State markers of depression in sleep EEG: dependency on drug and gender in patients treated with tianeptine or paroxetine

Evaluating the evidence for sex differences: a scoping review of human neuroimaging in psychopharmacology research

Although sex differences in psychiatric disorders abound, few neuropsychopharmacology (NPP) studies consider sex as a biological variable (SABV). We conducted a scoping review of this literature in humans by systematically searching PubMed to identify peer-reviewed journal articles published before March 2020 that (1) studied FDA-approved medications used to treat psychiatric disorders (or related symptoms) and (2) adequately evaluated sex differences using in vivo neuroimaging methodologies. Of the 251 NPP studies that included both sexes and considered SABV in analyses, 80% used methodologies that eliminated the effect of sex (e.g., by including sex as a covariate to control for its effect). Only 20% (50 studies) adequately evaluated sex differences either by testing for an interaction involving sex or by stratifying analyses by sex. Of these 50 studies, 72% found statistically significant sex differences in at least one outcome. Sex differences in neural and behavioral outcomes were studied more often in drugs indicated for conditions with known sex differences. Likewise, the majority of studies conducted in those drug classes noted sex differences: antidepressants (13 of 16), antipsychotics (10 of 12), sedative-hypnotics (6 of 10), and stimulants (6 of 10). In contrast, only two studies of mood stabilizers evaluated SABV, with one noting a sex difference. By mapping this literature, we bring into sharp relief how few studies adequately evaluate sex differences in NPP studies. Currently, all NIH-funded studies are required to consider SABV. We urge scientific journals, peer reviewers, and regulatory agencies to require researchers to consider SABV in their research. Continuing to ignore SABV in NPP research has ramifications both in terms of rigor and reproducibility of research, potentially leading to costly consequences and unrealized benefits.

Association of Sleep Architecture and Physiology with Depressive Disorder and Antidepressants Treatment

Sleep problems are frequently associated with the principal diagnostic criteria for many mental disorders. Alterations in the sleep of depressive patients are of high clinical significance because continuous sleep problems raise the chance of relapse, recurrence, or suicide, as well as the need for augmenting medications. Most antidepressants have been proven to influence the sleep architecture. While some classes of antidepressants improve sleep, others may cause sleep impairment. The successful treatment of depressive disorder also requires an understanding of the effects of antidepressants on sleep. This article briefly reviews the physiology of sleep and the typical alterations in the sleep architecture in depressive patients and updates the different effects of the majority of antidepressants including novel drugs in clinical practice on sleep. The summary of the updated scientific findings of the relationship between depression and sleep disturbances could be clinically beneficial in choosing the best medication for depressive patients with concurrent sleep disorders.

Dreams, Sleep, and Psychotropic Drugs

Over the past 60 years, the impact of psychotropic drugs on dream recall and content has been scarcely explored. A review of the few existing experimental results on the topic leads us to the following conclusions. For antidepressant drugs, in the great majority, they reduce dream recall frequency (DRF), and the improvement of depressive symptoms is associated with an increase of positive emotion in dream content. For sedative psychotropic drugs, their improvement of sleep quality is associated with a reduction of DRF, but the effect on dream content is less clear. Few occurrences of nightmare frequency increase have been reported, with intake of molecules disturbing sleep or with the withdrawal of some psychotropic drugs. Importantly, the impact of psychotropic drugs on rapid eye movement (REM) sleep does not explain DRF modulations. The reduction of intra-sleep awakenings seems to be the parameter explaining best the modulation of DRF by psychotropic drugs. Indeed, molecules that improve sleep continuity by reducing intra-sleep awakenings also reduce the frequency of dream recall, which is coherent with the “arousal-retrieval model” stating that nighttime awakenings enable dreams to be encoded into long-term memory and therefore facilitate dream recall. DRF is nonetheless influenced by several other factors (e.g., interest in dreams, the method of awakening, and personality traits), which may explain a large part of the variability of results observed and cited in this article.

Depression and Sleep

Impaired sleep is both a risk factor and a symptom of depression. Objective sleep is assessed using the sleep electroencephalogram (EEG). Characteristic sleep-EEG changes in patients with depression include disinhibition of rapid eye movement (REM) sleep, changes of sleep continuity, and impaired non-REM sleep. Most antidepressants suppress REM sleep both in healthy volunteers and depressed patients. Various sleep-EEG variables may be suitable as biomarkers for diagnosis, prognosis, and prediction of therapy response in depression. In family studies of depression, enhanced REM density, a measure for frequency of rapid eye movements, is characteristic for an endophenotype. Cordance is an EEG measure distinctly correlated with regional brain perfusion. Prefrontal theta cordance, derived from REM sleep, appears to be a biomarker of antidepressant treatment response. Some predictive sleep-EEG markers of depression appear to be related to hypothalamo-pituitary-adrenocortical system activity.

