The impact of lithium on circadian rhythms and implications for bipolar disorder pharmacotherapy

Effect of lithium on circadian activity level and flexibility in patients with bipolar disorder: results from the Oxford Lithium Trial

BACKGROUND

Disruption of circadian rest-activity is prevalent in patients with bipolar disorder (BD). Lithium's impact on circadian rhythms has been documented in cell lines, animal models, and pharmacogenomics studies in patients with BD. However, the causal relationship between such disruption and BD remains unclear.

METHODS

We investigated the early effects of lithium on circadian rest-activity in an exploratory analysis of a randomised, placebo-controlled, double-blind six-week study on patients with BD. Participants were assigned to receive either lithium or a placebo in a 1:1 ratio. Circadian activity was monitored using actigraphy, and daily affect was assessed through ecological momentary assessment. A computational model was used to quantify different types of activity variability, and the impact of lithium on activity level, activity onset time and their variability were analysed using linear mixed models.

FINDINGS

Of the thirty-five participants who began treatment, 19 received lithium and 16 received a placebo. Lithium significantly altered circadian rest-activity patterns, including reducing daytime activity levels (after 4 weeks, below as well: Cohen's d = -0.19, p = 0.002, linear mixed model, ibid.), advancing the onset of daytime activity (Cohen's d = -0.14, p = 0.018), and increasing the volatility of both daytime activity level (Cohen's d = 0.10, p = 0.002) and its onset time (Cohen's d = 0.13, p < 0.001), independent of affective symptoms changes.

INTERPRETATION

This study establishes a causal link between lithium treatment and reduced circadian activity with advanced circadian phase, potentially via temporarily increasing their volatility (flexibility). Significant circadian changes were detected within one week of starting lithium, highlighting their potential as an early biomarker for treatment response.

FUNDING

This research was supported by the Wellcome Trust Strategic Award (CONBRIO: Collaborative Oxford Network for Bipolar Research to Improve Outcomes, reference No. 102,616/Z), NIHR Oxford Health Biomedical Research Centre and the NIHR Oxford cognitive health Clinical Research Facility.

Synaptic protein expression in bipolar disorder patient-derived neurons implicates PSD-95 as a marker of lithium response

Bipolar disorder (BD) is a severe mental illness characterized by recurrent episodes of depression and mania. Lithium is the gold standard pharmacotherapy for BD, but outcomes are variable, and the relevant therapeutic mechanisms underlying successful treatment response remain uncertain. To identify synaptic markers of BD and lithium response, we measured the effects of lithium on induced pluripotent stem cell-derived neurons from BD patients and controls. We determined that baseline expression of synapsin I (SYN1) and PSD-95 is reduced in BD neurons compared to controls. In control neurons, lithium treatment had modest, transient effects increasing SYN1 and PSD-95 expression. In BD neurons, lithium increased SYN1 expression regardless of lithium response history. However, lithium only increased PSD-95 expression selectively in neurons from lithium-responders and not in neurons from lithium non-responders, leading to group differences in the colocalization of SYN1 and PSD-95. In conclusion, this preliminary work indicates synaptic protein markers are associated with BD pathology and correction of post-synaptic protein expression may be an important mechanism underlying lithium response.

The crosstalk between CREB and PER2 mediates the transition between mania- and depression-like behavior

Bipolar disorder (BD) is a severe psychiatric disorder characterized by alternating manic and depressive episodes. The molecular mechanisms underlying the transition between mania and depression remain unclear. Utilizing a mania animal model induced by ouabain, we observed reduced phosphorylated level of cyclic AMP-responsive element-binding protein (pCREB) and Period (PER)2 expression in the cornu ammonis (CA1) region of the hippocampus, which were restored by lithium treatment. shRNA knockdown of CREB or Per2 in CA1 region induced mania-like behavior, while overexpression of both factors resulted in depression-like behavior. Furthermore, our protein analyses revealed that the upregulation or downregulation of CREB or Per2 influenced each other's expression. Co-immunoprecipitation results demonstrated that CREB interacts with PER2. Taken together, our data suggest for potential inter-regulatory crosstalk between CREB-PER2 in hippocampal CA1 region, which mediates the transition between mania- and depression-like behaviors.

