Circadian rhythm in bipolar disorder: A review of the literature

Development and validation of a predictive model for depression in patients with advanced stage of cardiovascular-kidney-metabolic syndrome

Depression is highly prevalent among patients with chronic disease advanced and with poor clinical outcomes. However, effective tools for identifying individuals at risk remain limited. This study aimed to develop and validate a predictive model for depression in patients with advanced stage of cardiovascular-kidney-metabolic (CKM) syndrome. A total of 1072 participants from National Health and Nutrition Examination Survey (NHANES) were included, with 750 assigned to the training set and 322 to the test set. The three external validation sets consist of 164, 249, and 166 individuals. Depression was assessed using the Patient Health Questionnaire-9 (PHQ-9). Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to identify key predictors construct model 1. LASSO regression and followed with multivariate logistic regression used to construct the model 2. Random forest, support vector machines, or decision trees were used to construct the model 3, model 4, or model 5. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and calibration plots. Model 2 demonstrated the best performance among all models, with an AUC of 0.768 in the test set. The final model included sleep disorder age, sex, poverty-income ratio, waist circumference, and gamma-glutamyl transferase as significant predictors of depression. External validation showed consistent predictive accuracy, with AUCs ranging from 0.765 to 0.794 across three independent validation sets.

Exploring nightly variability and clinical influences on sleep measures: insights from a digital brain health platform

BACKGROUND

Digital technology offers a convenient way to continuously monitor sleep and assess night-to-night variability, particularly in aging populations where traditional self-reported sleep assessments may be limited.

AIMS

This study aimed to investigate nightly variability in sleep measures obtained via a ring oximeter sensor in older adults and to explore the influence of demographic and cognitive factors on the stability of these metrics.

METHODS

The study included 62 participants (mean age 74, 67.7 % women, 90.3 % White) from the Boston University Alzheimer's Disease Research Center (BU ADRC) cohort. Each participant wore a SleepImage Ring for at least three consecutive nights. Thirty-four continuous sleep measures, such as mean SpO2 and apnea-hypopnea index within unstable sleep, were analyzed. Night-to-night variability was assessed using intraclass correlation coefficients (ICC) based on a two-way random-effects model. Subgroup analyses examined variability by sex, age, and cognitive status. Group-level changes were assessed using one-way repeated measures ANOVA.

RESULTS

Seven sleep measures demonstrated high stability across nights (ICC: 0.70-0.88), with average heart rate being the most stable, followed by mean SpO2 and apnea-hypopnea indices. Sleep latency exhibited the highest variability. Stability improved between the second and third nights compared to the first and second nights. Women and participants under 75 years old showed greater stability in several metrics, while cognitively intact individuals exhibited more consistent breathing-related measures.

CONCLUSION

At least three nights of monitoring are required for reliable estimates of key sleep metrics. Expanding studies with larger samples and extended monitoring periods could further elucidate sleep variability as a potential non-invasive marker for general health.

Investigation of the relationship between biological rhythm pattern and eating attitude in patients diagnosed with bipolar disorder

BACKGROUND

In this study, it was aimed to investigate the relationship of circadian rhythm disorders with eating behavior and clinical features in patients diagnosed with Bipolar Disorder (BD).

METHODS

The study included 95 patients with BD and a control group of 60 healthy individuals. Hamilton Depression Rating Scale (HDRS), Young Mania Rating Scale (YMRS), Eating Attitudes Test (EAT), and Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) were applied to the participants who volunteered to participate in the study.

RESULTS

In the study, patients diagnosed with BD were compared with the healthy individuals in the control group in terms of circadian rhythms and eating behaviors. In the comparison, it was found that the total and subscale scores of BRIAN scale were higher in patients diagnosed with BD (BRIAN total score: 33.31 ± 9.30) compared to the control group (BRIAN total score: 25.07 ± 5.70). In addition, it was also observed that EAT scores were also higher in patients diagnosed with BD (EAT total score: 18.42 ± 9.11) compared to the control group (EAT total score: 14.82 ± 4.86). In the analysis of the relationship between circadian rhythms and eating behavior and clinical characteristics, it was found that circadian rhythms were associated with clinical characteristics but not with eating behavior (p = 0.785).

CONCLUSION

In the study, it was found that circadian rhythm disorders and eating behavior disorders were higher in patients diagnosed with BD compared to the control group. It was also observed that the deteriorated circadian rhythm was associated with clinical features.

