelin or axonal damage is unclear. The objective was to examine myelin and axonal changes in patients with newly diagnosed OSA over control subjects.

Design: Cross-sectional study.

Insular cortex metabolite changes in obstructive sleep apnea.

Study Objective: Adults with obstructive sleep apnea (OSA) show significant autonomic and neuropsychologic deficits, which may derive from damage to insular regions that serve those functions. The aim was to assess glial and neuronal status from anterior insular metabolites in OSA versus controls, using proton magnetic resonance spectroscopy (PMRS), and thus to provide insights for neuroprotection against tissue changes, and to reduce injury consequences.

Design: Cross-sectional study.

Brain putamen volume changes in newly-diagnosed patients with obstructive sleep apnea.

Obstructive sleep apnea (OSA) is accompanied by cognitive, motor, autonomic, learning, and affective abnormalities. The putamen serves several of these functions, especially motor and autonomic behaviors, but whether global and specific sub-regions of that structure are damaged is unclear. We assessed global and regional putamen volumes in 43 recently-diagnosed, treatment-naïve OSA (age, 46.

Heart rate responses to autonomic challenges in obstructive sleep apnea.

Obstructive sleep apnea (OSA) is accompanied by structural alterations and dysfunction in central autonomic regulatory regions, which may impair dynamic and static cardiovascular regulation, and contribute to other syndrome pathologies. Characterizing cardiovascular responses to autonomic challenges may provide insights into central nervous system impairments, including contributions by sex, since structural alterations are enhanced in OSA females over males. The objective was to assess heart rate responses in OSA versus healthy control subjects to autonomic challenges, and, separately, characterize female and male patterns.

Sex differences in white matter alterations accompanying obstructive sleep apnea.

Study Objectives: Females with obstructive sleep apnea (OSA) show different psychological and physiological symptoms from males, which may be associated with sex-related variations in neural injury occurring with the disorder. To determine whether male- or female-specific brain injury is present in OSA, we assessed influences of sex on white matter changes in the condition.

Design: Two-group factorial.

Altered global and regional brain mean diffusivity in patients with obstructive sleep apnea.

Obstructive sleep apnea (OSA) is a common and progressive disorder accompanied by severe cardiovascular and neuropsychological sequelae, presumably induced by brain injury resulting from the intermittent hypoxia and cardiovascular processes accompanying the syndrome. However, whether the predominant brain tissue pathology is acute or chronic in newly-diagnosed, untreated OSA subjects is unclear; this assessment is essential for revealing pathological processes. Diffusion tensor imaging (DTI)-based mean diffusivity (MD) procedures can detect and differentiate acute from chronic pathology and may be useful to reveal processes in the condition.

Neural alterations associated with anxiety symptoms in obstructive sleep apnea syndrome.

Background: Neuropsychological comorbidities, including anxiety symptoms, accompany obstructive sleep apnea (OSA); structural and functional brain alterations also occur in the syndrome. The objective was to determine whether OSA patients expressing anxiety symptoms show injury in specific brain sites.

Methods: Magnetic resonance T2-relaxometry was performed in 46 OSA and 66 control subjects.

Neural alterations and depressive symptoms in obstructive sleep apnea patients.

Study Objectives: Depressive symptoms are common in obstructive sleep apnea (OSA) patients, and brain injury occurs with both OSA and depression independently. The objective was to determine whether brain alterations in OSA bear relationships to depressive symptoms.

Design: Cross-sectional study.

Brain structural changes in obstructive sleep apnea.

Study Objectives: Determine whether obstructive sleep apnea (OSA) subjects show indications of axonal injury.

Design: We assessed fiber integrity in OSA and control subjects with diffusion tensor imaging (DTI). We acquired four whole-brain DTI series from each subject.

Reduced mammillary body volume in patients with obstructive sleep apnea.

Obstructive sleep apnea (OSA) patients show compromised emotional and cognitive functions, including anterograde memory deficits. While some memory inadequacies in OSA may result from earlier-described structural deficits in the hippocampus, mammillary body injury also could contribute, since these structures receive projections from the hippocampus via the fornix, project heavily to the anterior thalamus, and have been implicated in other conditions with memory deficiencies, such as Korsakoff's syndrome. However, volume loss in mammillary bodies has not been reported in OSA, likely a consequence of logistic difficulties in size assessment.

