REM sleep dysregulation in depression: state of the art

Depression as a mediator between frequent nightmares and non-suicidal self-injury among adolescents: a 3-wave longitudinal model

BACKGROUND

Frequent nightmares and depression are associated with non-suicidal self-injury (NSSI) in adolescents. Little is known about the mediating role of depression in the nightmare-NSSI link. This study explores the longitudinal mediating effect of depression on the relationship between frequent nightmares and NSSI as well as the moderating effect of gender using a three-wave longitudinal design.

METHODS

Participants were adolescents from the Shandong Adolescent Behavior and Health Cohort who were surveyed at baseline, 1 year later, and 2 years later. A self-administered questionnaire was used to measure nightmare frequency, depression, and NSSI. Structural equation modeling and multiple-group analysis were used to test the mediating effect of depression and the moderating effect of gender. Covariates included demographics and earlier measures of depression and NSSI.

RESULTS

Among 6995 participants, 3399 (48.6%) were females, mean age was 14.86 (SD = 1.50) years at baseline. Frequent nightmares had a significant mediation effect on NSSI through depression (B_ab = 0.06, 95% CI = 0.02-0.10) after controlling for demographics and earlier measures of depression and NSSI. Gender had no significant moderating effect on the nightmare-NSSI association.

LIMITATIONS

All data were collected by self-report.

CONCLUSIONS

The association between frequent nightmares and NSSI in adolescents was partially mediated by depression. Frequent nightmares and depression should be assessed and treated to prevent self-harm in adolescents.

The association between emotional dysregulation and REM sleep features in insomnia disorder

Rapid Eye Movement (REM) sleep is involved in nightly emotional processing; therefore, its disruption might be associated with an impaired ability of emotional regulation during daytime. Accordingly, the aim of the present study was to evaluate the presence of emotional dysregulation in insomnia patients and to test its correlation with REM sleep features. Forty-six subjects (23 insomnia patients and 23 healthy controls) were enrolled. All subjects underwent an assessment for the evaluation of emotion dysregulation (Difficulties in Emotion Regulation Scale, DERS), sleep quality, insomnia severity, excessive daytime sleepiness, worry, rumination, depressive and anxious symptomatology. Insomnia patients underwent a nocturnal polysomnographic recording to characterize sleep macrostructure and REM sleep microstructure variables. Insomnia patients reported increased values of emotional dysregulation. REM sleep percentage and REM sleep latency significantly correlated with DERS total score, and with the subscales "Lack of Confidence in Emotional Regulation Skills", "Difficulties in Behavioral Control" and "Difficulty in recognizing emotions". Furthermore, positive correlations between REM arousal index and emotion dysregulation were found, whereas REM density negatively correlated with DERS. Our results suggest the presence of a relationship between REM sleep and emotional regulation in insomnia patients.

Sleep-Wake Control by Melanin-Concentrating Hormone (MCH) Neurons: a Review of Recent Findings

PURPOSE OF THE REVIEW

Melanin-concentrating hormone (MCH)-expressing neurons located in the lateral hypothalamus are considered as an integral component of sleep-wake circuitry. However, the precise role of MCH neurons in sleep-wake regulation has remained unclear, despite several years of research employing a wide range of techniques. We review recent data on this aspect, which are mostly inconsistent, and propose a novel role for MCH neurons in sleep regulation.

RECENT FINDINGS

While almost all studies using "gain-of-function" approaches show an increase in rapid eye movement sleep (or paradoxical sleep; PS), loss-of-function approaches have not shown reductions in PS. Similarly, the reported changes in wakefulness or non-rapid eye movement sleep (slow-wave sleep; SWS) with manipulation of the MCH system using conditional genetic methods are inconsistent. Currently available data do not support a role for MCH neurons in spontaneous sleep-wake but imply a crucial role for them in orchestrating sleep-wake responses to changes in external and internal environments.

Sleep Inconsistency and Markers of Inflammation

Objective: Poor sleep is associated with higher levels of inflammatory biomarkers. Conventionally, higher average time awake, lower average time asleep, and lower sleep efficiency define poor sleep. Recent research suggests that, in addition to average sleep, sleep inconsistency is an important indicator of sleep dysfunction. The current study sought to extend our knowledge of the relationship between sleep and inflammation through an examination of sleep inconsistency and inflammatory biomarkers. Methods: Secondary analyses of the Survey of Midlife in the United States (MIDUS) sleep study were conducted. Five hundred thirty-three individuals completed nightly sleep diaries, actigraphy, and underwent a blood draw for the inflammatory biomarkers C-reactive protein, interleukin-6, and fibrinogen. Sleep inconsistency was derived from 7 consecutive nights of assessment and was operationalized as nightly fluctuations in the following variables: terminal wakefulness, number of awakenings, time in bed, sleep onset latency, and wake after sleep onset. Structural equation modeling was used to examine the influence of a latent average sleep and a latent sleep inconsistency variable on a latent inflammation variable. Models were subsequently adjusted for age, sex, BMI, health, and medication. Stratified models by sex were also analyzed. Results: The average sleep model would not converge. The sleep inconsistency model fit the data well. A significant positive association between the latent factors sleep inconsistency and inflammation was observed (β = 10.18, SE = 4.40, p = 0.021), suggesting inconsistent sleep is associated with higher levels of inflammatory biomarkers. When stratified by sex, the association between the latent sleep inconsistency factor and inflammation was significant for women (β = 1.93, SE = 0.82, p = 0.018), but not men (β = 0.20, SE = 0.35, p = 0.566). The association between sleep inconsistency and inflammation weakened following multivariate adjustment (β = 6.23, SE = 3.71, p = 0.093). Conclusions: Inconsistent sleep may be an associated feature of inflammatory dysfunction, especially in women. Future studies should build upon this preliminary work and examine these associations longitudinally and through treatment trials.

Associations between sex hormones, sleep problems and depression: A systematic review

Sleep problems and depression are both common and have a high impact on quality of life. They are also strongly associated and commonly occur together. During the reproductive age, both sleep problems and depression are almost twice as common in women than men. Epidemiological studies show that women experience more sleep problems and depressive symptoms around times when sex hormones change, such as puberty and menopause, but it is unclear what effect sex hormones have on sleep problems and depression. This systematic review aims to summarize and evaluate studies that investigated the relationship between sex hormones, sleep and depression. Systematic search resulted in 2895 articles, of which 13 met inclusion criteria. Depressed patients showed worse sleep than controls, but no significant difference in endogenous hormone levels was found. Additionally, higher endogenous estrogen was associated with better sleep in controls, but associations between endogenous sex hormones and depressive symptoms were inconclusive. More research on the effect of sex hormones on sleep and depression is necessary.

Clarifying the role of sleep in depression: A narrative review

It has been established that 4.4 to 20% of the general population suffers from a major depressive disorder (MDD), which is frequently associated with a dysregulation of normal sleep-wake mechanisms. Disturbances of circadian rhythms are a cardinal feature of psychiatric dysfunctions, including MDD, which tends to indicate that biological clocks may play a role in their pathophysiology. Thus, episodes of depression and mania or hypomania can arise as a consequence of the disruption of zeitgebers (time cues). In addition, the habit of sleeping at a time that is out of phase with the body's other biological rhythms is a common finding in depressed patients. In this review, we have covered a vast area, emerging from human and animal studies, which supports the link between sleep and depression. In doing so, this paper covers a broad range of distinct mechanisms that may underlie the link between sleep and depression. This review further highlights the mechanisms that may underlie such link (e.g. circadian rhythm alterations, melatonin, and neuroinflammatory dysregulation), as well as evidence for a link between sleep and depression (e.g. objective findings of sleep during depressive episodes, effects of pharmacotherapy, chronotherapy, comorbidity of obstructive sleep apnea and depression), are presented.

