Lithium and bipolar disorder: Impacts from molecular to behavioural circadian rhythms

The Relationship Among Seasonality, Night Eating, and Chronotype in Bipolar Disorder: Exploring the Mediating Role of Sleep Quality

ABSTRACT

The purpose of the study was to explore the association among chronotype, seasonality, sleep quality, and night eating syndrome (NES) among patients with bipolar disorder (BD) and the mediating role of sleep quality in this relationship. Ninety-two individuals with BD type 1 who had been euthymic for at least 8 weeks and 87 healthy controls were included. In addition to sociodemographic/clinical data, chronotype, seasonality, sleep quality, and NES were evaluated using the Morningness-Eveningness Questionnaire (MEQ), Seasonal Pattern Assessment Questionnaire, Pittsburgh Sleep Quality Index, and Night Eating Questionnaire. The prevalence of NES (17.4%) was higher among BD than the controls. BD patients with NES had poorer sleep quality, greater seasonality, and lower MEQ scores. Chronotype had an indirect effect that was partially mediated by sleep quality on night eating symptoms in BD patients, in addition to a direct effect. Seasonality was found to have a direct effect on night eating symptoms. Therapeutic interventions that target both sleep and circadian disruption should be implemented when addressing NES in patients with BD.

The sleep-circadian interface: A window into mental disorders

Sleep, circadian rhythms, and mental health are reciprocally interlinked. Disruption to the quality, continuity, and timing of sleep can precipitate or exacerbate psychiatric symptoms in susceptible individuals, while treatments that target sleep-circadian disturbances can alleviate psychopathology. Conversely, psychiatric symptoms can reciprocally exacerbate poor sleep and disrupt clock-controlled processes. Despite progress in elucidating underlying mechanisms, a cohesive approach that integrates the dynamic interactions between psychiatric disorder with both sleep and circadian processes is lacking. This review synthesizes recent evidence for sleep-circadian dysfunction as a transdiagnostic contributor to a range of psychiatric disorders, with an emphasis on biological mechanisms. We highlight observations from adolescent and young adults, who are at greatest risk of developing mental disorders, and for whom early detection and intervention promise the greatest benefit. In particular, we aim to a) integrate sleep and circadian factors implicated in the pathophysiology and treatment of mood, anxiety, and psychosis spectrum disorders, with a transdiagnostic perspective; b) highlight the need to reframe existing knowledge and adopt an integrated approach which recognizes the interaction between sleep and circadian factors; and c) identify important gaps and opportunities for further research.

Circadian rhythms and mood disorders: Time to see the light

The importance of time is ever prevalent in our world, and disruptions to the normal light/dark and sleep/wake cycle have now become the norm rather than the exception for a large part of it. All mood disorders, including seasonal affective disorder (SAD), major depressive disorder (MDD), and bipolar disorder (BD), are strongly associated with abnormal sleep and circadian rhythms in a variety of physiological processes. Environmental disruptions to normal sleep/wake patterns, light/dark changes, and seasonal changes can precipitate episodes. Moreover, treatments that target the circadian system have proven to be therapeutic in certain cases. This review will summarize much of our current knowledge of how these disorders associate with specific circadian phenotypes, as well as the neuronal mechanisms that link the circadian clock with mood regulation. We also discuss what has been learned from therapies that target circadian rhythms and how we may use current knowledge to develop more individually designed treatments.

Effectiveness of light therapy as adjunctive treatment in bipolar depression: A pilot study

BACKGROUND

About 1 and 4 % of people suffering from depression is affected by bipolar disorder. Few patients respond to the first-line antidepressants, and a 4-week latency pharmacological treatment period has been observed. This pilot study aimed to evaluate the effectiveness and safety of bright light therapy (BLT) in accelerating and increasing therapeutic response in patients with bipolar depression.

METHODS

A pilot study was conducted. Patients with bipolar depression, already treated with antidepressants, were included. The treatment group was composed of patients treated with antidepressants combined with BLT (30 min/4 days a week at 10,000 lx for eight weeks). The control group included patients treated with antidepressants with exposure to red light (30 min/4 days a week at a red light for eight weeks). MADRS, HAMD-17, CGI-S, FSS, and QoLS were collected at the baseline and after 4 and 8 weeks of treatments.

RESULTS

Forty-one patients (18 males and 23 females; mean age 49.1 ± 15 years) were included in the study. After four weeks, MADRS and HAMD-17 scores in treatment groups were significantly lower than those reported in the control group (p < 0.001). After eight weeks, all scales except FSS reported significantly lower values in patients treated with BLT (p < 0.0001).

LIMITATIONS

Small sample size and significant heterogeneity in the antidepressant treatments.

CONCLUSION

BLT has shown reliable effectiveness and safety in treating patients with bipolar depression and should be considered a clinically relevant approach in accelerating patients' therapeutic response and reducing the impact of long-lasting therapy.

Can circadian rhythm predict changes in neurocognitive functioning in bipolar disorder: protocol of a 12-month longitudinal cohort study based on research domain criteria

Introduction: Bipolar disorder (BD) is a prevalent and disabling mental disorder characterized by disrupted circadian rhythms and impaired neurocognitive features, both of which fall under the major domains of Research Domain Criteria (RDoC). However, there is limited evidence regarding the interaction between circadian rhythms and long-term neurocognitive functioning. Therefore, this longitudinal cohort study protocol aims to explore whether circadian rhythm can predict changes in neurocognitive functioning over time in patients with BD.Methods: This study adopts a longitudinal cohort design, aiming to recruit 100 BD patients in either depressive or remitted states. Participants will undergo evaluations from clinical, circadian rhythm, and neurocognitive perspectives at baseline, 6-month, and 12-month follow-ups, involving questionnaires, actigraphy, and computed neurocognitive tests. We will examine both cross-sectional and longitudinal associations between participants' circadian rhythm patterns and neurocognitive functioning. Statistical analyses will employ Spearman correlation and mixed regression models.Discussion: We anticipate that circadian rhythms may serve as predictors of neurocognitive functioning changes. The findings of this study could offer supplementary insights into BD pathophysiology, potential treatment targets, and prediction.Trial Registration: This study has been registered with the Chinese Clinical Trial Registry under the registration code ChiCTR2200064922 on 21st October 2022.

Circadian rhythms and disorders of the timing of sleep

The daily alternation between sleep and wakefulness is one of the most dominant features of our lives and is a manifestation of the intrinsic 24 h rhythmicity underlying almost every aspect of our physiology. Circadian rhythms are generated by networks of molecular oscillators in the brain and peripheral tissues that interact with environmental and behavioural cycles to promote the occurrence of sleep during the environmental night. This alignment is often disturbed, however, by contemporary changes to our living environments, work or social schedules, patterns of light exposure, and biological factors, with consequences not only for sleep timing but also for our physical and mental health. Characterised by undesirable or irregular timing of sleep and wakefulness, in this Series paper we critically examine the existing categories of circadian rhythm sleep-wake disorders and the role of the circadian system in their development. We emphasise how not all disruption to daily rhythms is driven solely by an underlying circadian disturbance, and take a broader, dimensional approach to explore how circadian rhythms and sleep homoeostasis interact with behavioural and environmental factors. Very few high-quality epidemiological and intervention studies exist, and wider recognition and treatment of sleep timing disorders are currently hindered by a scarcity of accessible and objective tools for quantifying sleep and circadian physiology and environmental variables. We therefore assess emerging wearable technology, transcriptomics, and mathematical modelling approaches that promise to accelerate the integration of our knowledge in sleep and circadian science into improved human health.

