Polymorphism of circadian clock genes and temperamental dimensions of the TEMPS-A in bipolar disorder

Moderating effect of shift work on sleep and depression in individuals at high risk of bipolar disorder

BACKGROUND

Social Zeitgeber Theory posits that disruptions in social rhythms can increase susceptibility to bipolar disorder (BD). Shift work (SW) is one of the external factors that cause instability in social rhythms and the sleep-wake cycle. This study evaluated the moderating influences of SW on the risks of BD and sleep-related parameters and depressive symptoms. Furthermore, we evaluated the specific work schedules including daytime, nighttime, and regular and irregular rotating SW.

METHODS

An online survey was administered to 6665 participants, with 3379 (50.7 %) classified as individuals with high scores of Mood Disorder Questionnaire (MDQ). The survey included the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Scale (ISI), Epworth Sleepiness Scale (ESS), and Center for Epidemiologic Studies Depression Scale (CES-D).

RESULTS

A multivariate regression model revealed significant interactive effects of MDQ positivity and SW on PSQI, ISI, and CES-D scores, but not ESS scores. In a secondary analysis of the high MDQ screen group, daytime workers had lower scores in sleep disturbances and depressive symptoms compared to those engaged in other forms of SW.

LIMITATIONS

Online surveys were accessible voluntarily, leading to potential selection bias. Cross-sectional data identified associations, not causal relationships. Only a self-reported questionnaire was used.

CONCLUSIONS

Our findings emphasize the advantages of a daytime work schedule for individuals at high risk of BD. In accordance with the principles of social rhythm interpersonal therapy, sleep interventions for individuals at high risk of BD should include the maintenance of a consistent daytime schedule.

Synthesising 30 years of clinical experience and scientific insight on affective temperaments in psychiatric disorders: State of the art

The concept of affective temperament has been extensively discussed throughout the history of psychopathology and represents a cornerstone in the study of mood disorders. This review aims to trace the evolution of the concept of affective temperaments (ATs) from Kraepelin's seminal work to the present day. In the 1980s, Akiskal redefined Kraepelin's concept of affective temperaments (ATs) by integrating the five recognized ATs into the broader framework of the soft bipolar spectrum. This conceptualization viewed ATs as non-pathological predispositions underlying psychiatric disorders, particularly mood disorders. Epidemiological and clinical studies have validated the existence of the five ATs. Furthermore, evidence suggests that ATs may serve as precursors to various psychiatric disorders and influence clinical dimensions such as disease course, psychopathology, and treatment adherence. Additionally, ATs appear to play a significant role in moderating phenomena such as suicide risk and stress coping. Incorporating an evaluation of temperamental bases of disorders into the multidimensional psychiatric diagnostic process could enhance treatment optimization and prognosis estimation.

Personality Traits Interact With Sleep and Biological Rhythm in Patients With Bipolar Disorder

ABSTRACT

Sleep disturbances and circadian rhythm changes in bipolar disorder (BD) may have behavioral components as well as biological components. This study aimed to examine the relationship between personality traits, sleep and circadian rhythm in BD. A total of 150 participants with BD, and 150 healthy controls completed the Big Five Personality Test-50 (B5PT-50-TR), Biological Rhythm Interview of Assessment in Neuropsychiatry (BRIAN), Functioning Assessment Short Test (FAST), Pittsburgh Sleep Quality Index (PSQI), Young Mania Rating Scale and Beck Depression Inventory. In the BD group, B5PT-50-TR emotional stability and openness subscale scores were significantly lower in comparison with the healthy control group. Agreeableness and emotional stability subscales were covariates for the BRIAN sleep subscale and emotional stability was a covariate for PSQI total score. Emotional instability might be a vulnerability factor for sleep disorders and biological rhythm abnormalities in BD. Improvement in emotional instability may relieve sleep disorders and biological rhythm, thereby leading to better treatment outcomes in BD.

Gene expression analysis of MAOA and the clock gene ARNTL in individuals with bipolar disorder compared to healthy controls

INTRODUCTION

Circadian rhythms are associated with bipolar disorder (BD). This cross-sectional study aimed at investigating ARNTL and MAOA gene expression differences (1) between individuals with BD and controls, (2) between affective episodes, and (3) the relationship between ARNTL and MAOA expression.