Sleep Quality, Sleep Structure, and PER3 Genotype Mediate Chronotype Effects on Depressive Symptoms in Young Adults

Depression and its related mood disorders are a major global health issue that disproportionately affects young adults. A number of factors that influence depressive symptoms are particularly relevant to the young adult developmental stage, including sleep loss, poor sleep quality, and the tendency toward eveningness in circadian preferences. However, relatively few studies have examined the relationship between sleep and circadian phenotypes, and their respective influences on mood, or considered potential molecular mechanisms driving these associations. Here, we use a multi-year, cross-sectional study of 806 primarily undergraduates to examine the relationships between sleep-wake chronotype, sleep disturbance, depression and genotypes associated with the PER3 variable number of tandom repeats (VNTR) polymorphism-circadian gene variants associated with both chronotype and sleep homeostatic drive. In addition, we use objective, Fitbit-generated sleep structure data on a subset of these participants (n = 67) to examine the relationships between chronotype, depression scores, actual measures of sleep duration, social jetlag, and the percent of deep and rapid eye movement (REM) sleep per night. In this population, chronotype is weakly associated with depressive symptoms and moderately correlated with self-reported sleep disturbance. Sleep disturbance is significantly associated with depression scores, but objective sleep parameters are not directly correlated with Beck Depression Inventory (BDI-II) scores, with the exceptions of a moderate correlation between social jetlag and depression scores in females and a marginal correlation between sleep duration and depression scores. Multiple regression and path analyses reveal that chronotype effects on depressive symptoms in this population are mediated largely by sleep disturbance. The PER3 VNTR genotype significantly predicts depressive symptoms in a model with objective sleep parameters, but it does not significantly predict depressive symptoms in a model with chronotype or subjective sleep disturbance. Interestingly, PER35,5 genotypes, in males only, are independently related to chronotype and depression scores. Our results support hypotheses linking subjective sleep quality and chronotype and provide a first step in understanding how objective sleep structure may be linked to chronotype and depressive symptoms. Our results also suggest that circadian gene variants may show sex-specific effects linking sleep duration and sleep structure to depression.

REM sleep loss-induced elevated noradrenaline could predispose an individual to psychosomatic disorders: a review focused on proposal for prediction, prevention, and personalized treatment

Historically and traditionally, it is known that sleep helps in maintaining healthy living. Its duration varies not only among individuals but also in the same individual depending on circumstances, suggesting it is a dynamic and personalized physiological process. It has been divided into rapid eye movement sleep (REMS) and non-REMS (NREMS). The former is unique that adult humans spend the least time in this stage, when although one is physically asleep, the brain behaves as if awake, the dream state. As NREMS is a pre-requisite for appearance of REMS, the latter can be considered a predictive readout of sleep quality and health. It plays a protective role against oxidative, stressful, and psychopathological insults. Several modern lifestyle activities compromise quality and quantity of sleep (including REMS) affecting fundamental physiological and psychopathosomatic processes in a personalized manner. REMS loss-induced elevated brain noradrenaline (NA) causes many associated symptoms, which are ameliorated by preventing NA action. Therefore, we propose that awareness about personalized sleep hygiene (including REMS) and maintaining optimum brain NA level should be of paramount significance for leading physical and mental well-being as well as healthy living. As sleep is a dynamic, multifactorial, homeostatically regulated process, for healthy living, we recommend addressing and treating sleep dysfunctions in a personalized manner by the health professionals, caregivers, family, and other supporting members in the society. We also recommend that maintaining sleep profile, optimum level of NA, and/or prevention of elevation of NA or its action in the brain must be seriously considered for ameliorating lifestyle and REMS disturbance-associated dysfunctions.

Pharmacological Modulation of Sleep Homeostasis in Rat: Novel Effects of an mGluR2/3 Antagonist

Increasing vigilance without incurring the negative consequences of extended wakefulness such as daytime sleepiness and cognitive impairment is a major challenge in treating many sleep disorders. The present work compares two closely related mGluR2/3 antagonists LY3020371 and LY341495 with two well-known wake-promoting compounds caffeine and d-amphetamine. Sleep homeostasis properties were explored in male Wistar rats by manipulating levels of wakefulness via (1) physiological sleep restriction (SR), (2) pharmacological action, or (3) a combination of these. A two-phase nonlinear mixed-effects model combining a quadratic and exponential function at an empirically estimated join point allowed the quantification of wake-promoting properties and any subsequent sleep rebound. A simple response latency task (SRLT) following SR assessed functional capacity of sleep-restricted animals treated with our test compounds. Caffeine and d-amphetamine increased wakefulness with a subsequent full recovery of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep and were unable to fully reverse SR-induced impairments in SRLT. In contrast, LY3020371 increased wakefulness with no subsequent elevation of NREM sleep, delta power, delta energy, or sleep bout length and count, yet REM sleep recovered above baseline levels. Prior sleep pressure obtained using an SR protocol had no impact on the wake-promoting effect of LY3020371 and NREM sleep rebound remained blocked. Furthermore, LY341495 increased functional capacity across SRLT measures following SR. These results establish the critical role of glutamate in sleep homeostasis and support the existence of independent mechanisms for NREM and REM sleep homeostasis.

Relationship of physical activity and sleep with depression in college students

Objectives: This study examined the relationship between physical activity, sleep and depression among college students and gender differences in physical activity, sleep and depression. Methods: Participants were 1143 students from a large public university in Beijing and completed three questionnaires to measure their physical activity habits, sleep patterns, and depression levels. Data from were analyzed using descriptive statistics, stepwise regression, and an independent t test. Results: Results indicated that vigorous physical activity and sleep variables significantly predicted depression levels for the overall sample (F = 77.286, p = .000). When examined by gender, vigorous and moderate physical activity variables significantly predicted depression for males (t = -2.772, p = .006; t = -2.622, p = .009), whereas no level of physical activity had a significant relationship with depression for females. Conclusions: Rigorous physical activity and quality sleep may be beneficial to helping college students reduce and regulate depressive symptoms, however may vary by gender.

Sleep disturbance and psychiatric disorders

Signs of mental ill health that cut across psychiatric diagnostic categories at high rates are typically viewed as non-specific occurrences, downgraded in importance and disregarded. However, problems not associated with particular diagnoses should be expected if there is shared causation across mental health conditions. If dynamic networks of interacting symptoms are the reality of mental health presentations, then particularly disruptive and highly connected problems should be especially common. The non-specific occurrence might be highly consequential. One non-specific occurrence that is often overlooked is patients' chronic difficulty in getting good sleep. In this Review, we consider whether disrupted sleep might be a contributory causal factor in the occurrence of major types of mental health disorders. It is argued that insomnia and other mental health conditions not only share common causes but also show a bidirectional relationship, with typically the strongest pathway being disrupted sleep as a causal factor in the occurrence of other psychiatric problems. Treating insomnia lessens other mental health problems. Intervening on sleep at an early stage might be a preventive strategy for the onset of clinical disorders. Our recommendations are that insomnia is assessed routinely in the occurrence of mental health disorders; that sleep disturbance is treated in services as a problem in its own right, yet also recognised as a pathway to reduce other mental health difficulties; and that access to evidence-based treatment for sleep difficulties is expanded in mental health services.

