Non-REM sleep instability in patients with major depressive disorder: Subjective improvement and improvement of non-REM sleep instability with treatment (Agomelatine)

Preliminary evidence of transcutaneous vagus nerve stimulation effects on sleep in veterans with post-traumatic stress disorder

Sleep problems are common among veterans with post-traumatic stress disorder and closely associated with hyperarousal symptoms. Transcutaneous vagus nerve stimulation (tVNS) may have potential to improve sleep quality in veterans with PTSD through effects on brain systems relevant to hyperarousal and sleep-wake regulation. The current pilot study examines the effect of 1 h of tVNS administered at "lights out" on sleep architecture, microstructure, and autonomic activity. Thirteen veterans with PTSD completed two nights of laboratory-based polysomnography during which they received 1 h of either active tVNS (tragus) or sham stimulation (earlobe) at "lights out" with randomised order. Sleep staging and stability metrics were derived from polysomnography data. Autonomic activity during sleep was assessed using the Porges-Bohrer method for calculating respiratory sinus arrhythmia (RSAP-B ). Paired t-tests revealed a small decrease in the total sleep time (d = -0.31), increase in N3 sleep (d = 0.23), and a small-to-moderate decrease in REM sleep (d = -0.48) on nights of active tVNS relative to sham stimulation. tVNS was also associated with a moderate reduction in cyclic alternating pattern (CAP) rate (d = -0.65) and small-to-moderate increase in RSAP-B during NREM sleep. Greater NREM RSAP-B was associated with a reduced CAP rate and NREM alpha power. This pilot study provides preliminary evidence that tVNS may improve sleep depth and stability in veterans with PTSD, as well as increase parasympathetically mediated nocturnal autonomic activity. These results warrant continued investigation into tVNS as a potential tool for treating sleep disturbance in veterans with PTSD.

Restraint stress induced anxiety and sleep in mice

In humans and animals, exposure to changes in internal or external environments causes acute stress, which changes sleep and enhances neurochemical, neuroendocrine, and sympathetic activities. Repeated stress responses play an essential role in the pathogenesis of psychiatric diseases and sleep disorders. However, the underlying mechanism of sleep changes and anxiety disorders in response to acute stress is not well established. In the current study, the effects of restraint stress (RS) on anxiety and sleep-wake cycles in mice were investigated. We found that after RS, the mice showed anxiety-like behavior after RS manipulation and increased the amounts of both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep in the dark period. The increase in sleep time was mainly due to the increased number of episodes of NREM and REM sleep during the dark period. In addition, the mice showed an elevation of the EEG power spectrum of both NREM and REM sleep 2 h after RS manipulation. There was a significant reduction in the EEG power spectrum of both NREM and REM sleep during the darkperiod in the RS condition. The expression of the c-Fos protein was significantly increased in the parabrachial nucleus, bed nucleus of the stria terminalis, central amygdala, and paraventricular hypothalamus by RS manipulation. Altogether, the findings from the present study indicated that neural circuits from the parabrachial nucleus might regulate anxiety and sleep responses to acute stress, and suggest a potential therapeutic target for RS induced anxiety and sleep alterations.

Investigating the relationship between objective measures of sleep and self-report sleep quality in healthy adults: a review

STUDY OBJECTIVES

Sleep is one of the most common factors related to health, yet a standard definition of sleep quality has not been identified. Polysomnography provides important information about objective sleep variables. However, the relationship between objective sleep variables and perception of sleep quality remains unclear. The purpose of this review was to (1) summarize the current methods of measuring objective sleep macrostructure and microstructure, including electroencephalography arousals, spectral frequency, cyclic alternating pattern, and self-report sleep quality, and (2) investigate the relationship between objective measures of sleep physiology and self-report sleep quality in healthy adults.

METHODS

A literature search was conducted using Medline, PubMed, and PsycInfo databases and cited reference searches. Eligible studies included a comparison between self-report sleep quality and polysomnography sleep measures in healthy adults.

RESULTS

Thirteen studies were identified. Measurement of self-report sleep quality varied widely across studies. Total sleep time and sleep efficiency were most consistently related to sleep quality, while other objective sleep variables, including electroencephalography spectral analysis, were not reliably predictive of self-report sleep quality in healthy adults. There is preliminary support that microstructural sleep analysis with cyclic alternating pattern may be related to self-reported sleep quality.

CONCLUSIONS

Further research is needed to define and standardize self-report measures of sleep quality and investigate the microstructure of sleep. Objective measures of sleep and experiences of "quality" sleep are not as closely related as one may expect in healthy individuals, and understanding this relationship further is necessary to improve the clinical utility of sleep physiology.

CITATION

Cudney LE, Frey BN, McCabe RE, Green SM. Investigating the relationship between objective measures of sleep and self-report sleep quality in healthy adults: a review. J Clin Sleep Med. 2022;18(3):927-936.

Agomelatine: An astounding sui-generis antidepressant?

Major depressive disorder (MDD) is one of the foremost causes of disability and premature death worldwide. Although the available antidepressants are effective and well tolerated, they also have many limitations. Therapeutic advances in developing a new drug's ultimate relation between MDD and chronobiology, which targets the circadian rhythm, have led to a renewed focus on psychiatric disorders. In order to provide a critical analysis about antidepressant properties of agomelatine, a detailed PubMed (Medline), Scopus (Embase), Web of Science (Web of Knowledge), Cochrane Library, Google Scholar, and PsycInfo search was performed using the following keywords: melatonin analog, agomelatine, safety, efficacy, adverse effects, pharmacokinetics, pharmacodynamics, circadian rhythm, sleep disorders, neuroplasticity, MDD, bipolar disorder, anhedonia, anxiety, generalized anxiety disorder (GAD), and mood disorders. Agomelatine is a unique melatonin analog with antidepressant properties and a large therapeutic index that improves clinical safety. It is a melatonin receptor agonist (MT1 and MT2) and a 5-HT2C receptor antagonist. The effects on melatonin receptors enable the resynchronization of irregular circadian rhythms with beneficial effects on sleep architectures. In this way, agomelatine is accredited for its unique mode of action, which helps to exert antidepressant effects and resynchronize the sleep-wake cycle. To sum up, an agomelatine has not only antidepressant properties but also has anxiolytic effects.

