Genetics of circadian rhythms and mood spectrum disorders

The purpose of early maladaptive schemas (EMS) in the relationship dysfunction among people with bipolar disorder in the euthymic phase

OBJECTIVES

Although free from characterized manic and depressive episodes, the euthymic period in bipolar disorder (BD) remains characterized by a whole host of difficulties, particularly relational. These difficulties are factors of vulnerabilities and relapses. People's perception of their own relationships has an impact on their symptomatology, their responses to treatment and on relapse rates. Young's early maladaptive schemas (EMS) approach proves to be relevant for understanding the construction of these perceptions and working on them. Nevertheless, to this date, few studies have investigated which EMS are related to relationship dysfunction in this particular population. Determining the link between EMS and relationship difficulties would be relevant to understand psychosocial impairment of people with BD in euthymic states. The present study aims to investigate the associations between the different domains of EMS and relationship dysfunction among patients with bipolar disorder in the euthymic phase.

METHODS

Data are extracted from the FACE-BD cohort, within the BD Expert Center in Versailles. Inclusion criteria were to be aged between 18 and 65 and to be an outpatient with a diagnosis of bipolar disorder (DSM-IV-TR). Patients had to be euthymic at the time of inclusion, according to DSM-IV-TR criteria with a cut-off score of 14 on the Montgomery-Asberg Depression Rating Scale and the Young Mania Rating Scale. Non-inclusion criteria were meeting at the time of the study the criteria for characteristic depressive episode, hypomania or mania according to the DSM-IV-TR. Sociodemographic data, clinical features associated with relationship dysfunction were assessed. EMS and EMS domains were assessed with the YSQ-R short form (Young Schema Questionnaire 3 Short Form) and current relationship dysfunction were assessed with the FAST (Functioning assessment short test subscale). Successive simple linear regression analyses were performed to investigate the association between the severity scores of each EMS and the intensity of relationship dysfunction. Furthermore, successive simple linear regression analyses investigated the association between EMS domain scores and intensity of relationship dysfunction. Multiple linear regression analyses were performed to test the association between EMS scores, then EMS domains, and the intensity of relationship dysfunction after adjusting for age as well as the intensity of residual depressive and manic symptoms.

RESULTS

Relationship dysfunction is partly associated with EMS activation in particular in the separation and rejection domain (P<0.0001), the other-directedness domain (P=0.031) and the over-vigilance and inhibition domain (P=0.005). Having residual depressive symptoms is also among the factors contributing to the relationship dysfunctions of people with bipolar disorder in the euthymic phase.

DISCUSSION

This is the first study demonstrating that the activation of several domains of EMS is a risk factor of relationships difficulties for people in euthymic phase of bipolar disorder. It is necessary to identify which EMS are specifically activated and their domains of belonging in order to prevent and reduce them. EMS are a lever for functional remission. It is therefore relevant to refer people reporting relationship problems to schema therapy consistent with a personalized care. Finally, future studies should focus on the mechanisms underlying the complex relationship between EMS domains and relationship dysfunction in people with bipolar disorder in the euthymic phase. It may also be relevant for future research to control for different types of relationship dysfunction. EMS may be differentially associated with several types of interpersonal problems. The relations between different adaptation styles and EMS should be further investigated to offer more personalized care, with the aim to improve functional remission.

Circadian Biology and the Neurovascular Unit

Mammalian physiology and cellular function are subject to significant oscillations over the course of every 24-hour day. It is likely that these daily rhythms will affect function as well as mechanisms of disease in the central nervous system. In this review, we attempt to survey and synthesize emerging studies that investigate how circadian biology may influence the neurovascular unit. We examine how circadian clocks may operate in neural, glial, and vascular compartments, review how circadian mechanisms regulate cell-cell signaling, assess interactions with aging and vascular comorbidities, and finally ask whether and how circadian effects and disruptions in rhythms may influence the risk and progression of pathophysiology in cerebrovascular disease. Overcoming identified challenges and leveraging opportunities for future research might support the development of novel circadian-based treatments for stroke.

Role of polygenic risk scores in the association between chronotype and health risk behaviors

BACKGROUND

This study explores the association between chronotypes and adolescent health risk behaviors (HRBs) by testing how genetic background moderates these associations and clarifies the influence of chronotypes and polygenic risk score (PRS) on adolescent HRBs.

METHODS

Using VOS-viewer software to select the corresponding data, this study used knowledge domain mapping to identify and develop the research direction with respect to adolescent risk factor type. Next, DNA samples from 264 students were collected for low-depth whole-genome sequencing. The sequencing detected HRB risk loci, 49 single nucleotide polymorphisms based to significant SNP. Subsequently, PRSs were assessed and divided into low, moderate, and high genetic risk according to the tertiles and chronotypes and interaction models were constructed to evaluate the association of interaction effect and clustering of adolescent HRBs. The chronotypes and the association between CLOCK-PRS and HRBs were examined to explore the association between chronotypes and mental health and circadian CLOCK-PRS and HRBs.

RESULTS

Four prominent areas were displayed by clustering information fields in network and density visualization modes in VOS-viewer. The total score of evening chronotypes correlated with high-level clustering of HRBs in adolescents, co-occurrence, and mental health, and the difference was statistically significant. After controlling covariates, the results remained consistent. Three-way interactions between chronotype, age, and mental health were observed, and the differences were statistically significant. CLOCK-PRS was constructed to identify genetic susceptibility to the clustering of HRBs. The interaction of evening chronotypes and high genetic risk CLOCK-PRS was positively correlated with high-level clustering of HRBs and HRB co-occurrence in adolescents, and the difference was statistically significant. The interaction between the sub-dimensions of evening chronotypes and the high genetic CLOCK-PRS risk correlated with the outcome of the clustering of HRBs and HRB co-occurrence.

CONCLUSIONS

The interaction of PRS and chronotype and the HRBs in adolescents appear to have an association, and the three-way interaction between the CLOCK-PRS, chronotype, and mental health plays important roles for HRBs in adolescents.

Why do owls have it worse? Mediating role of self-perceptions in the links between diurnal preference and features of mental health

Recent research provides evidence for the negative social perceptions of evening chronotypes and their consequences on mental health. However, there is a lack of studies indicating whether these negative, socially shared beliefs may become internalized in negative self-perceptions of evening-types (E-types). The present article provides a seminal empirical analysis of the role of self-liking and self-competence in the associations between chronotype and both depressiveness and well-being. In the first part of the study, the participants completed the Composite Scale of Morningness. On the basis of the chronotype cut-off criteria for Composite Scale of Morningness distribution, 100 individuals were classified as morning-types (M-types) and 66 individuals as E-types. Therefore, 166 participants (80 women and 86 men) aged 18-36 years (M ± SD: 29.27 ± 4.81 years) took part in the second part of the study, and completed questionnaires measuring self-liking, self-competence, life satisfaction, positive and negative affect, and depressiveness. Results show that E-types scored lower in self-liking, self-competence and subjective well-being, and higher in depressive symptoms than M-types. Controlling for age and gender, we obtained significant mediation effects, showing that the relationship between chronotype and subjective well-being might stem from the lower levels of self-liking and self-competence among E-types, and that the relationship between chronotype and depressive symptoms might stem from the lower level of self-liking among E-types. Our results suggest that self-liking and self-competence are important antecedents of lower well-being and higher depressiveness reported by E-types. Socially shared stereotypes of M-types and E-types can be internalized by the extreme chronotypes, which may significantly affect their psychological health.

Circadian Regulation of the Neuroimmune Environment Across the Lifespan: From Brain Development to Aging

Circadian clocks confer 24-h periodicity to biological systems, to ultimately maximize energy efficiency and promote survival in a world with regular environmental light cycles. In mammals, circadian rhythms regulate myriad physiological functions, including the immune, endocrine, and central nervous systems. Within the central nervous system, specialized glial cells such as astrocytes and microglia survey and maintain the neuroimmune environment. The contributions of these neuroimmune cells to both homeostatic and pathogenic demands vary greatly across the day. Moreover, the function of these cells changes across the lifespan. In this review, we discuss circadian regulation of the neuroimmune environment across the lifespan, with a focus on microglia and astrocytes. Circadian rhythms emerge in early life concurrent with neuroimmune sculpting of brain circuits and wane late in life alongside increasing immunosenescence and neurodegeneration. Importantly, circadian dysregulation can alter immune function, which may contribute to susceptibility to neurodevelopmental and neurodegenerative diseases. In this review, we highlight circadian neuroimmune interactions across the lifespan and share evidence that circadian dysregulation within the neuroimmune system may be a critical component in human neurodevelopmental and neurodegenerative diseases.

