A meta-analysis of electroencephalographic sleep in depression: evidence for genetic biomarkers

Resting State EEG in Children With Learning Disabilities: An Independent Component Analysis Approach

In this study, the neurophysiological underpinnings of learning disabilities (LD) in children are examined using resting state EEG. We were particularly interested in the neurophysiological differences between children with learning disabilities not otherwise specified (LD-NOS), learning disabilities with verbal disabilities (LD-Verbal), and healthy control (HC) children. We applied 2 different approaches to examine the differences between the different groups. First, we calculated theta/beta and theta/alpha ratios in order to quantify the relationship between slow and fast EEG oscillations. Second, we used a recently developed method for analyzing spectral EEG, namely the group independent component analysis (gICA) model. Using these measures, we identified substantial differences between LD and HC children and between LD-NOS and LD-Verbal children in terms of their spectral EEG profiles. We obtained the following findings: (a) theta/beta and theta/alpha ratios were substantially larger in LD than in HC children, with no difference between LD-NOS and LD-Verbal children; (b) there was substantial slowing of EEG oscillations, especially for gICs located in frontal scalp positions, with LD-NOS children demonstrating the strongest slowing; (c) the estimated intracortical sources of these gICs were mostly located in brain areas involved in the control of executive functions, attention, planning, and language; and (d) the LD-Verbal children demonstrated substantial differences in EEG oscillations compared with LD-NOS children, and these differences were localized in language-related brain areas. The general pattern of atypical neurophysiological activation found in LD children suggests that they suffer from neurophysiological dysfunction in brain areas involved with the control of attention, executive functions, planning, and language functions. LD-Verbal children also demonstrate atypical activation, especially in language-related brain areas. These atypical neurophysiological activation patterns might provide a helpful guide for rehabilitation strategies to treat the deficiencies in these children with LD.

Sleep-dependent memory consolidation and its implications for psychiatry

Both sleep disturbance and memory impairment are very common in psychiatric disorders. Since sleep has been shown to play a role in the process of transferring newly acquired information into long-term memory, i.e., consolidation, it is important to highlight this link in the context of psychiatric disorders. Along these lines, after providing a brief overview of healthy human sleep, current neurobiological models on sleep-dependent memory consolidation and resultant opportunities to manipulate the memory consolidation process, recent findings on sleep disturbances and sleep-dependent memory consolidation in patients with insomnia, major depression, schizophrenia, and post-traumatic stress disorder are systematically reviewed. Furthermore, possible underlying neuropathologies and their implications on therapeutic strategies are discussed. This review aims at sensitizing the reader for recognizing sleep disturbances as a potential contributor to cognitive deficits in several disorders, a fact which is often overlooked up to date.

Slow-wave disruption enhances the accessibility of positive memory traces

The purpose of this study was to explore the effects of slow-wave disruption on positive and negative word recognition in a sample of healthy control participants and those with major depressive disorder. Prior to sleep, participants learned a set of emotional and neutral words during an encoding task by responding whether or not the word described them. Following baseline sleep, participants underwent one night of selective slow-wave disruption by auditory stimuli. Accuracy and reaction time to a recognition word set, including both positive and negative words, was assessed in the morning. Repeated-measures ANOVA revealed a significant interaction between word valence and condition, with positive words recognized significantly faster than negative words after disruption, in only healthy control participants. There were no significant results in those with major depressive disorder, or with regard to accuracy. These results may add to the increasing body of literature suggesting a hedonic bias to positive stimuli following sleep disruption.

Ventromedial prefrontal cortex regulates depressive-like behavior and rapid eye movement sleep in the rat

Major depressive disorder (MDD) is a debilitating disease with symptoms like persistent depressed mood and sleep disturbances. The prefrontal cortex (PFC) has been implicated as an important structure in the neural circuitry of MDD, with pronounced abnormalities in blood flow and metabolic activity in PFC subregions, including the subgenual cingulate cortex (sgACC, or Brodmann area 25). In addition, deep brain stimulation in the sgACC has recently been shown to alleviate treatment-resistant depression. Depressed patients also show characteristic changes in sleep: insomnia, increased rapid-eye-movement (REM) sleep and shortened REM sleep latency. We hypothesized that sleep changes and depressive behavior may be a consequence of the abnormal PFC activity in MDD. The rat ventromedial PFC (vmPFC, prelimbic and infralimbic cortices) is considered to be the homolog of the human sgACC, so we examined the effect of excitotic lesions in the vmPFC on sleep-wake and depressive behavior. We also made lesions in the adjacent dorsal region (dmPFC) to compare the effect of this similar but distinct mPFC region. We found that both dmPFC and vmPFC lesions led to increased REM sleep, but only vmPFC-lesioned animals displayed increased sleep fragmentation, shortened REM latency and increased immobility in the forced swim test. Anatomic tracing suggests that the mPFC projects to the pontine REM-off neurons that interact with REM-on neurons in the dorsal pons. These results support our hypothesis that neuronal loss in the rat vmPFC resembles several characteristics of MDD and may be a critical area for modulating both mood and sleep.