Moving toward precision and personalized treatment strategies in psychiatry

Precision psychiatry aims to improve routine clinical practice by integrating biological, clinical, and environmental data. Many studies have been performed in different areas of research on major depressive disorder, bipolar disorder, and schizophrenia. Neuroimaging and electroencephalography findings have identified potential circuit-level abnormalities predictive of treatment response. Protein biomarkers, including IL-2, S100B, and NfL, and the kynurenine pathway illustrate the role of immune and metabolic dysregulation. Circadian rhythm disturbances and the gut microbiome have also emerged as critical transdiagnostic contributors to psychiatric symptomatology and outcomes. Moreover, advances in genomic research and polygenic scores support the perspective of personalized risk stratification and medication selection. While challenges remain, such as data replication issues, prediction model accuracy, and scalability, the progress so far achieved underscores the potential of precision psychiatry in improving diagnostic accuracy and treatment effectiveness.

Associations between light at night and mental health: A systematic review and meta-analysis

Light at night (LAN) disrupts the circadian rhythm by altering the natural light-dark cycle. With increasing interest in the relationship between LAN and mental health, there is value in an updated systematic review and meta-analysis considering prominent mental health conditions that also critically appraises LAN exposure assessment. We conducted a systematic review of six databases, two registries, and Google Scholar to identify studies examining the associations between indoor and outdoor LAN exposure (high vs. low exposure) and mental health outcomes (depression, bipolar disorder, anxiety, and schizophrenia), completing inverse-variance random-effects meta-analyses. Nineteen studies with a total population of 556,861 were included in the review. LAN exposure was associated with increased odds of depression prevalence (odds ratio [OR]: 1.18; 95 % confidence interval [CI]: 1.09 to 1.28), with stronger associations for bedside (OR: 1.45; 95 % CI: 1.03 to 2.04) or wrist-measured indoor LAN (OR: 1.30; 95 % CI: 1.22 to 1.38) than satellite-measured outdoor LAN exposure (OR: 1.10; 95 % CI: 1.04 to 1.17) and in older adults (OR: 1.56; 95 % CI: 1.24 to 1.96) compared to general adults (OR: 1.16; 95 % CI: 1.06 to 1.28) or youth (OR: 1.07; 95 % CI: 0.99 to 1.16). LAN exposure was also associated with an increased prevalence of bipolar disorder (OR: 1.19; 95 % CI: 1.08 to 1.31) and anxiety (OR: 1.10; 95 % CI: 1.02 to 1.20) and increased incidence of anxiety (hazard ratio [HR]: 1.08; 95 % CI: 1.02 to 1.15) and schizophrenia (HR: 1.55; 95 % CI: 1.01 to 2.39); however, the incidence of depression did not achieve statistical significance (HR: 1.53; 95 % CI: 0.98 to 2.38). Overall, our results suggest that LAN exposure influences adverse mental health conditions, with differences in results appreciated for depression prevalence depending on how LAN exposure was measured. Additional research is needed on the effects of LAN given its undoubted interest in the prevention and treatment of mental disorders.

Circadian attributes of neurological and psychiatric disorders as basis for their medication chronotherapy

This review focuses on (i) 24 h patterns in the symptom intensity of common neurologic and psychiatric disorders and (ii) medications prescribed for their management that have a recommended administration time or schedule, presumably to potentiate desired and minimize undesired effects and by definition qualify them as chronotherapies. Predictable-in-time patterning of symptoms is exhibited by many neurologic - headaches, multiple sclerosis, neurogenic orthostatic hypotension, neuropathic pain, Parkinson's disease, epileptic seizure, attention deficit hyperactivity, Alzheimer's disease - and psychiatric - eating, depressive, obsessive-compulsive, post-traumatic stress, anxiety, and panic - disorders, due either to circadian rhythms of disease pathophysiology or inadequacies of medication-delivery systems. Circadian disruption and circadian misalignment of the sleep-wake and other 24 h rhythms plus late chronotype are characteristic of many of these disorders, suggesting involvement in the mechanisms or consequence of their pathology or as an adverse effect of therapy, especially when administered at an inappropriate biological time. The Prescribers' Digital Reference, a compendium of all prescription medications approved for marketing in the US, reveals 65 of them are utilized to manage neurologic and psychiatric disorders by a recommended specified time-of-day or an asymmetrical interval or strength of dose schedule, presumably to optimize beneficial and minimize adverse effects, thereby qualifying them as chronotherapies. Overall, the contents of this review are intended to inform the development of future chronotherapies that incorporate state-of-the-art drug-delivery systems to improve management of neurologic and psychiatric disorders and associated circadian malalignment and disruption.