Emotionally clocked out: cell-type specific regulation of mood and anxiety by the circadian clock system in the brain

Circadian rhythms are self-sustained oscillations of biological systems that allow an organism to anticipate periodic changes in the environment and optimally align feeding, sleep, wakefulness, and the physiological and biochemical processes that support them within the 24 h cycle. These rhythms are generated at a cellular level by a set of genes, known as clock genes, which code for proteins that inhibit their own transcription in a negative feedback loop and can be perturbed by stress, a risk factor for the development of mood and anxiety disorders. A role for circadian clocks in mood and anxiety has been suggested for decades on the basis of clinical observations, and the dysregulation of circadian rhythms is a prominent clinical feature of stress-related disorders. Despite our understanding of central clock structure and function, the effect of circadian dysregulation in different neuronal subtypes in the suprachiasmatic nucleus (SCN), the master pacemaker region, as well as other brain systems regulating mood, including mesolimbic and limbic circuits, is just beginning to be elucidated. In the brain, circadian clocks regulate neuronal physiological functions, including neuronal activity, synaptic plasticity, protein expression, and neurotransmitter release which in turn affect mood-related behaviors via cell-type specific mechanisms. Both animal and human studies have revealed an association between circadian misalignment and mood disorders and suggest that internal temporal desynchrony might be part of the etiology of psychiatric disorders. To date, little work has been conducted associating mood-related phenotypes to cell-specific effects of the circadian clock disruptions. In this review, we discuss existing literature on how clock-driven changes in specific neuronal cell types might disrupt phase relationships among cellular communication, leading to neuronal circuit dysfunction and changes in mood-related behavior. In addition, we examine cell-type specific circuitry underlying mood dysfunction and discuss how this circuitry could affect circadian clock. We provide a focus for future research in this area and a perspective on chronotherapies for mood and anxiety disorders.

An ecological study of objective rest-activity markers of lithium response in bipolar-I-disorder

BACKGROUND

Despite its pivotal role in prophylaxis for bipolar-I-disorders (BD-I), variability in lithium (Li) response is poorly understood and only a third of patients show a good outcome. Converging research strands indicate that rest-activity rhythms can help characterize BD-I and might differentiate good responders (GR) and non-responders (NR).

METHODS

Seventy outpatients with BD-I receiving Li prophylaxis were categorized as GR or NR according to the ratings on the retrospective assessment of response to lithium scale (Alda scale). Participants undertook 21 consecutive days of actigraphy monitoring of sleep quantity (SQ), sleep variability (SV) and circadian rhythmicity (CR).

RESULTS

Twenty-five individuals were categorized as GR (36%). After correcting statistical analysis to minimize false discoveries, four variables (intra-daily variability; median activity level; amplitude; and relative amplitude of activity) significantly differentiated GR from NR. The odds of being classified as a GR case were greatest for individuals showing more regular/stable CR (1.41; 95% confidence interval (CI) 1.08, 2.05; p < 0.04). Also, there was a trend for lower SV to be associated with GR (odds ratio: 0.56; 95% CI 0.31, 1.01; p < 0.06).

CONCLUSIONS

To our knowledge, this is the largest actigraphy study of rest-activity rhythms and Li response. Circadian markers associated with fragmentation, variability, amount and/or amplitude of day and night-time activity best-identified GR. However, associations were modest and future research must determine whether these objectively measured parameters, singly or together, represent robust treatment response biomarkers. Actigraphy may offer an adjunct to multi-platform approaches aimed at developing personalized treatments or stratification of individuals with BD-I into treatment-relevant subgroups.

A Pattern to Link Adenosine Signaling, Circadian System, and Potential Final Common Pathway in the Pathogenesis of Major Depressive Disorder

Several studies have reported separate roles of adenosine receptors and circadian clockwork in major depressive disorder. While less evidence exists for regulation of the circadian clock by adenosine signaling, a small number of studies have linked the adenosinergic system, the molecular circadian clock, and mood regulation. In this article, we review relevant advances and propose that adenosine receptor signaling, including canonical and other alternative downstream cellular pathways, regulates circadian gene expression, which in turn may underlie the pathogenesis of mood disorders. Moreover, we summarize the convergent point of these signaling pathways and put forward a pattern by which Homer1a expression, regulated by both cAMP-response element binding protein (CREB) and circadian clock genes, may be the final common pathogenetic mechanism in depression.

Chronotype, circadian rhythm, and psychiatric disorders: Recent evidence and potential mechanisms

The circadian rhythm is crucial for physiological and behavioral functions. Chronotype, which represents individual preferences for activity and performance, is associated with human health issues, particularly psychiatric disorders. This narrative review, which focuses on the relationship between chronotype and mental disorders, provides an insight into the potential mechanism. Recent evidence indicates that (1) the evening chronotype is a risk factor for depressive disorders and substance use disorders, whereas the morning chronotype is a protective factor. (2) Evening chronotype individuals with bipolar disorder tend to have more severe symptoms and comorbidities. (3) The evening chronotype is only related to anxiety symptoms. (4) The relationship between chronotype and schizophrenia remains unclear, despite increasing evidence on their link. (5) The evening chronotype is significantly associated with eating disorders, with the majority of studies have focused on binge eating disorders. Furthermore, the underlying mechanisms or influence factors are described in detail, including clock genes, brain characteristics, neuroendocrinology, the light/dark cycle, social factors, psychological factors, and sleep disorders. These findings provide the latest evidence on chronotypes and psychiatric disorders and serve as a valuable reference for researchers.

Phenotypes, mechanisms and therapeutics: insights from bipolar disorder GWAS findings

Genome-wide association studies (GWAS) have reported substantial genomic loci significantly associated with clinical risk of bipolar disorder (BD), and studies combining techniques of genetics, neuroscience, neuroimaging, and pharmacology are believed to help tackle clinical problems (e.g., identifying novel therapeutic targets). However, translating findings of psychiatric genetics into biological mechanisms underlying BD pathogenesis remains less successful. Biological impacts of majority of BD GWAS risk loci are obscure, and the involvement of many GWAS risk genes in this illness is yet to be investigated. It is thus necessary to review the progress of applying BD GWAS risk genes in the research and intervention of the disorder. A comprehensive literature search found that a number of such risk genes had been investigated in cellular or animal models, even before they were highlighted in BD GWAS. Intriguingly, manipulation of many BD risk genes (e.g., ANK3, CACNA1C, CACNA1B, HOMER1, KCNB1, MCHR1, NCAN, SHANK2 etc.) resulted in altered murine behaviors largely restoring BD clinical manifestations, including mania-like symptoms such as hyperactivity, anxiolytic-like behavior, as well as antidepressant-like behavior, and these abnormalities could be attenuated by mood stabilizers. In addition to recapitulating phenotypic characteristics of BD, some GWAS risk genes further provided clues for the neurobiology of this illness, such as aberrant activation and functional connectivity of brain areas in the limbic system, and modulated dendritic spine morphogenesis as well as synaptic plasticity and transmission. Therefore, BD GWAS risk genes are undoubtedly pivotal resources for modeling this illness, and might be translational therapeutic targets in the future clinical management of BD. We discuss both promising prospects and cautions in utilizing the bulk of useful resources generated by GWAS studies. Systematic integrations of findings from genetic and neuroscience studies are called for to promote our understanding and intervention of BD.