Progress in Elucidating Biomarkers of Antidepressant Pharmacological Treatment Response: A Systematic Review and Meta-analysis of the Last 15 Years

BACKGROUND

Antidepressant drugs are widely prescribed, but response rates after 3 months are only around one-third, explaining the importance of the search of objectively measurable markers predicting positive treatment response. These markers are being developed in different fields, with different techniques, sample sizes, costs, and efficiency. It is therefore difficult to know which ones are the most promising.

OBJECTIVE

Our purpose was to compute comparable (i.e., standardized) effect sizes, at study level but also at marker level, in order to conclude on the efficacy of each technique used and all analyzed markers.

METHODS

We conducted a systematic search on the PubMed database to gather all articles published since 2000 using objectively measurable markers to predict antidepressant response from five domains, namely cognition, electrophysiology, imaging, genetics, and transcriptomics/proteomics/epigenetics. A manual screening of the abstracts and the reference lists of these articles completed the search process.

RESULTS

Executive functioning, theta activity in the rostral Anterior Cingular Cortex (rACC), and polysomnographic sleep measures could be considered as belonging to the best objectively measured markers, with a combined d around 1 and at least four positive studies. For inter-category comparisons, the approaches that showed the highest effect sizes are, in descending order, imaging (combined d between 0.703 and 1.353), electrophysiology (0.294-1.138), cognition (0.929-1.022), proteins/nucleotides (0.520-1.18), and genetics (0.021-0.515).

CONCLUSION

Markers of antidepressant treatment outcome are numerous, but with a discrepant level of accuracy. Many biomarkers and cognitions have sufficient predictive value (d ≥ 1) to be potentially useful for clinicians to predict outcome and personalize antidepressant treatment.

The 'affect tagging and consolidation' (ATaC) model of depression vulnerability

Since the 1960's polysomnographic sleep research has demonstrated that depressive episodes are associated with REM sleep alterations. Some of these alterations, such as increased REM sleep density, have also been observed in first-degree relatives of patients and remitted patients, suggesting that they may be vulnerability markers of major depressive disorder (MDD), rather than mere epiphenomena of the disorder. Neuroimaging studies have revealed that depression is also associated with heightened amygdala reactivity to negative emotional stimuli, which may also be a vulnerability marker for MDD. Several models have been developed to explain the respective roles of REM sleep alterations and negatively-biased amygdala activity in the pathology of MDD, however the possible interaction between these two potential risk-factors remains uncharted. This paper reviews the roles of the amygdala and REM sleep in the encoding and consolidation of negative emotional memories, respectively. We present our 'affect tagging and consolidation' (ATaC) model, which argues that increased REM sleep density and negatively-biased amygdala activity are two separate, genetically influenced risk-factors for depression which interact to promote the development of negative memory bias - a well-known cognitive vulnerability marker for depression. Predictions of the ATaC model may motivate research aimed at improving our understanding of sleep dependent memory consolidation in depression aetiology.

Cordance derived from REM sleep EEG as a biomarker for treatment response in depression--a naturalistic study after antidepressant medication

OBJECTIVE

To evaluate whether prefrontal cordance in theta frequency band derived from REM sleep EEG after the first week of antidepressant medication could characterize the treatment response after 4 weeks of therapy in depressed patients.

METHOD

20 in-patients (15 females, 5 males) with a depressive episode and 20 healthy matched controls were recruited into 4-week, open label, case-control study. Patients were treated with various antidepressants. No significant differences in age (responders (mean ± SD): 45 ± 22) years; non-responders: 49 ± 12 years), medication or Hamilton Depression Rating Scale (HAM-D) score (responders: 23.8 ± 4.5; non-responders 24.5 ± 7.6) at inclusion into the study were found between responders and non-responders. Response to treatment was defined as a ≥50% reduction of HAM-D score at the end of four weeks of active medication. Sleep EEG of patients was recorded after the first and the fourth week of medication. Cordance was computed for prefrontal EEG channels in theta frequency band during tonic REM sleep.