A systematic review and meta-analysis of the cyclic alternating pattern across the lifespan

BACKGROUND

Cyclic alternating pattern (CAP) is the electroencephalogram (EEG) pattern described as a marker of sleep instability and assessed by NREM transient episodes in sleep EEG. It has been associated with brain maturation. The aim of this review was to evaluate the normative data of CAP parameters according to the aging process in healthy subjects through a systematic review and meta-analysis.

METHODS

Two authors independently searched databases using PRISMA guidelines. Discrepancies were reconciled by a third reviewer. Subgroup analysis and tests for heterogeneity were conducted.

RESULTS

Of 286 studies, 10 submitted a total of 168 healthy individuals to CAP analysis. Scoring of CAP can begin at 3 months of life, when K-complexes, delta bursts, or spindles can be recognized. Rate of CAP increased with age, mainly during the first 2 years of life, then decreased in adolescence, and increased in the elderly. The A1 CAP subtype and CAP rate were high in school-aged children during slow-wave sleep (SWS). A1 CAP subtypes were significantly more numerous in adolescents compared with other groups, while the elderly showed the highest amounts of A2 and A3 CAP subtypes. Our meta-analysis registered the lowest CAP rate in infants younger than 2 years old and the highest in the elderly.

CONCLUSIONS

This review summarized the normative data of CAP in NREM sleep during the aging process. The CAP rate increased with age and sleep depth, especially during SWS. Parameters of CAP may reflect gender hormonal effects and neuroplasticity. More reports on CAP subtypes are needed for their reference values establishment.

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.

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.

Hyperarousal during sleep in untreated, major depressed subjects with prodromal insomnia: A polysomnographic study

In primary insomnia, specific dynamics of hyperarousal are evident during the night. Similarly, in major depression, many elements also favor of the presence of hyperarousal. Thus, it would be interesting to investigate if hyperarousal presents the same dynamic in major depression. Polysomnographic data from 30 healthy controls, 66 patients with major depression and prodromal insomnia, and 86 primary insomnia sufferers recruited from the sleep laboratory database were studied for whole night and thirds of the night. Insomnia sufferers and patients with depression exhibit a similar polysomnographic pattern both for whole night (increased sleep latency and WASO and reduced SWS and REM) and thirds of night (increased WASO at first and last thirds, reduced SWS in first third, and reduced in REM in first and last third). No alterations were detected during the second third of the night. Just as in primary insomnia, the hyperarousal phenomenon is found mainly in major depression with prodromal insomnia during the sleep-onset period and the first and last thirds of the night, but lesser during the second third of the night. These specific dynamics of hyperarousal may aid in the understanding of the particular relationship between insomnia and depression.

Similar polysomnographic pattern in primary insomnia and major depression with objective insomnia: a sign of common pathophysiology?

BACKGROUND

Our aim is to verify empirically the existence of a major depressed subgroup with a similar polysomnographic pattern as primary insomnia, including at rapid eye movement sleep level.

METHODS

The polysomnographic data from 209 untreated individuals (30 normative, 84 primary insomnia sufferers, and 95 major depressed patients with objective insomnia) who were recruited retrospectively from the Erasme hospital database were studied for the whole night and thirds of the night.

RESULTS

Primary insomnia sufferers and major depressed patients with objective insomnia exhibit a similar polysomnographic pattern both for the whole night (excess of wake after sleep onset, deficit in slow-wave sleep/rapid eye movement sleep, and non-shortened rapid eye movement latency) and thirds of the night (excess of wake after sleep onset at first and last third, deficit in slow-wave sleep in first third, and deficit in rapid eye movement sleep in first and last third), including at rapid eye movement sleep level.

CONCLUSION

In our study, we demonstrated that major depressed patients with objective insomnia showed a similar polysomnographic pattern as primary insomnia, including at rapid eye movement sleep level, which supports the hypothesis of a common pathophysiology that could be hyperarousal. This opens new avenues for understanding the pathophysiology of major depression with objective insomnia.

Personalized Medicine: Review and Perspectives of Promising Baseline EEG Biomarkers in Major Depressive Disorder and Attention Deficit Hyperactivity Disorder

Personalized medicine in psychiatry is in need of biomarkers that resemble central nervous system function at the level of neuronal activity. Electroencephalography (EEG) during sleep or resting-state conditions and event-related potentials (ERPs) have not only been used to discriminate patients from healthy subjects, but also for the prediction of treatment outcome in various psychiatric diseases, yielding information about tailored therapy approaches for an individual. This review focuses on baseline EEG markers for two psychiatric conditions, namely major depressive disorder and attention deficit hyperactivity disorder. It covers potential biomarkers from EEG sleep research and vigilance regulation, paroxysmal EEG patterns and epileptiform discharges, quantitative EEG features within the EEG main frequency bands, connectivity markers and ERP components that might help to identify favourable treatment outcome. Further, the various markers are discussed in the context of their potential clinical value and as research domain criteria, before giving an outline for future studies that are needed to pave the way to an electrophysiological biomarker-based personalized medicine.