It's About Time: The Circadian Network as Time-Keeper for Cognitive Functioning, Locomotor Activity and Mental Health

A variety of organisms including mammals have evolved a 24h, self-sustained timekeeping machinery known as the circadian clock (biological clock), which enables to anticipate, respond, and adapt to environmental influences such as the daily light and dark cycles. Proper functioning of the clock plays a pivotal role in the temporal regulation of a wide range of cellular, physiological, and behavioural processes. The disruption of circadian rhythms was found to be associated with the onset and progression of several pathologies including sleep and mental disorders, cancer, and neurodegeneration. Thus, the role of the circadian clock in health and disease, and its clinical applications, have gained increasing attention, but the exact mechanisms underlying temporal regulation require further work and the integration of evidence from different research fields. In this review, we address the current knowledge regarding the functioning of molecular circuits as generators of circadian rhythms and the essential role of circadian synchrony in a healthy organism. In particular, we discuss the role of circadian regulation in the context of behaviour and cognitive functioning, delineating how the loss of this tight interplay is linked to pathological development with a focus on mental disorders and neurodegeneration. We further describe emerging new aspects on the link between the circadian clock and physical exercise-induced cognitive functioning, and its current usage as circadian activator with a positive impact in delaying the progression of certain pathologies including neurodegeneration and brain-related disorders. Finally, we discuss recent epidemiological evidence pointing to an important role of the circadian clock in mental health.

Bipolar disorders and retinal electrophysiological markers (BiMAR): Study protocol for a comparison of electroretinogram measurements between subjects with bipolar disorder and a healthy control group

BACKGROUND

Bipolar disorders (BD) is a common, chronic and disabling psychiatric condition. In addition to being characterized by significant clinical heterogeneity, notable disturbances of sleep and cognitive function are frequently observed in all phases of the disease. Currently, there is no readily available biomarker in current clinical practice to help diagnose or predict the disease course. Thus, identification of biomarkers in BD is today a major challenge. In this context, the study of electrophysiological biomarkers based on electroretinogram (ERG) measurements in BD seems highly promising. The BiMAR study aims to compare electrophysiological data measured with ERG between a group of euthymic patients with BD and a group of healthy control subjects. Secondarily, we will also describe the existing potential relationship between clinical, sleep and neuropsychological phenotypes of patients and electrophysiological data.

METHODS

The BiMAR study is a comparative and monocentric study carried out at the Expert Center for BD in Nancy, France. In total, 70 euthymic adult patients with BD and 70 healthy control subjects will be recruited. Electrophysiological recordings with ERG and electroencephalogram (EEG) will be performed with a virtual reality headset after a standardized clinical evaluation to all participants. Then, an actigraphic monitoring of 21 consecutive days will be carried out. At the end of this period a neuropsychological evaluation will be performed during a second visit. The primary outcome will be electrophysiological measurements with ERG flash and pattern. Secondary outcomes will be EEG data, sleep settings, clinical and neuropsychological assessments. For patients only, a complementary ancillary study, carried out at the University Hospital of Nancy, will be proposed to assess the retinal structure and microvascularization using Optical Coherence Tomography. Recruitment started in January 2022 and will continue until the end of July 2023.

DISCUSSION

The BiMAR study will contribute to identifying candidate ERG electrophysiological markers for helping the diagnosis of BD and identify subgroups of patients with different clinical profiles. Eventually, this would allow earlier diagnosis and personalized therapeutic interventions.

CLINICAL TRIAL REGISTRATION

The study is registered at Clinicaltrials.gov, NCT05161546, on 17 December 2021 (https://clinicaltrials.gov/ct2/show/NCT05161546).

Associations between Melatonin, Neuroinflammation, and Brain Alterations in Depression

Pro-inflammatory systemic conditions that can cause neuroinflammation and subsequent alterations in brain regions involved in emotional regulation have been suggested as an underlying mechanism for the pathophysiology of major depressive disorder (MDD). A prominent feature of MDD is disruption of circadian rhythms, of which melatonin is considered a key moderator, and alterations in the melatonin system have been implicated in MDD. Melatonin is involved in immune system regulation and has been shown to possess anti-inflammatory properties in inflammatory conditions, through both immunological and non-immunological actions. Melatonin has been suggested as a highly cytoprotective and neuroprotective substance and shown to stimulate all stages of neuroplasticity in animal models. The ability of melatonin to suppress inflammatory responses through immunological and non-immunological actions, thus influencing neuroinflammation and neurotoxicity, along with subsequent alterations in brain regions that are implicated in depression, can be demonstrated by the antidepressant-like effects of melatonin. Further studies that investigate the associations between melatonin, immune markers, and alterations in the brain structure and function in patients with depression could identify potential MDD biomarkers.

Mammalian circadian networks mediated by the suprachiasmatic nucleus

The brain has a complex structure composed of hundreds of regions, forming networks to cooperate body functions. Therefore, understanding how various brain regions communicate with each other and with peripheral organs is important to understand human physiology. The suprachiasmatic nucleus (SCN) in the brain is the circadian pacemaker. The SCN receives photic information from the environment and conveys this to other parts of the brain and body to synchronize all circadian clocks. The circadian clock is an endogenous oscillator that generates daily rhythms in metabolism and physiology in almost all cells via a conserved transcriptional-translational negative feedback loop. So, the information flow from the environment to the SCN to other tissues synchronizes locally distributed circadian clocks to maintain homeostasis. Thus, understanding the circadian networks and how they adjust to environmental changes will better understand human physiology. This review will focus on circadian networks mediated by the SCN to understand how the environment, brain, and peripheral tissues form networks for cooperation.

Molecular Link between Circadian Rhythmicity and Mood Disorders

BACKGROUND

The internal clock is driven by circadian genes [e.g., Clock, Bmal1, Per1-3, Cry1-2], hormones [e.g., melatonin, cortisol], as well as zeitgeber ['synchronisers']. Chronic disturbances in the circadian rhythm in patients diagnosed with mood disorders have been recognised for more than 50 years.

OBJECTIVES

The aim of this review is to summarise the current knowledge and literature regarding circadian rhythms in the context of mood disorders, focussing on the role of circadian genes, hormones, and neurotransmitters.

METHOD

The review presents the current knowledge and literature regarding circadian rhythms in mood disorders using the Pubmed database. Articles with a focus on circadian rhythms and mood disorders [n=123], particularly from 1973 to 2020, were included.

RESULTS

The article suggests a molecular link between disruptions in the circadian rhythm and mood disorders. Circadian disturbances, caused by the dysregulation of circadian genes, hormones, and neurotransmitters, often result in a clinical picture resembling depression.

CONCLUSION

Circadian rhythms are intrinsically linked to affective disorders, such as unipolar depression and bipolar disorder.

The moderating role of personality traits in the relationship between chronotype and depressive symptoms

Due to the undeniably morning orientation of the social clock, the evening chronotype can be associated with negative consequences, both at the affective and cognitive levels. Evening-oriented individuals are more susceptible to affective disorders, show poorer educational achievements and consume stimulants more often than morning-oriented individuals. However, little is known about potential factors that may attenuate or amplify these negative emotional consequences of the evening preference. Thus, our aim was to examine whether personality traits interplay with chronotype in predicting depressive symptoms. We assessed the Big Five and the Big Two personality traits, morningness-eveningness and depressive symptoms in an online sample of 913 Polish individuals (468 females, 445 males), aged 18-35 (M = 26.34, SD = 5.15). Eveningness, higher neuroticism, lower conscientiousness and lower alpha-stability were associated with higher depressive symptoms. The magnitude of the association between eveningness and depressive symptoms decreased with higher conscientiousness and alpha-stability, as well as with lower neuroticism. In conclusion, high neuroticism, low conscientiousness and low alpha-stability increase the risk of depressive symptoms, particularly among evening chronotypes. The patients' chronotypes and personality traits should be taken into account in both the prevention and diagnostics of depression.

Depressed mood and repetitive negative thinking in Delayed Sleep-Wake Phase Disorder: Treatment effects and a comparison with good sleepers

Circadian dysregulation and depressed mood commonly co-occur in young people, yet mechanisms linking Delayed Sleep-Wake Phase disorder (DSWPD) with depression are poorly understood. The present study aimed to examine the role of repetitive negative thinking (RNT), by comparing sleep, RNT and depressive symptomology between 40 'good' sleeping young people and 63 with DSWPD, with (n = 30) and without (n = 33) self-reported doctor-diagnosed depression. Secondary analysis from a randomised controlled trial was also undertaken to observe changes in depressive symptoms and RNT as a result of treatment for DSWPD. The 60 young people with DSWPD (mean [SD] age of 15.9 [2.2] years, 63% female) received either short (green) or long (red) wavelength bright light therapy (BLT) over 3 weeks. Cross-sectional baseline comparisons revealed an escalating pattern of worse sleep, more RNT and higher depressed mood scores in the DSWPD young people compared to good sleepers. Across all participants, RNT accounted for the associations between sleep-onset difficulties and depressed mood at baseline. Symptoms of depression, RNT and sleep onset difficulties in DSWPD individuals significantly improved after treatment (d = 0.47-0.65) and at the 1- (d = 0.43-1.00) and 3-month follow-up (d = 0.39-1.38), yet there were no differences between short- and long-wavelength BLT. Results provide preliminary evidence that RNT may link delayed sleep phase with depression. BLT conferred sleep benefits, but also improvements in depressed mood and RNT, and thus represents a potentially cost-effective strategy for young people experiencing delayed sleep phase and low mood.