METHODS

ARNTL and MAOA gene expression in peripheral mononuclear blood cells were analysed from fasting blood samples (BD n =  81, controls n = 54) with quantitative real-time PCR operating on TaqMan® assays (normalised to 18S RNA expression). ANCOVAs corrected for age, sex, body mass index, and medication was used to evaluate expression differences and correlation analyses for the relation between ARNTL and MAOA expression.

RESULTS

ARNTL gene expression differed between affective episodes (F(2,78) = 3.198, p = 0.047, Partial Eta2= 0.083), but not between BD and controls (n.s.). ARNTL and MAOA expression correlated positively in BD (r = 0.704, p < 0.001) and in controls (r = 0.932, p < 0.001). MAOA expression differed neither between BD and controls nor between affective episodes (n.s.).

DISCUSSION

Clock gene expression changes were observed in different affective states of BD. More precisely, ARNTL gene expression was significantly higher in euthymia than in depression. ARNTL and MAOA gene expression correlated significantly in BD and in controls, which emphasises the strong concatenation between circadian rhythms and neurotransmitter breakdown.

Relationships Among Delayed Sleep Phase Disorder, Emotional Dysregulation, and Affective Temperaments in Adults With Attention Deficit Hyperactivity Disorder and Cyclothymia

This study aims to explore the relationships between delayed sleep phase disorder (DSPD) and emotional dysregulation in 240 patients (134 with cyclothymia, 81 with attention deficit hyperactivity disorder [ADHD] and 25 with both conditions). DSPD was assessed using the Morningness-Eveningness Questionnaire, followed by a clinical evaluation. Affective temperaments and emotional dysregulation were also investigated through the brief version of the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego and the Reactivity, Intensity, Polarity, Stability questionnaires, respectively. Clinical variables were compared in patients with and without DSPD, and a logistic regression model was used to identify the predictive value of the clinical characteristics on the presence of DSPD. DSPD patients (19% of the total sample) were significantly younger than patients without DSPD, showed an about 4 times higher lifetime history of comorbid ADHD and cyclothymia, and reported higher scores in the irritable and cyclothymic temperamental subscales and in the affective instability and impulsivity dimensions. In the multiple logistic regression, we found a negative predictive value of increasing age on the presence of DSPD, whereas comorbid cyclothymia and ADHD and cyclothymic temperament seem to represent risk factors for DSPD.

Sleep and Microbiome in Psychiatric Diseases

Objectives: Disturbances in the gut–brain barrier play an essential role in the development of mental disorders. There is considerable evidence showing that the gut microbiome not only affects digestive, metabolic and immune functions of the host but also regulates host sleep and mental states through the microbiota–gut–brain axis. The present review summarizes the role of the gut microbiome in the context of circadian rhythms, nutrition and sleep in psychiatric disorders. Methods: A PubMed search (studies published between April 2015–April 2020) was conducted with the keywords: “sleep, microbiome and psychiatry”; “sleep, microbiome and depression”; “sleep, microbiome and bipolar disorder”, “sleep, microbiome and schizophrenia”, “sleep, microbiome and anorexia nervosa”, “sleep, microbiome and substance use disorder”, “sleep, microbiome and anxiety”; “clock gene expression and microbiome”, “clock gene expression and nutrition”. Only studies investigating the relationship between sleep and microbiome in psychiatric patients were included in the review. Results: Search results yielded two cross-sectional studies analyzing sleep and gut microbiome in 154 individuals with bipolar disorder and one interventional study analyzing the effect of fecal microbiota transplantation in 17 individuals with irritable bowel syndrome on sleep. In patients with bipolar disorder, Faecalibacterium was significantly associated with improved sleep quality scores and a significant correlation between Lactobacillus counts and sleep. Conclusion: Translational research on this important field is limited and further investigation of the bidirectional pathways on sleep and the gut microbiome in mood disorders is warranted.

Nature and Nurture: Effects of Affective Temperaments on Depressive Symptoms Are Markedly Modified by Stress Exposure

BACKGROUND

Lack of proper consideration of the interaction between biological and environmental factors limits our understanding of the development of depression. Our cross-sectional study investigated whether recent stress influences the effect of affective temperaments on depressive symptoms.

METHODS

1015 general population participants completed the Brief Symptom Inventory to capture depressive symptoms, the List of Threatening Experiences Questionnaire to assess recent stressors, and the Temperament Evaluation of Memphis Pisa, Paris, and San Diego Autoquestionnaire to evaluate affective temperaments (TEMPS-A). Linear regression models were built to investigate the effect of temperament and stress on depression, temperament on stress, and the effect of temperament on depressive symptoms in different stress exposure groups.