Circadian rhythm and lithium response in bipolar disorder: Insights from actigraphy and NR1D1 polymorphism

Lithium has long been used as a cornerstone mood stabilizer in the treatment of bipolar disorder (BD). However, reliable biomarkers that can predict which patients will respond better to lithium are still lacking. This study aims to evaluate the potential of NR1D1 gene SNP; rs2071427 and actigraphic measurements in predicting lithium response. Thirty-one patients diagnosed with BD at Selçuk University Faculty of Medicine and who were euthymic for at least 8 weeks were included in the study. Sleep-wake cycles and circadian rhythms of the participants were monitored by actigraph for approximately 1 week. For genetic analyses, the SNP rs2071427 variant of the NR1D1 gene was evaluated. A significant proportion of patients with homozygous (AA/GG) genotypes responded well to lithium, whereas some patients with heterozygous (AG) genotypes did not respond to lithium. Actigraphic data showed that there were marked variations in the sleep patterns of BD patients. The Morningness-Eveningness Questionnaire scale did not adequately discriminate the morning chronotype. Seasonal Pattern Assessment Questionnaire results showed that most patients had a seasonal pattern, but this was insufficient to predict response to lithium. This study once again demonstrates the need for new biomarkers to predict lithium response. The findings are an important step in the personalization of BD treatment and may improve treatment efficacy and minimize side effects by tailoring the treatment process to the individual characteristics of patients. Future studies should support these findings with larger sample groups and studies on different genetic markers.

The interaction network and potential clinical effectiveness of dimensional psychopathology phenotyping based on EMR: a Bayesian network approach

The current DSM-oriented diagnostic paradigm has introduced the issue of heterogeneity, as it fails to account for the identification of the neurological processes underlying mental illnesses, which affects the precision of treatment. The Research Domain Criteria (RDoC) framework serves as a recognized approach to addressing this heterogeneity, and several assessment and translation techniques have been proposed. Among these methods, transforming RDoC scores from electronic medical records (EMR) using Natural Language Processing (NLP) has emerged as a suitable technique, demonstrating clinical effectiveness. Numerous studies have sought to use RDoC to understand the Diagnostic and Statistical Manual of Mental Disorders (DSM) categories from a qualified perspective, but few studies have examined the distribution variations and interaction characteristics of RDoC within various DSM categories through retrospective analyses. Therefore, we employed unsupervised learning to translate five domains of eRDoC scores derived from electronic medical records (EMR) of patients diagnosed with Major Depressive Disorder (MDD), Schizophrenia (SCZ), and Bipolar Disorder (BD) at West China Hospital between 2008 and 2021. The distribution characteristics, interaction networks, and potential clinical effectiveness of RDoC domains were analyzed. Using non-parametric statistical tests, we found that MDD had the highest score in Negative Valence System (NVS) (4.1, p < 0.001), while BD exhibited the highest score in Positive Valence System (PVS) score (4.9, p < 0.001) and Arousal System (AS) (4.4, p < 0.001). SCZ demonstrated the highest scores in Cognitive Systems (CS) (5.8, p < 0.001) and Social Processes Systems (SPS) (4.6, p < 0.001). Through Bayesian network (BN) analysis, we identified relatively consistent interaction relationships among various RDoC domains (NVS → AS, NVS → CS, NVS → PVS, as well as CS → SPS; parameter range = 0.156 to 0.635, p < 0.001). Lastly, using logistic regression and Cox proportional hazards models, we demonstrated that AS was significantly associated with the length of hospital stay (-0.21, p < 0.05) and 30-day readmission risk (adjusted odds ratio [aOR] = 0.91, 95% confidence interval [CI] 0.91-0.99) to some extent. In conclusion, we suggest that the eRDoC characteristics varied in different DSM. By Bayesian Network, we found NVS and CS might be potential source in interacting with other system. Furthermore, CS, SPS and AS were associated with the length of stay and 30-days readmission, making them effective for predicting prognosis of psychiatric disorders.