Clinical correlates of seasonality in bipolar disorder: A specifier that needs specification?

OBJECTIVE

Seasonal pattern (SP) is a bipolar disorder (BD) specifier that indicates a tendency towards affective relapses during specific moments of the year. SP affects 15%-25% of BD patients. In the past, SP was applied only to depressive relapses while, in DSM-5, SP may be applied to both depressive and (hypo)manic episodes. We examined the association between different clinical correlates of BD and SP according to its current definition in a cohort of patients with BD type I (BDI) and II (BDII).

METHODS

Patients were recruited from a specialized unit and assessed according to the season of relapse and type of episode per season. SP and non-SP patients were compared looking into sociodemographic and clinical correlates. Significant variables at univariate comparisons were included in multivariate logistic regression with SP as the dependent variable.

RESULTS

708 patients were enrolled (503 BDI, 205 BDII), and 117 (16.5%) fulfilled DSM-5 criteria for SP. The mean age was 45.3 years (SD = 14.18), and 389 were female (54.9%). The logistic regression model included a significant contribution of BDII (OR = 2.23, CI 1.4-3.55), family history of mood disorder (OR = 1.97, CI 1.29-3.01), undetermined predominant polarity (OR = 0.44, CI 0.28-0.70), and aggressive behavior (OR = 0.42, CI 0.23-0.75).

CONCLUSION

Our results outline a novel positive association of SP with undetermined predominant polarity, BDII, family history of mood disorder, and with fewer aggressiveness-related symptoms. Seasonality is associated with a biphasic pattern with similar dominance of (hypo)mania and depression and is more frequent in BDII as compared to BDI. Seasonal episodes may be easier to predict, but difficult to prevent.

Chronobiology and Chronotherapy in Depression: Current Knowledge and Chronotherapeutic Promises

Background:

Depression is a heavily prevalent mental disorder. Symptoms of depression extend beyond mood, cognition, and behavior to include a spectrum of somatic manifestations in all organic systems. Changes in sleep and neuroendocrine rhythms are especially prominent, and disruptions of circadian rhythms have been closely related to the neurobiology of depression. With the advent of increased research in chronobiology, various pathophysiologic mechanisms have been proposed, including anomalies of sleep architecture, the effects of clock gene polymorphisms in monoamine metabolism, and the deleterious impact of social zeitgebers. The identification of these chronodisruptions has propelled the emergence of several chronotherapeutic strategies, both pharmacological and non-pharmacological, with varying degrees of clinical evidence.

Methods:

The fundamental objective of this review is to integrate current knowledge about the role of chronobiology and depression and to summarize the interventions developed to resynchronize biorhythms both within an individual and with geophysical time.

Results:

We have found that among the non-pharmacological alternatives, triple chronotherapywhich encompasses bright light therapy, sleep deprivation therapy, and consecutive sleep phase advance therapy-has garnered the most considerable scientific interest. On the other hand, agomelatine appears to be the most promising pharmacological option, given its unique melatonergic pharmacodynamics.

Conclusions:

Research in chronotherapy as a treatment for depression is currently booming. Novel interventions could play a significant role in adopting new options for the treatment of depression, with Tripe Cronotherapy standing out as the most promising treatment.

Disrupted circadian rhythms and mental health

During the evolution of life, the temporal rhythm of our rotating planet was internalized in the form of circadian rhythms. Circadian rhythms are ~24h internal manifestations that drive daily patterns of physiology and behavior. These rhythms are entrained (synchronized) to the external environment, primarily by the light-dark cycle, and precisely controlled via molecular clocks located within the suprachiasmatic nucleus of the hypothalamus. Misalignment and/or disruption of circadian rhythms can have detrimental consequences for human health. Indeed, studies suggest strong associations between mental health and circadian rhythms. However, direct interactions between mood regulation and the circadian system are just beginning to be uncovered and appreciated. This chapter examines the relationship between disruption of circadian rhythms and mental health. The primary focus will be outlining the association between circadian disruption, in the form of night shift work, exposure to light at night, jet lag, and social jet lag, and psychiatric illness (i.e., anxiety, major depressive disorder, bipolar disorder, and schizophrenia). Additionally, we review animal models of disrupted circadian rhythms, which provide further evidence in support of a strong association between circadian disruption and affective responses. Finally, we discuss future directions for the field and suggest areas of study that require further investigation.

The Association Between Shift Work And Affective Disorders: A Systematic Review

Atypical working time patterns are known to be associated with adverse physical health consequences. The impact of chronic exposure to shift work on psychological wellbeing and mental health is also reported, but not fully appreciated. We conducted a systematic review of the literature on the association between shift work and affective disorders using the electronic databases Medline, PsycINFO, Embase, Web of Science and Google Scholar. Data extracted included detailed characteristics of shift work, the affective disorders under study, and the population targeted. Some 25 extracted articles satisfied all inclusion and exclusion criteria. Findings of these articles reveal shift work is associated with increases in depressive symptoms (12 studies), anxiety (2 studies), and depression and anxiety (7 studies). Only three studies found no association between shift work and depression. The findings of this review suggest that shift work increases the symptoms of depression and anxiety.

Chronobiology Revisited in Psychiatric Disorders: From a Translational Perspective

OBJECTIVE

Several lines of evidence support a relationship between circadian rhythms disruption in the onset, course, and maintenance of mental disorders. Despite the study of circadian phenotypes promising a decent understanding of the pathophysiologic or etiologic mechanisms of psychiatric entities, several questions still need to be addressed. In this review, we aimed to synthesize the literature investigating chronobiologic theories and their associations with psychiatric entities.

METHODS

The Medline, Embase, PsycInfo, and Scopus databases were comprehensively and systematically searched and articles published between January 1990 and October 2019 were reviewed. Different combinations of the relevant keywords were polled. We first introduced molecular elements and mechanisms of the circadian system to promote a better understanding of the chronobiologic implications of mental disorders. Then, we comprehensively and systematically reviewed circadian system studies in mood disorders, schizophrenia, and anxiety disorders.

RESULTS

Although subject characteristics and study designs vary across studies, current research has demonstrated that circadian pathologies, including genetic and neurohumoral alterations, represent the neural substrates of the pathophysiology of many psychiatric disorders. Impaired HPA-axis function-related glucocorticoid rhythm and disrupted melatonin homeostasis have been prominently demonstrated in schizophrenia and other psychotic disorders, while alterations of molecular expressions of circadian rhythm genes including CLOCK, PER, and CRY have been reported to be involved in the pathogenesis of mood disorders.

CONCLUSION

Further translational work is needed to identify the causal relationship between circadian physiology abnormalities and mental disorders and related psychopathology, and to develop sound pharmacologic interventions.

Le trouble bipolaire : une maladie du sommeil et des rythmes circadiens ?

Le trouble bipolaire (TB) est une maladie psychiatrique multifactorielle à hérédité complexe faisant intervenir des facteurs de risque génétiques et environnementaux [1]. Parmi ces facteurs de risque, des anomalies des rythmes circadiens et du sommeil ont été mises en évidence dans les TB et témoignent de l’implication d’anomalies de l’horloge circadienne dans la physiopathologie du TB [2]. En effet, Il existe une littérature importante sur les anomalies circadiennes observées dans le TB (sommeil, rythmes veille/sommeil, chronotypes, perturbations circadiennes biologiques et comportementales, etc.). Ces anomalies sont présentes, non seulement en phase aiguë, mais aussi au cours des phases de stabilité de l’humeur (ou euthymiques) constituant ainsi des anomalies « trait » du TB [2]. Ainsi, l’exploration du sommeil et des rythmes circadiens chez des patients euthymiques avec TB par des mesures objectives (actigraphie) et subjectives (questionnaires) démontre que les patients présentent un sommeil plus long, de moins bonne qualité, avec retard important à l’endormissement, plus de réveils nocturnes et un retentissement diurne plus important que des témoins sains [3]. Par ailleurs, certains variants de gènes circadiens associés au TB peuvent s’associer chez les patients à des modifications particulières de ces rythmes circadiens. Ainsi, dans une étude pilote, il a été observé qu’un variant commun associé au TB du gène ASMT (codant pour l’une des deux enzymes de synthèse de la mélatonine) était associé à une modification des rythmes circadiens marquée par une période de sommeil allongée, une plus grande activité nocturne et une plus grande stabilité des rythmes [4]. Ces résultats intéressants soulignent l’intérêt de l’exploration des anomalies circadiennes du TB dans un but étiopathogénique et diagnostique, mais aussi possiblement thérapeutique.