RESULTS

Recent life events and anxious, depressive, cyclothymic, and hyperthymic temperaments significantly predicted depressive symptoms, and cyclothymic, and hyperthymic temperaments significantly predicted recent life event exposure. While in case of mild stress all affective temperaments except irritable predicted depression, in case of moderate exposure only the effect of depressive, cyclothymic, and hyperthymic temperament, while in the high exposure group only the effect of anxious temperament was significant.

LIMITATIONS

All measures were based on self-report, and subjective impact of life events was not considered. This was a cross-sectional study with a correlational nature which does not allow for causative conclusions.

CONCLUSIONS

The contribution of affective temperaments to depression is much higher compared to stress, and severity of exposure to life events influences the impact of affective temperaments on depressive symptoms, pointing to divergent pathways of emotional reactivity mediating the effects of stress on depression which can be exploited for prevention and treatment.

Association between affective temperaments and mood features in bipolar disorder II: The role of insomnia and chronobiological rhythms desynchronization

BACKGROUND

Bipolar disorders are complex disorders involving the interaction of multiple factors. Affective temperaments, insomnia, and chronobiological rhythms desynchronization may all contribute to bipolar disorder. Since there is a paucity of research examining this topic we aimed to study how they are interrelated and collectively associated with clinical features of bipolar disorder.

METHOD

One-hundred patients with Bipolar Disorder type II depressive episode with and without mixed features were recruited and compared. Subjects were evaluated with SCID -5, the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN), the Insomnia Severity Index (ISI), and the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Auto-questionnaire (TEMPS-A) while evaluating depressive (Beck Depression Inventory-BDI-II) and manic (Young Mania Rating Scale-YMRS) symptoms. Logistic regression and mediation analyses were conducted.

RESULTS

Subjects with mixed features showed a higher scores in both insomnia and chronobiological rhythms scores. When considering affective temperaments not only depressive, cyclothymic and irritable temperaments predicted mood symptoms but also insomnia (depressive symptoms O.R. 4.17, p = 0.043) and chronobiological sleep de-synchronization (manic symptoms O.R. 8.69, p = 0.001). Insomnia symptoms and chronobiological alterations mediated the association between affective temperaments and mood symptoms.

LIMITATIONS

the cross-sectional design limited any causal interpretation.

CONCLUSION

Subjects with mixed features showed a greater severity of insomnia and chronobiological rhythm de-synchronization compared to subjects without. Insomnia and chronobiological alterations may contribute to mood disorders together with affective temperaments in a complex interplay also mediating their effect on mood. Preventive strategies for bipolars should also act on the dysregulation of sleep and circadian rhythms.

Regulação molecular do ritmo circadiano e transtornos psiquiátricos: uma revisão sistemática

RESUMO Objetivo O artigo possui como objetivo investigar os genes relógio que estão mais associados com os transtornos psiquiátricos, as funções e localizações desses genes, assim como investigar o principal transtorno, método e modelo considerados nas análises. O trabalho busca resumir os achados e discutir o impacto dessas pesquisas no conhecimento científico. Métodos Esta revisão utilizou-se de uma metodologia sistemática (Prospero; ID 152031) e seguiu as diretrizes PRISMA. A busca dos estudos foi realizada nas bases de dados PubMed/MEDLINE e Scientific Eletronic Library Online e foram utilizados os termos do Medical Subject Headings Terms . Foram selecionados estudos quantitativos com resultados conclusivos referentes à associação de transtornos psiquiátricos com a regulação molecular do ritmo circadiano. As informações úteis foram extraídas e utilizadas para a elaboração de gráficos e tabelas. Resultados Foram incluídos 24 artigos em nosso estudo. Observou-se que o transtorno bipolar consistiu no transtorno psiquiátrico mais abordado (40% dos estudos); a nacionalidade polonesa dos participantes também se destacou em 39% dos trabalhos. Adicionalmente, o gene PER foi o mais estudado (25%) e o córtex cerebral foi a principal região em que os genes relógio avaliados se expressam (34%). A PCR comum mostrou ser o método mais utilizado (38%) e o metabolismo da serotonina mostrou ser a principal função desempenhada pelos produtos gênicos (16%). Conclusões Em conjunto, os resultados sugerem que o transtorno bipolar consiste no distúrbio psiquiátrico mais prevalente entre as pesquisas relacionadas aos genes circadianos, expressos principalmente no córtex cerebral de humanos, em especial o gene PER .