Magnetic field effects in biology from the perspective of the radical pair mechanism

Hundreds of studies have found that weak magnetic fields can significantly influence various biological systems. However, the underlying mechanisms behind these phenomena remain elusive. Remarkably, the magnetic energies implicated in these effects are much smaller than thermal energies. Here, we review these observations, and we suggest an explanation based on the radical pair mechanism, which involves the quantum dynamics of the electron and nuclear spins of transient radical molecules. While the radical pair mechanism has been studied in detail in the context of avian magnetoreception, the studies reviewed here show that magnetosensitivity is widespread throughout biology. We review magnetic field effects on various physiological functions, discussing static, hypomagnetic and oscillating magnetic fields, as well as isotope effects. We then review the radical pair mechanism as a potential unifying model for the described magnetic field effects, and we discuss plausible candidate molecules for the radical pairs. We review recent studies proposing that the radical pair mechanism provides explanations for isotope effects in xenon anaesthesia and lithium treatment of hyperactivity, magnetic field effects on the circadian clock, and hypomagnetic field effects on neurogenesis and microtubule assembly. We conclude by discussing future lines of investigation in this exciting new area of quantum biology.

Insomnia, sleep loss, and circadian sleep disturbances in mood disorders: a pathway toward neurodegeneration and neuroprogression? A theoretical review

The present paper aims at reviewing and commenting on the relationships between sleep and circadian phasing alterations and neurodegenerative/neuroprogressive processes in mood disorder. We carried out a systematic review, according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, in PubMed, PsycINFO, and Embase electronic databases for literature related to mood disorders, sleep disturbances, and neurodegenerative/neuroprogressive processes in relation to (1) neuroinflammation, (2) activation of the stress system, (3) oxidative stress, (4) accumulation of neurotoxic proteins, and (5) neuroprotection deficit. Seventy articles were collectively selected and analyzed. Experimental and clinical studies revealed that insomnia, conditions of sleep loss, and altered circadian sleep may favor neurodegeneration and neuroprogression in mood disorders. These sleep disturbances may induce a state of chronic inflammation by enhancing neuroinflammation, both directly and indirectly, via microglia and astrocytes activation. They may act as neurobiological stressors that by over-activating the stress system may negatively influence neural plasticity causing neuronal damage. In addition, sleep disturbances may favor the accumulation of neurotoxic proteins, favor oxidative stress, and a deficit in neuroprotection hence contributing to neurodegeneration and neuroprogression. Targeting sleep disturbances in the clinical practice may hold a neuroprotective value for mood disorders.

Is Poor Lithium Response in Individuals with Bipolar Disorder Associated with Increased Degradation of Tryptophan along the Kynurenine Pathway? Results of an Exploratory Study

Bipolar disorder is associated with an inflammation-triggered elevated catabolism of tryptophan to the kynurenine pathway, which impacts psychiatric symptoms and outcomes. The data indicate that lithium exerts anti-inflammatory effects by inhibiting indoleamine-2,3-dioxygenase (IDO)-1 activity. This exploratory study aimed to investigate the tryptophan catabolism in individuals with bipolar disorder (n = 48) compared to healthy controls (n = 48), and the associations with the response to mood stabilizers such as lithium, valproate, or lamotrigine rated with the Retrospective Assessment of the Lithium Response Phenotype Scale (or the Alda scale). The results demonstrate an association of a poorer response to lithium with higher levels of kynurenine, kynurenine/tryptophan ratio as a proxy for IDO-1 activity, as well as quinolinic acid, which, overall, indicates a pro-inflammatory state with a higher degradation of tryptophan towards the neurotoxic branch. The treatment response to valproate and lamotrigine was not associated with the levels of the tryptophan metabolites. These findings support the anti-inflammatory properties of lithium. Furthermore, since quinolinic acid has neurotoxic features via the glutamatergic pathway, they also strengthen the assumption that the clinical drug response might be associated with biochemical processes. The relationship between the lithium response and the measurements of the tryptophan to the kynurenine pathway is of clinical relevance and may potentially bring advantages towards a personalized medicine approach to bipolar disorder that allows for the selection of the most effective mood-stabilizing drug.

Which Actigraphy Dimensions Predict Longitudinal Outcomes in Bipolar Disorders?

Bipolar disorder (BD) is characterized by recurrent mood episodes. It is increasingly suggested that disturbances in sleep–wake cycles and/or circadian rhythms could represent valuable predictors of recurrence, but few studies have addressed this question. Euthymic individuals with BD (n = 69) undertook 3 weeks of actigraphy recording and were then followed up for a median duration of 3.5 years. Principal component analyses were used to identify core dimensions of sleep quantity/variability and circadian rhythmicity. Associations between clinical variables and actigraphy dimensions and time to first recurrence were explored using survival analyses, and then using area under the curve (AUC) analyses (early vs. late recurrence). Most participants (64%) experienced a recurrence during follow-up (median survival time: 18 months). After adjusting for potential confounding factors, an actigraphy dimension comprising amplitude and variability/stability of circadian rhythms was a significant predictor of time to recurrence (p = 0.009). The AUC for correct classification of early vs. late recurrence subgroups was only 0.64 for clinical predictors, but combining these variables with objectively measured intra-day variability improved the AUC to 0.82 (p = 0.04). Actigraphy estimates of circadian rhythms, particularly variability/stability and amplitude, may represent valid predictive markers of future BD recurrences and could be putative targets for future psychosocial interventions.

Effects of cluster headache preventatives on mouse hypothalamic transcriptional homeostasis

OBJECTIVE

To investigate how cluster headache preventatives verapamil, lithium and prednisone affect expression of hypothalamic genes involved in chronobiology.

METHODS

C57Bl/6 mice were exposed to daily, oral treatment with verapamil, lithium, prednisone or amitriptyline (as negative control), and transcripts of multiple genes quantified in the anterior, lateral and posterior hypothalamus.

RESULTS

Verapamil, lithium or prednisone did not affect expression of clock genes of the anterior hypothalamus (Clock, Bmal1, Cry1/2 and Per1/2). Prednisone altered expression of hypothalamic neuropeptides melanin-concentrating hormone and histidine decarboxylase within the lateral and posterior hypothalamus, respectively. The three preventatives did not affect expression of the neurohypophyseal hormones oxytocin and arginine-vasopressin in the posterior hypothalamus. Conversely, amitriptyline reduced mRNA levels of Clock, oxytocin and arginine-vasopressin.

CONCLUSION

Data suggest that cluster headache preventatives act upstream or downstream from the hypothalamus. Our findings provide new insights on hypothalamic homeostasis during cluster headache prophylaxis, as well as neurochemistry underlying cluster headache treatment.

Supersensitivity of Patients With Bipolar I Disorder to Light-Induced Phase Delay by Narrow Bandwidth Blue Light

Background

Bipolar disorder is a severe chronic mental disorder. There is a bidirectional relationship between disease course and circadian phase. Significant circadian phase shifts occur during transitions between episodes, but episodes can also be elicited during euthymia by forced rapid changes in circadian phase. Although an instability of circadian phase has been described in multiple observational reports, no studies quantifying the propensity to phase shift following an experimental standardized stimulus have been published. This study therefore aimed to assess whether patients with bipolar I disorder (BDI) are more prone to phase delay following blue light exposure in the evening than healthy control subjects.