Maternal Separation Early in Life Alters the Expression of Genes Npas4 and Nr1d1 in Adult Female Mice: Correlation with Social Behavior

Early-life stress affects neuronal plasticity of the brain regions participating in the implementation of social behavior. Our previous studies have shown that brief and prolonged separation of pups from their mothers leads to enhanced social behavior in adult female mice. The goal of the present study was to characterize the expression of genes (which are engaged in synaptic plasticity) Egr1, Npas4, Arc, and Homer1 in the prefrontal cortex and dorsal hippocampus of adult female mice with a history of early-life stress. In addition, we evaluated the expression of stress-related genes: glucocorticoid and mineralocorticoid receptors (Nr3c1 and Nr3c2) and Nr1d1, which encodes a transcription factor (also known as REVERBα) modulating sociability and anxiety-related behavior. C57Bl/6 mice were exposed to either maternal separation (MS, 3 h once a day) or handling (HD, 15 min once a day) on postnatal days 2 through 14. In adulthood, the behavior of female mice was analyzed by some behavioral tests, and on the day after the testing of social behavior, we measured the gene expression. We found increased Npas4 expression only in the prefrontal cortex and higher Nr1d1 expression in both the prefrontal cortex and dorsal hippocampus of adult female mice with a history of MS. The expression of the studied genes did not change in HD female mice. The expression of stress-related genes Nr3c1 and Nr3c2 was unaltered in both groups. We propose that the upregulation of Npas4 and Nr1d1 in females with a history of early-life stress and the corresponding enhancement of social behavior may be regarded as an adaptation mechanism reversing possible aberrations caused by early-life stress.

Poor sleep quality associates with self-reported psychiatric and cardiometabolic symptoms independently of sleep timing patterns in a large sample of rural and urban workers

Poor sleep associates with mental and cardiometabolic pathological outcomes. The participation of sleep timing features in the pathways by which this relationship occurs is not clear. This study aims to evaluate the interrelationship between sleep quality and self-reported psychiatric/cardiometabolic symptoms, considering mediation and moderation effects of sleep timing patterns, and urban versus rural work environment, respectively; and to verify the association between sleep quality and polymorphisms of AANAT, RORA and TIMELESS genes. An epidemiological survey was performed in a rural area in southern Brazil. Eight-hundred and twenty-nine subjects were evaluated for sleep quality using the Pittsburgh Sleep Quality Index, and sleep timing patterns using the Munich Chronotype Questionnaire. Work characteristics and psychiatric/cardiometabolic symptoms were assessed using a structured self-report questionnaire. Three polymorphisms of AANAT, RORA and TIMELESS (rs3760138, rs782931 and rs774045, respectively) were genotyped in blood samples. We found statistically significant associations of poor sleep quality with self-reported psychiatric symptoms (B = 0.382; 95% CI 0.289-0.476; adjusted p-value <.001), and with self-reported cardiometabolic symptoms (B = 0.079; 95% CI 0.013-0.151; adjusted p-value = .048). The genetic analysis showed that RORA GA/AA genotype was associated to poor sleep quality (B = 0.146, 95% CI 0.054-0.239; adjusted p-value = .004). No moderated mediation effects were observed in the conditional analysis. TIMELESS polymorphism was not included in the analysis due to the low frequency of risk genotypes. These results yield new insights regarding the interrelationship between sleep characteristics and psychiatric/cardiometabolic self-reported symptoms, taking into account genes related to the biological clocks and melatonin pathways.

Pineal Gland Volume in Major Depressive and Bipolar Disorders

Abnormal melatonin secretion has been demonstrated in patients with affective disorders such as major depressive disorder (MDD) and bipolar disorder (BD). However, magnetic resonance imaging (MRI) studies that previously investigated the volume of the pineal gland, which regulates circadian rhythms by secreting melatonin, in these patients reported inconsistent findings. The present study employed MRI to examine pineal gland volumes and pineal cyst prevalence in 56 MDD patients (29 currently depressed and 27 remitted patients), 26 BD patients, and matched controls (33 for MDD and 24 for BD). Pineal volumes and cyst prevalence in the current MDD, remitted MDD, and BD groups did not significantly differ from those of the healthy controls. However, pineal gland volumes were significantly smaller in the current MDD subgroup of non-melancholic depression than in the melancholic MDD subgroup. Interestingly, pineal volumes correlated negatively with the severity of loss of interest in the current MDD group. Medication and the number of affective episodes were not associated with pineal volumes in the MDD or BD group. While these results do not suggest that pineal volumes reflect abnormal melatonin secretion in affective disorders, they do point to the possibility that pineal abnormalities are associated with clinical subtypes of MDD and its symptomatology.

Sex differences in stress-related disorders: Major depressive disorder, bipolar disorder, and posttraumatic stress disorder

Stress-related disorders, such as mood disorders and posttraumatic stress disorder (PTSD), are more common in women than in men. This sex difference is at least partly due to the organizing effect of sex steroids during intrauterine development, while activating or inhibiting effects of circulating sex hormones in the postnatal period and adulthood also play a role. Such effects result in structural and functional changes in neuronal networks, neurotransmitters, and neuropeptides, which make the arousal- and stress-related brain systems more vulnerable to environmental stressful events in women. Certain brainstem nuclei, the amygdala, habenula, prefrontal cortex, and hypothalamus are important hubs in the stress-related neuronal network. Various hypothalamic nuclei play a central role in this sexually dimorphic network. This concerns not only the hypothalamus-pituitary-adrenal axis (HPA-axis), which integrates the neuro-endocrine-immune responses to stress, but also other hypothalamic nuclei and systems that play a key role in the symptoms of mood disorders, such as disordered day-night rhythm, lack of reward feelings, disturbed eating and sex, and disturbed cognitive functions. The present chapter focuses on the structural and functional sex differences that are present in the stress-related brain systems in mood disorders and PTSD, placing the HPA-axis in the center. The individual differences in the vulnerability of the discussed systems, caused by genetic and epigenetic developmental factors warrant further research to develop tailor-made therapeutic strategies.

Mood-related central and peripheral clocks

Mood disorders, including major depression, bipolar disorder, and seasonal affective disorder, are debilitating disorders that affect a significant portion of the global population. Individuals suffering from mood disorders often show significant disturbances in circadian rhythms and sleep. Moreover, environmental disruptions to circadian rhythms can precipitate or exacerbate mood symptoms in vulnerable individuals. Circadian clocks exist throughout the central nervous system and periphery, where they regulate a wide variety of physiological processes implicated in mood regulation. These processes include monoaminergic and glutamatergic transmission, hypothalamic-pituitary-adrenal axis function, metabolism, and immune function. While there seems to be a clear link between circadian rhythm disruption and mood regulation, the mechanisms that underlie this association remain unclear. This review will touch on the interactions between the circadian system and each of these processes and discuss their potential role in the development of mood disorders. While clinical studies are presented, much of the review will focus on studies in animal models, which are attempting to elucidate the molecular and cellular mechanisms in which circadian genes regulate mood.