RESULTS

The group of 8 responders had significantly higher prefrontal theta cordance in relation to the group of 12 non-responders after the first week of antidepressant medication. This finding was significant also when controlling for age, gender and number of previous depressive episodes (F1,15 = 6.025, P = .027). Furthermore, prefrontal cordance of all patients showed significant positive correlation (r = 0.52; P = .019) with the improvement of HAM-D score between the inclusion week and fourth week of medication.

CONCLUSIONS

The results suggest that prefrontal cordance derived from REM sleep EEG could provide a biomarker for the response to antidepressant treatment in depressed patients.

Are there meaningful biomarkers of treatment response for depression?

During the past decades, the prevalence of affective disorders has been on the rise globally, with only one out of three patients achieving remission in acute treatment with antidepressants. The identification of physiological markers that predict treatment course proves useful in increasing therapeutic success. On the basis of well-documented, recent findings in depression research, we highlight and discuss the most promising biomarkers for antidepressant therapy response. These include genetic variants and gene expression profiles, proteomic and metabolomic markers, neuroendocrine function tests, electrophysiology and imaging techniques. Ultimately, this review proposes an integrative use of biomarkers for antidepressant treatment outcome.

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.

Can sleep disturbance in depression predict repetitive transcranial magnetic stimulation (rTMS) treatment response?

Treatment for depression is not effective in all patients and it is therefore important to identify factors that can be used to tailor treatments. One potential factor is insomnia. Several repetitive transcranial magnetic stimulation (rTMS) studies have reported on this symptom, however, they did not take into account the presence of hypersomnia or that insomnia was related to their outcome measure. Our aim was to investigate whether baseline sleep disruption was related to rTMS treatment response. We pooled data from four clinical trials using rTMS to treat depression, including 139 subjects in data analysis. Insomnia was measured using the Hamilton Depression Rating Scale (HamD) sleep questions and hypersomnia from the Beck Depression Inventory (BDI). To reduce the possible impact of insomnia on our treatment response outcome we created an adjusted HamD score which omitted sleep items. Sleep disturbances were common in our study: 66% had insomnia and 38% hypersomnia. Using regression analysis with our adjusted HamD score we found no relation between baseline insomnia or hypersomnia and rTMS treatment response. Our data are consistent with previous studies; however, this is the first rTMS study to our knowledge that has attempted to dissociate baseline insomnia from the HamD outcome measure and to report no relationship between hypersomnia and rTMS outcome.

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.

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.

Acute escitalopram treatment inhibits REM sleep rebound and activation of MCH-expressing neurons in the lateral hypothalamus after long term selective REM sleep deprivation

RATIONALE

Selective rapid eye movement sleep (REMS) deprivation using the platform-on-water ("flower pot") method causes sleep rebound with increased REMS, decreased REMS latency, and activation of the melanin-concentrating hormone (MCH) expressing neurons in the hypothalamus. MCH is implicated in the pathomechanism of depression regarding its influence on mood, feeding behavior, and REMS.

OBJECTIVES

We investigated the effects of the most selective serotonin reuptake inhibitor escitalopram on sleep rebound following REMS deprivation and, in parallel, on the activation of MCH-containing neurons.

METHODS

Escitalopram or vehicle (10 mg/kg, intraperitoneally) was administered to REMS-deprived (72 h) or home cage male Wistar rats. During the 3-h-long "rebound sleep", electroencephalography was recorded, followed by an MCH/Fos double immunohistochemistry.

RESULTS

During REMS rebound, the time spent in REMS and the number of MCH/Fos double-labeled neurons in the lateral hypothalamus increased markedly, and REMS latency showed a significant decrease. All these effects of REMS deprivation were significantly attenuated by escitalopram treatment. Besides the REMS-suppressing effects, escitalopram caused an increase in amount of and decrease in latency of slow wave sleep during the rebound.

CONCLUSIONS

These results show that despite the high REMS pressure caused by REMS deprivation procedure, escitalopram has the ability to suppress REMS rebound, as well as to diminish the activation of MCH-containing neurons, in parallel. Escitalopram caused a shift from REMS to slow wave sleep during the rebound. Furthermore, these data point to the potential connection between the serotonergic system and MCH in sleep regulation, which can be relevant in depression and in other mood disorders.