The Impact of Mental Illness Stigma on Seeking and Participating in Mental Health Care

Treatments have been developed and tested to successfully reduce the symptoms and disabilities of many mental illnesses. Unfortunately, people distressed by these illnesses often do not seek out services or choose to fully engage in them. One factor that impedes care seeking and undermines the service system is mental illness stigma. In this article, we review the complex elements of stigma in order to understand its impact on participating in care. We then summarize public policy considerations in seeking to tackle stigma in order to improve treatment engagement. Stigma is a complex construct that includes public, self, and structural components. It directly affects people with mental illness, as well as their support system, provider network, and community resources. The effects of stigma are moderated by knowledge of mental illness and cultural relevance. Understanding stigma is central to reducing its negative impact on care seeking and treatment engagement. Separate strategies have evolved for counteracting the effects of public, self, and structural stigma. Programs for mental health providers may be especially fruitful for promoting care engagement. Mental health literacy, cultural competence, and family engagement campaigns also mitigate stigma's adverse impact on care seeking. Policy change is essential to overcome the structural stigma that undermines government agendas meant to promote mental health care. Implications for expanding the research program on the connection between stigma and care seeking are discussed.

Stress and sleep reactivity: a prospective investigation of the stress-diathesis model of insomnia

STUDY OBJECTIVES

To prospectively assess sleep reactivity as a diathesis of insomnia, and to delineate the interaction between this diathesis and naturalistic stress in the development of insomnia among normal sleepers.

DESIGN

Longitudinal.

SETTING

Community-based.

PARTICIPANTS

2,316 adults from the Evolution of Pathways to Insomnia Cohort (EPIC) with no history of insomnia or depression (46.8 ± 13.2 y; 60% female).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Participants reported the number of stressful events they encountered at baseline (Time 1), as well as the level of cognitive intrusion they experienced in response to each stressor. Stressful events (OR = 1.13; P < 0.01) and stress-induced cognitive intrusion (OR = 1.61; P < 0.01) were significant predictors of risk for insomnia one year hence (Time 2). Intrusion mediated the effects of stressful events on risk for insomnia (P < 0.05). Trait sleep reactivity significantly increased risk for insomnia (OR = 1.78; P < 0.01). Further, sleep reactivity moderated the effects of stress-induced intrusion (P < 0.05), such that the risk for insomnia as a function of intrusion was significantly higher in individuals with high sleep reactivity. Trait sleep reactivity also constituted a significant risk for depression (OR = 1.67; P < 0.01) two years later (Time 3). Insomnia at Time 2 significantly mediated this effect (P < 0.05).

CONCLUSIONS

This study suggests that premorbid sleep reactivity is a significant risk factor for incident insomnia, and that it triggers insomnia by exacerbating the effects of stress-induced intrusion. Sleep reactivity is also a precipitant of depression, as mediated by insomnia. These findings support the stress-diathesis model of insomnia, while highlighting sleep reactivity as an important diathesis.

CITATION

Drake CL, Pillai V, Roth T. Stress and sleep reactivity: a prospective investigation of the stress-diathesis model of insomnia.

Blockade of the metabotropic glutamate (mGluR2) modulates arousal through vigilance states transitions: evidence from sleep-wake EEG in rodents