Association Between Period 3 Gene Polymorphisms and Adverse Effects of Antidepressants for Major Depressive Disorder

Aims: Circadian rhythm genes including Period 3 (Per3) are associated with major depressive disorder (MDD) and have an effect on the patient's response to selective serotonin reuptake inhibitor (SSRI) antidepressants. The aim of this study was to identify possible associations between three single nucleotide polymorphisms (SNPs) of Per3 (rs10746473, rs228697, and rs228729), the MDD symptoms, and adverse effects of SSRIs. Materials and Methods: A total of 600 MDD patients who had been treated with SSRIs were enrolled. The 17-item Hamilton Rating Scale for Depression (HAMD₁₇) was used to evaluate symptoms and treatment efficacy. In addition, the Treatment Emergent Symptom Scale/UKU Consumer Satisfaction Rating Scale (TESS/UKU) was used to assess adverse effects. The Per3 locus was genotyped by PCR and DNA sequencing. Results: The Per3 rs228697 CC genotype was associated with a higher sleep factor score when compared with the CG genotype (F = 4.027, p = 0.046). In addition, the rs228729 TC genotype was associated with a greater risk of suffering from excitement/agitation (p = 0.002, OR [odds ratio] = 4.049), akathisia (p = 0.014, OR = 4.905) and weight loss (p = 0.041, OR = 2.287) when compared with the CC genotype. Finally, the rs10746473 AA genotype patients were more likely to suffer from dizziness (p = 0.042, OR = 0.362) and the GA genotype patients from tachycardia (p = 0.015, OR = 0.340) when compared with those with GG genotype. Conclusion: The Per3 gene variants in patients can predict adverse effects of SSRIs and drug compliance.

Correlation between GRIK2 rs6922753, rs2227283 polymorphism and aggressive behaviors with Bipolar Mania in the Chinese Han population

OBJECTIVES

Animal studies have shown that glutamate receptor ionotropic kainate 2 (GRIK2) gene knockout mice are more impulsive and aggressive. This study aims to verify whether the rs6922753 and rs2227283 polymorphisms of the GRIK2 gene are associated with both aggressive behavior and bipolar mania in the Chinese Han population.

METHODS

Polymerase chain reaction (PCR) was applied in the genotype rs6922753 and rs2227283 polymorphisms of the GRIK2 gene in 201 bipolar manic patients with aggressive behaviors, 198 bipolar manic patients without aggressive behaviors, and 132 healthy controls. The Modified Overt Aggression Scale (MOAS) was used to evaluate aggressive behavior in patients with bipolar mania.

RESULTS

No correlation was found between aggressive behavior and the rs6922753 polymorphism in the three groups. The A/A genotype and A allele of the rs2227283 polymorphism were found significantly more frequently in patients with aggressive behavior than in healthy controls (p = .004 and p = .013, respectively) and in patients with nonaggressive behavior (p = .002 and p = .018, respectively). The A/A genotype and A allele were associated with an increased risk of aggressive behavior.

CONCLUSION

This study suggests that the rs2227283 polymorphism of the GRIK2 gene is related to aggressive behaviors in bipolar manic patients and that the A/A genotype and A allele may increase the risk of the aggressive behavior in bipolar manic patients.

Clinical phenotype and genetic risk factors for bipolar disorder with binge eating: an update

Introduction: Clinical and genetic study of psychiatric conditions has underscored the co-occurrence of complex phenotypes and the need to refine them. Bipolar Disorder (BD) and Binge Eating (BE) behavior are common psychiatric conditions that have high heritability and high co-occurrence, such that at least one quarter of BD patients have BE (BD + BE). Genetic studies of BD alone and of BE alone suggest complex polygenic risk models, with many genetic risk loci yet to be identified. Areas covered: We review studies of the epidemiology of BD+BE, its clinical features (cognitive traits, psychiatric comorbidity, and role of obesity), genomic studies (of BD, eating disorders (ED) defined by BE, and BD + BE), and therapeutic implications of BD + BE. Expert opinion: Subphenotyping of complex psychiatric disorders reduces heterogeneity and increases statistical power and effect size; thus, it enhances our capacity to find missing genetic (and other) risk factors. BD + BE has a severe clinical picture and genetic studies suggests a distinct genetic architecture. Differential therapeutic interventions may be needed for patients with BD + BE compared with BD patients without BE. Recognizing the BD + BE subphenotype is an example of moving towards more precise clinical and genetic entities.

Longitudinal Associations Between Sleep Patterns and Psychiatric Symptom Severity in High-Risk and Community Comparison Youth

OBJECTIVE

Sleep disturbance may be involved in symptom progression across multiple domains of psychopathology and could represent a target for treatment development in youth. Our objective was to identify sleep patterns that longitudinally change in conjunction with psychiatric symptom severity in at-risk youth.

METHOD

The study included 484 Pittsburgh Bipolar Offspring Study (BIOS) youth with at least 2 sleep assessments occurring between 10 and 18 years of age: 267 offspring of parents with bipolar I or II disorder and 217 community comparison offspring. Assessments occurred approximately every 2 years (mean number of assessments, 2.8 ± 0.8; mean follow-up duration, 3.8 ± 1.6 years). Offspring had a range of psychiatric diagnoses at baseline. Multivariate lasso regression was implemented to select offspring-reported sleep patterns associated with changes in five psychiatric symptom measures from baseline through last follow-up (mania, depression, mood lability, anxiety, inattention/externalizing). Analyses accounted for parent psychiatric diagnoses and offspring demographics, psychiatric diagnoses, and medications.

RESULTS

Follow-up duration, baseline socioeconomic status, parental history of bipolar disorder, offspring attention-deficit/hyperactivity disorder, and disruptive behavior disorder, and five sleep patterns were identified as predictors of change in all five psychiatric symptom measures. Decreasing sleep duration, later sleep timing preference, longer sleep latency, increasing nighttime awakenings, and greater sleepiness over follow-up were associated with increasing severity the five psychiatric symptom outcomes over follow-up. These 10 predictors explained 16% of the variance in longitudinal psychiatric symptom change, 33% of which was accounted for by sleep predictors.

CONCLUSION

A constellation of sleep features were associated with psychiatric symptom changes in youth, and may represent viable targets for future interventions.

Guarana improves behavior and inflammatory alterations triggered by methylmercury exposure: an in vivo fruit fly and in vitro neural cells study

Methylmercury (MeHg) is a well-known environmental pollutant associated with neurological and developmental deficits in animals and humans. However, epidemiological data showed that people living in the Amazon region although exposed to MeHg do not present these effects probably due to the protective effect of certain foods. We hypothesized here if guarana, a highly caffeinated fruit and consumed on a daily basis by Amazon people, could have some protective effect against MeHg toxicity using two complementary approaches. To assess locomotor impairment and sleep disruption, we used fruit fly (Drosophila melanogaster) model, and to evaluate neuroinflammation, we used human SH-SY5Y neural cells by measuring inflammatory cytokines levels. Results showed that guarana had a protective effect on the locomotor activity of male fruit flies reducing the excessive sleepiness caused by MeHg and increasing daily activity. Also, guarana increased the viability of flies and attenuated neural cells mortality. In addition, guarana reduced all pro-inflammatory cytokines levels increased by MeHg, along with caspase-1, caspase -3, caspase-8, and 8-dOHG levels, whereas increased the anti-inflammatory (IL-10) cytokine levels, which was decreased by MeHg. Our study provides new insights on the protective effects of guarana on the viability, locomotor activity, sleep, and activity patterns in vivo and the in vitro neuronal anti-inflammatory effect against MeHg toxicity.

Sleep and circadian rhythms as possible trait markers of suicide attempt in bipolar disorders: An actigraphy study

BACKGROUND

The poor prognostic of Bipolar disorders (BD) is closely linked to deaths by suicide. Sleep and circadian abnormalities are observed during all phases of BD and are also associated with suicide attempt (SA). In this context, this study sought to identify specific sleep and circadian rhythms markers associated with suicidal attempt in euthymic patients with BD.

METHODS

The sample (N = 236) comprised 3 groups: 147 patients with BD including 57 with a history of SA and 90 without (NoSA), and 89 healthy controls (HC). All participants were recorded during 21 days with actigraphy.

RESULTS

SA was associated with women gender (p = 0.03), familial history of SA (p = 0.03), mixed episodes (p = 0.001), and benzodiazepines (p = 0.019). SA, compared to noSA, had a morning phase preference (p = 0.04), and were more vigorous on the circadian type inventory (p = 0.04), and tended to suffer more from insomnia (45% versus 25% respectively, p = 0.10). SA was also associated with an earlier onset of daily activity assessed with actigraphy (M10 onset: p = 0.01). Backward stepwise linear regression indicated that a combination of four variables (Gender, vigour, insomnia, M10onset) significantly differentiated patients with SA from NoSA (p = 0.03).