High-frequency cardiopulmonary coupling during sleep correlates with memory in depressed patients: A pilot study

BACKGROUND

It has been demonstrated that a reduction in the amount of high-frequency cardiopulmonary coupling (CPC) is indicative of unstable sleep in unmedicated patients with major depressive disorder (MDD). Considering the close relationship between sleep quality and memory consolidation, this study sought to investigate the potential of high-frequency CPC as a novel biomarker for objective evaluation of memory impairment in MDD.

METHODS

A total of 64 depressed patients and 35 healthy controls were included in this cross-sectional study. High-frequency coupling (HFC) was assessed by electrocardiogram-based CPC analysis using a portable sleep-respiration monitor during sleep for one night. The next day, subjects completed the cognition assessment with the Assessment of Neuropsychological Status (RBANS). The 17-Item Hamilton Depression Rating Scale (HAMD₁₇) and the Hamilton Rating Scales for Anxiety (HAMA) were used to evaluate the severity of depression and anxiety in each patient, respectively.

RESULTS

There was no significant difference in the proportion of HFC between depressed patients and healthy controls. In patients with low HFC proportion (<35%), severe anxiety could significantly decrease HFC proportion. The HFC proportion positively correlated with immediate and delayed memory in depressed patients. Further analysis showed that patients with low HFC proportion may have worse delayed memory.

LIMITATIONS

The lack of prior exposure to the monitoring equipment and procedure could have generated artefacts that would have disappeared after habituation.

CONCLUSIONS

These results support a positive correlation between the HFC proportion and memory in depressed patients. Further research is required to explore the clinical implications of these findings.

Circadian rhythm and sleep alterations in older people with lifetime depression: a case-control study

BACKGROUND

Depression is common in older people and is associated with underlying brain change increasing the risk of dementia. Sleep disturbance is frequently reported by those with lifetime depression, however whether circadian misalignment also exists is unclear. We aimed to examine circadian rhythms and sleep associations in older patients with and without lifetime depression.

METHODS

Thirty-four older people meeting DSM-IV criteria for lifetime major depression (mean age = 63.9 years), and 30 healthy controls (mean age = 65.7 years) were recruited. Participants underwent 2-weeks of actigraphy followed by a 3-night protocol including dim light melatonin onset (DLMO) assessment and overnight polysomnography (PSG) for sleep architecture. DLMO and phase angle of entrainment were computed.

RESULTS

Compared to controls, participants with depression had a significantly longer phase angle of entrainment (6.82 h ± 1.45 vs. 5.87 h ± 1.60, p = 0.02, Cohens-d = 0.62). A small to moderate yet non-significant difference in DLMO times, with earlier DLMO (34 ± 27 min) observed in depression (20:36 ± 1:48 vs. 21:10 ± 1:48, p = 0.22, Cohens-d = 0.32). Individuals with depression had longer sleep latency and latency to rapid eye movement sleep than controls (all p < 0.05).

CONCLUSION

Circadian advancement and alterations to the timing of sleep and REM onset are evident in older people with lifetime major depression, despite having only mild residual symptoms. Further research examining the prognostic significance of these changes is warranted as well as chronotherapeutic treatment studies.

Alterations of neural network organization during REM sleep in women: implication for sex differences in vulnerability to mood disorders

BACKGROUND

Sleep plays an important role in vulnerability to mood disorders. However, despite the existence of sex differences in vulnerability to mood disorders, no study has yet investigated the sex effect on sleep network organization and its potential involvement in vulnerability to mood disorders. The aim of our study was to empirically investigate the sex effect on network organization during REM and slow-wave sleep using the effective connectivity measured by Granger causality.

METHODS

Polysomnographic data from 44 healthy individuals (28 men and 16 women) recruited prospectively were analysed. To obtain the 19 × 19 connectivity matrix of all possible pairwise combinations of electrodes by Granger causality method from our EEG data, we used the Toolbox MVGC multivariate Granger causality. The computation of the network measures was realized by importing these connectivity matrices into EEGNET Toolbox.

RESULTS

In men and women, all small-world coefficients obtained are compatible with a small-world network organization during REM and slow-wave sleep. However, compared to men, women present greater small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage, which indicates the presence of a small-world network organization less marked during REM sleep as well as for all EEG bands during this sleep stage in women. In addition, in women, these small-world coefficients during REM sleep as well as for all EEG bands during this sleep stage are positively correlated with the presence of subclinical symptoms of depression.

CONCLUSIONS

Thus, the highlighting of these sex differences in network organization during REM sleep indicates the presence of differences in the global and local processing of information during sleep between women and men. In addition, this small-world network organization less marked during REM sleep appears to be a marker of vulnerability to mood disorders specific to women, which opens up new perspectives in understanding sex differences in the occurrence of mood disorders.

Comorbid Depression Is Associated with a Negative Treatment Response in Idiopathic REM Sleep Behavior Disorder

Background and Purpose

The first-line medications for the symptomatic treatment of rapid eye movement sleep behavior disorder (RBD) are clonazepam and melatonin taken at bedtime. We aimed to identify the association between depression and treatment response in patients with idiopathic RBD (iRBD).

Methods

We reviewed the medical records of 123 consecutive patients (76 males; age, 66.0±7.7 years; and symptom duration, 4.1±4.0 years) with iRBD who were treated with clonazepam and/or melatonin. Clonazepam and melatonin were initially administered at 0.25–0.50 and 2 mg/day, respectively, at bedtime, and the doses were subsequently titrated according to the response of individual patients. Treatment response was defined according to the presence or absence of any improvement in dream-enacting behaviors or unpleasant dreams after treatment.

Results

Forty (32.5%) patients were treated with clonazepam, 56 (45.5%) with melatonin, and 27 (22.0%) with combination therapy. The doses of clonazepam and melatonin at followup were 0.5±0.3 and 2.3±0.7 mg, respectively. Ninety-six (78.0%) patients reported improvement in their RBD symptoms during a mean follow-up period of 17.7 months. After adjusting for potential confounders, depression was significantly associated with a negative treatment response (odds ratio=3.76, 95% confidence interval=1.15–12.32, p=0.029).

Conclusions

We found that comorbid depression is significantly associated with a negative response to clonazepam and/or melatonin in patients with iRBD. Further research with larger numbers of patients is needed to verify our observations and to determine the clinical implications of comorbid depression in the pathophysiology of iRBD.

Establishing the objective sleep phenotype in hypersomnolence disorder with and without comorbid major depression

STUDY OBJECTIVES

To clarify whether hypersomnolence disorder is associated with a specific sleep phenotype and altered neurophysiological function in persons with and without hypersomnolence disorder and major depressive disorder (MDD).

METHODS

Eighty-three unmedicated persons with and without hypersomnolence disorder and/or MDD underwent ad libitum high-density EEG polysomnography. Clinical and sleep architecture variables were compared between groups. Topographic patterns of slow-wave activity (SWA) relative to healthy controls were compared, with correlations between topographic SWA and daytime sleepiness assessed. Reductions in SWA in hypersomnolence disorder were mapped to specific cortical areas using source localization.

RESULTS

Regardless of the presence or absence of comorbid MDD, persons with hypersomnolence disorder had increased sleep duration relative to both controls and persons with MDD without hypersomnolence. Participants with hypersomnolence disorder also demonstrated reduced bilateral centroparietal low-frequency activity during nonrapid eye movement sleep relative to controls, a pattern not observed in persons with MDD but without hypersomnolence. SWA in these regions was negatively correlated with subjective measures of daytime sleepiness. Source localization demonstrated reductions in SWA in the supramarginal gyrus, somatosensory, and transverse temporal cortex in participants with hypersomnolence disorder.