Regional brain response patterns to Cheyne-Stokes breathing.

Cheyne-Stokes breathing (CSB) results from impaired integration of sensory information with respiratory motor output; however, regions mediating the disturbed control are unknown. We examined functional magnetic resonance imaging signals during CSB within sleep to determine affected areas. Two male patients with severe obstructive sleep apnea were scanned while asleep over multiple sessions during which they exhibited CSB.

Inspiratory loading elicits aberrant fMRI signal changes in obstructive sleep apnea.

We hypothesized that neural processes mediating deficient sensory and autonomic regulatory mechanisms in obstructive sleep apnea (OSA) would be revealed by responses to inspiratory loading in brain regions regulating sensory and motor control. Functional magnetic resonance imaging (fMRI) signals and physiologic changes were assessed during baseline and inspiratory loading in 7 OSA patients and 11 controls, all male and medication-free. Heart rate increases to inspiratory loading began earlier and load pressures were achieved later in OSA patients.

Functional magnetic resonance imaging responses to expiratory loading in obstructive sleep apnea.

Obstructive sleep apnea (OSA) is characterized by diminished upper airway muscle phasic and tonic activation during sleep, but enhanced activity during waking. We evaluated neural mechanisms underlying these patterns with functional magnetic resonance imaging procedures during baseline and expiratory loading conditions in nine medication-free OSA and 16 control subjects. Both groups developed similar expiratory loading pressures, but appropriate autonomic responses did not emerge in OSA cases.

fMRI responses to cold pressor challenges in control and obstructive sleep apnea subjects.

Obstructive sleep apnea (OSA) patients exhibit altered sympathetic outflow, which may reveal mechanisms underlying the syndrome. We used functional MRI (fMRI) in 16 control and 10 OSA subjects who were free of cardiovascular or mood-altering drugs to examine neural responses to a forehead cold pressor challenge, which elicits respiratory slowing, bradycardia, and enhanced sympathetic outflow. The magnitude of cold-induced bradycardia was smaller, and respiratory slowing showed greater intersubject variability and reached a nadir later in OSA patients.

Brain responses associated with the Valsalva maneuver revealed by functional magnetic resonance imaging.

The Valsalva maneuver, a test frequently used to evaluate autonomic function, recruits discrete neural sites. The time courses of neural recruitment relative to accompanying cardiovascular and breathing patterns are unknown. We examined functional magnetic resonance imaging signal changes within the brain to repeated Valsalva maneuvers and correlated these changes with physiological trends.

Neural responses during Valsalva maneuvers in obstructive sleep apnea syndrome.

The repetitive upper airway muscle atonic episodes and cardiovascular sequelae of obstructive sleep apnea (OSA) suggest dysfunction of specific neural sites that integrate afferent airway signals with autonomic and somatic outflow. We determined neural responses to the Valsalva maneuver by using functional magnetic resonance imaging. Images were collected during a baseline and three Valsalva maneuvers in 8 drug-free OSA patients and 15 controls.

Brain morphology associated with obstructive sleep apnea.

Obstructive sleep apnea (OSA) is characterized by repeated occurrences of hypoxic, hypercapnic, and transient blood pressure elevation episodes that may damage or alter neural structures. Underdeveloped structures or pre-existing damage in brain areas may also contribute to the genesis of the syndrome. Brain morphology in 21 patients with OSA and in 21 control subjects was assessed using high-resolution T1-weighted magnetic resonance imaging.

Does nocturnal panic represent a more severe form of panic disorder?

Nocturnal panic (NP), or waking from sleep in a state of panic, occurs in 18% to 45% of panic disorder patients. This relatively common phenomenon, however, is not well understood. In this study, the authors tested the hypotheses that NP represents a more severe form of panic disorder or is a manifestation of heightened vulnerability to sleep disturbance.

Presleep attributions about arousal during sleep: nocturnal panic.

This study examined the role of presleep attributions about physiological events during sleep in nocturnal panic attacks. Patients who regularly experienced nocturnal panic were physiologically monitored as audio signals were presented during sleep. They were randomly assigned to 1 of 3 conditions: expected, in which signals of intense physiological changes were expected; unexpected, in which signals of intense physiological changes were not expected; or control, involving distinctly different signals unrelated to physiological responses.