Accumulating data continue to support the therapeutic potential of glutamate metabotropic (mGluR2) receptors for treatment of psychiatric disorders such as depression, anxiety and schizophrenia. Glutamate neurotransmission is an integral component of sleep-wake mechanisms, which have translational relevance to assess on-target activity of drugs. Here, we investigated the influence of mGluR2 inactivation upon sleep-wake electroencephalogram (EEG) in rodents. Rats were administered with vehicle, the specific mGluR2 antagonist LY341495 (2.5, 5, 10mg/kg) or negative allosteric modulator (NAM) Ro-4491533 (2.5, 10 and 40 mg/kg) at lights onset. mGluR2 (-/-) mice were used to confirm the selectivity of functional response. Both LY341495 and Ro-4491533 induced an immediate and endured desynchronized cortical activity during 3-6h associated with enhanced theta and gamma oscillations and depressed slow oscillations during sleep. The arousal-promoting effect is consistent with the marked lengthening of sleep onset latency, an increased number of state transitions from light sleep to waking and the gradual increase in homeostatic compensatory sleep. The arousal response to mGluR2 blockade was not accompanied by sharp rebound hypersomnolence as found with the classical psycho-stimulant amphetamine. mGluR2 (-/-) mice and their WT littermates exhibited similar sleep-wake phenotype, while Ro-4491533 (40 mg/kg) enhanced waking associated with increased locomotor activity and body temperature in WT but not in mGluR2 (-/-) mice, which confirm the role of mGluR2 inactivation in the arousal response. Our results lend support for a role of mGluR2 blockade in promoting cortical arousal associated with theta/gamma oscillations as well as high thresholds transitions from sleep to waking.

Gamma band activity in the RAS-intracellular mechanisms

Gamma band activity participates in sensory perception, problem solving, and memory. This review considers recent evidence showing that cells in the reticular activating system (RAS) exhibit gamma band activity, and describes the intrinsic membrane properties behind such manifestation. Specifically, we discuss how cells in the mesopontine pedunculopontine nucleus, intralaminar parafascicular nucleus, and pontine SubCoeruleus nucleus dorsalis all fire in the gamma band range when maximally activated, but no higher. The mechanisms involve high-threshold, voltage-dependent P/Q-type calcium channels, or sodium-dependent subthreshold oscillations. Rather than participating in the temporal binding of sensory events as in the cortex, gamma band activity in the RAS may participate in the processes of preconscious awareness and provide the essential stream of information for the formulation of many of our actions. We address three necessary next steps resulting from these discoveries: an intracellular mechanism responsible for maintaining gamma band activity based on persistent G-protein activation, separate intracellular pathways that differentiate between gamma band activity during waking versus during REM sleep, and an intracellular mechanism responsible for the dysregulation in gamma band activity in schizophrenia. These findings open several promising research avenues that have not been thoroughly explored. What are the effects of sleep or REM sleep deprivation on these RAS mechanisms? Are these mechanisms involved in memory processing during waking and/or during REM sleep? Does gamma band processing differ during waking versus REM sleep after sleep or REM sleep deprivation?

Polysomnographic features of early-onset depression: a meta-analysis

BACKGROUND

Undiagnosed major depressive disorder (MDD) is associated with increased morbidity in children and adolescents. This study evaluated features of sleep macro- and microarchitecture assessed by polysomnography (PSG) as diagnostic markers for MDD in children and adolescents.

METHODS

MEDLINE, PSYCINFO, EMBASE and PUBMED were searched from their availability dates to March 1st, 2013. The literature search identified 932 abstracts of which 51 studies were retrieved and 28 were included in the analysis. Study design, features of sleep macro- and microarchitecture, demographic and clinical characteristics of study groups were extracted for each study.

RESULTS

There were modest differences on sleep macroarchitecture between children and adolescents with MDD and healthy controls. The most robust difference was found in sleep latency, 31% of adolescents with MDD had increased sleep latency. Age, suicidal ideation, suicidal behavior, and psychiatric comorbidities were significant predictors of sleep macroarchitecture. Modest differences were found for sleep microarchitecture, intrahemispheric and interhemispheric temporal coherence was decreased in a third of patients with MDD. Age was a significant predictor of sleep microarchitecture.

LIMITATIONS

This meta-analysis is limited by the small number of studies on sleep macroarchitecture in children with MDD and studies on sleep microarchitecture overall and by the heterogeneity in methodology between studies.

CONCLUSIONS

This synthetic review of the existing literature is among the largest to quantitatively assess impaired sleep as a diagnostic marker for MDD in children and adolescents. Knowledge of sleep macro- and microarchitecture in early-onset MDD may aid the clinician in developing a treatment strategy for MDD-related sleep symptoms in a subset of patients.