CONCLUSIONS

Hypersomnolence disorder is characterized by increased sleep duration with normal sleep continuity, regardless of the presence or absence of comorbid depression. Reduced local SWA may be a specific neurophysiological finding in hypersomnolence disorder. Further research is warranted to elucidate the mechanisms through which these cortical changes are related to clinical complaints of daytime sleepiness.

Sleeping Patterns in Patients with Opioid Use Disorder: Effects of Opioid Maintenance Treatment and Detoxification

The aim of the study was to explore whether abstinent patients on recent opioid detoxification or on opioid maintenance treatment suffer from sleeping problems. 199 patients on opioid maintenance treatment (methadone, diacetylmorphine and buprenorphine) or recent opioid detoxification were included in this exploratory cross-sectional study. We used the Pittsburgh Sleep Quality Index (PSQI) and the Regensburger Insomnia Scale (RIS) in order to assess potential sleeping problems. There was a significant effect of the condition "opioid maintenance" or "recent opioid detoxification" on the total score of PSQI and RIS. All opioid maintenance drugs used by the study population were associated with more sleeping problems compared to the detoxification group when calculated with RIS values. Recently abstinent patients (opioid detoxification) displayed significantly fewer sleep disturbances than opioid-maintained patients. Since sleeping problems can seriously impair treatment success and quality of life, screening for sleep disturbances and their subsequent treatment is of pronounced relevance.

Copine-7 is required for REM sleep regulation following cage change or water immersion and restraint stress in mice

Sleep is affected by the environment. In rodents, changes in the amount of rapid eye movement sleep (REMS) can precede those of other sleep/wake stages. The molecular mechanism underlying the dynamic regulation of REMS remains poorly understood. Here, we focused on the sublaterodorsal nucleus (SLD), located in the pontine tegmental area, which plays a crucial role in the regulation of REMS. We searched for genes selectively expressed in the SLD and identified copine-7 (Cpne7), whose involvement in sleep was totally unknown. We generated Cpne7-Cre knock-in mice, which enabled both the knockout (KO) of Cpne7 and the genetic labeling of Cpne7-expressing cells. While Cpne7-KO mice exhibited normal sleep under basal conditions, the amount of REMS in Cpne7-KO mice was larger compared to wildtype mice following cage change or water immersion and restraint stress, both of which are conditions that acutely reduce REMS. Thus, it was suggested that copine-7 is involved in negatively regulating REMS under certain conditions. In addition, chemogenetically activating Cpne7-expressing neurons in the SLD reduced the amount of REMS, suggesting that these neurons negatively regulate REMS. These results identify copine-7 and Cpne7-expressing neurons in the SLD as candidate molecular or neuronal components of the regulatory system that controls REMS.

Melanin-concentrating hormone (MCH) in the median raphe nucleus: Fibers, receptors and cellular effects

Serotonergic neurons of the median raphe nucleus (MnR) and hypothalamic melanin-concentrating hormone (MCH)-containing neurons, have been involved in the control of REM sleep and mood. In the present study, we examined in rats and cats the anatomical relationship between MCH-containing fibers and MnR neurons, as well as the presence of MCHergic receptors in these neurons. In addition, by means of in vivo unit recording in urethane anesthetized rats, we determined the effects of MCH in MnR neuronal firing. Our results showed that MCH-containing fibers were present in the central and paracentral regions of the MnR. MCHergic fibers were in close apposition to serotonergic and non-serotonergic neurons. By means of an indirect approach, we also analyzed the presence of MCHergic receptors within the MnR. Accordingly, we microinjected MCH conjugated with the fluorophore rhodamine (R-MCH) into the lateral ventricle. R-MCH was internalized into serotonergic and non-serotonergic MnR neurons; some of these neurons were GABAergic. Furthermore, we determined that intracerebroventricular administration of MCH induced a significant decrease in the firing rate of 53 % of MnR neurons, while the juxtacellular administration of MCH reduced the frequency of discharge in 67 % of these neurons. Finally, the juxtacellular administration of the MCH-receptor antagonist ATC-0175 produced an increase in the firing rate in 78 % of MnR neurons. Hence, MCH produces a strong regulation of MnR neuronal activity. We hypothesize that MCHergic modulation of the MnR neuronal activity may be involved in the promotion of REM sleep and in the pathophysiology of depressive disorders.

Neuroimaging Biomarkers for Predicting Treatment Response and Recurrence of Major Depressive Disorder

The acute treatment duration for major depressive disorder (MDD) is 8 weeks or more. Treatment of patients with MDD without predictors of treatment response and future recurrence presents challenges and clinical problems to patients and physicians. Recently, many neuroimaging studies have been published on biomarkers for treatment response and recurrence of MDD using various methods such as brain volumetric magnetic resonance imaging (MRI), functional MRI (resting-state and affective tasks), diffusion tensor imaging, magnetic resonance spectroscopy, near-infrared spectroscopy, and molecular imaging (i.e., positron emission tomography and single photon emission computed tomography). The results have been inconsistent, and we hypothesize that this could be due to small sample size; different study design, including eligibility criteria; and differences in the imaging and analysis techniques. In the future, we suggest a more sophisticated research design, larger sample size, and a more comprehensive integration including genetics to establish biomarkers for the prediction of treatment response and recurrence of MDD.

Sleep in the anxiety-related disorders: A meta-analysis of subjective and objective research

Although sleep disturbance is implicated in psychopathology, its role in anxiety-related disorders remains unclear. The present meta-analysis characterizes sleep disturbance in anxiety-related disorders collectively and individually. Subjective measures of total sleep time and sleep continuity were included with objective measures. Results indicate a large effect for increased subjective sleep disturbance (g = 2.16), medium effects for decreased total sleep time (g = -.40) and sleep continuity (g = -.49), and a small effect for decreased sleep depth (g = -.20) in anxiety-related disorders compared to healthy controls. Each anxiety-related disorder exhibited a distinct sleep disturbance pattern, suggesting that sleep may facilitate identification of unique biopsychological underpinnings. Effects were not moderated by comorbid depression and were similar in magnitude to those found for depression. Sleep disturbances, particularly decreased sleep continuity, may be a key pathology in the anxiety-related disorders that could highlight novel etiological mechanisms and intervention targets.

Impact of number of sleep ultradian cycles on polysomnographic parameters related to REM sleep in major depression: Implications for future sleep research in psychiatry

Given the contradictory data on REMS alterations in major depression, the aim of this study was to empirically demonstrate that based on the number of sleep ultradian cycles, it was possible to highlight different subtypes of major depression characterized by specific patterns of REMS alterations. Demographic and polysomnographic data from 211 individuals (30 healthy controls and 181 untreated major depressed individuals) recruited from the sleep laboratory database were analyzed. Major depressed individuals with sleep ultradian cycles <4 showed alterations consistent with REMS deficiency (non-shortened REM latency as well as decrease in REMS percentage, REMS duration and REMS/NREMS ratio) whereas major depressed individuals with sleep ultradian cycles >4 showed alterations consistent with REMS disinhibition (shortened REM latency as well as increase in REMS percentage, REMS duration and REMS/NREMS ratio). Regarding major depressed individuals with 4 sleep ultradian cycles, their REMS alterations were intermediate to those present in major depressed individuals with sleep ultradian cycles <4 and >4. Thus, in major depressed individuals, the highlighting of this heterogeneity of REMS alterations based on the number of sleep ultradian cycles seems to suggest the involvement of distinct pathophysiological mechanisms and could open new perspectives for future sleep research in psychiatry.