Methods

Euthymic participants with BDI confirmed by Structured Clinical Interview for DSM-IV Axis I (n = 32) and healthy control subjects (n = 55) underwent a 3-day phase shift protocol involving exposure to a standardized dose of homogeneous, constant, narrow bandwidth blue light (478 nm, half bandwidth = 18 nm, photon flux = 1.29 × 1015 photons/cm2/s) for 2 hours at 9:00 pm via a ganzfeld dome on day 2. On days 1 and 3, serial serum melatonin assessments during total darkness were performed to determine the dim light melatonin onset.

Results

Significant differences in the light-induced phase shift between BDI and healthy control subjects were detected (F 1,82 = 4.110; p = .046), with patients with bipolar disorder exhibiting an enhanced phase delay (η2 = 0.49). There were no significant associations between the magnitude of the phase shift and clinical parameters.

Conclusions

Supersensitivity of patients with BDI to light-induced phase delay may contribute to the observed phase instability and vulnerability to forced phase shifts associated with the disorder.

A panel of rhythm gene polymorphisms is involved in susceptibility to type 2 diabetes mellitus and bipolar disorder

Background

Biological rhythm is closely related to health. We aimed to identify the potential correlations of rhythm gene polymorphisms to type 2 diabetes mellitus (DM) or bipolar disorder (BD), which both have many abnormal rhythmic activities, in a sample of Chinese Han origin.

Methods

A total of 136 patients with BD, 166 patients with DM, and 130 healthy controls were collected. We screened 28 single nucleotide polymorphisms (SNPs) located in rhythm genes CLOCK, ARNTL, PER2, PER3, CRY1, and CRY2 respectively. Snapshot typing technology was used for genotyping.

Results

Both the rs10832022-G and rs11022765-A allele frequencies of the ARNTL gene were significantly higher in patients with DM than in those with BD (corrected P=0.03, 0.004, respectively). The frequency of rs10832022-G, rs1022765-A, and rs11022762-T haplotypes, which was significantly lower in patients with BD than in controls (P=0.003, OR =0.579), was significantly higher in patients with DM than in those with BD (P=0.0002, OR =1.878). The rs2292910-CC genotypic frequency of the CRY2 gene was significantly higher in patients with BD than in controls (OR of regression =2.203, P=0.01), while the frequency of the AA genotype was significantly lower than in patients with DM (P=0.01). The frequency of rs1972874-G and rs36124720-G haplotype of the PER2 gene was significantly higher in patients with DM than in controls (P=0.01, OR =1.577).

Conclusions

Our study preliminarily suggested that both BD and type 2 DM could be considered as dysrhythmias with different rhythmic genetic backgrounds, which contribute to the early prediction of an individual’s susceptibility to different rhythm disorders and early intervention.

A Comparison of Different Approaches to Clinical Phenotyping of Lithium Response: A Proof of Principle Study Employing Genetic Variants of Three Candidate Circadian Genes

Optimal classification of the response to lithium (Li) is crucial in genetic and biomarker research. This proof of concept study aims at exploring whether different approaches to phenotyping the response to Li may influence the likelihood of detecting associations between the response and genetic markers. We operationalized Li response phenotypes using the Retrospective Assessment of Response to Lithium Scale (i.e., the Alda scale) in a sample of 164 cases with bipolar disorder (BD). Three phenotypes were defined using the established approaches, whilst two phenotypes were generated by machine learning algorithms. We examined whether these five different Li response phenotypes showed different levels of statistically significant associations with polymorphisms of three candidate circadian genes (RORA, TIMELESS and PPARGC1A), which were selected for this study because they were plausibly linked with the response to Li. The three original and two revised Alda ratings showed low levels of discordance (misclassification rates: 8–12%). However, the significance of associations with circadian genes differed when examining previously recommended categorical and continuous phenotypes versus machine-learning derived phenotypes. Findings using machine learning approaches identified more putative signals of the Li response. Established approaches to Li response phenotyping are easy to use but may lead to a significant loss of data (excluding partial responders) due to recent attempts to improve the reliability of the original rating system. While machine learning approaches require additional modeling to generate Li response phenotypes, they may offer a more nuanced approach, which, in turn, would enhance the probability of identifying significant signals in genetic studies.

Association between circadian activity rhythms and mood episode relapse in bipolar disorder: a 12-month prospective cohort study

A significant proportion of patients with bipolar disorder experience mood episode relapses. We examined whether circadian activity rhythms were associated with mood episode relapses in patients with bipolar disorder. This prospective cohort study included outpatients with bipolar disorder who participated in a study titled "Association between the Pathology of Bipolar Disorder and Light Exposure in Daily Life (APPLE) cohort study." The participants' physical activity was objectively assessed using a wrist-worn accelerometer over 7 consecutive days for the baseline assessment and then at the 12-month follow-up for mood episode relapses. The levels and timing of the circadian activity rhythms were estimated using a cosinor analysis and a nonparametric circadian rhythm analysis. Of the 189 participants, 88 (46%) experienced mood episodes during follow-up. The Cox proportional hazards model adjusting for potential confounders showed that a robust circadian activity rhythm, including midline-estimating statistic of rhythm (MESOR) and amplitude by cosinor analysis and 10 consecutive hours with the highest amplitude values (M10) by the nonparametric circadian rhythm analysis, was significantly associated with a decrease in mood episode relapses (per counts/min, hazard ratio [95% confidence interval]: MESOR, 0.993 [0.988-0.997]; amplitude, 0.994 [0.988-0.999]; and M10, 0.996 [0.993-0.999]). A later timing of the circadian activity rhythm (M10 onset time) was significantly associated with an increase in the depressive episode relapses (per hour; 1.109 [1.001-1.215]). We observed significant associations between circadian activity rhythms and mood episode relapses in bipolar disorder.

Effect of lithium on circadian rhythm in bipolar disorder: A systematic review and meta-analysis

OBJECTIVES

Circadian rhythm disruption is commonly reported in patients with bipolar disorder. Lithium has been suggested to have effects on the circadian clock, the biological basis of the circadian rhythm. The objective of the current review was to review systematically the existing studies on the effect of lithium on circadian rhythm in patients with bipolar disorder.

METHODS

We systematically searched the scientific literature up to September 2020 for experimental or observational studies which measured circadian rhythm in bipolar patients taking lithium (in comparison with placebo or other active treatments) and carried out a meta-analysis. Circadian rest-activity was our primary outcome, but we also collected data about sleep quality and chronotype (Morningness-Eveningness). The protocol was registered in PROSPERO (CRD42018109790).

RESULTS

Four observational studies (n = 668) and one experimental study (n = 29) were included. Results from the meta-analysis suggest a potential association between lithium and shifts towards morningness (standardized mean difference [SMD]: 0.42, 95% confidence interval [CI]: -0.05 to 0.90). One cohort study with 21 days of follow-up found that patients treated with lithium had significantly larger amplitude (0.68, 0.01 to 1.36) when compared to anticonvulsants.

CONCLUSION

This review highlights the insufficient evidence to inform us about the effect of lithium on circadian rhythm. However, we found that chronotype can be a potential target for further exploration of biomarkers or biosignatures of lithium treatment in patients with bipolar disorder. Further studies with prospective and longitudinal study design, adopting actigraphy to monitor daily circadian rest-activity changes are needed.