A New Neurofeedback Protocol for Depression

Context: Neurofeedback represents an exciting complementary option in the treatment of depression that builds upon a huge body of research on electroencephalographic correlates of depression. Objective: The objectives of this article are threefold: review the literature on neurofeedback protocols for depression; introduce a new protocol, which aims to synthesize the best qualities of the currently available protocols; and present the results of a small clinical experiment with the new protocol. Method: Structured survey of the literature; software development; clinical trial with one subject, submitted to ten sessions of neurofeedback (one hour each). Results: Currently there are twenty-one articles in neurofeedback for depression, among which only six present original experimental results. All of them report positive results with the technique. The most used protocols focus on Alpha inter-hemispheric asymmetry, and Theta/Beta ratio within the left prefrontal cortex. Our new protocol integrates both dimensions in a single circuit, adding to it a third programming line, which divides Beta frequencies and reinforces the decrease of Beta-3, in order to reduce anxiety. The favorable outcome of our clinical experiment, suggests that new research with this protocol is worthwhile.

Sleep phenotyping in a mouse model of extreme trait anxiety

Background

There is accumulating evidence that anxiety impairs sleep. However, due to high sleep variability in anxiety disorders, it has been difficult to state particular changes in sleep parameters caused by anxiety. Sleep profiling in an animal model with extremely high vs. low levels of trait anxiety might serve to further define sleep patterns associated with this psychopathology.

Methodology/Principal Findings

Sleep-wake behavior in mouse lines with high (HAB), low (LAB) and normal (NAB) anxiety-related behaviors was monitored for 24 h during baseline and recovery after 6 h sleep deprivation (SD). The amounts of each vigilance state, sleep architecture, and EEG spectral variations were compared between the mouse lines. In comparison to NAB mice, HAB mice slept more and exhibited consistently increased delta power during non-rapid eye movement (NREM) sleep. Their sleep patterns were characterized by heavy fragmentation, reduced maintenance of wakefulness, and frequent intrusions of rapid eye movement (REM) sleep. In contrast, LAB mice showed a robust sleep-wake rhythm with remarkably prolonged sleep latency and a long, persistent period of wakefulness. In addition, the accumulation of delta power after SD was impaired in the LAB line, as compared to HAB mice.

Conclusions/Significance

Sleep-wake patterns were significantly different between HAB and LAB mice, indicating that the genetic predisposition to extremes in trait anxiety leaves a biological scar on sleep quality. The enhanced sleep demand observed in HAB mice, with a strong drive toward REM sleep, may resemble a unique phenotype reflecting not only elevated anxiety but also a depression-like attribute.

Clinical relevance of disturbances of sleep and vigilance in major depressive disorder: a review

OBJECTIVE

The primary objective of this article is to provide a concise review of the clinical relevance of sleep and vigilance in major depressive disorder.

DATA SOURCES

PubMed was reviewed (1990-2009) and English-language articles were identified using the key words sleep and depression and sleep and antidepressants. Secondary searches included articles cited in sources identified by the primary search.

STUDY SELECTION

The narrative review provides brief descriptions of the normal physiology of sleep and changes associated with depression, as well as the impact of various treatments on these processes.

DATA SYNTHESIS

Although it has long been known that sleep disturbances are an important characteristic of depression, relatively few studies have been conducted with the newer-generation antidepressants. Neither of the most widely used classes of antidepressants, the selective serotonin reuptake inhibitors and the serotonin-norepinephrine reuptake inhibitors, have particularly beneficial effects on sleep and, among the medications that reliably improve sleep efficiency, including mirtazapine and the tricyclic antidepressants, problems with daytime sedation can offset therapeutic benefit. Despite relatively widespread use, trazodone has not been demonstrated to be an effective and safe hypnotic in patients taking other antidepressants. For many patients, ongoing concomitant treatment with benzodiazepines and related drugs is the preferred option, again without convincing empirical support of longer-term efficacy. Among newer and investigational antidepressants, agomelatine shows promise with respect to both overall safety and effects on insomnia, although possible negative effects on liver function warrant further study.

CONCLUSIONS

Sleep disturbances are a significant aspect of depressive syndromes, and relief of insomnia remains an important unmet need in antidepressant therapeutics. Development of a well-tolerated antidepressant medication that rapidly improves sleep maintenance without daytime sedation is a priority for drug development.

Sex differences in sleep after a single oral morning dose of olanzapine in healthy volunteers

OBJECTIVE

Polysomnography abnormalities are frequent in schizophrenia and have been correlated with clinical variables. Because women with schizophrenia present a general better clinical outcome than men, we aimed to determine whether sex differences in antipsychotic-induced effects on sleep could contribute to this difference.