The role of affective temperaments assessed by the Temperament Evaluation of Memphis, Pisa and San Diego-Autoquestionnaire (TEMPS-A) in the relationship between morningness-eveningness and bipolarity

BACKGROUND

Growing number of studies indicates a link between eveningness chronotype, affective temperaments and bipolarity, both in patients with mood disorders and in general population. Given these tripartite associations, we hypothesized that the effect of circadian preferences on the bipolarity may be mediated by the temperamental traits.

METHODS

The study included 1449 subjects (402 men and 1047 women). They all fulfilled a web-based questionnaire, consisting of the Composite Scale of Morningness (CSM), Mood Disorder Questionnaire (MDQ), Hypomania Checklist-32 (HCL-32) and the Temperament Evaluation of the Memphis, Pisa and San Diego-Autoquestionnaire (TEMPS-A). The role of temperamental traits in the relationship between morningness-eveningness and bipolarity was assessed using mediation analysis.

RESULTS

Morningness is correlated with lower bipolarity measured by the MDQ and HCL-32, and to lower scores of depressive, cyclothymic, irritable and anxious temperaments of the TEMPS-A. There is no significant association between morningness and hyperthymic traits. Cyclothymic and irritable traits are full mediators of the association between chronotype and bipolarity, influencing bipolarity independently from circadian preferences. Depressive and anxious traits are partial mediators of this association, increasing the effect of eveningness on bipolarity.

LIMITATIONS

The indirectness of the findings in the web-based study and disproportion of participants' gender.

CONCLUSIONS

Our study confirmed that eveningness is associated with bipolarity. In case of depressive and anxious temperaments, bipolarity is associated stronger with eveningness than with the TEMPS-A scores. On the other hand, cyclothymic and irritable temperaments were associated with bipolarity independently from circadian preferences.

The role of CLOCK gene in psychiatric disorders: Evidence from human and animal research

The circadian clock system drives daily rhythms in physiology, metabolism, and behavior in mammals. Molecular mechanisms of this system consist of multiple clock genes, with Circadian Locomotor Output Cycles Kaput (CLOCK) as a core member that plays an important role in a wide range of behaviors. Alterations in the CLOCK gene are associated with common psychiatric disorders as well as with circadian disturbances comorbidities. This review addresses animal, molecular, and genetic studies evaluating the role of the CLOCK gene on many psychiatric conditions, namely autism spectrum disorder, schizophrenia, attention-deficit/hyperactivity disorder, major depressive disorder, bipolar disorder, anxiety disorder, and substance use disorder. Many animal experiments focusing on the effects of the Clock gene in behavior related to psychiatric conditions have shown consistent biological plausibility and promising findings. In humans, genetic and gene expression studies regarding disorder susceptibility, sleep disturbances related comorbidities, and response to pharmacological treatment, in general, are in agreement with animal studies. However, the number of controversial results is high. Literature suggests that the CLOCK gene exerts important influence on these conditions, and influences the susceptibility to phenotypes of psychiatric disorders.

Evaluation of the Association Between Genetic Variants in Circadian Rhythm Genes and Posttraumatic Stress Symptoms Identifies a Potential Functional Allele in the Transcription Factor TEF

Previous studies suggest that genetic variants within genes affecting the circadian rhythm influence the development of posttraumatic stress symptoms (PTSS). In the present study, we used data from three emergency care-based cohorts to search genetic variants in circadian pathway genes previously associated with neuropsychiatric disorders for variants that influence PTSS severity. The three cohorts used included a discovery cohort of African American men and women enrolled following motor vehicle collision (n = 907) and two replication cohorts: one of multi-ethnic women enrolled following sexual assault (n = 274) and one of multi-ethnic men and women enrolled following major thermal burn injury (n = 68). DNA and RNA were collected from trauma survivors at the time of initial assessment. Validated questionnaires were used to assess peritraumatic distress severity and to assess PTSS severity 6 weeks, 6 months, and 1 year following trauma exposure. Thirty-one genetic variants from circadian rhythm genes were selected for analyses, and main effect and potential gene^*stress and gene^*sex interactions were evaluated. Secondary analyses assessed whether associated genetic variants affected mRNA expression levels. We found that six genetic variants across five circadian rhythm-associated genes predicted PTSS outcomes following motor vehicle collision (p < 0.05), but only two of these variants survived adjustment for multiple comparisons (False Discovery Rate < 5%). The strongest of these associations, an interaction between the PAR-zip transcription factor, thyrotroph embryonic factor (TEF) variant rs5758324 and peritraumatic distress, predicted PTSS development in all three cohorts. Further analysis of genetic variants in the genetic region surrounding TEFrs5758324 (±125,000 nucleotides) indicated that this allele showed the strongest association. Further, TEF RNA expression levels (determined via RNA-seq) were positively associated with PTSS severity in distressed individuals with at least one copy of the TEFrs5758324 minor allele. These results suggest that rs5758324 genetic variant in TEF, a regulator of clock-controlled genes and key mediator of the core circadian rhythm, influence PTSS severity in a stress-dependent manner.