Transcranial Magnetic Stimulation of the Medial Prefrontal Cortex Decreases Emotional Memory Schemas

Mood-congruent memory bias is a critical characteristic of depression, but the underlying neural mechanism is largely unknown. Negative memory schemas might enhance encoding and consolidation of negative experiences, thereby contributing to the genesis and perpetuation of depressive pathology. To investigate this relationship, we aimed to perturb medial prefrontal cortex (mPFC) processing, using neuronavigated transcranial magnetic stimulation (TMS) targeting the mPFC. Forty healthy volunteers first underwent a negative mood induction to activate negative schema processing after which they received either active inhibitory (N = 20) or control (N = 20) stimulation to the mPFC. Then, all participants performed the encoding of an emotional false memory task. Recall and recognition performance was tested the following morning. Polysomnographic data were recorded continuously during the night before and after encoding. We observed a significantly lower false recognition of negative critical lures following mPFC inhibition, but no differences in veridical memory. These findings were supported by reaction time data, showing a relative slower response to negative compared with positive critical lures. The current findings support previous causal evidence for a role of the mPFC in schema memory processing and further suggest a role of the mPFC in memory bias.

Neurochemical mechanisms for memory processing during sleep: basic findings in humans and neuropsychiatric implications

Sleep is essential for memory formation. Active systems consolidation maintains that memory traces that are initially stored in a transient store such as the hippocampus are gradually redistributed towards more permanent storage sites such as the cortex during sleep replay. The complementary synaptic homeostasis theory posits that weak memory traces are erased during sleep through a competitive down-selection mechanism, ensuring the brain's capability to learn new information. We discuss evidence from neuropharmacological experiments in humans to show how major neurotransmitters and neuromodulators are implicated in these memory processes. As to the major excitatory neurotransmitter glutamate that plays a prominent role in inducing synaptic consolidation, we show that these processes, while strengthening cortical memory traces during sleep, are insufficient to explain the consolidation of hippocampus-dependent declarative memories. In the inhibitory GABAergic system, we will offer insights how drugs may alter the intricate interplay of sleep oscillations that have been identified to be crucial for strengthening memories during sleep. Regarding the dopaminergic reward system, we will show how it is engaged during sleep replay, but that dopaminergic neuromodulation likely plays a side role for enhancing relevant memories during sleep. Also, we briefly go into basic evidence on acetylcholine and cortisol whose low tone during slow wave sleep (SWS) is crucial in supporting hippocampal-to-neocortical memory transmission. Finally, we will outline how these insights can be used to improve treatment of neuropsychiatric disorders focusing mainly on anxiety disorders, depression, and addiction that are strongly related to memory processing.

Increased Global PSQI Score Is Associated with Depressive Symptoms in an Adult Population from the United States

BACKGROUND

Although sleep problems are associated with a wide range of mental problems, it remains uncertain whether the global Pittsburgh Sleep Quality Index (PSQI) score is related to depressive symptoms in an adult population.

PATIENTS AND METHODS

Data from the Midlife in the United States (MIDUS) study, including a general adult population, were obtained. A total of 1002 individuals (aged 34-84 years) were included in this study. Linear regression and logistic regression analyses were performed to investigate the association between sleep parameters from the PSQI score and depressive symptoms.

RESULTS

The median age of all participants was 53.0 years old, and 45.2% of them were male. After adjustments were made for sociodemographic characteristics, lifestyle factors, currently diagnosed diseases and inflammatory markers, global PSQI score was significantly associated with depression score in the linear regression model (0.298 [0.207-0.389], P<0.001; Model 3). A higher global PSQI score was independently and significantly associated with depressive symptoms (score ≥16) in the logistic regression model (1.235 [1.150-1.325], P<0.001; Model 3). Stratified analysis showed that the independent association between global PSQI score and depressive symptoms was affected by hypnotics use, but not antidepressants use.

CONCLUSIONS

A higher global PSQI score is significantly associated with a higher risk of depressive symptoms in an adult population from the United States. Future longitudinal and interventional studies are warranted to assess whether reducing the global PSQI score may improve symptoms of depression.

Sleep Quality, Depression, and Cognitive Function in Non-Demented Older Adults

BACKGROUND

Both sleep quality and depression could affect cognitive performance in older adults. Previous studies have suggested that there are bi-directional relationships between sleep quality and depression. Possibly, the influence of sleep quality on cognition is partly mediated by depression, and vice versa.

OBJECTIVE

We aimed to assess the mediation effects of sleep quality and depression on each other's relationship with various cognitive functions in non-demented older adults.

METHODS

Correlations were examined among sleep quality indices, depressive severity score, and five cognitive functions in 206 cognitively normal (CN) older adults and all participants that included these CN and 40 mild cognitive impairment (MCI) individuals. We then analyzed the mediation effects for the significant cognitive correlations of sleep disturbance and depression using the bias-corrected Bootstrap method in the two populations.

RESULTS

Both sleep disturbance and depression were significantly correlated with memory recall and processing speed. In CN, depression could mediate the relationships of sleep disturbance with both cognitive functions, while sleep disturbance could only mediate the relationship of depression with processing speed, but not memory recall. However, in all participants, sleep disturbance could mediate the relationships of depression with both cognitive functions.

CONCLUSION

Different mediation effects in the two models in CN older adults might suggest differential mechanisms underlying the pathways from sleep disturbance and depression to various cognitive functions. The mediation results in all participants might indicate that the mechanisms underlying the pathways from sleep disturbance and depression to memory recall were different between MCI and CN older adults.

Effects of REM sleep during a daytime nap on emotional perception in individuals with and without depression

BACKGROUND

It has been theoretically proposed that alteration in sleep physiology may contribute to the development of biased emotional processing featured in depression. The current study investigated the role of sleep and especially REM in modulating perception of emotional faces in depressed versus non-depressed individuals using a napping paradigm.

METHODS

Forty-six individuals with major depressive disorder and 66 age- and education-matched healthy controls completed an emotional face perception task before and after random assignment to one of the three intention-to-treat (ITT) conditions, namely 30-min-nap, 90-min-nap and wake. To delineate the effects of REM, as-treated (30-min-nap, 90-min-REM-nap, 90-min-noREM-nap and wake) analyses were also conducted.

RESULTS

Repeated measures multivariate analysis of covariance (MANCOVA) showed a significant Time *Group *Condition interaction on angry faces for both analyses of ITT (p = .017) and AT (p = .027). Pairwise comparison with Bonferroni corrections revealed a significant increase in the intensity rating of angry faces only after 90-min-REM-nap in the depressed group. Correlational analyses convergingly showed that the increase of intensity rating of angry faces was associated with the proportion of REM sleep in the depressed group, p = .035.

LIMITATIONS

The observed effect of REM sleep during daytime napping may not represent the effect of nighttime REM sleep in depression.

CONCLUSIONS

We provide the first evidence of the association of daytime sleep, particularly REM sleep, with a more negative perception of angry faces exclusively in individuals with depression. The differentiated impact of sleep observed may contribute to the development of altered emotional processing in depression.