METHODS

Single oral morning doses of olanzapine (5 mg) were administered to 10 men and 10 women. Sleep variables were evaluated using traditional polysomnography Rechstschaffen and Kales criteria and all-night sleep electroencephalogram spectral analysis. Drug plasma concentrations were also measured.

RESULTS

Significant sex-by-drug interactions were obtained in slow-wave sleep. After olanzapine, women showed an increase in slow-wave sleep, whereas men showed a decrease. We did not observe sex differences in olanzapine-induced hypnotic effects. Neither did we find any significant differences in pharmacokinetic parameters between sexes. Significant sex effects were observed in deep sleep, with women showing longer periods than men.

CONCLUSION

Our results showed significant pharmacodynamic differences in olanzapine sleep effects between men and women. Further studies in clinical populations are needed to assess if these sex-based differences suggest that optimal treatment and doses should differ between men and women.

Does antiepileptogenesis affect sleep in genetic epileptic rats?

Recently it was established that early long lasting treatment with the anti-absence drug ethosuximide (ETX) delays the occurrence of absences and reduces depressive-like symptoms in a genetic model for absence epilepsy, rats of the WAG/Rij strain. Here it is investigated whether anti-epileptogenesis (chronic treatments with ETX for 2 and 4 months) affects REM sleep in this model. Four groups of weaned male WAG/Rij rats were treated with ETX for 4 months, two groups for 2 months (at 2-3 and 4-5 months of age), the fourth group was untreated. Next, the rats were recorded 6 days after the last day of the treatment for 22.5 h. Non-REM sleep and REM sleep parameters and delta power were analyzed in four characteristic and representative hours of the recoding period. Four months treatment with ETX reduced the amount of REM sleep and REM sleep as percentage of total sleep time. Other sleep parameters were not affected by the treatment. Clear differences between the various hours of the light-dark phase in amounts of non-REM and REM sleep and delta power were found, in line with commonly reported circadian sleep patterns. It can be concluded that the reduction of REM sleep is unique for the early and long lasting chronic treatment. The outcomes may explain our earlier finding that a reduction of REM sleep might alleviate depressive like symptoms.

Biomarkers in development of psychotropic drugs

Biomarkers have been receiving increasing attention, especially in the field of psychiatry. In contrast to the availability of potent therapeutic tools including pharmacotherapy, psychotherapy, and biological therapies, unmet needs remain in terms of onset of action, stability of response, and further improvement of the clinical course. Biomarkers are objectively measured characteristics which serve as indicators of the causes of illnesses, their clinical course, and modification by treatment. There exist a variety of markers: laboratory markers which comprise the determination of genetic and epigenetic markers, neurotransmitters, hormones, cytokines, neuropeptides, enzymes, and others as single measures; electrophysiological markers which usually comprise electroencephalography (EEG) measures, and in particular sleep EEG and evoked potentials, magnetic encephalography, electrocardiogram, facial electromyography, skin conductance, and others; brain imaging techniques such as cranial computed tomography, magnetic resonance imaging, functional MRl, magnetic resonance spectroscopy, positron emission tomography, and single photon emission computed tomography; and behavioral approaches such as cue exposure and challenge tests which can be used to induce especially emotional processes in anxiety and depression. Examples for each of these domains are provided in this review. With a view to developing more individually tailored therapeutic strategies, the characterization of patients and the courses of different types of treatment will become even more important in the future.

Wake and sleep EEG provide biomarkers in depression

Both wake and sleep electroencephalogram (EEG) provide biomarkers of depression and antidepressive therapy, respectively. For a long time it is known that EEG activity is altered by drugs. Quantitative EEG analysis helps to delineate effects of antidepressants on brain activity. Cordance is an EEG measure with a superior correlation with regional brain perfusion. Prefrontal quantitative EEG cordance appears to be a predictor of the response to antidepressants. Sleep EEG shows characteristic changes in depression as impaired sleep continuity, desinhibition of REM sleep and changes of nonREM sleep. Elevated REM density (a measure for frequency of rapid eye movements) characterizes an endophenotype in family studies of depression. REM-sleep changes including a more distinct REM rebound after sleep deprivation are found in animal models of depression. Most antidepressants suppress REM sleep in depressed patients, normal controls and laboratory animals. REM suppression appears to be a distinct, but not an absolute requirement for antidepressive effects of a compound. Sleep-EEG variables like REM latency or certain clusters of variables were shown to predict the response to the treatment with a certain antidepressant or even the course of the disorder for several years. Some of these predictive sleep-EEG markers of the longterm course of depression appear to be closely related to hypothalamo-pituitary-adrenocortical system activity.