ARNTL, CLOCK and PER3 polymorphisms - links with chronotype and affective dimensions

Recently, seven single nucleotide polymorphisms (SNPs) of ARNTL, TIM and PER3 genes were found associated with affective temperaments in bipolar disorder patients. This study aimed to test whether a) the same associations appear in a non-clinical sample; b) the SNPs are related to other affective dimensions; c) the SNPs underpin the associations between chronotype and affective temperaments/dimensions. Three hundred thirty-eight university students completed the Temperament Scale of Memphis, Pisa, Paris and San Diego Auto-questionnaire, the Centre for Epidemiological Studies Depression Scale, the Perceived Stress Scale, the General Health Questionnaire, the Seasonal Pattern Assessment Questionnaire and the Composite Scale of Morningness. Seven SNPs of the ARNTL, TIM and PER3 genes were genotyped. According to nominal significance, ARNTL rs7107287 was associated with a cyclothymic temperament, depressive and stress symptoms, general mental health and perceived negative impact of seasonality, while TIM rs10876890 was associated with a hyperthymic temperament, and the TIM rs2291738 was associated with chronotype. Different SNPs were related to chronotype and affective temperaments/dimensions, and therefore, they seem to not underpin relationships between chronotype and affective dysfunction, that is, in the present study, eveningness was related to dysthymic, cyclothymic and irritable temperaments, more symptoms of depression, stress, worse mental health and a negative impact of seasonality, while morningness was related to hyperthymic temperament. The SNPs associations need further replication given that they did not achieve Bonferroni criteria of significance accounting for the number of polymorphisms considered and tests conducted.

Increased glutamic acid decarboxylase expression in the hypothalamic suprachiasmatic nucleus in depression

In depression, disrupted circadian rhythms reflect abnormalities in the central circadian pacemaker, the hypothalamic suprachiasmatic nucleus (SCN). Although many SCN neurons are said to be GABAergic, it was not yet known whether and how SCN GABA changes occur in the SCN in depression. We, therefore, studied GABA in the SCN in relation to the changes in arginine vasopressin (AVP), which is one of the major SCN output systems. Postmortem hypothalamus specimens of 13 subjects suffering from depression and of 13 well-matched controls were collected. Quantitative immunocytochemistry was used to analyze the protein levels of glutamic acid decarboxylase (GAD)65/67 and AVP, and quantitative in situ hybridization was used to measure transcript levels of GAD67 in the SCN. There were a significant 58% increase of SCN GAD65/67-ir and a significant 169% increase of SCN GAD67-mRNA in the depression group. In addition, there were a significant 253% increase of AVP-ir in female depression subjects but not in male depression patients. This sex difference was supported by a re-analysis of SCN AVP-ir data of a previous study of our group. Moreover, SCN-AVP-ir showed a significant negative correlation with age in the control group and in the male, but not in the female depression group. Given the crucial role of GABA in mediating SCN function, our finding of increased SCN GABA expression may significantly contribute to the disordered circadian rhythms in depression. The increased SCN AVP-ir in female-but not in male-depression patients-may reflect the higher vulnerability for depression in women.

Sleep and circadian alterations in people at risk for bipolar disorder: A systematic review

BACKGROUND

Sleep and circadian abnormalities have been mostly demonstrated in bipolar patients. However, it is not clear whether these alterations are present in population at high risk for bipolar disorder (BD), indicating a possible risk factor for this condition.

OBJECTIVE

This systematic review aims to define current evidence about sleep and rhythm alterations in people at risk for BD and to evaluate sleep and circadian disorders as risk factor for BD.