Network of co-expressed circadian genes, childhood maltreatment and sleep quality in bipolar disorders

Bipolar disorder (BD) is a chronic and burdensome psychiatric disease, characterized by variations in mood and energy. The literature has consistently demonstrated an association between BD and childhood maltreatment (CM), and genetic variants of circadian genes have been associated with an increased vulnerability to develop BD. In this context, environmental factors such as CM may also contribute to the susceptibility to BD through alterations in the functioning of the biological clock linked to modifications of expression of circadian genes. In this study, we explored the associations between childhood maltreatment, sleep quality, and the level of expression of a comprehensive set of circadian genes in lymphoblastoid cell lines from patients with BD. The sample consisted of 52 Caucasian euthymic patients with a diagnosis of BD type 1 or type 2. The exposure to CM was assessed with the Childhood Trauma Questionnaire (CTQ), and the sleep quality was assessed using the Pittsburgh Sleep Quality Index. We measured the expression of 18 circadian genes using quantitative RT-PCR: ARNTL2, BHLHE40, BHLHE41, CLOCK, CRY1, CRY2, CSNK1D, CSNK1E, DBP, GSK3B, NPAS2, NR1D1, PER1, PER2, PER3, PPARGC1A, RORA, and RORB. Gene expression networks were analyzed with the disjoint graphs method. Compared to the other investigated transcripts, PPARGC1A was the only one whose expression level was differentially affected in patients who have experienced CM and, more specifically, physical abuse. We observed no significant effects of the other CTQ subscores (emotional and sexual abuses, physical and emotional neglects), nor of the sleep quality on the network of circadian genes expression. Although requiring replication in larger cohorts, the result obtained here is consistent with the hypothesis of an influence of CM exposure on circadian systems and highlights the importance of PPARGC1A in these processes.

Association between the Arylalkylamine N-Acetyltransferase (AANAT) Gene and Seasonality in Patients with Bipolar Disorder

OBJECTIVE

Bipolar disorder (BD) is complex genetic disorder. Therefore, approaches using clinical phenotypes such as biological rhythm disruption could be an alternative. In this study, we explored the relationship between melatonin pathway genes with circadian and seasonal rhythms of BD.

METHODS

We recruited clinically stable patients with BD (n=324). We measured the seasonal variation of mood and behavior (seasonality), and circadian preference, on a lifetime basis. We analyzed 34 variants in four genes (MTNR1a, MTNR1b, AANAT, ASMT) involved in the melatonin pathway.

RESULTS

Four variants were nominally associated with seasonality and circadian preference. After multiple test corrections, the rs116879618 in AANAT remained significantly associated with seasonality (corrected p=0.0151). When analyzing additional variants of AANAT through imputation, the rs117849139, rs77121614 and rs28936679 (corrected p=0.0086, 0.0154, and 0.0092) also showed a significant association with seasonality.

CONCLUSION

This is the first study reporting the relationship between variants of AANAT and seasonality in patients with BD. Since AANAT controls the level of melatonin production in accordance with light and darkness, this study suggests that melatonin may be involved in the pathogenesis of BD, which frequently shows a seasonality of behaviors and symptom manifestations.

Cluster headache pathophysiology - insights from current and emerging treatments

Cluster headache is a debilitating primary headache disorder that affects approximately 0.1% of the population worldwide. Cluster headache attacks involve severe unilateral pain in the trigeminal distribution together with ipsilateral cranial autonomic features and a sense of agitation. Acute treatments are available and are effective in just over half of the patients. Until recently, preventive medications were borrowed from non-headache indications, so management of cluster headache is challenging. However, as our understanding of cluster headache pathophysiology has evolved on the basis of key bench and neuroimaging studies, crucial neuropeptides and brain structures have been identified as emerging treatment targets. In this Review, we provide an overview of what is known about the pathophysiology of cluster headache and discuss the existing treatment options and their mechanisms of action. Existing acute treatments include triptans and high-flow oxygen, interim treatment options include corticosteroids in oral form or for greater occipital nerve block, and preventive treatments include verapamil, lithium, melatonin and topiramate. We also consider emerging treatment options, including calcitonin gene-related peptide antibodies, non-invasive vagus nerve stimulation, sphenopalatine ganglion stimulation and somatostatin receptor agonists, discuss how evidence from trials of these emerging treatments provides insights into the pathophysiology of cluster headache and highlight areas for future research.

Bipolar disorders

Bipolar disorders are a complex group of severe and chronic disorders that includes bipolar I disorder, defined by the presence of a syndromal, manic episode, and bipolar II disorder, defined by the presence of a syndromal, hypomanic episode and a major depressive episode. Bipolar disorders substantially reduce psychosocial functioning and are associated with a loss of approximately 10-20 potential years of life. The mortality gap between populations with bipolar disorders and the general population is principally a result of excess deaths from cardiovascular disease and suicide. Bipolar disorder has a high heritability (approximately 70%). Bipolar disorders share genetic risk alleles with other mental and medical disorders. Bipolar I has a closer genetic association with schizophrenia relative to bipolar II, which has a closer genetic association with major depressive disorder. Although the pathogenesis of bipolar disorders is unknown, implicated processes include disturbances in neuronal-glial plasticity, monoaminergic signalling, inflammatory homoeostasis, cellular metabolic pathways, and mitochondrial function. The high prevalence of childhood maltreatment in people with bipolar disorders and the association between childhood maltreatment and a more complex presentation of bipolar disorder (eg, one including suicidality) highlight the role of adverse environmental exposures on the presentation of bipolar disorders. Although mania defines bipolar I disorder, depressive episodes and symptoms dominate the longitudinal course of, and disproportionately account for morbidity and mortality in, bipolar disorders. Lithium is the gold standard mood-stabilising agent for the treatment of people with bipolar disorders, and has antimanic, antidepressant, and anti-suicide effects. Although antipsychotics are effective in treating mania, few antipsychotics have proven to be effective in bipolar depression. Divalproex and carbamazepine are effective in the treatment of acute mania and lamotrigine is effective at treating and preventing bipolar depression. Antidepressants are widely prescribed for bipolar disorders despite a paucity of compelling evidence for their short-term or long-term efficacy. Moreover, antidepressant prescription in bipolar disorder is associated, in many cases, with mood destabilisation, especially during maintenance treatment. Unfortunately, effective pharmacological treatments for bipolar disorders are not universally available, particularly in low-income and middle-income countries. Targeting medical and psychiatric comorbidity, integrating adjunctive psychosocial treatments, and involving caregivers have been shown to improve health outcomes for people with bipolar disorders. The aim of this Seminar, which is intended mainly for primary care physicians, is to provide an overview of diagnostic, pathogenetic, and treatment considerations in bipolar disorders. Towards the foregoing aim, we review and synthesise evidence on the epidemiology, mechanisms, screening, and treatment of bipolar disorders.

Higher prevalence of intentional self-harm in bipolar disorder with evening chronotype: A finding from the APPLE cohort study

BACKGROUND

Patients with bipolar disorder (BD) frequently self-harm, and this is strongly associated with subsequent suicide. This study investigated the association between chronotype and intentional self-harm in patients with BD.

METHODS

Two-hundred and five outpatients with BD participated in this cross-sectional study. Each participant's chronotype was evaluated using the Morningness-Eveningness Questionnaire, dividing the scores into three types: evening, 16-41 points; intermediate, 42-58 points; and morning, 59-86 points. Intentional self-harm over the past year were self-reported by questionnaire. Propensity score for evening chronotype was estimated from age, sex, socioeconomic factors, mood symptoms, total sleep time, age at the onset of BD, psychiatric inpatient history, family history of suicide, psychiatric comorbidity, and use of lithium.