LIMITATIONS

Cross-sectional design, and no examination of suicidal behaviors' subgroups such as first attempters or repeaters, or violent suicide attempt.

CONCLUSIONS

Woman gender, vigorous circadian type, insomnia and an earlier daily activity appeared independently associated with SA in BD. If these biomarkers are confirmed in prospective studies, they should be screened and used to prevent suicide, with the development of personal and targeted chronobiological treatments.

The human hypothalamus in mood disorders: The HPA axis in the center

There are no specific structural neuropathological hallmarks found in the brain of mood disorders. Instead, there are molecular, functional and structural alterations reported in many brain areas. The neurodevelopmental underpinning indicated the presence of various genetic and developmental risk factors. The effect of genetic polymorphisms and developmental sequalae, some of which may start in the womb, result in functional changes in a network mediated by neurotransmitters and neuropeptides, which make the emotion- and stress-related brain systems more vulnerable to stressful events. This network of stress-related neurocircuits consists of, for instance, brainstem nuclei, the amygdala, habenula, prefrontal cortex and hypothalamus. Various nuclei of the hypothalamus form indeed one of the crucial hubs in this network. This structure concerns not only the hypothalamo-pituitary-adrenal (HPA) axis that integrate the neuro-endocrine-immune responses to stress, but also other hypothalamic nuclei and systems that play a key role in the symptoms of depression, such as disordered day-night rhythm, lack of reward feelings, disturbed eating, sex, and disturbed cognitive functions. The present review will focus on the changes in the human hypothalamus in depression, with the HPA axis in the center. We will discuss the inordinate network of neurotransmitters and neuropeptides involved, with the hope to find the most vulnerable neurobiological systems and the possible development of tailor-made treatments for mood disorders in the future.

Prospects for circadian treatment of mood disorders

Disruption of circadian clocks is strongly associated with mood disorders. Chronotherapies targeting circadian rhythms have been shown to be very effective treatments of mood disorders, but still are not widely used in clinical practice. The mechanisms by which circadian disruption leads to mood disorders are poorly characterized and, therefore, may not convince clinicians to apply chronotherapies. Hence, in this review, we describe specific potential mechanisms, in order to make this connection more credible to clinicians. We believe that four major features of disrupted clocks may contribute to the development of mood disorders: (1) loss of synchronization to environmental 24-h rhythms, (2) internal desynchronization among body clocks, (3) low rhythm amplitude, and (4) changes in sleep architecture. Discussing these attributes and giving plausible examples, we will discuss prospects for relatively simple chronotherapies addressing these features that are easy to implement in clinical practice. Key messages In this review, we describe specific potential mechanisms by which disrupted clocks may contribute to the development of mood disorders: (1) loss of synchronization to environmental 24-h rhythms, (2) internal desynchronization among body clocks, (3) low rhythm amplitude, and (4) changes in sleep architecture. We provide prospects for relatively simple chronotherapies addressing these features that are easy to implement in clinical practice.

Circadian Disruptions in the Myshkin Mouse Model of Mania Are Independent of Deficits in Suprachiasmatic Molecular Clock Function

BACKGROUND

Alterations in environmental light and intrinsic circadian function have strong associations with mood disorders. The neural origins underpinning these changes remain unclear, although genetic deficits in the molecular clock regularly render mice with altered mood-associated phenotypes.

METHODS

A detailed circadian and light-associated behavioral characterization of the Na+/K+-ATPase α3 Myshkin (Myk/+) mouse model of mania was performed. Na+/K+-ATPase α3 does not reside within the core circadian molecular clockwork, but Myk/+ mice exhibit concomitant disruption in circadian rhythms and mood. The neural basis of this phenotype was investigated through molecular and electrophysiological dissection of the master circadian pacemaker, the suprachiasmatic nuclei (SCN). Light input and glutamatergic signaling to the SCN were concomitantly assessed through behavioral assays and calcium imaging.

RESULTS

In vivo assays revealed several circadian abnormalities including lengthened period and instability of behavioral rhythms, and elevated metabolic rate. Grossly aberrant responses to light included accentuated resetting, accelerated re-entrainment, and an absence of locomotor suppression. Bioluminescent recording of circadian clock protein (PERIOD2) output from ex vivo SCN revealed no deficits in Myk/+ molecular clock function. Optic nerve crush rescued the circadian period of Myk/+ behavior, highlighting that afferent inputs are critical upstream mediators. Electrophysiological and calcium imaging SCN recordings demonstrated changes in the response to glutamatergic stimulation as well as the electrical output indicative of altered retinal input processing.

CONCLUSIONS

The Myshkin model demonstrates profound circadian and light-responsive behavioral alterations independent of molecular clock disruption. Afferent light signaling drives behavioral changes and raises new mechanistic implications for circadian disruption in affective disorders.

Lithium response in bipolar disorders and core clock genes expression

OBJECTIVES

We examine whether the lithium response is associated with changes in the expression of core clock genes.

METHODS

The effect of a therapeutic concentration of lithium (1 mM) on the expression levels of 17 circadian genes was examined in lymphoblastoid cell lines (LCLs) derived from two well-characterized groups of bipolar disorder patients, defined as lithium non-responders (NR, n = 20) or excellent responders (ER, n = 16). Quantitative real-time PCR (qRT-PCR) was conducted at 2, 4 and 8 days (d2, d4 and d8) with and without lithium exposure.

RESULTS

At d2, in ER only, BHLHE41, RORA, PER1, ARNTL, CRY2, BHLHE40 and CSNK1D were upregulated, whereas NR1D1 was downregulated. At d4, in ER only, CRY1 was downregulated. At d8, in NR only, GSK3β was upregulated and DBP, TIMELESS and CRY1 were downregulated. Significant Group × Lithium interactions existed for NR1D1 at d2 (P = 0.02), and CRY1 at d4 (P = 0.02). Longitudinal analyses showed differential temporal evolutions between NR and ER (significant Time × Group interaction) for PER3, NR1D1, DBP, RORA, CSNK1D and TIMELESS; and a significant Time × Lithium interaction for NR1D1. Coexpression data analyses suggested distinct groups of circadian genes concurrently modulated by lithium.

CONCLUSIONS

In LCLs, lithium influences expression of circadian genes with differences in amplitude and kinetics according to the patient's lithium response status.

Genetic association study of CSNK1E gene in bipolar disorder and circadian characteristics

BACKGROUND

A circadian rhythm disturbance is one of the essential components of the phenotype of bipolar disorder. It has been reported that casein kinase 1 epsilon (CSNK1E), a member of the clock gene family, is associated with psychiatric phenotypes.

OBJECTIVES

We performed a genetic association study to determine the genetic role of CSNK1E in bipolar disorder and circadian rhythm disturbances in the Korean population.

METHODS

The present study included 215 patients with bipolar disorder and 773 controls. Circadian characteristics were measured by the Korean version of the Composite Scale of Morningness (CS). Single-nucleotide polymorphisms (SNPs) of CSNK1E, rs1534891 and rs2075984, were genotyped. Chi-square analyses were performed to evaluate associations involving alleles and genotypes. Haplotype analysis was also performed, and the permutation p value was calculated. We also tested further associations involving these SNPs and scores on the CS.

RESULTS

We found a positive association between SNP rs2075984 and bipolar disorder in both the allelic (p = .003) and genotypic (p = .006) distributions. No allelic or genotypic association between SNP rs1534891 and bipolar disorder was observed. A significant association of haplotype with bipolar disorder was found (p = .033). However, no association between the CS and the genotype of either SNP was found in the total sample.

CONCLUSION

CSNK1E SNP rs2075984 seemed to play a significant role in the development of bipolar disorder in this Korean sample. This association does not seem to relate to the phase preference measured by the CS. Further studies on CSNK1E with larger samples and more SNPs are necessary.

Genome-Wide Association Study of Circadian Rhythmicity in 71,500 UK Biobank Participants and Polygenic Association with Mood Instability

BACKGROUND

Circadian rhythms are fundamental to health and are particularly important for mental wellbeing. Disrupted rhythms of rest and activity are recognised as risk factors for major depressive disorder and bipolar disorder.

METHODS

We conducted a genome-wide association study (GWAS) of low relative amplitude (RA), an objective measure of rest-activity cycles derived from the accelerometer data of 71,500 UK Biobank participants. Polygenic risk scores (PRS) for low RA were used to investigate potential associations with psychiatric phenotypes.