Guidelines for the recording and evaluation of pharmaco-sleep studies in man: the International Pharmaco-EEG Society (IPEG)

The International Pharmaco-EEG Society (IPEG) presents guidelines summarising the requirements for the recording and computerised evaluation of pharmaco-sleep data in man. Over the past years, technical and data-processing methods have advanced steadily, thus enhancing data quality and expanding the palette of sleep assessment tools that can be used to investigate the activity of drugs on the central nervous system (CNS), determine the time course of effects and pharmacodynamic properties of novel therapeutics, hence enabling the study of the pharmacokinetic/pharmacodynamic relationship, and evaluate the CNS penetration or toxicity of compounds. However, despite the presence of robust guidelines on the scoring of polysomnography -recordings, a review of the literature reveals inconsistent -aspects in the operating procedures from one study to another. While this fact does not invalidate results, the lack of standardisation constitutes a regrettable shortcoming, especially in the context of drug development programmes. The present guidelines are intended to assist investigators, who are using pharmaco-sleep measures in clinical research, in an effort to provide clear and concise recommendations and thereby to standardise methodology and facilitate comparability of data across laboratories.

Sleep Organisation in Depression and Schizophrenia: Index of Endogenous Periodicity of Sleep as a State Marker [Retracted]

Background: Sleep disorders are frequent symptoms described in psychiatric patients with major depression or schizophrenia. These patients also exhibit changes in the sleep architecture measured by polysomnography (PSG) during sleep. The aim of the present study was to identify potential biomarkers that would facilitate the diagnosis based on polysomnography (PSG) measurements.Subjects and Methods: 30 patients with schizophrenia, 30 patients with major depression and 30 healthy control subjects were investigated in the present study. The mean age in the group with schizophrenia was 36.73 (SD 6.43), in the group of patients with depression 40.77 (SD 7.66), in the healthy controls group 34.40 (SD 5.70). The gender distribution was as follows: 18 male, 12 female in the group with schizophrenia; in the group of patients with depression 11 male, 19 female; in the control group 16 male and 14 female. All subjects underwent polysomnography (PSG) for a minimum time of 8 hours according to the criteria of Rechtschaffen & Kales (1968). The following polysomnographic (PSG) parameters were analyzed: sleep latency (SL), total sleep time (TST), waking time after sleep onset (WTASO), number of awakenings (NAW), slow wave sleep (SWS), rapid eye movement sleep (REM), rapid eye movement sleep latency (REML), first REM period (REM 1), and first NREM period (NREM 1). We tested the potential of multiple sleep variables to predict diagnosis in different groups by using linear discriminate analysis (LDA).Results: There were significant differences in polysomnography (PSG) variables between healthy control subjects and psychiatric patients (total sleep time, sleep latency, number of awakenings, time of awakening after sleep onset, REM 1 latency, REM 1 and index of endogenous periodicity). Importantly, LDA was able to predict the correct diagnosis in 88% of all cases.Conclusions: The presented analysis showed commonalities and differences in polysomnography (PSG) changes in patients with major depressive disorder and in patients with schizophrenia. Our results underline the potential of polysomnography (PSG) measurements to facilitate diagnostic processes.

Self-reported sleep disturbance is associated with elevated levels of PAI-1 in individuals with a recorded history of depressive symptoms

BACKGROUND

The majority of depressed individuals report insomnia. Self-reported symptoms of insomnia, in particular, more strongly predict adverse health effects than the actual measured sleep time. The physiological alterations in individuals with insomnia are complex, as both autonomic and endocrine dysfunctions are present. Plasminogen activator inhibitor (PAI)-1 is a stress-related acute-phase reactant that has also been suggested to regulate the circadian rhythm and sleep patterns. It has been suggested to contribute to both depressive symptoms and sleep disorders, although data on the relationships between these parameters are scarce.

OBJECTIVE

This study examined the role of self-reported sleep disturbance and its association with PAI-1 among individuals with a history of depressive symptoms.

METHODS

Differences in the serum levels of PAI-1 between two groups (group 1: moderate to very severe sleep disturbance, n=37; group 2: mild or no sleep disturbance, n = 90) were examined in a population-based sample of individuals with a recorded history of depressive symptoms.

RESULTS

Multivariate analysis controlling for potential confounding factors (age, sex, body mass index, depression severity) showed that each 1-unit increase in PAI-1 (μg/mL) increased the likelihood for belonging to the group with moderate to very severe sleep disturbance by 23% (OR = 1.23, C.I. 95% = 1.04-1.45, p = 0.016). This statistical significance remained after additional adjustments for regular smoking and the use of sleep or lipid-lowering medication.

CONCLUSION

Our observations may further clarify the physiological alterations related to sleep disturbance in depressive individuals. In the present study, self-reported sleep disturbance in individuals with a recorded history of depressive symptoms was associated with an elevation of PAI-1. This finding may illustrate the association of subjective sleep disturbance with sympathetic activation. Our study highlights the importance of effects of perceived sleep disturbance on individual homeostasis, and may provide potential directions for research on treatment options.