Comorbidity of insomnia and depression

During the last decade, several studies have shown that insomnia, rather than a symptom of depression, could be a medical condition on its own, showing high comorbidity with depression. Epidemiological research indicates that insomnia could lead to depression and/or that common causalities underlie the two disorders. Neurobiological and sleep EEG studies suggest that a heightened level of arousal may play a common role in both conditions and that signs of REM sleep disinhibition may appear in individuals prone to depression. The effects of antidepressant drugs on non-REM and REM sleep are discussed in relation to their use in insomnia comorbid with depression. Empirical treatment approaches are behavioral management of sleep combined with prescription of a sedative antidepressant alone, co-prescription of two antidepressants, or of an antidepressant with a hypnotic drug.

Comparison of different methods for the evaluation of treatment effects from the sleep EEG of patients with major depression

In healthy subjects, sleep has a typical structure of three to five cyclic transitions between different sleep states. In major depression, this regular pattern is often destroyed but can be reestablished during successful treatment. The differences between healthy and abnormal sleep are generally assessed in a time-consuming process, which consists of determining the nightly variations of the sleep states (the hypnogram) based on visual inspection of the electroencephalogram (EEG), electrooculogram, and electromyogram. In this study, three different methods of sleep EEG analysis (spectrum, outlier, and recurrence analysis) have been examined with regard to their ability to extract information about treatment effects in patients with major depression. Our data suggest that improved sleep patterns during treatment with antidepressant medication can be identified with an appropriate analysis of the EEG. By comparing different methods, we have found that many treatment effects identified by spectrum analysis can be reproduced by the much simpler technique of outlier analysis. Finally, the cyclic structure of sleep and its modification by antidepressant treatment is best illustrated by a non-linear approach, the so-called recurrence method.

The glutamatergic system and its relation to the clinical effect of therapeutic-sleep deprivation in depression - an MR spectroscopy study

Rapid improvement of depressive symptoms occurs after the administration of the NMDA antagonist ketamine. Ketamine administration is accompanied by an increase in GLX (sum-peak of glutamate, glutamine (GLN) and GABA) and GLN in the brain, as measured by magnetic-resonance (MR) spectroscopy. In healthy subjects, we observed an increase in GLX and GLN levels after total sleep deprivation (TSD), which has a rapid antidepressant effects. We examined, if an increase in GLX or GLN is related to the therapeutic effect of TSD. We examined 13 patients with major depression by means of proton MR spectroscopy (field strength: 1.5T) before and after 24h of TSD. Two anatomical areas (dorsolateral prefrontal cortex (DLPC) and parieto-occipital cortex (POC)) were studied. In the DLPC TSD did not change GLX or its elements, whereas the total creatine and choline signal increased marginally. No change could be observed in the POC. For further exploration we took gender and the presence of vegetative characteristics of melancholic depression into account, i.e. the presence of early morning awakening, appetite and weight loss was taken into account, to define vegetative melancholia (VM). TSD led to an increase in GLX and GLN in the DLPC only of male patients. In patients with VM an increase in GLN occurred in this area. The low field strength limits the accuracy for GLX and GLN estimates. Despite the exploratory nature of the study, it nevertheless supports earlier data on the importance of glutamatergic neurotransmission and furthermore of gender and/or vegetative features in depression.

Modulation of group II metabotropic glutamate receptor (mGlu2) elicits common changes in rat and mice sleep-wake architecture

Compiling pharmacological evidence implicates metabotropic glutamate mGlu(2) receptors in the regulation of emotional states and suggests positive modulators as a novel therapeutic approach of Anxiety/Depression and Schizophrenia. Here, we investigated subcutaneous effects of the metabotropic glutamate mGlu(2/3) agonist (LY354740) on sleep-wake architecture in rat. To confirm the specific effects on rapid eye movement (REM) sleep were mediated via metabotropic glutamate mGlu(2) receptors, we characterized the sleep-wake cycles in metabotropic glutamate mGlu(2) receptor deficient mice (mGlu(2)R(-/-)) and their arousal response to LY354740. We furthermore examined effects on sleep behavior in rats of the positive allosteric modulator, biphenyl-indanone A (BINA) alone and in combination with LY354740 at sub-effective doses. LY354740 (1, 3 and 10 mg/kg) dose-dependently suppressed REM sleep and prolonged its onset latency. Metabotropic glutamate mGlu(2)R(-/-) and their wild type (WT) littermates exhibited similar spontaneous sleep-wake phenotype, while LY354740 (10 mg/kg) significantly affected REM sleep variables in WT but not in the mutant. In rats, BINA (1, 3, 10, 20, 40 mg/kg) dose-dependently suppressed REM sleep, lengthened its onset latency and slightly enhanced passive waking. Additionally, combined treatment elicited a synergistic action on REM sleep variables. Our findings show common changes of REM sleep variables following modulation of metabotropic glutamate mGlu(2) receptor and support an active role of this receptor in the regulation of REM sleep. The synergistic action of BINA on LY354740's effects on sleep pattern implies that positive modulators would tune the endogenous glutamate tone suggesting potential benefit in the treatment of psychiatric disorders, in which REM sleep overdrive is manifested.