METHODS

The systematic review included all articles about the topic until February 2016. Two researchers performed an electronic search of PubMed and Cochrane Library. Keywords used were 'sleep' or 'rhythm' or 'circadian' AND 'bipolar disorder' or 'mania' or 'bipolar depression' AND 'high-risk' or 'risk'.

RESULTS

Thirty articles were analyzed (7451 participants at risk for BD). Sleep disturbances are frequent in studies using both subjective measures and actigraphy. High-risk individuals reported irregularity of sleep/wake times, poor sleep and circadian rhythm disruption. Poor sleep quality, nighttime awakenings, and inadequate sleep are possible predictive factors for BD. A unique study suggested that irregular rhythms increase risk of conversion. People at risk for BD showed high cortisol levels in different times of day. Studies about anatomopathology, melatonin levels, inflammatory cytokines and oxidative stress were not identified. The most important limitations were differences in sleep and rhythm measures, heterogeneity of study designs, and lack of consistency in the definition of population at risk.

CONCLUSION

Sleep and circadian disturbances are common in people at risk for BD. However, the pathophysiology of these alterations and the impact on BD onset are still unclear.

The Biological Rhythms Interview of Assessment in Neuropsychiatry in patients with bipolar disorder: correlation with affective temperaments and schizotypy

Objective:

To assess the relationship of biological rhythms, evaluated by the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN), with affective temperaments and schizotypy.

Methods:

The BRIAN assessment, along with the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego-Autoquestionnaire (TEMPS-A) and the Oxford-Liverpool Inventory for Feelings and Experiences (O-LIFE), was administered to 54 patients with remitted bipolar disorder (BD) and 54 healthy control (HC) subjects.

Results:

The TEMPS-A cyclothymic temperament correlated positively and the hyperthymic temperament correlated negatively with BRIAN scores in both the BD and HC groups, although the correlation was stronger in BD subjects. Depressive temperament was associated with BRIAN scores in BD but not in HC; conversely, the irritable temperament was associated with BRIAN scores in HC, but not in BD. Several positive correlations between BRIAN scores and the schizotypal dimensions of the O-LIFE were observed in both BD and HC subjects, especially with cognitive disorganization and less so with unusual experiences and impulsive nonconformity. A correlation with introversion/anhedonia was found only in BD subjects.

Conclusion:

Cyclothymic and depressive temperaments predispose to disturbances of biological rhythms in BD, while a hyperthymic temperament can be protective. Similar predispositions were also found for all schizotypal dimensions, mostly for cognitive disorganization.

Is the molecular clock ticking differently in bipolar disorder? Methylation analysis of the clock gene ARNTL

OBJECTIVES

The clock gene ARNTL is associated with the transcription activation of monoamine oxidase A according to previous literature. Thus, we hypothesised that methylation of ARNTL may differ between bipolar disorder (BD) and controls.

METHODS

The methylation status of one CpG island covering the first exon of ARNTL (PS2) and one site in the 5' region of ARNTL (cg05733463) were analysed in patients with BD (n = 151) versus controls (n = 66). Methylation analysis was performed by bisulphite-conversion of DNA from fasting blood with the EpiTect Bisulfite Kit, PCR and pyrosequencing. Analysis of covariances considering the covariates age, body mass index, sex, smoking, lithium and anticonvulsant intake were performed to test methylation differences between BD and controls.

RESULTS

Methylation at cg05733463 of ARNTL was significantly higher in BD than in controls (F(1,209) = 44.500, P < .001). In contrast, methylation was significantly lower in BD at PS2_POS1 compared to controls (F(1,128) = 5.787, P = .018) and by trend at PS2_POS2 (F(1,128) = 3.033, P = .084) and POS7 (F(1,34) = 3.425, P = .073).

CONCLUSIONS

Methylation of ARNTL differed significantly between BD and controls. Thus, our study suggests that altered epigenetic regulation of ARNTL might provide a mechanistic basis for better understanding circadian rhythms and mood swings in BD.

Fluoxetine normalizes disrupted light-induced entrainment, fragmented ultradian rhythms and altered hippocampal clock gene expression in an animal model of high trait anxiety- and depression-related behavior

INTRODUCTION

Disturbances of circadian rhythms are a key symptom of mood and anxiety disorders. Selective serotonin reuptake inhibitors (SSRIs) - commonly used antidepressant drugs - also modulate aspects of circadian rhythmicity. However, their potential to restore circadian disturbances in depression remains to be investigated.