Sleep and mental disorders: A meta-analysis of polysomnographic research

Investigating sleep in mental disorders has the potential to reveal both disorder-specific and transdiagnostic psychophysiological mechanisms. This meta-analysis aimed at determining the polysomnographic (PSG) characteristics of several mental disorders. Relevant studies were searched through standard strategies. Controlled PSG studies evaluating sleep in affective, anxiety, eating, pervasive developmental, borderline and antisocial personality disorders, attention-deficit-hyperactivity disorder (ADHD), and schizophrenia were included. PSG variables of sleep continuity, depth, and architecture, as well as rapid-eye movement (REM) sleep were considered. Calculations were performed with the "Comprehensive Meta-Analysis" and "R" software. Using random effects modeling, for each disorder and each variable, a separate meta-analysis was conducted if at least 3 studies were available for calculation of effect sizes as standardized means (Hedges' g). Sources of variability, that is, sex, age, and mental disorders comorbidity, were evaluated in subgroup analyses. Sleep alterations were evidenced in all disorders, with the exception of ADHD and seasonal affective disorders. Sleep continuity problems were observed in most mental disorders. Sleep depth and REM pressure alterations were associated with affective, anxiety, autism and schizophrenia disorders. Comorbidity was associated with enhanced REM sleep pressure and more inhibition of sleep depth. No sleep parameter was exclusively altered in 1 condition; however, no 2 conditions shared the same PSG profile. Sleep continuity disturbances imply a transdiagnostic imbalance in the arousal system likely representing a basic dimension of mental health. Sleep depth and REM variables might play a key role in psychiatric comorbidity processes. Constellations of sleep alterations may define distinct disorders better than alterations in 1 single variable. (PsycINFO Database Record

Effects of the 5-HT(1A) Receptor Agonist Tandospirone on ACTH-Induced Sleep Disturbance in Rats

The aim of this study was to compare the effect of the serotonin (5-HT)1A receptor agonist tandospirone versus that of the benzodiazepine hypnotic flunitrazepam in a rat model of long-term adrenocorticotropic hormone (ACTH)-induced sleep disturbance. Rats implanted with electrodes for recording electroencephalogram and electromyogram were injected with ACTH once daily at a dose of 100 µg/rat. Administration of ACTH for 10 d caused a significant increase in sleep latency, decrease in non-rapid eye movement (non-REM) sleep time, and increase in wake time. Tandospirone caused a significant decrease in sleep latency and increase in non-REM sleep time in rats treated with ACTH. The effect of tandospirone on sleep patterns was antagonized by the 5-HT1A receptor antagonist WAY-100635. In contrast, flunitrazepam had no significant effect on sleep parameters in ACTH-treated rats. These results clearly indicate that long-term administration of ACTH causes sleep disturbance, and stimulating the 5-HT1A receptor by tandospirone may be efficacious for improving sleep in cases in which benzodiazepine hypnotics are ineffective.

Sleep state instabilities in major depressive disorder: Detection and quantification with electrocardiogram-based cardiopulmonary coupling analysis

Sleep disruption is an important aspect of major depressive disorder but lacks an objective and inexpensive means of assessment. We evaluated the utility of electrocardiogram (ECG)-based cardiopulmonary coupling analysis to quantify physiologic sleep stability in patients with major depression. Relative to controls, unmedicated depressed patients had a reduction in high-frequency coupling, an index of stable sleep, an increase in low-frequency coupling, an index of unstable sleep, and an increase in very-low-frequency coupling, an index of wakefulness/REM sleep. The medicated depressed group showed a restoration of stable sleep to a level comparable with that of the control group. ECG-based cardiopulmonary coupling analysis may provide a simple, cost-efficient point-of-care method to quantify sleep quality/stability and to objectively evaluate the severity of insomnia in patients with major depression.

Sleep quality changes in chronically depressed patients treated with Mindfulness-based Cognitive Therapy or the Cognitive Behavioral Analysis System of Psychotherapy: a pilot study

OBJECTIVE

To capture any sleep quality changes associated with group psychotherapy.

PATIENTS/METHODS

Physician-referred, chronically depressed patients (n = 25) were randomized to either eight group sessions of Mindfulness-based Cognitive Therapy (MBCT, n = 9) plus Treatment As Usual (TAU), or the Cognitive Behavioral Analysis System of Psychotherapy (CBASP, n = 8) plus TAU, or to TAU only (control group, n = 8). Participants recorded their sleep at home. The primary outcome variables were: stable and unstable sleep, which were assessed using cardiopulmonary coupling (CPC) analysis, and estimated total sleep and wake time (minutes). Cardiopulmonary coupling measures heart rate variability and the electrocardiogram's R-wave amplitude fluctuations associated with respiration.

RESULTS

By post-treatment night 6, the CBASP group had more stable sleep (p= 0.044) and less wake (p = 0.004) compared with TAU, and less wake vs MBCT (p = 0.039).

CONCLUSION

The CBASP group psychotherapy treatment improved sleep quality compared with Treatment As Usual.

The Neurobiological Mechanisms and Treatments of REM Sleep Disturbances in Depression

Most depressed patients suffer from sleep abnormalities, which are one of the critical symptoms of depression. They are robust risk factors for the initiation and development of depression. Studies about sleep electroencephalograms have shown characteristic changes in depression such as reductions in non-rapid eye movement sleep production, disruptions of sleep continuity and disinhibition of rapid eye movement (REM) sleep. REM sleep alterations include a decrease in REM sleep latency, an increase in REM sleep duration and REM sleep density with respect to depressive episodes. Emotional brain processing dependent on the normal sleep-wake regulation seems to be failed in depression, which also promotes the development of clinical depression. Also, REM sleep alterations have been considered as biomarkers of depression. The disturbances of norepinephrine and serotonin systems may contribute to REM sleep abnormalities in depression. Lastly, this review also discusses the effects of different antidepressants on REM sleep disturbances in depression.