Blocking melanin-concentrating hormone MCH1 receptor affects rat sleep-wake architecture

Melanin-concentrating hormone (MCH) is a hypothalamic peptide that centrally regulates food intake, energy balance and emotion. Interestingly, MCH and melanin-concentrating hormone MCH(1) receptors are distributed in brain areas known to regulate vigilance states. Effects of subcutaneous administration of two selective melanin-concentrating hormone MCH(1) receptor antagonists, labeled A and B were examined over a broad dose range (1, 3, 10, 20, 40 mg/kg) on rat sleep-wake architecture. Both compounds have a nanomolar antagonist activity at recombinant human melanin-concentrating hormone MCH(1) receptor (IC(50)=44.1+/-6.1 nM and 26.6+/-5.4 nM, respectively) and potently inhibited the MCH-induced mobilization of [Ca(2+)] (IC(50) 29.1+/-8.1 nM and 10.5+/-4.1 nM, respectively). The selectivity of both compounds was further confirmed on a panel of receptors, transporters and channels. In vivo, both compounds dose-dependently decreased deep sleep primarily by decreasing the mean duration of episodes during the first 4 h post-administration. In parallel, REM sleep and intermediate stage sleep were decreased while active and passive waking increased. Deep sleep and REM sleep onset latencies were significantly prolonged at higher doses. No homeostatic rebound of deep sleep was observed, while a tendency for recovery of REM sleep was found during subsequent dark phase. Together, the results support a role of the melanin-concentrating hormone MCH(1) receptor in the regulation of deep slow-wave sleep-REM sleep cycle. Therapeutic application of melanin-concentrating hormone MCH(1) receptor-inhibiting agents should take into account the significant decreases in deep sleep without recovery as these may interfere with sleep dependent memory consolidation.

Changes of sleep architecture, spectral composition of sleep EEG, the nocturnal secretion of cortisol, ACTH, GH, prolactin, melatonin, ghrelin, and leptin, and the DEX-CRH test in depressed patients during treatment with mirtazapine

The noradrenergic and specific serotoninergic antidepressant mirtazapine improves sleep, modulates hormone secretion including blunting of hypothalamic-pituitary-adrenocortical (HPA) activity, and may prompt increased appetite and weight gain. The simultaneous investigation of sleep electroencephalogram (EEG) and hormone secretion during antidepressive treatment helps to further elucidate these effects. We examined sleep EEG (for later conventional and quantitative analyses) and the nocturnal concentrations of cortisol, adrenocorticotropin (ACTH), growth hormone (GH), prolactin, melatonin and the key factors of energy balance, ghrelin, and leptin before and after 28 days of treatment of depressed patients (seven women, three men, mean age 39.9+/-4.2 years) with mirtazapine. In addition, a sleep EEG was recorded at day 2 and the dexamethasone-corticotropin-releasing hormone (DEX-CRH) test was performed to assess HPA activity at days -3 and 26. Psychometry and mirtazapine plasma concentrations were measured weekly. Already at day 2, sleep continuity was improved. This effect persisted at day 28, when slow-wave sleep, low-delta, theta and alpha activity, leptin and (0300-0700) melatonin increased, and cortisol and ghrelin decreased. ACTH and prolactin remained unchanged. The first two specimens of GH collected after the start of quantitative EEG analysis were reduced at day 28. The DEX-CRH test showed, at day 26, a blunting of the overshoot of ACTH and cortisol found at day -3. The Hamilton Depression score decreased from 32.1+/-7.3 to 15.5+/-6.7 between days -1 and 28. A weight gain of approximately 3 kg was observed. This unique profile of changes is compatible with the action of mirtazapine at 5-HT-2 receptors, at presynaptic adrenergic alpha 2 receptors, at the HPA system, and on ghrelin and leptin.