A physical perspective on lithium therapy

Lithium salts have strong medical properties in neurological disorders such as bipolar disorder and lithium-responsive headaches. They have recently gathered attention due to their potential preventive effect in viral infections. Though the therapeutic effect of lithium was documented by Cade in the late 1940s, its underlying mechanism of action is still disputed. Acute lithium exposure has an activating effect on excitable organic tissue and organisms, and is highly toxic. Lithium exposure is associated with a strong metabolic response in the organism, with large changes in phospholipid and cholesterol expression. Opposite to acute exposure, this metabolic response alleviates excessive cellular activity. The presence of lithium ions strongly affects lipid conformation and membrane phase unlike other alkali ions, with consequences for membrane permeability, buffer property and excitability. This review investigates how lithium ions affect lipid membrane composition and function, and how lithium response might in fact be the body's attempt to counteract the physical presence of lithium ions at cell level. Ideas for further research in microbiology and drug development are discussed.

Transitional photoperiod induces a mania-like behavior in male mice

This study aimed to investigate the behavioral responses and circadian rhythms of mice to both rapid and gradual increases in photoperiod, mimicking the transition from winter to summer, which is associated with a heightened prevalence of hospitalizations for mania and suicidal behavior. Behavioral tests were performed in C57BL/6 male mice exposed to a transitional photoperiod, from short to long durations. To determine if circadian rhythms are affected, we measured spontaneous locomotor activity and body temperature. Mice exhibited heightened exploratory and risk-taking behaviors compared with equatorial and static long (16:8 h of light-dark cycle for several days) groups. These behaviors were prevented by lithium. Spontaneous locomotor activity and body temperature rhythms persisted and were effectively synchronized; however, the relative amplitude of activity and interdaily stability were diminished. Additionally, the animals displayed increased activity during the light phase. Photoperiodic transition modulates behavior and circadian rhythms, mirroring certain features observed in bipolar disorder patients. This study introduces an animal model for investigating mania-like behavior induced by photoperiodic changes, offering potential insights for suicide prevention strategies and the management of mood disorders.

The relationship between anxiety symptoms and disturbances in biological rhythms in patients with depression

BACKGROUND

Biological rhythms denote the cyclical patterns of life activities anchored to a 24-hour cycle. Research shows that depression exhibits disturbances in biological rhythms. Yet, the relationship between these biological rhythms and concomitant anxiety symptoms is insufficiently investigated in structured clinical assessments.

METHODS

This multicenter study, carried out in four Chinese hospitals, comprehensively examined the relationship between anxiety and disruptions in biological rhythms among patients with depression. The study encompassed 218 patients diagnosed with depression and 205 matched healthy controls. The Chinese version of the Biological Rhythms Interview of Assessment in Neuropsychiatry was utilized to evaluate the participants' biological rhythms, focusing on four dimensions: sleep, activity, social, and diet.

RESULTS

In patients with depression, there is a significant positive correlation between the severity of anxiety symptoms and the disturbances in biological rhythms. The severity of anxiety and depression, along with the quality of life, are independently associated with disruptions in biological rhythms. The mediation model reveals that anxiety symptoms mediate the relationship between depressive symptoms and biological rhythms.

CONCLUSION

This research highlights the role of anxiety within the spectrum of depressive disorders and the associated disturbances in biological rhythms. Our findings shed light on potential pathways towards more targeted preventive strategies and therapeutic interventions for individuals battling depression and anxiety.

Differential contributions of circadian clock genes to cell survival in bipolar disorder patient derived neuronal progenitor cells distinguishes lithium responders and non-responders

Bipolar disorder (BD) is characterized by disrupted circadian rhythms and neuronal loss. Lithium is neuroprotective and used to treat BD, but outcomes are variable. Past research identified that circadian rhythms in BD patient neurons are associated with lithium response (Li-R) or non-response (Li-NR). However, the underlying cellular mechanisms remain unknown. To study interactions among circadian clock genes and cell survival, and their role in BD and predicting lithium response, we tested selected genes (PER1, BMAL1 and REV-ERBα) and small molecule modulators of ROR/REV-ERB nuclear receptors in models of cell survival using mouse neurons and stem-cell derived neuronal progenitor cells (NPC) from BD patients and controls. In apoptosis assays using staurosporine (STS), lithium was neuroprotective. Knockdown of PER1, BMAL1 and REV-ERBα modified cell survival across models. In NPCs, reduced expression of PER1 and BMAL1 led to more extensive cell death in Li-NR vs. Li-R. Reduced REV-ERBα expression caused more extensive cell death in BD vs. control NPCs, without distinguishing Li-R and Li-NR. In IMHN, The REV-ERB agonist GSK4112 had strong effects on circadian rhythm amplitude, and was neuroprotective in mouse neurons and control NPCs, but not in BD NPCs. Expression of cell survival genes following STS and GSK4112 treatments revealed BD-associated, and Li-R associated differences in expression profiles. We conclude that the neuroprotective response to lithium is similar in NPCs from Li-R and Li-NR. However, knockdown of circadian clock genes or stimulation of REV-ERBs reveal distinct contributions to cell death in BD patient NPCs, some of which distinguish Li-R and Li-NR.