WITHDRAWN: Sleep quality changes in chronically depressed patients treated with mindfulness-based cognitive therapy or cognitive behavioral analysis system for psychotherapy: a pilot study

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Bupropion response on sleep quality in patients with depression: implications for increased cardiovascular disease risk

Depression could be an independent risk factor for cardiovascular disease. We assessed bupropion response in depressed patients by polysomnography (PSG) and cardiopulmonary coupling (CPC) variables. Nineteen subjects participated in a two-session, two consecutive night PSG protocol. Participants received either placebo or bupropion-SR 150 mg, orally, in a randomized, double-blind cross-over fashion on night two. Outcome variables were: sleep stages, REM latency, stable, unstable sleep and very low frequency coupling (VLFC). CPC analysis uses heart rate variability and the electrocardiogram's R-wave amplitude fluctuations associated with respiration to generate frequency maps. Bupropion increased REM latency (p=0.043) but did not impact PSG sleep continuity, architecture and CPC variables. A trend (p=0.092) was observed towards increasing VLFC duration. Bupropion increased the number of stable-unstable sleep transitions (p=0.036). Moderate to strong correlations between PSG and CPC variables were found on placebo and bupropion nights. Limitations include a small sample size, limited power to detect CPC changes and lack of normal controls for comparison. Increased stable-unstable sleep transitions and VLFC duration may indicate vulnerability to cardiovascular disease due to their association with low heart rate variability that has been associated with increased mortality raising the question whether the beneficial effects of the antidepressant medication outweighs the impact on cardiopulmonary dynamics.

Therapeutic potential of agomelatine in epilepsy and epileptic complications

Epilepsy is a chronic neurologic disorder which often induces numerous adverse long-term neurologic effects, such as behavioral and cognitive deficits, increased predisposition to additional seizures, and cell injury or death. Cognitive dysfunction, depression, anxiety and sleep disorders are some of the highly prevalent and most disabling complications of epilepsy. The mechanisms that lead to the generation of epileptic comorbidities are poorly understood. Treatment for epileptic complications still remains a challenge because of the poor adherence and drug interactions associated with multi drug prescriptions and also for the fear of worsening seizures by the individual medications for complications. Melatonin, an endogenous hormone secreted by pineal gland has a prominent role in epilepsy. Agomelatine is a novel antidepressant which acts as melatonin MT1 and MT2 receptor agonist and serotonin 5Ht2C receptor antagonist. The combined action at MT1/2 and 5HT2C receptors, reduction in the depolarization-evoked release of glutamate, strong neuroprotective action and possible antioxidant properties of agomelatine could make it a potential agent in the treatment of epilepsy. The effect of agomelatine on hippocampal neuronal cell survival and neurogenesis, neuroprotective effect in hippocampus and frontal cortex and the antioxidant potential may contribute to the protective action of agomelatine against epilepsy induced memory decline. Agomelatine is proven to be an antidepressant and it has relieved anxiety symptoms and improved the quality of sleep in patients with depressive disorder. The action of agomelatine as a melatonin agonist and the consequent circadian resynchronizing property as well as its action as 5-HT2C receptor antagonist, could possibly suggest an antidepressant and anxiolytic action of agomelatine in epilepsy induced depressive behavior and anxiety. Since one of the many causes of sleep disruption in epilepsy is circadian rhythm disturbances and sleep promoting and circadian effects of melatonin is attributed to the MT1 and MT2 subtypes of human melatonin receptors, agomelatine may also have a promising effect on epilepsy induced sleep disruptions. Thus with all these potential pharmacological actions, agomelatine could be recommended as a potential drug to treat epilepsy and its complications.

EEG biomarkers in major depressive disorder: discriminative power and prediction of treatment response

Major depressive disorder (MDD) has high population prevalence and is associated with substantial impact on quality of life, not least due to an unsatisfactory time span of sometimes several weeks from initiation of treatment to clinical response. Therefore extensive research focused on the identification of cost-effective and widely available electroencephalogram (EEG)-based biomarkers that not only allow distinguishing between patients and healthy controls but also have predictive value for treatment response for a variety of treatments. In this comprehensive overview on EEG research on MDD, biomarkers that are either assessed at baseline or during the early course of treatment and are helpful in discriminating patients from healthy controls and assist in predicting treatment outcome are reviewed, covering recent decades up to now. Reviewed markers include quantitative EEG (QEEG) measures, connectivity measures, EEG vigilance-based measures, sleep-EEG-related measures and event-related potentials (ERPs). Further, the value and limitations of these different markers are discussed. Finally, the need for integrated models of brain function and the necessity for standardized procedures in EEG biomarker research are highlighted to enhance future research in this field.

Agomelatine, a novel intriguing antidepressant option enhancing neuroplasticity: a critical review

OBJECTIVES

The treatment of major affective disorders, commonly associated with high disability and elevated social costs may be still considered unsatisfactory. Among all antidepressant drugs, predominantly acting through monoaminergic mechanisms, agomelatine is of particular interest due to another alternative mechanism of action. Targeting melatonergic receptors, agomelatine play a crucial role in synchronizing circadian rhythms, known to be altered in depressed subjects.

METHODS

A critical review of the literature focusing on efficacy, safety and tolerability of agomelatine in major affective disorders was performed. Additionally, we focused on the potential of agomelatine in enhancing neuroplasticity mechanisms and promote neurogenesis. A total of 136 articles from peer-reviewed journals were identified, of which 50 were assessed for eligibility and 21 were included.

RESULTS

Agomelatine, a melatonergic analogue drug acting as MT1/MT2 agonist and 5-HT2C antagonist, has been reported to be effective as antidepressant drug. Studies confirmed not only clinical efficacy but also safety and tolerability of agomelatine. Also, it enhances neuroplasticity mechanisms and adult neurogenesis in brain areas such as hippocampus and prefrontal cortex.

CONCLUSIONS

Agomelatine actually represents an intriguing option in the treatment of affective disorders.