Comparing primary insomnia to the insomnia occurring in major depression and general anxiety disorder

Apart from possibly distinguishing the different clinical causes of insomnia, this article explores the subjective and objective sleep differences amongst primary insomnia, major depression with insomnia and general anxiety disorder with insomnia. Subjective sleep and objective sleep of the participants were evaluated by using the Pittsburgh sleep quality index and polysomnography, respectively. We found that major depression with insomnia exhibited higher daytime dysfunction than primary insomnia; showed significantly higher values of rapid eye movement (REM) periods, time of REM sleep and percentage of REM stage; and presented lower percentage of non-rapid eye movement stage compared with primary insomnia and general anxiety disorder with insomnia (p < 0.05). General anxiety disorder with insomnia showed lower awakening number (AN) than primary insomnia, and other objective and subjective sleep values of general anxiety disorder with insomnia and primary insomnia showed no significant difference (p > 0.05). Our findings showed that major depression with insomnia increased active REM sleep and severe daytime function, which could alert clinicians to the risk of depression. Major depression with insomnia and primary insomnia may be categorically different. However, general anxiety disorder with insomnia and primary insomnia might be a continuum of a disease rather than be categorically distinct.

Contributions of the Women's Health Initiative to understanding associations between sleep duration, insomnia symptoms, and sleep-disordered breathing across a range of health outcomes in postmenopausal women

The Women's Health Initiative (WHI), a longitudinal study of more than 161,000 postmenopausal women across the United States, provides an opportunity to investigate the link between sleep health and healthy aging. The purpose of this paper was to systematically review all published WHI articles examining sleep as a predictor of health outcomes and health behaviors/quality of life outcomes. A strength of the WHI is that for most participants, sleep measures were completed before a major health diagnosis, with a significant portion of participants also providing sleep measures after diagnosis. Twenty-three WHI articles were identified and examined for this review. The combination of sleep duration and insomnia symptoms was the most commonly investigated sleep measure. The results indicated that both short (≤6 hours) and long (≥9 hours) sleep duration were associated with a higher risk of cardiovascular disease, colorectal cancer, mortality, cognitive decline, and poor diet. Insomnia symptoms, frequent snoring, and risk of sleep-disordered breathing (SDB) were also associated with increased risk for ischemic stroke and cardiovascular disease. However, many significant results were attenuated after multivariable adjustment. Limitations of these WHI examinations include the use of different categories for sleep measures across studies and a lack of examination by race/ethnicity. Owing to the longitudinal study design, large sample size, and long-term follow-up for health outcomes, the WHI serves as a rich resource for examining associations between sleep characteristics, demographics, and health in postmenopausal women.

Effects of 3 Weeks of Water Immersion and Restraint Stress on Sleep in Mice

Repeated stress is a risk factor for mental disorders and can also lead to sleep disturbances. Although the effects of stress on sleep architecture have been investigated in rodents, the length of the stress exposure period in most studies has been limited to about 10 days, and few studies have analyzed the effects of chronic stress over a longer period. Here we investigated how sleep is affected in a mouse model of depression induced by 3 weeks of daily water immersion and restraint stress (WIRS). Sleep was recorded after 1, 2, and 3 weeks of stress exposure. Some stress-induced changes in several sleep measures were maintained across the 3 weeks, whereas other changes were most prominent during the 1st week. The total amount of non-rapid eye movement sleep (NREMS) was increased and the total amount of time spent awake was decreased across all 3 weeks. On the other hand, the amount of REMS during the dark phase was significantly increased in the 1st week compared with that at baseline or the 2nd and 3rd weeks. Electroencephalogram (EEG) power in the delta range was decreased during NREMS, although the total amount of NREMS was increased. These findings indicate that repeated WIRS, which eventually leads to a depression-like phenotype, differentially affects sleep between the early and subsequent periods. The increase in the amount of REMS during the dark phase in the 1st week significantly correlated with changes in body weight. Our results show how sleep changes throughout a long period of chronic stress in a mouse model of depression.

Alterations of neural network organisation during rapid eye movement sleep and slow-wave sleep in major depression: Implications for diagnosis, classification, and treatment

The aim of this study was to empirically investigate the network organisation during rapid eye movement sleep (REMS) and slow-wave sleep (SWS) using the effective connectivity measured using the Granger causality to identify new potential biomarkers for the diagnosis, classification, and potential favourable response to treatment in major depression. Polysomnographic data were analysed from 24 healthy individuals and 16 major depressed individuals recruited prospectively. To obtain the 19×19 connectivity matrix of all possible pairwise combinations of electrodes by the Granger causality method from our electroencephalographic data, we used the Toolbox MVGC multivariate Granger causality. The computation of network measures was realised by importing these connectivity matrices into the EEGNET Toolbox. Major depressed individuals (versus healthy individuals) and those with endogenous depression (versus those with neurotic depression) present alterations of small-world network organisation during REMS, whereas major depressed individuals with potential favourable response to electroconvulsive therapy (versus those with potential unfavourable response) have a less efficient small-world network organisation during SWS. Thus, alterations in network organisation during REMS could be biomarkers for the diagnosis and classification of major depressive episodes, whereas alterations of network organisation during SWS could be a biomarker to predict potential favourable response to treatment by electroconvulsive therapy.

The involvement of sleep in the relationship between the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and depression: A systematic review

BACKGROUND

Recent meta-analyses stimulate an ongoing debate whether 5-HTTLPR modulates the risk for depression including a more pronounced association between stress and depression in the short (S) allele relative to the long (L) allele. Elucidating the pathways by which 5-HTTLPR contributes to depression could resolve this controversy. Insomnia independently contributes to the onset and course of negative affective symptoms and, hence, represents one of the primary risk factors for depression. To evaluate the relevance of this relationship for the interaction between 5-HTTLPR and stress in depression, the present review investigated the moderating influence of 5-HTTLPR on the relationship between stress and sleep quality as well as on the relationship between sleep and affective symptomatology.

METHODS

A systematic search was performed in the PubMed and PsycINFO databases to include a complete outline of studies investigating the relationships of interest.

RESULTS

Results of the included articles reveal that the 5-HTTLPR S-allele relative to the L-allele increases the risk for stress-related sleep quality reductions and promotes the negative affective consequences of inadequate sleep.

LIMITATIONS

The apparent involvement of sleep in the association between 5-HTTLPR and depression remains to be more directly (empirically) examined and studies exploring the influence of 5-HTTLPR on sleep quality produced inconsistent results.

CONCLUSIONS

The reviewed findings support the involvement of sleep in the interaction between 5-HTTLPR and stress in depression. This could have important implications for the inconsistent findings characterizing this field of research and may provide valuable insight into the pathophysiological mechanisms underlying genetic contributions to depression.

Circadian insights into the biology of depression: Symptoms, treatments and animal models

In depression, symptoms range from loss of motivation and energy to suicidal thoughts. Moreover, in depression alterations might be also observed in the sleep-wake cycle and in the daily rhythms of hormonal (e.g., cortisol, melatonin) secretion. Both, the sleep-wake cycle and hormonal rhythms, are regulated by the internal biological clock within the hypothalamic suprachiasmatic nucleus (SCN). Therefore, a dysregulation of the internal mechanism of the SCN might lead in the disturbance of temporal physiology and depression. Hence, circadian symptoms in mood disorders can be used as important biomarkers for the prevention and treatment of depression. Disruptions of daily rhythms in physiology and behavior are also observed in animal models of depression, giving thus an important tool of research for the understanding of the circadian mechanisms implicated in mood disorders. This review discusses the alterations of daily rhythms in depression, and how circadian perturbations might lead in mood changes and depressive-like behavior in humans and rodents respectively. The use of animal models with circadian disturbances and depressive-like behaviors will help to understand the central timing mechanisms underlying depression, and how treating the biological clock(s) it may be possible to improve mood.