Sex differences in objective measures of sleep in post-traumatic stress disorder and healthy control subjects

A growing literature shows prominent sex effects for risk for post-traumatic stress disorder and associated medical comorbid burden. Previous research indicates that post-traumatic stress disorder is associated with reduced slow wave sleep, which may have implications for overall health, and abnormalities in rapid eye movement sleep, which have been implicated in specific post-traumatic stress disorder symptoms, but most research has been conducted in male subjects. We therefore sought to compare objective measures of sleep in male and female post-traumatic stress disorder subjects with age- and sex-matched control subjects. We used a cross-sectional, 2 × 2 design (post-traumatic stress disorder/control × female/male) involving83 medically healthy, non-medicated adults aged 19-39 years in the inpatient sleep laboratory. Visual electroencephalographic analysis demonstrated that post-traumatic stress disorder was associated with lower slow wave sleep duration (F(3,82)  = 7.63, P = 0.007) and slow wave sleep percentage (F(3,82)  = 6.11, P = 0.016). There was also a group × sex interaction effect for rapid eye movement sleep duration (F(3,82)  = 4.08, P = 0.047) and rapid eye movement sleep percentage (F(3,82)  = 4.30, P = 0.041), explained by greater rapid eye movement sleep in post-traumatic stress disorder females compared to control females, a difference not seen in male subjects. Quantitative electroencephalography analysis demonstrated that post-traumatic stress disorder was associated with lower energy in the delta spectrum (F(3,82)  = 6.79, P = 0.011) in non-rapid eye movement sleep. Slow wave sleep and delta findings were more pronounced in males. Removal of post-traumatic stress disorder subjects with comorbid major depressive disorder, who had greater post-traumatic stress disorder severity, strengthened delta effects but reduced rapid eye movement effects to non-significance. These findings support previous evidence that post-traumatic stress disorder is associated with impairment in the homeostatic function of sleep, especially in men with the disorder. These findings suggest that group × sex interaction effects on rapid eye movement may occur with more severe post-traumatic stress disorder or with post-traumatic stress disorder comorbid with major depressive disorder.

In pre-school children, cortisol secretion remains stable over 12 months and is related to psychological functioning and gender

OBJECTIVES

Cross-sectional studies provide evidence that cortisol secretion as a marker of hypothalamus-pituitary-adrenocortical axis activity (HPA AA) is related to psychological functioning and behavior. However, there are no studies of the stability of the HPA AA in pre-schoolers over the longer term. The aim of the present study was therefore to investigate cortisol secretion in pre-schoolers longitudinally, and to predict psychological functioning 12 months later.

METHOD

92 pre-schoolers (mean age: 5.4 years; 44% females) took part in a follow-up assessment 12 months after initial assessment. Cortisol secretion was assessed both at baseline (morning cortisol secretion) and under challenge conditions, and a thorough psychological assessment was included.

RESULTS

Increased cortisol secretion at 5.4 years predicted increased cortisol secretion and psychological difficulties at 6.4 years. Compared to boys, girls had higher cortisol secretion at both 5.4 and 6.4 years. Cross-sectionally, at the age of 6.4 years, levels of cortisol secretion impacted differentially on girls' and boys' behavior.

CONCLUSION

In pre-schoolers, HPA axis activity at 5.4 years is stable over the following 12 months and is associated with psychological functioning. Pre-schoolers with higher cortisol levels are at increased risk of developing further psychological difficulties. Gender affects the manner in which HPA axis activity impacts on psychological functioning. Moreover, gender differences in cortisol secretion occur already in prepubertal children and appear to be independent from sex steroids.

Sleep as a biomarker for depression

Sleep is a complex biological process that involves cyclic changes of brain activity. The smooth transition between wakefulness and sleep and cyclic succession of sleep stages depend on the function of numerous neurotransmitters that reciprocally influence each other. For this reason sleep is a very sensitive biomarker of brain functioning. This article provides an overview of sleep changes in depression, mechanisms involved in sleep regulation and pathophysiology underlying depression, studies on sleep as a biomarker for depression, effects of antidepressants on sleep EEG, and studies in depression with the use of quantitative sleep EEG analysis. Research on sleep in depression has provided several valuable biomarkers that are related to increased risk for depression, show worsening during depressive episode, and are related to treatment outcome and relapse risk during remission phase. Among many sleep parameters, increased REM density and diminished delta sleep ratio deserve special interest. Sleep studies are also an important research tool for antidepressant drug development. However, due to sensitivity of sleep parameters to pharmacological interventions, the patients have to be investigated before the start of pharmacological treatment or after washout from the antidepressant drug, to obtain reliable data on disease-related biological processes from polysomnography.