The melatonergic system in mood and anxiety disorders and the role of agomelatine: implications for clinical practice

Melatonin exerts its actions through membrane MT1/MT2 melatonin receptors, which belong to the super family of G-protein-coupled receptors consisting of the typical seven transmembrane domains. MT1 and MT2 receptors are expressed in various tissues of the body either as single ones or together. A growing literature suggests that the melatonergic system may be involved in the pathophysiology of mood and anxiety disorders. In fact, some core symptoms of depression show disturbance of the circadian rhythm in their clinical expression, such as diurnal mood and other symptomatic variation, or are closely linked to circadian system functioning, such as sleep-wake cycle alterations. In addition, alterations have been described in the circadian rhythms of several biological markers in depressed patients. Therefore, there is interest in developing antidepressants that have a chronobiotic effect (i.e., treatment of circadian rhythm disorders). As melatonin produces chronobiotic effects, efforts have been aimed at developing agomelatine, an antidepressant with melatonin agonist activity. The present paper reviews the role of the melatonergic system in the pathophysiology of mood and anxiety disorders and the clinical characteristics of agomelatine. Implications of agomelatine in "real world" clinical practice will be also discussed.

Chronic agomelatine treatment corrects the abnormalities in the circadian rhythm of motor activity and sleep/wake cycle induced by prenatal restraint stress in adult rats

Agomelatine is a novel antidepressant acting as an MT1/MT2 melatonin receptor agonist/5-HT2C serotonin receptor antagonist. Because of its peculiar pharmacological profile, this drug caters the potential to correct the abnormalities of circadian rhythms associated with mood disorders, including abnormalities of the sleep/wake cycle. Here, we examined the effect of chronic agomelatine treatment on sleep architecture and circadian rhythms of motor activity using the rat model of prenatal restraint stress (PRS) as a putative 'aetiological' model of depression. PRS was delivered to the mothers during the last 10 d of pregnancy. The adult progeny ('PRS rats') showed a reduced duration of slow wave sleep, an increased duration of rapid eye movement (REM) sleep, an increased number of REM sleep events and an increase in motor activity before the beginning of the dark phase of the light/dark cycle. In addition, adult PRS rats showed an increased expression of the transcript of the primary response gene, c-Fos, in the hippocampus just prior to the beginning of the dark phase. All these changes were reversed by a chronic oral treatment with agomelatine (2000 ppm in the diet). The effect of agomelatine on sleep was largely attenuated by treatment with the MT1/MT2 melatonin receptor antagonist, S22153, which caused PRS-like sleep disturbances on its own. These data provide the first evidence that agomelatine corrects sleep architecture and restores circadian homeostasis in a preclinical model of depression and supports the value of agomelatine as a novel antidepressant that resynchronizes circadian rhythms under pathological conditions.

Agomelatine: Its Role in the Management of Major Depressive Disorder

Circadian rhythm abnormalities, as shown by sleep/wake cycle disturbances, constitute one the most prevalent signs of depressive illness; advances or delays in the circadian phase are documented in patients with major depressive disorder (MDD), bipolar disorder, and seasonal affective disorder (SAD). The disturbances in the amplitude and phase of rhythm in melatonin secretion that occur in patients with depression resemble those seen in chronobiological disorders, thus suggesting a link between disturbed melatonin secretion and depressed mood. Based on this, agomelatine, the first MT1/MT2 melatonergic agonist displaying also 5-HT2C serotonergic antagonism, has been introduced as an antidepressant. Agomelatine has been shown to be effective in several animal models of depression and anxiety and it has beneficial effects in patients with MDD, bipolar disorder, or SAD. Among agomelatine's characteristics are a rapid onset of action and a pronounced effectiveness for correcting circadian rhythm abnormalities and improving the sleep/wake cycle. Agomelatine also improves the 3 functional dimensions of depression—emotional, cognitive, and social—thus aiding in the full recovery of patients to a normal life.

Melatonin and its analogs in insomnia and depression

Benzodiazepine sedative-hypnotic drugs are widely used for the treatment of insomnia. Nevertheless, their adverse effects, such as next-day hangover, dependence and impairment of memory, make them unsuitable for long-term treatment. Melatonin has been used for improving sleep in patients with insomnia mainly because it does not cause hangover or show any addictive potential. However, there is a lack of consistency on its therapeutic value (partly because of its short half-life and the small quantities of melatonin employed). Thus, attention has been focused either on the development of more potent melatonin analogs with prolonged effects or on the design of slow release melatonin preparations. The MT(1) and MT(2) melatonergic receptor ramelteon was effective in increasing total sleep time and sleep efficiency, as well as in reducing sleep latency, in insomnia patients. The melatonergic antidepressant agomelatine, displaying potent MT(1) and MT(2) melatonergic agonism and relatively weak serotonin 5HT(2C) receptor antagonism, was found effective in the treatment of depressed patients. However, long-term safety studies are lacking for both melatonin agonists, particularly considering the pharmacological activity of their metabolites. In view of the higher binding affinities, longest half-life and relative higher potencies of the different melatonin agonists, studies using 2 or 3mg/day of melatonin are probably unsuitable to give appropriate comparison of the effects of the natural compound. Hence, clinical trials employing melatonin doses in the range of 50-100mg/day are warranted before the relative merits of the melatonin analogs versus melatonin can be settled.