Interplay of dopamine and GABA in substantia nigra for the regulation of rapid eye movement sleep in rats

Substantia nigra (SN) is rich in dopamine (DA)-ergic and GABA-ergic neurons, which project to and receive inputs from locus coeruleus (LC) and pedunculo-pontine tegmentum (PPT) possessing REM-OFF and REM-ON neurons, respectively. Loss of DA-ergic neurons and disturbed REM sleep (REMS) are associated with Parkinson's disease, depression and REMS behavior disorder. GABA-ergic projections from SN act pre-synaptically on the noradrenaline (NA)-ergic terminals coming from the LC-REM-OFF neurons onto the REM-ON neurons in PPT and play a critical role in initiating REMS. However, it was unknown how SN neurons get activated and whether the SN-DA-ergic neurons interact with the SN-GABA-ergic neurons for REMS regulation. In freely moving chronically prepared rats, neurons in SN (bilateral) were stimulated by local microinjection of Glutamate (Glut), sparing the fibers of passage, in the presence and absence of i.p. Haloperidol (Hal, DA-antagonist). In other sets, either Hal or Bicuculine (Bic, GABA-antagonist) alone or simultaneously was microinjected bilaterally into the SN and the effects on sleep-wakefulness were recorded. We observed that Glut in SN significantly increased REMS, which was prevented by Hal. REMS was decreased and increased by Hal and Bic, respectively; while their co-injection neutralized (ineffective) the individual effects. Combining these findings with previous reports suggest that the SN-DA-ergic neurons act on the SN-GABA-ergic to regulate REMS. The results advance our understanding of the neuro-anatomo-chemical connections and pharmaco-physiological regulation of REMS in health and diseases.

The acute effects of aerobic exercise on sleep in patients with depression: study protocol for a randomized controlled trial

BACKGROUND

Unipolar depression is one of the most important mental disorders. Insomnia is a symptom of cardinal importance in depression. It increases the risk to develop depression, negatively affects disease trajectory, is the most common symptom after remission, increases the risk of relapse, and is associated with higher suicide rates. Existing therapies for insomnia in depression have limitations. Further adjuvant therapies are therefore needed. Acute aerobic exercise has been shown to have beneficial effects on sleep in healthy individuals and patients with insomnia. We therefore hypothesize that a single session of aerobic exercise has a positive impact on sleep in patients with unipolar depression. This trial aims to investigate the effects of a single bout of aerobic exercise on the subsequent night's sleep in patients with depression.

METHODS/DESIGN

This is a two-arm parallel group, randomized, outcome assessor blinded, controlled, superiority trial. Patients between 18 and 65 years of age with a primary diagnosis of unipolar depression (without a psychotic episode) are included. Exclusion criteria are regular use of hypnotic agents, opioids, and certain beta-blockers, as well as the presence of factors precluding exercise, history of epilepsy, restless legs syndrome, moderate obstructive sleep apnea, and a BMI > 40. The intervention is a single bout of aerobic exercise, performed for 30 min on a bicycle ergometer at 80% individual anaerobic threshold. The control group sits and reads for 30 min. The primary outcome is sleep efficiency measured by polysomnography. Secondary outcomes include further polysomnographic variables, subjective pre-sleep arousal, nocturnal cardiovascular autonomic modulation, subjective sleep quality, daytime sleepiness, and adverse events. According to the sample size calculation, a total of 92 patients will be randomized using minimization.

DISCUSSION

This trial will add new information to the body of knowledge concerning the treatment of insomnia in patients with depression. Thereby, the results will inform decision makers on the utility of acute aerobic exercise.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03673397 . Protocol version 1 registered on 17 September 2018.

Evaluating the role of orexins in the pathophysiology and treatment of depression: A comprehensive review

Orexins are neuropeptides that are postulated to play a central role in the regulation of the sleep-wake cycle, appetite, affect, and reward circuitry. The objectives of the current review are to comprehensively evaluate (1) the potential role of orexins in the pathophysiology of major depressive disorders (MDD) and (2) the orexin system as a novel target in the treatment of MDD. Dysfunction of the sleep-wake cycle is observed as a central feature of MDD pathophysiology. Orexin system disturbances produce sleep-wake dysfunction, as observed in MDD. Orexin antagonists have been shown to treat insomnia effectively without disrupting normal sleep architecture in both preclinical (e.g., animal models) and clinical studies. Orexin antagonists are generally safe, well-tolerated, and associated with an acceptable long-term adverse effect profile with relatively low propensity for tolerance or dependence. Orexin antagonists have also been shown to possess antidepressant-like properties in some animal models of MDD. Extant evidence indicates that orexin-modulating treatments exert pleiotropic effects on multiple neural systems implicated in the phenomenology of mood disorders and suggests orexins as a promising target for investigation and intervention in mood disorders. To date, no human clinical trials evaluating the antidepressant effects of orexin antagonists in MDD have been completed. Given the promising results from preclinical studies, clinical trials are merited to evaluate the antidepressant effects of orexin antagonists in MDD.

Orexin/hypocretin receptor, Orx1, gene variants are associated with major depressive disorder

Objective: Orexins (hypocretins) are neuropeptides expressed in hypothalamic neurons and have regulatory roles in feeding/drinking behaviours, endocrine functions and sleep/wakefulness state. Major depressive disorder (MDD) is a major mood disorder and neurotransmitter dysfunction in hypothalamic neurons may have roles in its formation. Hence, we conducted experiments to determine whether orexin receptor 1 and 2 (Orx₁, Orx₂) genes were associated with MDD development. Methods: Seventy-five MDD patients and 87 healthy controls were enrolled for the study. Genotyping was carried out with real-time polymerase chain reaction (RT-PCR). Hamilton Rating-Scale for Depression (HRSD) and Beck Depression Inventory (BDI) were utilized to evaluate depressive symptom severity. Results: A significant relation was found in genotype frequencies of Orx₁ rs10914456 and rs2271933 variants between MDD patients and controls (p = .009, p = .006). Rs10914456 CC genotype increased MDD risk 3.57 times more than carrying other genotypes (p = .008, OR =3.57;95% CI: 1.39-9.14). However, no association was observed in Orx₂ rs2653349 genotypes for MDD development (p > .05). Although statistically not significant, HRSD scores were diminished in MDD subjects carrying rs10914456 CC variants when compared with CT and TT variants (p = .069). Conclusion. This study suggests that, Orx₁ rs10914456 and rs2271933 can be associated with MDD development. Hence, Orx₁ rs10914456 variants may affect depressive symptom severity.

Cholinergic regulation of mood: from basic and clinical studies to emerging therapeutics

Mood disorders are highly prevalent and are the leading cause of disability worldwide. The neurobiological mechanisms underlying depression remain poorly understood, although theories regarding dysfunction within various neurotransmitter systems have been postulated. Over 50 years ago, clinical studies suggested that increases in central acetylcholine could lead to depressed mood. Evidence has continued to accumulate suggesting that the cholinergic system has a important role in mood regulation. In particular, the finding that the antimuscarinic agent, scopolamine, exerts fast-onset and sustained antidepressant effects in depressed humans has led to a renewal of interest in the cholinergic system as an important player in the neurochemistry of major depression and bipolar disorder. Here, we synthesize current knowledge regarding the modulation of mood by the central cholinergic system, drawing upon studies from human postmortem brain, neuroimaging, and drug challenge investigations, as well as animal model studies. First, we describe an illustrative series of early discoveries which suggest a role for acetylcholine in the pathophysiology of mood disorders. Then, we discuss more recent studies conducted in humans and/or animals which have identified roles for both acetylcholinergic muscarinic and nicotinic receptors in different mood states, and as targets for novel therapies.