Sleep architecture variation: a mediator of metabolic disturbance in individuals with major depressive disorder

Remarkable proportions of individuals diagnosed with major depressive disorder (MDD) have comorbid metabolic disturbances (i.e., obesity, type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia), and vice versa. Accumulating evidence suggests that common pathophysiologic pathways such as a chronic, low-grade, proinflammatory state mediate this frequent co-occurrence. However, it remains unclear what traits precede the onset and increase the risk for these pathologic states. The aim of our review was to evaluate the evidentiary base supporting the hypothesis that the increased hazard for metabolic disturbance in MDD subpopulations (and vice versa) is mediated in part by endophenotypic variations in sleep architecture. We conducted a PubMed search of all English-language literature with the following search terms: sleep disturbance, circadian rhythm, inflammation, metabolic syndrome, obesity, MDD, mood disorder, prodrome, T2DM, cytokine, interleukin, hypertension, dyslipidemia, and hypercholesterolemia. Longitudinal and meta-analysis data indicate that specific variations in sleep architecture (i.e., decreased slow-wave sleep [SWS], increased rapid eye movement [REM] density) precede the onset of depressive symptomatology for a subpopulation of individuals. The same sleep architecture variations also are associated with obesity, T2DM, and hypertension. Decreased SWS and increased REM density is correlated with an increase in proinflammatory cytokines (e.g., IL-6, tumor necrosis factor, etc.). This proinflammatory state has been independently shown to be associated with MDD and metabolic disturbances. Taken together, our review suggests that sleep architecture variation of increased REM density and decreased SWS may be an endophenotypic trait, which serves to identify a subpopulation at increased risk for depressive symptoms and metabolic disturbances. Future research is needed to discern the predictive value, sensitivity, and specificity of using sleep architecture variation as a biomarker for MDD and metabolic disturbances. Validation of this marker would have broad clinical implications, such as primary, secondary, and tertiary preventative health strategies.

Dorsolateral prefrontal transcranial magnetic stimulation in patients with major depression locally affects alpha power of REM sleep

Sleep alterations are among the most important disabling manifestation symptoms of Major Depression Disorder (MDD). A critical role of sleep importance is also underlined by the fact that its adjustment has been proposed as an objective marker of clinical remission in MDD. Repetitive transcranial magnetic stimulation (rTMS) represents a relatively novel therapeutic tool for the treatment of drug-resistant depression. Nevertheless, besides clinical evaluation of the mood improvement after rTMS, we have no clear understanding of what are the neurophysiological correlates of such treatment. One possible marker underlying the clinical outcome of rTMS in MDD could be cortical changes on wakefulness and sleep activity. The aim of this open-label study was to evaluate the efficacy of a sequential bilateral rTMS treatment over the dorsolateral prefrontal cortex (DLPFC) to improve the mood in MDD patients, and to determine if rTMS can induce changes on the sleep structure, and if those changes can be used as a surrogate marker of the clinical state of the patient. Ten drug-resistant depressed patients participated to ten daily sessions of sequential bilateral rTMS with a low-frequency TMS (1 Hz) over right-DLPFC and a subsequent high-frequency (10 Hz) TMS over left-DLPFC. The clinical and neurophysiological effects induced by rTMS were evaluated, respectively by means of the Hamilton Depression Rating Scale (HDRS), and by comparing the sleep pattern modulations and the spatial changes of EEG frequency bands during both NREM and REM sleep, before and after the real rTMS treatment. The sequential bilateral rTMS treatment over the DLPFC induced topographical-specific decrease of the alpha activity during REM sleep over left-DLPFC, which is significantly associated to the clinical outcome. In line with the notion of a left frontal hypoactivation in MDD patients, the observed local decrease of alpha activity after rTMS treatment during the REM sleep suggests that alpha frequency reduction could be considered as a marker of up-regulation of cortical activity induced by rTMS, as well as a surrogate neurophysiological correlate of the clinical outcome.