Changes in sleep electroencephalogram and nocturnal hormone secretion after administration of the antidyskinetic agent sarizotan in healthy young male volunteers

RATIONALE

Sarizotan is a 5-HT(1A) agonist with high affinity to D(3) and D(4) receptors. In animal experiments, the drug shows a strong anti-cataleptic effect and suppresses effectively dyskinesias in animal models of L: -dopa-induced dyskinesia and of tardive dyskinesia. Data from an open pilot study in patients with Parkinson's disease show clear indication of a treatment effect against L: -dopa-induced dyskinesia.

OBJECTIVE

CNS-active drugs are known to modulate sleep electroencephalogram (EEG) and sleep-related hormone secretion. 5-HT(1A) agonists suppress rapid-eye movement (REM) sleep and enhance the secretion of ACTH, cortisol, prolactin and growth hormone (GH) at daytime. We hypothesised that sarizotan shares these effects. Furthermore, we were interested in the influence of sarizotan on leptin, which participates in the regulation of the energy balance and is enhanced after various psychoactive drugs.

METHODS

Ten healthy male subjects were investigated twice in a double-blind, placebo-controlled crossover design. Sleep EEG and nocturnal hormone secretion of ACTH, cortisol, prolactin, GH and leptin were examined after oral administration of either placebo or 20 mg of sarizotan at night.

RESULTS

After administration of sarizotan, a significant reduction of REM sleep and total sleep time in conventional sleep EEG and a significant reduction of sigma- and theta-power in spectral analysis were observed. The main effect on nocturnal hormone secretion was a significant elevation of prolactin and of ACTH in the first half of the night.

CONCLUSIONS

While REM sleep was suppressed, the endocrine effects of 20 mg sarizotan at night were weak. Its sleep-endocrine profile is comparable to the effects provoked by selective 5-HT reuptake inhibitors.

Discovering endophenotypes for major depression

The limited success of genetic studies of major depression has raised questions concerning the definition of genetically relevant phenotypes. This paper presents strategies to improve the phenotypic definition of major depression by proposing endophenotypes at two levels: First, dissecting the depressive phenotype into key components results in narrow definitions of putative psychopathological endophenotypes: mood bias toward negative emotions, impaired reward function, impaired learning and memory, neurovegetative signs, impaired diurnal variation, impaired executive cognitive function, psychomotor change, and increased stress sensitivity. A review of the recent literature on neurobiological and genetic findings associated with these components is given. Second, the most consistent heritable biological markers of major depression are proposed as biological endophenotypes for genetic studies: REM sleep abnormalities, functional and structural brain abnormalities, dysfunctions in serotonergic, catecholaminergic, hypothalamic-pituitary-adrenocortical axis, and CRH systems, and intracellular signal transduction endophenotypes. The associations among the psychopathological and biological endophenotypes are discussed with respect to specificity, temporal stability, heritability, familiality, and clinical and biological plausibility. Finally, the case is made for the development of a new classification system in order to reduce the heterogeneity of depression representing a major impediment to elucidating the genetic and neurobiological basis of this common, severe, and often life-threatening illness.

Atypical depression spectrum disorder - neurobiology and treatment

Depressive syndromes are a group of heterogeneous disorders. Atypical depression (AD) with reversed vegetative signs, such as hyperphagia or hypersomnia, is traditionally neglected, demonstrated by the fact that in the most widely used depression scales, such as the Hamilton Depression Scale (HAMD), melancholic symptoms have a specific weight, while, by contrast, reversed vegetative signs are not included. However, epidemiologically and phenomenologically related disorders to AD do exist, such as somatoform disorders, neurasthenia (chronic fatigue syndrome) and fibromyalgia (FM). In this spectrum, here called the AD spectrum, instead a decrease in hypothalamus-pituitary-adrenocortical (HPA) axis activity seems to exist. This has similarities to Cushing's disease, where a suppression of central HPA system activity is accompanied by features of AD and somatization in a considerable number of patients. Opposite vegetative features might therefore be related to the opposite dysregulation of the HPA system. The psychopharmacological intervention in the AD spectrum should therefore differ from that used in typical major depression. MAO inhibitors, low-dose tricyclic antidepressants and 5-HT3 antagonists demonstrated therapeutic efficacy, but the existing studies focused on different aspects. Hypericum extracts might be an alternative pharmacological intervention, which demonstrated therapeutic efficacy in the symptom range of the spectrum.