Disruption of sleep architecture in Prevotella enterotype of patients with obstructive sleep apnea-hypopnea syndrome

INTRODUCTION

Intermittent hypoxia and sleep fragmentation are critical pathophysiological processes involved in obstructive sleep apnea-hypopnea syndrome (OSAHS). Those manifestations independently affect similar brain regions and contribute to OSAHS-related comorbidities that are known to be related to the host gut alteration microbiota. We hypothesized that gut microbiota disruption may cross talk the brain function via the microbiota-gut-brain axis. Thus, we aim to survey enterotypes and polysomnographic data of patients with OSAHS.

METHODS

Subjects were diagnosed by polysomnography, from whom fecal samples were obtained and analyzed for the microbiome composition by variable regions 3-4 of 16S rRNA pyrosequencing and bioinformatic analyses. We examined the fasting levels of interleukin-6 and tumor necrosis factor-alpha of all subjects.

RESULTS

Three enterotypes Bacteroides, Ruminococcus, and Prevotella were identified in patients with OSAHS. Arousal-related parameters or sleep stages are significantly disrupted in apnea-hypopnea index (AHI) ≥15 patients with Prevotella enterotype; further analysis this enterotype subjects, obstructive, central, and mixed apnea indices, and mean heart rate are also significantly elevated in AHI ≥15 patients. However, blood cytokines levels of all subjects were not significantly different.

CONCLUSIONS

This study indicates the possibility of pathophysiological interplay between enterotypes and sleeps structure disruption in sleep apnea through a microbiota-gut-brain axis and offers some new insight toward the pathogenesis of OSAHS.

Circadian reinforcement therapy in combination with electronic self-monitoring to facilitate a safe post-discharge period of patients with depression by stabilizing sleep: protocol of a randomized controlled trial

BACKGROUND

The transition phase from inpatient to outpatient care for patients suffering from Major Depressive Disorder represents a vulnerable period associated with a risk of depression worsening and suicide. Our group has recently found that the sleep-wake cycle in discharged depressive patients became irregular and exhibited a drift towards later hours, associated with worsening of depression. In contrast, an advancement of sleep phase has earlier been shown to have an antidepressant effect. Thus, methods to prevent drift of the sleep-wake cycle may be promising interventions to prevent or reduce worsening of depression after discharge.

METHODS

In this trial, we apply a new treatment intervention, named Circadian Reinforcement Therapy (CRT), to patients discharged from inpatient psychiatric wards. CRT consists of a specialized psychoeducation on the use of regular time signals (zeitgebers): daylight exposure, exercise, meals, and social contact. The aim is to supply stronger and correctly timed zeitgebers to the circadian system to prevent sleep drift and worsening of depression. The CRT is used in combination with an electronic self-monitoring system, the Monsenso Daybuilder System (MDB). By use of the MDB system, all patients self-monitor their sleep, depression level, and activity (from a Fitbit bracelet) daily. Participants can inspect all their data graphically on the MDB interface and will have clinician contact. The aim is to motivate patients to keep a stable sleep-wake cycle. In all, 130 patients referred to an outpatient service will be included. Depression rating is blinded. Patients will be randomized 1:1 to a Standard group or a CRT group. The intervention period is 4 weeks covering the transition phase from inpatient to outpatient care. The primary outcome is score change in interviewer rated levels of depression on the Hamilton Depression Rating Scale. A subset of patients will be assessed with salivary Dim Light Melatonin Onset (DLMO) as a validator of circadian timing. The trial was initiated in 2016 and will end in 2020.

DISCUSSION

If the described intervention is beneficial it could be incorporated into usual care algorithms for depressed patients to facilitate a better and safer transition to outpatient treatment.

TRIAL REGISTRATION

Posted prospectively at ClinicalTrials.gov at February 10, 2016 with identifier NCT02679768 .

Sleep deprivation, oxidative stress and inflammation

Adequate sleep is essential for normal brain function, especially during early life developmental stages as postnatal brain maturation occurs during the critical period of childhood and adolescence. Therefore, sleep disturbance and/or deficit during this period can have detrimental consequences. Many epidemiological and clinical studies have linked early life sleep disturbance with occurrence of later life behavioral and cognitive impairments. Role of oxidative stress and inflammation has been implicated in sleep deprivation-related impairments. This review article presents a detailed description of the current state of the literature on the subject.

Overnight Urge Perception in Nocturia Is Independent of Depression, PTSD, or Anxiety in a Male Veterans Administration Population

STUDY OBJECTIVES

The goal of this study was to compare the urge perception associated with nocturnal voiding at the time of voiding in individuals with and without depression, posttraumatic stress disorder (PTSD), or anxiety diagnoses to test the hypothesis that patients with such diagnoses are more likely to experience insomnia-driven convenience voiding during the sleep period.

METHODS

A database of voiding diaries with urge perception grades (UPGs) from 429 adult males seeking treatment for nocturia at a Veterans Affairs-based urology clinic was analyzed. The UPG categorizes perception for urinating from 0 (out of convenience) to 4 (desperate urge). Diaries completed by males age 18 years and older showing ≥ 2 nocturnal voids were included. Those included (n = 178) were divided into two cohorts based on the presence (n = 62) or absence (n = 116) of one or more previously established mental health diagnoses (depression, PTSD, or anxiety). The chi-square test was used to determine significance between groups.

RESULTS

Patients with a mental health diagnosis were more likely to report convenience voiding compared to those without depression, PTSD, or anxiety (14.5% versus 0.8%, P < .01). However, most voids in both groups were associated with the perception of urinary urgency. There were no differences in urinary volumes or hourly rates of urine production between the groups.

CONCLUSIONS

A relatively small subset of urology patients experience nocturnal voiding because they are awake for reasons other than the urge to void. Mental health factors had a substantial, albeit minimal, effect. Most nocturia reflects urgency to urinate rather than voiding by convenience.

The Functional Role of Dreaming in Emotional Processes

Dream experience (DE) represents a fascinating condition linked to emotional processes and the human inner world. Although the overlap between REM sleep and dreaming has been overcome, several studies point out that emotional and perceptually vivid contents are more frequent when reported upon awakenings from this sleep stage. Actually, it is well-known that REM sleep plays a pivotal role in the processing of salient and emotional waking-life experiences, strongly contributing to the emotional memory consolidation. In this vein, we highlighted that, to some extent, neuroimaging studies showed that the processes that regulate dreaming and emotional salience in sleep mentation share similar neural substrates of those controlling emotions during wakefulness. Furthermore, the research on EEG correlates of the presence/absence of DE and the results on EEG pattern related to the incorporated memories converged to assign a crucial role of REM theta oscillations in emotional re-processing. In particular, the theta activity is involved in memory processes during REM sleep as well as during the waking state, in line with the continuity hypothesis. Also, the gamma activity seems to be related to emotional processes and dream recall as well as to lucid dreams. Interestingly, similar EEG correlates of DE have been found in clinical samples when nightmares or dreams occur. Research on clinical samples revealed that promoting the rehearsal of frightening contents aimed to change them is a promising method to treat nightmares, and that lucid dreams are associated with an attenuation of nightmares. In this view, DE can defuse emotional traumatic memories when the emotional regulation and the fear extinction mechanisms are compromised by traumatic and frightening events. Finally, dreams could represent a sort of simulation of reality, providing the possibility to create a new scenario with emotional mastery elements to cope with dysphoric items included in nightmares. In addition, it could be hypothesized that the insertion of bizarre items besides traumatic memories might be functional to "impoverish" the negative charge of the experiences.