Comorbid sleep disorders in neuropsychiatric disorders across the life cycle

The association between psychopathology and poor sleep has long been recognized. The current review focuses on the association between the most prevalent sleep disorders (insomnia, sleep-related breathing disorders and restless legs syndrome) and four major psychiatric disorders: alcohol dependence, schizophrenia, depression and anxiety disorders. Decreased total sleep time and increased sleep onset latency as measured by polysomnography as well an increase of the prevalence of insomnia has been reported in all of these psychiatric disorders. Furthermore, sleep disturbance is a risk factor for their development. Cognitive-behavioral therapy for insomnia has been shown to have a positive impact on both sleep and symptoms of depression and anxiety. Whether adequate treatment of sleep disorders can prevent the incidence of psychiatric disorders, remains to be investigated.

REM sleep dysregulation in depression: state of the art

Disturbances of sleep are typical for most depressed patients and belong to the core symptoms of the disorder. Since the 1960s polysomnographic sleep research has demonstrated that besides disturbances of sleep continuity, depression is associated with altered sleep architecture, i.e., a decrease in slow wave sleep (SWS) production and disturbed rapid eye movement (REM) sleep regulation. Shortened REM latency (i.e., the interval between sleep onset and the occurrence of the first REM period), increased REM sleep duration and increased REM density (i.e., the frequency of rapid eye movements per REM period) have been considered as biological markers of depression which might predict relapse and recurrence. High risk studies including healthy relatives of patients with depression demonstrate that REM sleep alterations may precede the clinical expression of depression and may thus be useful in identifying subjects at high risk for the illness. Several models have been developed to explain REM sleep abnormalities in depression, like the cholinergic-aminergic imbalance model or chronobiologically inspired theories, which are reviewed in this overview. Moreover, REM sleep alterations have been recently considered not only as biological "scars" but as true endophenotypes of depression. This review discusses the genetic, neurochemical and neurobiological factors that have been implicated to play a role in the complex relationships between REM sleep and depression. We hypothesize on the one hand that REM sleep dysregulation in depression may be linked to a genetic predisposition/vulnerability to develop the illness; on the other hand it is conceivable that REM sleep disinhibition in itself is a part of a maladaptive stress reaction with increased allostatic load. We also discuss whether the REM sleep changes in depression may contribute themselves to the development of central symptoms of depression such as cognitive distortions including negative self-esteem and the overnight consolidation of negatively toned emotional memories.

Effects of quetiapine extended release on sleep and quality of life in midlife women with major depressive disorder

Depression during midlife years may lead to significant sleep disturbances and adversely impact quality of life (QOL). In this report, we examined the effects of treatment with quetiapine extended release (XR), 150-300 mg/day, on sleep and QOL in 23 midlife women with major depressive disorder (MDD). Quetiapine XR improved subjective sleep distress, overall sleep parameters, and sleep-related QOL, ultimately leading to significant improvement in menopause-related QOL. While larger, controlled trials are still awaited, these preliminary results are encouraging and suggest that quetiapine XR may be a useful tool in treating symptomatic midlife women with MDD.

Sleep promotes lasting changes in selective memory for emotional scenes

Although we know that emotional events enjoy a privileged status in our memories, we still have much to learn about how emotional memories are processed, stored, and how they change over time. Here we show a positive association between REM sleep and the selective consolidation of central, negative aspects of complex scenes. Moreover, we show that the placement of sleep is critical for this selective emotional memory benefit. When testing occurred 24 h post-encoding, subjects who slept soon after learning (24 h Sleep First group) had superior memory for emotional objects compared to subjects whose sleep was delayed for 16 h post-encoding following a full day of wakefulness (24 h Wake First group). However, this increase in memory for emotional objects corresponded with a decrease in memory for the neutral backgrounds on which these objects were placed. Furthermore, memory for emotional objects in the 24 h Sleep First group was comparable to performance after just a 12 h delay containing a night of sleep, suggesting that sleep soon after learning selectively stabilizes emotional memory. These results suggest that the sleeping brain preserves in long-term memory only what is emotionally salient and perhaps most adaptive to remember.

Retrospective cross-validation of automated sleep staging using electroocular recording in patients with and without sleep disordered breathing

BACKGROUND

Alterations of sleep duration and architecture have been associated with increased morbidity and mortality, and specifically linked to chronic cardiovascular disease and psychiatric disorders, such as type 2 diabetes or depression. Measurement of sleep quality to assist in the diagnosis or treatment of these diseases is not routinely performed due to the complexity and cost of conventional methods. The objective of this study is to cross-validate the accuracy of an automated algorithm that stages sleep from the EEG signal acquired with sensors that can be self-applied by patients.

METHODS

This retrospective study design included polymsomnographic records from 19 presumably healthy individuals and 68 patients suspected of having sleep disordered breathing (SDB). Epoch-by-epoch comparisons were made between manual vs. automated sleeps staging (from the left and right electrooculogram) with the impact of SDB severity considered.