The Function, Regulation, and Mechanism of Protein Turnover in Circadian Systems in Neurospora and Other Species

Circadian clocks drive a large array of physiological and behavioral activities. At the molecular level, circadian clocks are composed of positive and negative elements that form core oscillators generating the basic circadian rhythms. Over the course of the circadian period, circadian negative proteins undergo progressive hyperphosphorylation and eventually degrade, and their stability is finely controlled by complex post-translational pathways, including protein modifications, genetic codon preference, protein-protein interactions, chaperon-dependent conformation maintenance, degradation, etc. The effects of phosphorylation on the stability of circadian clock proteins are crucial for precisely determining protein function and turnover, and it has been proposed that the phosphorylation of core circadian clock proteins is tightly correlated with the circadian period. Nonetheless, recent studies have challenged this view. In this review, we summarize the research progress regarding the function, regulation, and mechanism of protein stability in the circadian clock systems of multiple model organisms, with an emphasis on Neurospora crassa, in which circadian mechanisms have been extensively investigated. Elucidation of the highly complex and dynamic regulation of protein stability in circadian clock networks would greatly benefit the integrated understanding of the function, regulation, and mechanism of protein stability in a wide spectrum of other biological processes.

Insomnia and related mental health conditions: Essential neurobiological underpinnings towards reduced polypharmacy utilization rates

Insomnia represents a significant public health burden, with a 10% prevalence in the general population. Reduced sleep affects social and working functioning, productivity, and patient's quality of life, leading to a total of $100 billion per year in direct and indirect healthcare costs. Primary insomnia is unrelated to any other mental or medical illness; secondary insomnia co-occurs with other underlying medical, iatrogenic, or mental conditions. Epidemiological studies found a 40-50% comorbidity prevalence between insomnia and psychiatric disorders, suggesting a high relevance of mental health in insomniacs. Sleep disturbances also worsen the outcomes of several psychiatric disorders, leading to more severe psychopathology and incomplete remission, plausibly contributing to treatment-resistant conditions. Insomnia and psychiatric disorder coexistence can lead to polypharmacy, namely, the concurrent use of two or more medications in the same patient, regardless of their purpose or rationale. Polypharmacy increases the risk of using unnecessary drugs, the likelihood of drug interactions and adverse events, and reduces the patient's compliance due to regimen complexity. The workup of insomnia must consider the patient's sleep habits and inquire about any medical and mental concurrent conditions that must be handled to allow insomnia to be remitted adequately. Monotherapy or limited polypharmacy should be preferred, especially in case of multiple comorbidities, promoting multipurpose molecules with sedative properties and with bedtime administration. Also, non-pharmacological interventions for insomnia, such as sleep hygiene, relaxation training and Cognitive Behavioral Therapy may be useful in secondary insomnia to confront behaviors and thoughts contributing to insomnia and help optimizing the pharmacotherapy. However, insomnia therapy should always be patient-tailored, considering drug indications, contraindications, and pharmacokinetics, besides insomnia phenotype, clinical picture, patient preferences, and side effect profile.

Circadian biology to advance therapeutics for mood disorders

Mood disorders account for a significant global disease burden, and pharmacological innovation is needed as existing medications are suboptimal. A wide range of evidence implicates circadian and sleep dysfunction in the pathogenesis of mood disorders, and there is growing interest in these chronobiological pathways as a focus for treatment innovation. We review contemporary evidence in three promising areas in circadian-clock-based therapeutics in mood disorders: targeting the circadian system informed by mechanistic molecular advances; time-tailoring of medications; and personalizing treatment using circadian parameters. We also consider the limitations and challenges in accelerating the development of new circadian-informed pharmacotherapies for mood disorders.