RESULTS

Thirty-six (18%) of the 205 participants reported self-harm. A substantially higher proportion of the evening chronotype group self-harmed compared to the other groups (evening, 37%; intermediate, 13%; morning 10%). In multivariable analysis adjusted for propensity score, the odds ratio (OR) for self-harming significantly increased from morning to intermediate to evening chronotype (ORs: morning, 1.00; intermediate, 1.56; evening, 3.61; P for trend = 0.038).

LIMITATIONS

This study was a cross-sectional and small sample size.

CONCLUSIONS

Although a third factors, such as personality disorder or disrupted circadian rhythm, may have influenced, these findings suggest association between chronotype and intentional self-harm in BD patients.

Suicidal Ideation and Insomnia in Bipolar Disorders: Idéation suicidaire et insomnie dans les troubles bipolaires

OBJECTIVE

Bipolar disorder (BD) confers elevated suicide risk and associates with misaligned circadian rhythm. Real-time monitoring of objectively measured sleep is a novel approach to detect and prevent suicidal behavior. We aimed at understanding associations between subjective insomnia and actigraphy data with severity of suicidal ideation in BDs.

METHODS

This prospective cohort study comprised 76 outpatients with a BD aged 18 to 65 inclusively. Main measures included 10 consecutive days of wrist actigraphy; the Athens Insomnia Scale (AIS); the Montgomery-Åsberg Depression Rating Scale (MADRS); the Quick Inventory of Depressive Symptoms-16, self-rating (QIDS-SR-16); and the Columbia Suicide Severity Rating Scale. Diagnoses, medications, and suicide attempts were obtained from chart review.

RESULTS

Suicidal ideation correlated moderately with subjective insomnia (AIS with QIDS-SR-16 item 12 ρ =0.26, P = 0.03; MADRS item 10 ρ = 0.33, P = 0.003). Graphical sleep patterns showed that suicidal patients were enriched among the most fragmented sleep patterns, and this was confirmed by correlations of suicidal ideation with actigraphy data at 2 visits. Patients with lifetime suicide attempts (n = 8) had more varied objective sleep (a higher standard deviation of center of daily inactivity [0.64 vs. 0.26, P = 0.01], consolidation of daily inactivity [0.18 vs. 0.10, P = <0.001], sleep offset [3.02 hours vs. 1.90 hours, P = <0.001], and total sleep [105 vs. 69 minutes, P = 0.02], and a lower consolidation of daily inactivity [0.65 vs. 0.79, P = 0.03]).

CONCLUSIONS

Subjective insomnia, a nonstigmatized symptom, can complement suicidality screens. Longer follow-ups and larger samples are warranted to understand whether real-time sleep monitoring predicts suicidal ideation in patient subgroups or individually.

Sleep and Circadian Rhythm Disturbance in Remitted Schizophrenia and Bipolar Disorder: A Systematic Review and Meta-analysis

BACKGROUND

Sleep and circadian rhythm disturbances in schizophrenia are common, but incompletely characterized. We aimed to describe and compare the magnitude and heterogeneity of sleep-circadian alterations in remitted schizophrenia and compare them with those in interepisode bipolar disorder.

METHODS

EMBASE, Medline, and PsycINFO were searched for case-control studies reporting actigraphic parameters in remitted schizophrenia or bipolar disorder. Standardized and absolute mean differences between patients and controls were quantified using Hedges' g, and patient-control differences in variability were quantified using the mean-scaled coefficient of variation ratio (CVR). A wald-type test compared effect sizes between disorders.

RESULTS

Thirty studies reporting on 967 patients and 803 controls were included. Compared with controls, both schizophrenia and bipolar groups had significantly longer total sleep time (mean difference [minutes] [95% confidence interval {CI}] = 99.9 [66.8, 133.1] and 31.1 [19.3, 42.9], respectively), time in bed (mean difference = 77.8 [13.7, 142.0] and 50.3 [20.3, 80.3]), but also greater sleep latency (16.5 [6.1, 27.0] and 2.6 [0.5, 4.6]) and reduced motor activity (standardized mean difference [95% CI] = -0.86 [-1.22, -0.51] and -0.75 [-1.20, -0.29]). Effect sizes were significantly greater in schizophrenia compared with the bipolar disorder group for total sleep time, sleep latency, and wake after sleep onset. CVR was significantly elevated in both diagnoses for total sleep time, time in bed, and relative amplitude.

CONCLUSIONS

In both disorders, longer overall sleep duration, but also disturbed initiation, continuity, and reduced motor activity were found. Common, modifiable factors may be associated with these sleep-circadian phenotypes and advocate for further development of transdiagnostic interventions that target them.

Differences in telomere length between patients with bipolar disorder and controls are influenced by lithium treatment

Aim: To assess the role of lithium treatment in the relationship between bipolar disorder (BD) and leukocyte telomere length (LTL). Materials & methods: We compared LTL between 131 patients with BD, with or without a history of lithium treatment, and 336 controls. We tested the association between genetically determined LTL and BD in two large genome-wide association datasets. Results: Patients with BD with a history lithium treatment showed longer LTL compared with never-treated patients (p = 0.015), and similar LTL compared with controls. Patients never treated with lithium showed shorter LTL compared with controls (p = 0.029). Mendelian randomization analysis showed no association between BD and genetically determined LTL. Conclusion: Our data support previous findings showing that long-term lithium treatment might protect against telomere shortening.

Role of biological rhythm dysfunction in the development and management of bipolar disorders: a review

Disturbance of biological rhythms contributes to the onset of bipolar disorders and is an important clinical feature of the condition. To further explore the role of biological rhythms in bipolar disorders, 95 English articles published between 1968 and 2019 were retrieved from the PubMed database and analysed. We herein review the outcomes of studies on biological rhythm disturbance in bipolar disorders, including the epidemiology, aetiology, clinical features (eg, sleep, feeding and eating disorders) and treatment of the condition evaluated by patients’ self-report and biological indicators such as melatonin. Our report supports the characterisation of biological rhythm disturbance as a significant clinical feature affecting the onset and development of bipolar disorders and reviews classical and novel treatments, such as chronotherapy, that can be applied in the clinical practice. Our analysis indicates that a more comprehensive study of the pathophysiology, clinical phenomenology and treatment of biological rhythm disturbance is required.

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.

Lithium alters expression of RNAs in a type-specific manner in differentiated human neuroblastoma neuronal cultures, including specific genes involved in Alzheimer's disease

Lithium (Li) is a medication long-used to treat bipolar disorder. It is currently under investigation for multiple nervous system disorders, including Alzheimer's disease (AD). While perturbation of RNA levels by Li has been previously reported, its effects on the whole transcriptome has been given little attention. We, therefore, sought to determine comprehensive effects of Li treatment on RNA levels. We cultured and differentiated human neuroblastoma (SK-N-SH) cells to neuronal cells with all-trans retinoic acid (ATRA). We exposed cultures for one week to lithium chloride or distilled water, extracted total RNA, depleted ribosomal RNA and performed whole-transcriptome RT-sequencing. We analyzed results by RNA length and type. We further analyzed expression and protein interaction networks between selected Li-altered protein-coding RNAs and common AD-associated gene products. Lithium changed expression of RNAs in both non-specific (inverse to sequence length) and specific (according to RNA type) fashions. The non-coding small nucleolar RNAs (snoRNAs) were subject to the greatest length-adjusted Li influence. When RNA length effects were taken into account, microRNAs as a group were significantly less likely to have had levels altered by Li treatment. Notably, several Li-influenced protein-coding RNAs were co-expressed or produced proteins that interacted with several common AD-associated genes and proteins. Lithium's modification of RNA levels depends on both RNA length and type. Li activity on snoRNA levels may pertain to bipolar disorders while Li modification of protein coding RNAs may be relevant to AD.