RESULTS

Both scoring methods reported decreased Stage N3 and REM and increased wake and N1 as SDB severity increased. Inter-class correlations and Kappa coefficients were strong across all stages except N1. Agreements across all epochs for subjects with normal and patients with mild SDB were: wake = 80%, N1 = 25%, N2 = 78%, N3 = 84% and REM = 75%. Agreement decreased in patients with moderate and severe SDB amounting to: wake = 71%, N1 = 30%, N2 = 71%, N3 = 65%, and REM = 67%. Differences in detection of sleep onset were within three-minutes in 48 % of the subjects and 10-min in 73 % of the cases and were not impacted by SDB severity. Automated staging slightly underestimated total sleep time but this difference had a limited impact on the respiratory disturbance indexes.

CONCLUSIONS

This cross-validation study demonstrated that measurement of sleep architecture obtained from a single-channel of forehead EEG can be equivalent to between-rater agreement using conventional manual scoring. The accuracies obtained with automated sleep staging were inversely proportional to SDB severity at a rate similar to manual scorers. These results suggest that the automated sleep staging used in this study may prove useful in evaluating sleep quality in patients with chronic diseases.

Pre-schoolers suffering from psychiatric disorders show increased cortisol secretion and poor sleep compared to healthy controls

BACKGROUND

Various studies of child cortisol secretion and sleep show a close association between poor sleep, deterioration of the HPA axis and unfavorable psychological functioning. However, there is little evidence as to whether these associations are clearly present in pre-school children suffering from psychiatric disorders.

METHOD

A total of 30 pre-schoolers suffering from psychiatric disorders (anxiety, adjustment disorders, emotional and attachment disorder; hyperactivity or oppositional disorder) and 35 healthy controls took part in the study. Saliva cortisol secretion was assessed both at baseline and under challenge conditions. Sleep was assessed via activity monitoring for seven consecutive days and nights, using a digital movement-measuring instrument. Parents and teachers completed questionnaires assessing children's cognitive, emotional and social functioning. The Berkeley Puppet Interview provided child-based reports of cognitive-emotional processes.

RESULTS

Compared to healthy controls, children suffering from psychiatric disorders had much higher cortisol secretion both at baseline and under challenge conditions. Sleep was also more disturbed, and parents and teachers rated children suffering from psychiatric disorders as cognitively, emotionally and behaviorally more impaired, relative to healthy controls. Children with psychiatric disorders reported being more bullied and victimized.

CONCLUSIONS

In five-year old children the presence of psychiatric disorders is reflected not only at psychological, social and behavioral, but also at neuroendocrine and sleep-related levels. It is likely that these children remain at increased risk for suffering from psychiatric difficulties later in life.

R278995/CRA0450, a corticotropin-releasing factor (CRF(1)) receptor antagonist modulates REM sleep measures in rats: Implication for therapeutic indication

Abnormalities in the regulation of the hypothalamic stress hormone corticotropin-releasing factor (CRF) are thought to play a critical role in mood disorders. Consequently, CRF receptor antagonists have been proposed as potential novel therapeutic agents of these conditions. Sleep disturbance is common in depressed patients and changed sleep-wake architecture is considered as potential predictor or surrogate marker of response to treatment. The aim of our study was to characterise the effects of oral administration of the corticotropin-releasing factor CRF(1) receptor antagonist R278995/CRA0450 (3 and 10mg/kg) on sleep-wake organization and electroencephalographic (EEG) components in Sprague-Dawley rats, and to determine whether the changes observed in the sleep-EEG pattern resemble those seen with antidepressants. At 3mg/kg, R278995/CRA0450 produced minor changes in sleep behaviour, while an overall reduction in power spectra was observed during deep slow wave sleep. At 10mg/kg, R278995/CRA0450 consistently reduced rapid eye movement (REM) sleep (-75.4%) and increased the REM sleep onset latency (+67%, 92.1±4.9min for vehicle vs. 153.8±24min for R278995/CRA0450), in the absence of systematic changes in spectral EEG pattern, which are characteristic anti-depressant-like effects. These findings in rats indicate that the corticotropin-releasing factor CRF(1) receptor antagonist R278995/CRA0450 is centrally active under standard conditions as it inhibits REM sleep and promotes wakefulness. The characteristic changes found in the sleep EEG model further support the hypothesis that R278995/CRA0450 could exert a non-sedative, antidepressant-like action.