Mood disorders, circadian rhythms, melatonin and melatonin agonists

Recent advances in the understanding of circadian rhythms have led to an interest in the treatment of major depressive disorder with chronobiotic agents. Many tissues have autonomous circadian rhythms, which are orchestrated by the master clock, situated in the suprachiasmatic nucleus (SNC). Melatonin (N-acetyl-5-hydroxytryptamine) is secreted from the pineal gland during darkness. Melatonin acts mainly on MT1 and MT2 receptors, which are present in the SNC, regulating physiological and neuroendocrine functions, including circadian entrainment, referred to as the chronobiotic effet. Circadian rhythms has been shown to be either misaligned or phase shifted or decreased in amplitude in both acute episodes and relapse of major depressive disorder (MDD) and bipolar disorder. Manipulation of circadian rhythms either using physical treatments (such as high intensity light) or behavioral therapy has shown promise in improving symptoms. Pharmacotherapy using melatonin and pure melatonin receptor agonists, while improving sleep, has not been shown to improve symptoms of depression. A novel antidepressant, agomelatine, combines 5HT2c antagonist and melatonin agonist action, and has shown promise in both acute treatment of MDD and in preventing relapse.

Agomelatine in unipolar depression in clinical practice: a retrospective chart review

Agomelatine (Valdoxan), a synthetic melatonergic receptor agonist at the MT1 and MT2 receptors, was first used in the management of sleep disorder. Its 5HT2C receptor antagonistic properties support its antidepressant potential. It is currently licensed in the UK, Europe and USA for the treatment of major depressive disorder. Although the randomized controlled evidence base for its use is growing, there are no retrospective, naturalistic studies available. We aimed to determine the tolerability and clinical effectiveness of agomelatine in unipolar depression. We also examined whether being refractory to treatment altered clinical outcome. Forty-eight patient records were examined. Twenty-five percent were treatment refractory: Clinical Global Impression (CGI) Severity score at the start of treatment was 3.81 compared with 3.38 at the end of treatment. Fifty-four percent improved at least minimally; only 12.5% were much or very much improved. Treatment-refractory patients had a poorer outcome with higher discontinuation rates and lower CGI Improvement (p = 0.0205). Treatment-refractory patients also had a higher CGI Severity score at the end of treatment than at treatment commencement (3.92 versus 3.75), although this was not statistically significant.

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

BACKGROUND

Research on whether any electroencephalographic (EEG) sleep abnormalities observed among individuals with major depressive disorder (MDD) represent genetic biomarkers remains inconclusive. We aimed to identify EEG-based biomarkers of MDD through a review of studies from three populations: individuals with MDD, individuals with MDD under remission, and never depressed high-risk probands (HRPs) of individuals with MDD.

METHODS

We searched databases such as MEDLINE and PsycINFO for EEG studies published since 1970. Of the 886 records, our selection criteria identified 56 studies that employed standardized EEG scoring procedures and addressed confounds such as participant reactivity and drug effects. We then used fixed-effects models to calculate average weighted mean differences in EEG parameters between clinical groups across these studies.

RESULTS

Individuals with MDD differed significantly from control subjects on several EEG variables. However, remitted individuals showed normalization of all affected EEG parameters except rapid eye movement (REM) density and slow-wave sleep (SWS). Surprisingly, proportion of SWS was significantly shorter during remission than depression. Never-depressed HRPs also exhibited significantly elevated REM density and reduced SWS. Finally, these parameters constituted the only two EEG variables that were not moderated by depression severity.

CONCLUSIONS

Individuals experiencing MDD and those in remission exhibit increased REM density and shortened SWS, as do HRPs with no history of MDD. Thus, this combination of EEG features may represent a genetic biomarker of MDD. Further, SWS appears to be shorter during remission than depression, suggesting its role as both a genetic marker as well as a biological scar of the disorder.

Melatonin agonists in primary insomnia and depression-associated insomnia: are they superior to sedative-hypnotics?

Current pharmacological treatment of insomnia involves the use of sedative-hypnotic benzodiazepine and non-benzodiazepine drugs. Although benzodiazepines improve sleep, their multiple adverse effects hamper their application. Adverse effects include impairment of memory and cognitive functions, next-day hangover and dependence. Non-benzodiazepines are effective for initiating sleep but are not as effective as benzodiazepines for improving sleep quality or efficiency. Furthermore, their prolonged use produces adverse effects similar to those observed with benzodiazepines. Inasmuch as insomnia may be associated with decreased nocturnal melatonin, administration of melatonin is a strategy that has been increasingly used for treating insomnia. Melatonin can be effective for improving sleep quality without the adverse effects associated with hypnotic-sedatives. Ramelteon, a synthetic analog of melatonin which has a longer half life and a stronger affinity for MT1 and MT2 melatonergic receptors, has been reportedly effective for initiating and improving sleep in both adult and elderly insomniacs without showing hangover, dependence, or cognitive impairment. Insomnia is also a major complaint among patients suffering from depressive disorders and is often aggravated by conventional antidepressants especially the specific serotonin reuptake inhibitors. The novel antidepressant agomelatine, a dual action agent with affinity for melatonin MT1 and MT2 receptors and 5-HT2c antagonistic properties, constitutes a new approach to the treatment of major depressive disorders. Agomelatine ameliorates the symptoms of depression and improves the quality and efficiency of sleep. Taken together, the evidence indicates that MT1/MT2 receptor agonists like ramelteon or agomelatine may be valuable pharmacological tools for insomnia and for depression-associated insomnia.

Parasomnias and antidepressant therapy: a review of the literature

There exists a varying level of evidence linking the use of antidepressant medication to the parasomnias, ranging from larger, more comprehensive studies in the area of REM sleep behavior disorder to primarily case reports in the NREM parasomnias. As such, practice guidelines are lacking regarding specific direction to the clinician who may be faced with a patient who has developed a parasomnia that appears to be temporally related to use of an antidepressant. In general, knowledge of the mechanisms of action of the medications, particularly with regard to the impact on sleep architecture, can provide some guidance. There is a potential for selective serotonin reuptake inhibitors, tricyclic antidepressants, and serotonin-norepinephrine reuptake inhibitors to suppress REM, as well as the anticholinergic properties of the individual drugs to further disturb normal sleep architecture.