The chronotherapeutic treatment of bipolar disorders: A systematic review and practice recommendations from the ISBD task force on chronotherapy and chronobiology

AIMS

To systematically review the literature on the efficacy and tolerability of the major chronotherapeutic treatments of bipolar disorders (BD)-bright light therapy (LT), dark therapy (DT), treatments utilizing sleep deprivation (SD), melatonergic agonists (MA), interpersonal social rhythm therapy (IPSRT), and cognitive behavioral therapy adapted for BD (CBTI-BP)-and propose treatment recommendations based on a synthesis of the evidence.

METHODS

PRISMA-based systematic review of the literature.

RESULTS

The acute antidepressant (AD) efficacy of LT was supported by several open-label studies, three randomized controlled trials (RCTs), and one pseudorandomized controlled trial. SD showed rapid, acute AD response rates of 43.9%, 59.3%, and 59.4% in eight case series, 11 uncontrolled, studies, and one RCT, respectively. Adjunctive DT obtained significant, rapid anti-manic results in one RCT and one controlled study. The seven studies on MA yielded very limited data on acute antidepressant activity, conflicting evidence of both antimanic and maintenance efficacy, and support from two case series of improved sleep in both acute and euthymic states. IPSRT monotherapy for bipolar II depression had acute response rates of 41%, 67%, and 67.4% in two open studies and one RCT, respectively; as adjunctive therapy for bipolar depression in one RCT, and efficacy in reducing relapse in two RCTs. Among euthymic BD subjects with insomnia, a single RCT found CBTI-BP effective in delaying manic relapse and improving sleep. Chronotherapies were generally safe and well-tolerated.

CONCLUSIONS

The outcome literature on the adjunctive use of chronotherapeutic treatments for BP is variable, with evidence bases that differ in size, study quality, level of evidence, and non-standardized treatment protocols. Evidence-informed practice recommendations are offered.

Strengths and Weaknesses of the Gray Mouse Lemur (Microcebus murinus) as a Model for the Behavioral and Psychological Symptoms and Neuropsychiatric Symptoms of Dementia

To face the load of the prevalence of Alzheimer’s disease in the aging population, there is an urgent need to develop more translatable animal models with similarities to humans in both the symptomatology and physiopathology of dementia. Due to their close evolutionary similarity to humans, non-human primates (NHPs) are of primary interest. Of the NHPs, to date, the gray mouse lemur (Microcebus murinus) has shown promising evidence of its translatability to humans. The present review reports the known advantages and limitations of using this species at all levels of investigation in the context of neuropsychiatric conditions. In this easily bred Malagasy primate with a relatively short life span (approximately 12 years), age-related cognitive decline, amyloid angiopathy, and risk factors (i.e., glucoregulatory imbalance) are congruent with those observed in humans. More specifically, analogous behavioral and psychological symptoms and neuropsychiatric symptoms of dementia (BPSD/NPS) to those in humans can be found in the aging mouse lemur. Aged mouse lemurs show typical age-related alterations of locomotor activity daily rhythms such as decreased rhythm amplitude, increased fragmentation, and increased activity during the resting-sleeping phase of the day and desynchronization with the light-dark cycle. In addition, sleep deprivation successfully induces cognitive deficits in adult mouse lemurs, and the effectiveness of approved cognitive enhancers such as acetylcholinesterase inhibitors or N-methyl-D-aspartate antagonists is demonstrated in sleep–deprived animals. This result supports the translational potential of this animal model, especially for unraveling the mechanisms underlying dementia and for developing novel therapeutics to prevent age-associated cognitive decline. In conclusion, actual knowledge of BPSD/NPS-like symptoms of age-related cognitive deficits in the gray mouse lemur and the recent demonstration of the similarity of these symptoms with those seen in humans offer promising new ways of investigating both the prevention and treatment of pathological aging.

Significant role of gene-gene interactions of clock genes in mood disorder

BACKGROUND

The genetic interactions in the circadian rhythm biological system are promising as a source of pathophysiology in mood disorder. We examined the role of the gene-gene interactions of clock genes in mood disorder.

METHODS

We included 413 patients with mood disorder and 1294 controls. The clock genes investigated were BHLHB2, CLOCK, CSNK1E, NR1D1, PER2, PER3, and TIMELESS. Allele, genotype, and haplotype associations were tested. Gene--gene interactions were analyzed using the non-parametric model-free multifactor-dimensionality reduction (MDR) method.

RESULTS

TIMELESS rs4630333 and CSNK1E rs135745 were significantly associated with both major depressive disorder and bipolar disorder. The CLOCK haplotype was also strongly associated. The genetic roles of these SNPs were consistent from the allele and genotypic associations to the MDR interaction results. In MDR analysis, the combination of TIMELESS rs4630333 and CSNK1E rs135745 exhibited the most significant association with mood disorders in the two-locus model. BHLHB2 rs2137947 for major depressive disorder and CLOCK rs12649507 for bipolar disorder were the most significant third loci in the three-locus combination model. The four-locus SNP combination model showed the best balanced accuracy (BA), but its cross-validation consistency (CVC) was unsatisfactory.

LIMITATIONS

We included only 17 SNPs for seven circadian genes due to our limited resources; all subjects were ethnically Korean.

CONCLUSIONS

Our results suggest significant single-gene associations and gene-gene interactions of circadian genes with mood disorder. Gene-gene interactions play a crucial role in mood disorder, even when individual clock genes do not have significant roles.

Lithium Preparations in Psychiatry, Addiction Medicine and Neurology. Part II. Biochemical Mechanisms of Its Action

Lithium is the first and the lightest in the series of alkali metals, to which, in addition to lithium, two very biologically important elements – sodium and potassium, as well as trace elements rubidium and cesium, belong. Despite its formal affiliation to the group of alkali metals, lithium, like many other chemical elements of the «atypical» second period of the periodic table (for example, boron), is more similar in its chemical properties not to its counterparts in the group, but to its «diagonal brother» – magnesium. As we will show in this article, the diagonal chemical similarity between lithium and magnesium is of great importance for understanding the mechanisms of its intracellular biochemical action. At the same time, the intragroup chemical similarity of lithium with sodium and potassium is more important for understanding the mechanisms of its absorption, its distribution in the body and its excretion. Despite the 70 years that have passed since John Cade’s discovery of the antimanic effect of lithium, the mechanisms of its therapeutic action are still not completely understood. In the end, it turns out that the mechanism of the therapeutic action of lithium is extremely complex, multicomponent, unique and not imitable. Certain aspects of the mechanism of its action may be compatible with the mechanisms of action of other mood stabilizers, or with the mechanisms of action of so-called «lithium-mimetics», such as ebselen. However, no other drug to date failed to fully reproduce the biochemical effect of lithium on the body.

Study of 45 candidate genes suggests CACNG2 may be associated with lithium response in bipolar disorder

BACKGROUND

Bipolar disorder is a neuropsychiatric disorder that is characterized by fluctuations between manic and depressive phases. Lithium is the original and best mood stabilizing treatment for bipolar disorder. While its mechanism is not well understood, it is believed to have a strong genetic component, as several studies suggest that lithium responsiveness, in bipolar disorder, is heritable. In this study we aimed to identify genetic variants that are associated with lithium responsiveness in bipolar disorder.