MATERIALS AND METHODS

The effects of the SSRI fluoxetine on genetically based, depression-related circadian disruptions at the behavioral and molecular level were examined using mice selectively bred for high anxiety-related and co-segregating depression-like behavior (HAB) and normal anxiety/depression behavior mice (NAB).

RESULTS

The length of the circadian period was increased in fluoxetine-treated HAB as compared to NAB mice while the number of activity bouts and light-induced entrainment were comparable. No difference in hippocampal Cry2 expression, previously reported to be dysbalanced in untreated HAB mice, was observed, while Per2 and Per3 mRNA levels were higher in HAB mice under fluoxetine treatment.

DISCUSSION

The present findings provide evidence that fluoxetine treatment normalizes disrupted circadian locomotor activity and clock gene expression in a genetic mouse model of high trait anxiety and depression. An interaction between the molecular mechanisms mediating the antidepressant response to fluoxetine and the endogenous regulation of circadian rhythms in genetically based mood and anxiety disorders is proposed.

Evolutionary conservation of the circadian gene timeout in Metazoa

Timeless (Tim) is considered to function as an essential circadian clock gene in Drosophila. Putative homologues of the Drosophila timeless gene have been identified in both mice and humans. While Drosophila contains two paralogs, timeless and timeout, acting in clock/light entrainment and chromosome integrity/photoreception, respectively, mammals contain only one Tim homolog. In this paper, we study the phylogeny of the timeless/timeout family in 48 species [including 1 protozoan (Guillardia theta), 1 nematode (Caenorhabditis elegans), 8 arthropods and 38 chordates], for which whole genome data are available by using MEGA (Molecular Evolutionary Genetics Analysis). Phylogenetic Analysis by Maximum Likelihood (PAML) was used to analyze the selective pressure acting on metazoan timeless/timeout genes. Our phylogeny clearly separates insect timeless and timeout lineages and shows that non-insect animal Tim genes are homologs of insect timeout. In this study, we explored the relatively rapidly evolving timeless lineage that was apparently lost from most deuterostomes, including chordates, and from Caenorhabditis elegans. In contrast, we found that the timeout protein, often confusingly called “timeless” in the vertebrate literature, is present throughout the available animal genomes. Selection results showed that timeout is under weaker negative selection than timeless. Finally, our phylogeny of timeless/timeout showed an evolutionary conservation of the circadian clock gene timeout in Metazoa. This conservation is in line with its multifunctionality, being essential for embryonic development and maintenance of chromosome integrity, among others.

The bipolarity of light and dark: A review on Bipolar Disorder and circadian cycles

BACKGROUND

Bipolar Disorder is characterized by episodes running the full mood spectrum, from mania to depression. Between mood episodes, residual symptoms remain, as sleep alterations, circadian cycle disturbances, emotional deregulation, cognitive impairment and increased risk for comorbidities. The present review intends to reflect about the most recent and relevant information concerning the biunivocal relation between bipolar disorder and circadian cycles.

METHODS

It was conducted a literature search on PubMed database using the search terms "bipolar", "circadian", "melatonin", "cortisol", "body temperature", "Clock gene", "Bmal1 gene", "Per gene", "Cry gene", "GSK3β", "chronotype", "light therapy", "dark therapy", "sleep deprivation", "lithum" and "agomelatine". Search results were manually reviewed, and pertinent studies were selected for inclusion as appropriate.

RESULTS

Several studies support the relationship between bipolar disorder and circadian cycles, discussing alterations in melatonin, body temperature and cortisol rhythms; disruption of sleep/wake cycle; variations of clock genes; and chronotype. Some therapeutics for bipolar disorder directed to the circadian cycles disturbances are also discussed, including lithium carbonate, agomelatine, light therapy, dark therapy, sleep deprivation and interpersonal and social rhythm therapy.

LIMITATIONS

This review provides a summary of an extensive research for the relevant literature on this theme, not a patient-wise meta-analysis.

CONCLUSIONS

In the future, it is essential to achieve a better understanding of the relation between bipolar disorder and the circadian system. It is required to establish new treatment protocols, combining psychotherapy, therapies targeting the circadian rhythms and the latest drugs, in order to reduce the risk of relapse and improve affective behaviour.