Blockade of stress-induced increase of glutamate release in the rat prefrontal/frontal cortex by agomelatine involves synergy between melatonergic and 5-HT2C receptor-dependent pathways

Background

Agomelatine is a melatonergic receptor agonist and a 5HT_2C receptor antagonist that has shown antidepressant efficacy. In order to analyze separately the effect of the two receptorial components, rats were chronically treated with agomelatine, melatonin (endogenous melatonergic agonist), or S32006 (5-HT_2C antagonist), and then subjected to acute footshock-stress.

Results

Only chronic agomelatine, but not melatonin or S32006, completely prevented the stress-induced increase of glutamate release in the rat prefrontal/frontal cortex.

Conclusions

These results suggest a potential synergy between melatonergic and serotonergic pathways in the action of agomelatine.

Efficacy and safety of agomelatine in the treatment of major depressive disorder: a multicenter, randomized, double-blind, placebo-controlled trial

In this 8-week double-blind multicenter trial, we evaluated the efficacy and safety of 2 fixed doses of agomelatine in patients with moderate to severe major depressive disorder. Primary efficacy variable was the change in 17-item Hamilton Depression Rating Scale (HAM-D17) total score from baseline to week 8/end of treatment. Secondary efficacy assessment compared the improvements in clinical response and remission (HAM-D17), Clinical Global Impression--Improvement Score, Clinical Global Impression--Severity Score, Hospital Anxiety and Depression (HAD), sleep (Leeds Sleep Evaluation Questionnaire), disability (Sheehan Disability Scale), and overall Quality of Life in Depression Scale between the agomelatine and placebo groups. Eligible patients (n = 511; baseline mean HAM-D17 score = 27.0) were randomized (1:1:1) to once-daily agomelatine, 25 mg; agomelatine, 50 mg; or placebo. Agomelatine 50 mg provided a statistically significant improvement in HAM-D17 score from first baseline visit through week 8 compared with placebo (week 8 treatment difference, 2.5; P = 0.004), whereas agomelatine 25 mg did not show (P = 0.505) a significant improvement. Treatment differences for all secondary efficacy variables were also statistically significant for agomelatine 50 mg versus placebo: Clinical Global Impression--Improvement (P = 0.012); Clinical Global Impression--Severity difference (P = 0.003); improvement in HAD total score, 2.2 (P = 0.014); patients' ability to get sleep (P < 0.001); quality of sleep (P = 0.002). Both doses of agomelatine were well tolerated relative to placebo. However, clinically notable transient aminotransferase elevations were observed in 4.5% of the patients in the agomelatine 50 mg group. The results showed significant antidepressant efficacy of agomelatine 50 mg/d, including a positive effect on sleep compared with placebo in outpatients with moderate to severe major depressive disorder.

Impact of the novel antidepressant agomelatine on disturbed sleep-wake cycles in depressed patients

BACKGROUND

Disturbance of sleep-wake cycles is common in major depressive disorder (MDD), usually as insomnia, but also as hypersomnia or reduced daytime alertness. Agomelatine, an MT(1) and MT(2) receptor agonist and 5-HT(2C) receptor antagonist, represents a novel approach in MDD, with proven antidepressant efficacy and a positive impact on the sleep-wake cycle. We review the effects of agomelatine 25/50 mg/day on objective and subjective measures of the sleep-wake cycle in MDD.

SUBJECTIVE MEASURES

Agomelatine improved all aspects of the sleep-wake cycle from as early as 1 week in randomized trials versus selective serotonin reuptake inhibitors and venlafaxine, particularly getting off to sleep and quality of sleep, with an improvement in daytime alertness.

OBJECTIVE MEASURES

Agomelatine's effect on sleep architecture in MDD has been measured by polysomnography (PSG). There were significant improvements in sleep efficiency, slow-wave sleep (SWS), and the distribution of delta activity throughout the night, but no change in amount or latency of rapid eye movement (REM) sleep. Furthermore, the slow-wave sleep was resynchronized to the first sleep cycle of the night.

CONCLUSION

Agomelatine, a novel antidepressant, improves disturbed sleep-wake cycles in MDD. The improvement of both nighttime sleep and daytime functioning with agomelatine are promising features of this antidepressant regarding the management of MDD.

Agomelatine in the treatment of mood and anxiety disorders

The antidepressant agomelatine combines a novel mechanism of action with certain advantages over currently available antidepressants, in terms of restoration of sleep, absence of treatment-emergent sexual dysfunction, and fewer discontinuation symptoms. What is its potential role in clinical practice?

The use of antidepressants in clinical practice: focus on agomelatine

OBJECTIVE

Agomelatine (Valdoxan) is licensed by the European Medicines Agency for the treatment of major depressive episodes in adults. The objective of this review was to consider how the drug should be used in clinical practice in particular starting, stopping and switching to and from the drug.

METHODS

The existing clinical evidence was reviewed.

RESULTS

Data suggest that when switching to agomelatine from other antidepressants consideration should be given to tapering the previous antidepressant in order to minimize the risk of the original drug causing discontinuation/withdrawal symptoms. The risk of pharmacological interactions between most antidepressants and agomelatine is low and so tapering the previous antidepressant can usually be done after agomelatine has been started. An exception is fluvoxamine which should not be concurrently prescribed with agomelatine. As agomelatine appears to cause no significant discontinuation symptoms, it can probably be stopped abruptly when treatment is completed or when switching to another antidepressant.

CONCLUSIONS

While this guidance may change as clinical evidence and experience grows, currently agomelatine appears to have a good tolerability profile and is relatively easy to use, though prescribers should note the requirement to conduct liver function tests (LFTs) in accordance with the Summary of Product Characteristics (SPC).