METHODS

Here we present two cohorts; a retrospective cohort in which patients were surveyed about their response to lithium, and a prospective cohort, in which patients were placed on a lithium monotherapy and monitored for their response to lithium. In both cohorts, patients were stratified into two categories in terms of lithium response; good responders and poor responders. 45 genes were selected based on previous associations with lithium pathways or bipolar disorder and 684 SNPs within these genes were selected to test for association with lithium response.

RESULTS

While no single SNP was significant after correcting for multiple comparisons, there were several that were nominally significant (p < 0.05). Of these nominally significant SNPs, the most highly significant SNP in both the prospective and retrospective cohorts were found to be in CACNG2, or Stargazin. The second best association with lithium response was several SNPs in NRG1, a gene that has previously been associated with schizophrenia.

CONCLUSIONS

Evidence for the association of lithium response with SNPs in CACNG2 is consistent with previous findings that have identified CACNG2 as associated with both bipolar disorder and lithium responsiveness.

Maximum Temperature and Solar Radiation as Predictors of Bipolar Patient Admission in an Emergency Psychiatric Ward

Environmental variables can regulate behavior in healthy subjects. Recently, some authors investigated the role of meteorological variables in bipolar patients with an impact on both the onset and course of bipolar disorder (BD). The aim of this study was to investigate the impact of meteorological variables and other indexes in bipolar hospitalized patients. We examined all patients admitted to the Psychiatric Inpatient Unit of San Luigi Gonzaga Hospital, Orbassano (Turin, Italy) from September 2013 to August 2015, collecting several socio-demographic and clinical characteristics. Seven hundred and thirty patients were included. Compared to the day of admission of control individuals, patients with BD were admitted on a day that presented higher minimum, medium, and maximum temperature, higher maximum humidity, higher solar radiation, and higher hours of sunshine. After logistic regression analysis, admissions to the emergency psychiatric ward due to a primary diagnosis of BD were associated with maximum temperature and solar radiation. The current study provides a novel perspective on the question surrounding seasonal mood patterns in patients with BD. A greater awareness of all possible precipitating factors is needed to inform self-management and psycho-educational programs as well as to improve resilience regarding affective recurrences in the clinical practice.

Treating Circadian Rhythm Disruption in Bipolar Disorder

PURPOSE OF REVIEW

Disruptions in circadian rhythms are believed to underlie the illness course of bipolar disorder (BD). This review evaluates recent studies on the treatment of circadian dysfunction in BD.

RECENT FINDINGS

Targeted social rhythm therapy may be useful for bipolar depression though some studies suggest that a non-targeted psychosocial or pharmacological intervention may be just as efficacious. Lithium holds potential for addressing circadian dysfunction in BD. Blue-blocking therapy may be useful for mania and midday bright light therapy may relieve depression.

CONCLUSIONS

Psychosocial, pharmacological, and light-based approaches are promising avenues for treating circadian dysfunction in BD.

Bright Light as a Personalized Precision Treatment of Mood Disorders

Background: The use of light for its antidepressant action dates back to the beginnings of civilization. Three decades ago, the use of bright-light therapy (BLT) for treating Seasonal Affective Disorder (SAD) was officially proposed. Since then, a growing scientific literature reports its antidepressant efficacy in both unipolar and bipolar disorders (BD), with or without seasonal patterns. This review aims to examine the management of BLT as a personalized and precision treatment in SAD, unipolar, and BD. Methods: We conducted a narrative review using Medline and Google Scholar databases up to June 2018. Results: BLT has physiological effects by resynchronizing the biological clock (circadian system), enhancing alertness, increasing sleep pressure (homeostatic system), and acting on serotonin, and other monoaminergic pathways. Effects of BLT on mood depend on several factors such as light intensity, wavelength spectrum, illumination duration, time of the day, and individual circadian rhythms. A growing body of evidence has been generated over the last decade about BLT evolving as an effective depression treatment not only to be used in SAD, but also in non-seasonal depression, with efficiency comparable to fluoxetine, and possibly more robust in patients with BD. The antidepressant action of BLT is fast (within 1-week) and safe, with the need in BD to protect against manic switch with mood stabilizers. Side effects might be nausea, diarrhea, headache, and eye irritation, and are generally mild and rare. This good safety profile may be of particular interest, especially in women during the perinatal period or for the elderly. The management of BLT needs to be clarified across mood disorders and future studies are expected to compare different dose-titration protocols, to validate its use as a maintenance treatment, and also to identify predictive biomarkers of response and tolerability. We propose clinical guidelines for BLT use in SAD, non-seasonal depression, and BD. Conclusions : BLT is an efficient antidepressant strategy in mono- or adjunct-therapy, that should be personalized according the unipolar or bipolar subtype, the presence or absence of seasonal patterns, and also regarding its efficacy and tolerability.

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.

Circadian rhythm in bipolar disorder: A review of the literature

Sleep disturbances and circadian rhythm dysfunction have been widely demonstrated in patients with bipolar disorder (BD). Irregularity of the sleep-wake rhythm, eveningness chronotype, abnormality of melatonin secretion, vulnerability of clock genes, and the irregularity of social time cues have also been well-documented in BD. Circadian rhythm dysfunction is prominent in BD compared with that in major depressive disorders, implying that circadian rhythm dysfunction is a trait marker of BD. In the clinical course of BD, the circadian rhythm dysfunctions may act as predictors for the first onset of BD and the relapse of mood episodes. Treatments focusing on sleep disturbances and circadian rhythm dysfunction in combination with pharmacological, psychosocial, and chronobiological treatments are believed to be useful for relapse prevention. Further studies are therefore warranted to clarify the relation between circadian rhythm dysfunction and the pathophysiology of BD to develop treatment strategies for achieving recovery in BD patients.

Genetic polymorphisms associated with circadian rhythm dysregulation provide new perspectives on bipolar disorder

OBJECTIVES

The objective of this study was to present a broad view of how genetic polymorphisms in genes that control the rhythmicity and function of circadian rhythm may influence the etiology, pathophysiology and treatment of bipolar disorder (BD).

METHODS

A bibliographic search was performed to identify and select papers reporting studies on variations in circadian genes and BD. A search of Medline, Google Scholar, Scopus, and Web of Science was carried out to review the literature.

RESULTS

Several studies provide evidence of contributions of variations in circadian genes to disease etiology, pathophysiological variations and lithium drug response. Dysfunction of the sleep-wake cycle, an important brain function regulator, is indicated as the primary means by which circadian gene variations act in mood disorders.

CONCLUSIONS

Investigations of the effects of circadian genes have suggested that the chronotype offers hope for guiding and improving management of patients with BD. However, BD is a disease of a complex nature and presents multiple endophenotypes determined by different associations between genetics and the environment. Thus, new genomic studies to delimit variations that may help improve the clinical condition of these patients are extremely important.

Visceral theory of sleep and origins of mental disorders

Visceral theory of sleep states that the same brain neurons, which process external information in wakefulness, during sleep switch to the processing of internal information coming from various visceral systems. Here we hypothesize that a failure in the commutation of exteroceptive and interoceptive information flows in the brain can manifest itself as a mental illness.

Sleep spindles in bipolar disorder - a comparison to healthy control subjects

OBJECTIVE

Bipolar disorder is a severe mental disorder for which currently no reliable biomarkers exist. It has been shown that patients with schizophrenia but not with unipolar depression have a reduced density of fast sleep spindles during N2 sleep. The aim of this study was to assess fast sleep spindle density in euthymic patients with bipolar disorder.