OUTCOMES

Two independent genetic loci were associated with low RA, within genomic regions for Neurofascin (NFASC) and Solute Carrier Family 25 Member 17 (SLC25A17). A secondary GWAS of RA as a continuous measure identified a locus within Meis Homeobox 1 (MEIS1). There were no significant genetic correlations between low RA and any of the psychiatric phenotypes assessed. However, PRS for low RA was significantly associated with mood instability across multiple PRS thresholds (at PRS threshold 0·05: OR = 1·02, 95% CI = 1·01-1·02, p = 9·6 × 10-5), and with major depressive disorder (at PRS threshold 0·1: OR = 1·03, 95% CI = 1·01-1·05, p = 0·025) and neuroticism (at PRS threshold 0·5: Beta = 0·02, 95% CI = 0·007-0·04, p = 0·021).

INTERPRETATION

Overall, our findings contribute new knowledge on the complex genetic architecture of circadian rhythmicity and suggest a putative biological link between disrupted circadian function and mood disorder phenotypes, particularly mood instability, but also major depressive disorder and neuroticism.

FUNDING

Medical Research Council (MR/K501335/1).

The circadian gene Nr1d1 in the mouse nucleus accumbens modulates sociability and anxiety-related behaviour

Nuclear receptor subfamily 1, group D, member 1 (Nr1d1) (also known as Rev-erb alpha) has been linked to circadian rhythm regulation, mood-related behaviour and disorders associated with social deficits. Recent work from our laboratory found striking decreases in Nr1d1 in the nucleus accumbens (NAc) in the maternal condition and indirect evidence that Nr1d1 was interacting with numerous addiction and reward-related genes to modulate social reward. In this study, we applied our insights from the maternal state to nonparental adult mice to determine whether decreases in Nr1d1 expression in the NAc via adeno-associated viral (AAV) vectors and short hairpin RNA (shRNA)-mediated gene knockdown were sufficient to modulate social behaviours and mood-related behaviours. Knockdown of Nr1d1 in the NAc enhanced sociability and reduced anxiety, but did not affect depressive-like traits in female mice. In male mice, Nr1d1 knockdown had no significant behavioural effects. Microarray analysis of Nr1d1 knockdown in females identified changes in circadian rhythm and histone deacetylase genes and suggested possible drugs, including histone deacetylase inhibitors, that could mimic actions of Nr1d1 knockdown. Quantitative real-time PCR (qPCR) analysis confirmed expression upregulation of gene period circadian clock 1 (Per1) and period circadian clock 2 (Per2) with Nr1d1 knockdown. The evidence for roles for opioid-related genes opioid receptor, delta 1 (Oprd1) and preproenkephalin (Penk) was also found. Together, these results suggest that Nr1d1 in the NAc modulates sociability and anxiety-related behaviour in a sex-specific manner, and circadian, histone deacetylase and opioid-related genes may be involved in the expression of these behavioural phenotypes.

Parental and preimaginal exposure to methylmercury disrupts locomotor activity and circadian rhythm of adult Drosophila melanogaster

Methylmercury (MeHg) is a well-known toxic pollutant. However, little is known about the effects of this toxic agent in an adult as a consequence of a parental or preimaginal exposure. This study used Drosophila melanogaster to investigate whether a parental or a preimaginal (eggs-larvae-pupae stages) exposure could impact parameters as viability, locomotor activity, and sleep patterns of fruit flies. Thus, we performed two exposure protocols. One where just parents were exposed to MeHg (0-12 µM) during 24 h, then flies were transferred to lay eggs in a healthy medium (without MeHg). In the other, flies were set to lay eggs in a MeHg medium, same concentrations, and discarded after this (preimaginal exposure). Viability was evaluated from egg to adult flies. F1 progeny was collected within 24 h and transferred to a fresh healthy medium. Sleep behavior analysis was performed using Drosophila Active Monitoring System (DAMS), and the locomotor activity was evaluated by climbing assay. Results have shown that the parental exposure had a significant impact on F1 progeny reducing viability and locomotor activity performance, but no significant circadian rhythm alterations. Whereas the preimaginal exposure had a stronger effect decreasing viability and locomotor activity, it also disrupted sleep patterns. MeHg preimaginal exposure showed a longer sleep duration and lower daily activity. Results corroborate the hypothesis that low MeHg exposure could trigger subclinical symptoms related to a 'neurotoxicological development effect'. Complementary investigations could clarify the underlying mechanisms of MeHg effects in neural functions due to parental and early development exposure to this toxicant.

Psychological Impact of Shift Work

PURPOSE OF REVIEW

Technology and globalization have been central forces driving the need for shift work. This review examines recent scientific developments that inform our understanding of how psychological process contribute to and are impacted by shift work.

RECENT FINDINGS

Nascent research is beginning to expand beyond circadian misalignment to elucidate the phenomenology of shift work and the associated psychological impairments. Psychological processes and their interaction with biology are considered in the pathophysiology of shift work sleep disorder. Additionally, a review of the adverse consequences of shift work in the cognitive, emotional, and psychosocial domains are reviewed and discussed.

SUMMARY

The phenomenology of shift work encompasses multiple domains of biopsychosocial functioning. As such, interventions to reduce the adverse impact of shift work may benefit from an integrated approach.

Circadian modulation of neuroplasticity by melatonin: a target in the treatment of depression

Mood disorders are a spectrum of neuropsychiatric disorders characterized by changes in the emotional state. In particular, major depressive disorder is expected to have a worldwide prevalence of 20% in 2020, representing a huge socio-economic burden. Currently used antidepressant drugs have poor efficacy with only 30% of the patients in remission after the first line of treatment. Importantly, mood disorder patients present uncoupling of circadian rhythms. In this regard, melatonin (5-methoxy-N-acetyltryptamine), an indolamine synthesized by the pineal gland during the night, contributes to synchronization of body rhythms with the environmental light/dark cycle. In this review, we describe evidence supporting antidepressant-like actions of melatonin related to the circadian modulation of neuroplastic changes in the hippocampus. We also present evidence for the role of melatonin receptors and their signalling pathways underlying modulatory effects in neuroplasticity. Finally, we briefly discuss the detrimental consequences of circadian disruption on neuroplasticity and mood disorders, due to the modern human lifestyle. Together, data suggest that melatonin's stimulation of neurogenesis and neuronal differentiation is beneficial to patients with mood disorders. LINKED ARTICLES: This article is part of a themed section on Recent Developments in Research of Melatonin and its Potential Therapeutic Applications. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.16/issuetoc.

Glucocorticoid hormones are both a major circadian signal and major stress signal: How this shared signal contributes to a dynamic relationship between the circadian and stress systems

Glucocorticoid hormones are a powerful mammalian systemic hormonal signal that exerts regulatory effects on almost every cell and system of the body. Glucocorticoids act in a circadian and stress-directed manner to aid in adaptation to an ever-changing environment. Circadian glucocorticoid secretion provides for a daily waxing and waning influence on target cell function. In addition, the daily circadian peak of glucocorticoid secretion serves as a timing signal that helps entrain intrinsic molecular clock phase in tissue cells distributed throughout the body. Stress-induced glucocorticoid secretion also modulates the state of these same cells in response to both physiological and psychological stressors. We review the strong functional interrelationships between glucocorticoids and the circadian system, and discuss how these interactions optimize the appropriate cellular and systems response to stress throughout the day. We also discuss clinical implications of this dual aspect of glucocorticoid signaling, especially for conditions of circadian and HPA axis dysregulation.

Delayed sleep phase syndrome and bipolar disorder: Pathogenesis and available common biomarkers

Circadian rhythm disturbances are common in bipolar affective disorder (BD). Delayed sleep-wake phase syndrome (DSWPD) is the most prevalent circadian rhythm sleep-wake disorder (CRSWDs) and is frequently observed in BD. It is unclear whether DSWPD in BD is an independent process or is a consequence of BD. In this hypothetical review, we discuss the overlap between BD and DSWPD and potential common biomarkers for DSWPD and BD. The review will include a discussion of the genetics of DSWPD and BD. Biomarkers elucidating the pathophysiological processes occurring in these two disorders may offer insight into the etiology and prognosis of both conditions.