Physiology and pharmacology of melatonin in relation to biological rhythms

Melatonin is an evolutionarily conserved molecule that serves a time-keeping function in various species. In vertebrates, melatonin is produced predominantly by the pineal gland with a marked circadian rhythm that is governed by the central circadian pacemaker (biological clock) in the suprachiasmatic nuclei of the hypothalamus. High levels of melatonin are normally found at night, and low levels are seen during daylight hours. As a consequence, melatonin has been called the "darkness hormone". This review surveys the current state of knowledge regarding the regulation of melatonin synthesis, receptor expression, and function. In particular, it addresses the physiological, pathological, and therapeutic aspects of melatonin in humans, with an emphasis on biological rhythms.

Insomnia in patients with depression: some pathophysiological and treatment considerations

The almost ubiquitous sleep disturbances in patients with depression commonly, but not always, subside with the remission of depression. Evidence linking insomnia with the risk of relapses in recurrent depression, as well as suicide, makes optimization of the treatment of insomnia associated with depression a priority. However, most antidepressant agents do not adequately address the sleep complaints in depression: their effects on sleep range from sizeable improvement to equally significant worsening. One approach to the management of insomnia associated with depression is to choose a sedating antidepressant agent such as trazodone, mirtazapine or agomelatine. A second approach is to start with a non-sedating antidepressant (e.g. the selective serotonin reuptake inhibitors, bupropion, venlafaxine or duloxetine); those with a persistent or treatment-emergent insomnia can be switched to a more sedating antidepressant, or offered a hypnotic or cognitive-behavioural therapy as adjunctive treatment. The review discusses the advantages and disadvantages of all treatment options, pharmacological and otherwise.

Agomelatine treatment of major depressive disorder

OBJECTIVE

To review the efficacy, safety, pharmacologic, and pharmacokinetic data of agomelatine to better understand its potential role in the treatment of patients with major depressive disorder.

DATA SOURCES

A MEDLINE search (1966-October 2008) was conducted using the following terms: agomelatine, antidepressant, S20098, melatonin, serotonin, 5-HT(2C), MT, efficacy, safety, adverse effect, pharmacology, pharmacokinetic, receptor binding, depression, major depressive disorder, and mood disorder.

STUDY SELECTION AND DATA EXTRACTION

All articles in English identified from the data sources were evaluated. Randomized, controlled trials involving humans were prioritized in the review. The references of published articles identified in the initial search process were also examined for any additional studies appropriate for the review.

DATA SYNTHESIS

Agomelatine, a potent agonist at type 1 and 2 melatonin receptors, selectively inhibits serotonin. It is extensively metabolized via cytochrome P450 isoenyzmes 1A1, 1A2, and 2C9 to metabolites with less activity than the parent drug. Five randomized controlled studies were identified that examined the efficacy and safety of agomelatine in major depressive disorder. In general, agomelatine was found to produce significant improvements in depressive symptoms compared with placebo on many, but not all, rating scales. Three of the trials had active comparator arms (ie, venlafaxine, paroxetine). In these 3 investigations, agomelatine produced effects on depressive symptoms similar to those of the comparator drugs. A small number of studies have demonstrated sleep benefits with the use of agomelatine in depressed patients. Positive findings also exist for the use of agomelatine in seasonal affective disorder and bipolar depression. The most common adverse effects reported with agomelatine use were headache, nasopharyngitis, and gastrointestinal complaints. The magnitude of agomelatine-related adverse effects appears to be at least similar to some currently marketed antidepressants.

CONCLUSIONS

Overall, agomelatine is a promising and well-tolerated medication for the treatment of major depressive disorder. More large-scale controlled trials are needed to gain a better understanding of the relative efficacy and safety of agomelatine.

[Affective disorders and biological rhythms]

Disruptions of circadian rhythms are described in affective disorders, including unipolar and bipolar disorder, but also seasonal affective disorder. Sleep-wake and hormone circadian rhythms are among the most quoted examples. Depression could be conceptualized as a desynchronization between the endogenous circadian pacemaker and the exogenous stimuli, such as sunlight and social rhythms. Accordingly, Clock genes have been studied and the literature suggests that variants in these genes confer a higher risk of relapse, more sleep disturbances associated with depression, as well as incomplete treatment response. Most of therapeutic interventions in depression have an impact on biological rhythms. Some of them exclusively act via a biological pathway, such as sleep deprivation or light therapy. Some psychosocial interventions are specifically focusing on social rhythms, particularly in bipolar disorder, in which the promotion of stabilization is emphasized. Finally, all antidepressant medications could improve biological rhythms, but some new agents are now totally focusing this novel approach for the treatment of depression.

Therapeutic potential of melatonin agonists

Melatonin, a hormone secreted by the pineal gland, has been successfully employed to improve sleep in both normal patients and insomniacs, and for the treatment of circadian rhythm sleep disorders. Melatonergic MT₁ and MT₂ receptors exist in high concentrations in the suprachiasmatic nucleus of the hypothalamus and have been shown to be instrumental for the sleep-promoting and circadian rhythm-regulating effects of melatonin. A lack of consistency among reports on the therapeutic efficacy of melatonin has been attributed to differences in melatonin's bioavailability and the short half-life of the hormone. In view of the need for longer acting melatonergic agonists that improve sleep efficiency without causing drug abuse or dependency, ramelteon (Rozerem™, Takeda) was developed. Ramelteon, which acts via MT₁/MT₂ melatonergic agonism, has been found clinically effective for improving total sleep time and sleep efficiency in insomniacs. Agomelatine (Valdoxan™, Servier) is another MT₁/MT₂ melatonergic agonist that also displays antagonist activity at 5-HT_2C serotonin receptors. Agomelatine has been found effective in treating depression and sleep disorders in patients with major depressive disorder. A slow-release preparation of melatonin (Circadin™, Neurim) has been shown to be effective in treating sleep disorders in the elderly population.