A glutamatergic network mediates lithium response in bipolar disorder as defined by epigenome pathway analysis

AIM

A regulatory network in the human brain mediating lithium response in bipolar patients was revealed by analysis of functional SNPs from genome-wide association studies (GWAS) and published gene association studies, followed by epigenome mapping.

METHODS

An initial set of 23,312 SNPs in linkage disequilibrium with lead SNPs, and sub-threshold GWAS SNPs rescued by pathway analysis, were studied in the same populations. These were assessed using our workflow and annotation by the epigenome roadmap consortium.

RESULTS

Twenty-seven percent of 802 SNPs that were associated with lithium response (13 published studies gene association studies and two GWAS) were shared in common with 1281 SNPs from 18 GWAS examining psychiatric disorders and adverse events associated with lithium treatment. Nineteen SNPs were annotated as active regulatory elements such as enhancers and promoters in a tissue-specific manner. They were located within noncoding regions of ten genes: ANK3, ARNTL, CACNA1C, CACNG2, CDKN1A, CREB1, GRIA2, GSK3B, NR1D1 and SLC1A2. Following gene set enrichment and pathway analysis, these genes were found to be significantly associated (p = 10(-27); Fisher exact test) with an AMPA2 glutamate receptor network in human brain. Our workflow results showed concordance with annotation of regulatory elements from the epigenome roadmap. Analysis of cognate mRNA and enhancer RNA exhibited patterns consistent with an integrated pathway in human brain.

CONCLUSION

This pharmacoepigenomic regulatory pathway is located in the same brain regions that exhibit tissue volume loss in bipolar disorder. Although in silico analysis requires biological validation, the approach provides value for identification of candidate variants that may be used in pharmacogenomic testing to identify bipolar patients likely to respond to lithium.

Temperamental dimensions of the TEMPS-A in male and female subjects engaging in extreme or/and high risk sports

OBJECTIVES

We investigated temperamental dimensions of the Temperament Evaluation of Memphis, Pisa and San Diego Autoquestionnaire (TEMPS-A) as well as bipolarity features in male and female subjects engaging in extreme or/and high risk sports.

METHODS

The web-based case-control study was performed in 480 subjects engaging in extreme or/and high risk sports (255 male, 225 female) aged 26 ± 6 years and in 235 age- and sex-matched healthy controls subjects (107 male, 128 female), aged 28 + 9 years. The TEMPS-A questionnaire, 110 questions version, has been used, evaluating five temperament domains: depressive, cyclothymic, hyperthymic, irritable and anxious. The Mood Disorder Questionnaire (MDQ) was employed for the assessment of bipolarity.

RESULTS

Both male and female athletes had significantly higher scores of hyperthymic temperaments compared with control male and female subjects who had declared themselves as not involved into the activities of extreme or/and high risk sports. In addition, compared with controls, male sportsmen had lower scores of depressive and anxious temperaments, and female athletes had higher scores of cyclothymic and irritable temperaments. Both male and female athletes obtained significantly higher scores of bipolarity as measured by the MDQ, than control men and women.

LIMITATIONS

Web-based study involving a risk of selection and recall bias, problematic homogeneity of the experimental group.

CONCLUSIONS

Subjects engaged into extreme or/and high risk sports have significantly higher scores of hyperthymic temperament, measured by the TEMPS-A and present sex-specific features of other temperaments. Such subjects obtain also greater bipolarity scores as measured by the MDQ.

Circadian rhythms and sleep in bipolar disorder: implications for pathophysiology and treatment

PURPOSE OF REVIEW

Multiple lines of evidence support the conceptualization of bipolar disorder as a disorder of circadian rhythms. Considering bipolar disorder in the framework of circadian disturbances also helps understand the clinical phenomenology pointing toward a multisystemic involvement.

RECENT FINDINGS

Patients with bipolar disorder show altered rhythmicity in body temperature and melatonin rhythms, high day-to-day variability in activity and sleep timing, persistent disturbances of sleep or wake cycles, including disturbances of sleep continuity. The internal clocks are, indeed, responsible for regulating a variety of physiologic functions, including appetitive behaviors, cognitive functions and metabolism.

SUMMARY

An underlying circadian pathology in bipolar disorder is a unifying explicatory model for the high psychiatric and medical comorbidity observed during the long-term course of the disorder. This model also provides a rationale for therapeutic interventions aimed at re-entraining the internal clock.