METHODS

Patients with bipolar disorder (n = 24) and healthy control subjects (n = 25) were assessed using all-night polysomnography. Sleep spindles within stage N2 sleep were identified by visual inspection and subdivided into fast (>13 Hz) and slow (≤13 Hz) spindles. All spindles were subsequently characterised by density, frequency, amplitude, duration and coherence.

RESULTS

Euthymic patients with bipolar disorder were found to have a reduced density and a lower mean frequency of fast spindles. Slow spindle density and frequency did not differ between groups. There were no differences regarding amplitude, duration or coherence.

CONCLUSIONS

A reduction in fast spindle density during N2 sleep points towards thalamic dysfunction as a potential neurobiological mechanism of relevance in bipolar disorder. In addition, a reduced sleep spindle density could be interpreted as a common endophenotype shared with schizophrenia but not unipolar depression and may - if replicated - be of utility in early recognition and risk stratification.

Depressive disorders: Processes leading to neurogeneration and potential novel treatments

Mood disorders are wide spread with estimates that one in seven of the population are affected at some time in their life (Kessler et al., 2012). Many of those affected with severe depressive disorders have cognitive deficits which may progress to frank neurodegeneration. There are several peripheral markers shown by patients who have cognitive deficits that could represent causative factors and could potentially serve as guides to the prevention or even treatment of neurodegeneration. Circadian rhythm misalignment, immune dysfunction and oxidative stress are key pathologic processes implicated in neurodegeneration and cognitive dysfunction in depressive disorders. Novel treatments targeting these pathways may therefore potentially improve patient outcomes whereby the primary mechanism of action is outside of the monoaminergic system. Moreover, targeting immune dysfunction, oxidative stress and circadian rhythm misalignment (rather than primarily the monoaminergic system) may hold promise for truly disease modifying treatments that may prevent neurodegeneration rather than simply alleviating symptoms with no curative intent. Further research is required to more comprehensively understand the contributions of these pathways to the pathophysiology of depressive disorders to allow for disease modifying treatments to be discovered.

Efficacy and safety of sublingual ramelteon as an adjunctive therapy in the maintenance treatment of bipolar I disorder in adults: A phase 3, randomized controlled trial

BACKGROUND

The optimal long-term management strategy for bipolar I disorder patients is not yet established. Evidence supports the rationale for circadian rhythm regulation to prevent mood episode relapse in bipolar patients. This study evaluated the efficacy and safety of a new sublingual formulation of the melatonin receptor agonist ramelteon (ramelteon SL) as adjunctive therapy in the maintenance treatment of bipolar I patients.

METHODS

In a double-blinded trial in the United States and Latin America, adult bipolar I disorder patients stable for ≥ 8 weeks before baseline and with a mood episode 8 weeks to 9 months before screening, were randomized to once-daily ramelteon SL 0.1mg (n = 164), 0.4mg (n = 160), or 0.8mg (n = 154), or placebo (n = 164), in addition to their existing treatment. The primary endpoint was time from randomization to relapse of symptoms. The prespecified futility criterion in a planned, unblinded, independent interim analysis was the failure of all ramelteon SL doses to achieve a conditional power ≥ 30% compared with placebo.

RESULTS

No significant differences between any dose of ramelteon SL and placebo were observed. The study was terminated after meeting the futility criteria. Ramelteon SL was well tolerated, with a safety profile consistent with that for oral ramelteon.

LIMITATIONS

A low rate of relapse events precluded detection of any statistically significant difference between groups.

CONCLUSIONS

The study failed to demonstrate the efficacy of ramelteon SL as adjunctive maintenance therapy for bipolar disorder. Interim analyses for futility in clinical studies are valuable in preventing unnecessary exposure of subjects to interventions.

Evidence towards RNA Binding Motif (RNP1, RRM) Protein 3 (RBM3) as a Potential Biomarker of Lithium Response in Bipolar Disorder Patients

Lithium has been used for more than six decades for the management of bipolar disorder (BD). In a previous transcriptomic study, we showed that patients affected by either BD or cluster headache, both disorders characterized by circadian disturbances and response to lithium in a subgroup of patients, have higher expression of the RNA binding motif (RNP1, RRM) protein 3 (RBM3) gene compared to controls. To investigate whether RBM3 could represent a biomarker of lithium response, we screened raw microarray expression data from lymphoblastoid cell lines (LCLs) derived from 20 BD patients, responders or non-responders to lithium. RBM3 was the most significantly differentially expressed gene in the list, being overexpressed in responders compared to non-responders (fold change = 2.0; p = 1.5 × 10^-16). We therefore sought to validate the microarray finding by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and explore whether RBM3 expression was modulated by lithium treatment in vitro in LCLs as well as in human-derived neural progenitor cells (NPCs). Our findings confirmed the higher expression of RBM3 in responders compared to non-responders (fold change = 3.78; p = 0.0002). Lithium did not change RBM3 expression in LCLs in any of the groups, but it increased its expression in NPCs. While preliminary, our data suggest that higher levels of RBM3 might be required for better lithium response and that the expression of this gene could be modulated by lithium in a tissue-specific manner.

Bipolar disorders: is there an influence of seasonality or photoperiod?

Objective:

To increase understanding of the influence of photoperiod variation in patients with bipolar disorders.

Methods:

We followed a sample of Italian bipolar patients over a period of 24 months, focusing on inpatients. All patients admitted to the Psychiatric Inpatient Unit of San Luigi Gonzaga Hospital in Orbassano (Turin, Italy) between September 1, 2013 and August 31, 2015 were recruited. Sociodemographic and clinical data were collected.

Results:

Seven hundred and thirty patients were included. The admission rate for bipolar patients was significantly higher during May, June and July, when there was maximum sunlight exposure, although no seasonal pattern was found. Patients with (hypo)manic episodes were admitted more frequently during the spring and during longer photoperiods than those with major depressive episodes.

Conclusions:

Photoperiod is a key element in bipolar disorder, not only as an environmental factor but also as an important clinical parameter that should be considered during treatment.

Lithium ameliorates sleep deprivation-induced mania-like behavior, hypothalamic-pituitary-adrenal (HPA) axis alterations, oxidative stress and elevations of cytokine concentrations in the brain and serum of mice

OBJECTIVES

The goal of the present study was to investigate the effects of lithium administration on behavior, oxidative stress parameters and cytokine levels in the periphery and brain of mice subjected to an animal model of mania induced by paradoxical sleep deprivation (PSD).

METHODS

Male C57 mice were treated with saline or lithium for 7 days. The sleep deprivation protocol started on the 5th day during for the last 36 hours of the treatment period. Immediately after the sleep deprivation protocol, animals locomotor activity was evaluated and serum and brain samples was extracted to evaluation of corticosterone and adrenocorticotropic hormone circulating levels, oxidative stress parameters and citokynes levels.

RESULTS

The results showed that PSD induced hyperactivity in mice, which is considered a mania-like behavior. PSD increased lipid peroxidation and oxidative damage to DNA, as well as causing alterations to antioxidant enzymes in the frontal cortex, hippocampus and serum of mice. In addition, PSD increased the levels of cytokines in the brains of mice. Treatment with lithium prevented the mania-like behavior, oxidative damage and cytokine alterations induced by PSD.

CONCLUSIONS

Improving our understanding of oxidative damage in biomolecules, antioxidant mechanisms and the inflammatory system - alterations presented in the animal models of mania - is important in helping us to improve our knowledge concerning the pathophysiology of BD, and the mechanisms of action employed by mood stabilizers.