Factors associated with chronotype in individuals with bipolar disorder in remission

Background

Chronotype is trait-like construct reflecting long-term morningness-eveningness preferences. Higher eveningness scores are linked to sleep disturbances, night-eating, and addictive behaviors but remain understudied in subjects with bipolar disorder (BD).

Aim

This study aimed to explore the clinical and behavioral factors associated with chronotype in a euthymic cohort with BD.

Methods

Adult individuals (18-45 years) with DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition) diagnosis of BD in clinical remission (≥3 months) were enrolled, if they did not have current psychiatric or substance use disorder as per Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST score < 27). Participants were assessed using the validated Hindi version of Composite Scale of Morningness-Eveningness (CSM), the National Institute of Mental Health (NIMH)-Life Chart Method, IGLSI (International Group for Study of Lithium) Scale for typical/atypical features, Pittsburgh Sleep Quality Index, Cognitive complaints in BD Rating Assessment, Seasonal Pattern Assessment Questionnaire, Bipolar Eating Disorder Scale, Internet Disorder Scale, and Functioning Assessment Short Test. After data normalization, exploratory factor analysis was conducted using principal component analysis with varimax rotation on the study variables excluding the CSM. Subsequently, regression analysis was performed with CSM as the dependent variable.

Results

The mean age of the sample was 32.43 ± 7.68 years (n = 100; 35% females). Factor analysis revealed a latent structure with three factors: Factor 1 (global functioning), Factor 2 (disordered biological functions and rhythms), and Factor 3 (dysfunction due to sleep and internet use). The regression model was found to be statistically significant [F (3,96) = 5.520, P = 0.002; R2 = 0.147, adjusted R2 = 0.120). Factor-2 was a significant predictor of CSM score (B = -2.201, SE: 0.606, P < 0.001). For every unit increase in Factor 2 score, the CSM total score reduced on average by 2.2 units.

Conclusion

This study highlights the role of disrupted sleep, eating behaviors, and seasonality in influencing the chronotype and their interconnectedness in individuals with BD.

Chronotherapeutic Treatments for Psychiatric Disorders: A Narrative Review of Recent Literature

PURPOSE OF THE REVIEW

This narrative review examines the newest findings from clinical trials of chronotherapeutics for psychiatric disorders. We reviewed the potential effects of the most commonly-studied chronotherapeutics such as bright light therapy, dark therapy, melatonin, and chronotherapy on the psychiatric disorders of depression, bipolar disorder, and anxiety disorders.

RECENT FINDINGS

The preponderance of recent clinical trials in chronotherapeutics has focused on bright light therapy in depression. However, there is an emerging body of preliminary studies testing chronotherapeutics in other psychiatric disorders, including bipolar disorder and post-traumatic stress disorder. Chronotherapeutics hold potential to improve sleep in adults with psychiatric conditions as well as psychiatric symptoms. Although the most recent literature demonstrates the promise of these interventions, the current body of work is limited by small sample sizes and relatively few studies outside of depression. Larger-scale trials are needed to refine treatment protocols, develop personalized treatment approaches, and inform dissemination. Studies in psychiatric conditions besides depression are particularly needed.

Pathophysiological Models of Hypersomnolence Associated With Depression

Up to 25% of patients with depression experience hypersomnolence (e.g., excessive daytime sleepiness, hypersomnia, and/or sleep inertia), which is associated with treatment resistance, overall poorer outcomes, and safety concerns while driving. Hypersomnolence can result from various sleep/neurological disorders or side effects from medication but is often medically unexplained in depression. In this review, we aimed to summarize the different pathophysiological models of hypersomnolence in depression to discuss their impact on nosology and to foster the development of better tailored diagnostics and treatments. We identified several potential mechanisms underlying hypersomnolence including a daytime hypoactivity of dopaminergic and noradrenergic systems, nighttime GABA (gamma-aminobutyric acid) hypoactivation, hypoperfusion, and hypoconnectivity in the medial prefrontal cortex, as well as a longer circadian period and light hyposensitivity. In some patients with depression, nighttime hyperarousal can fragment sleep and result in a complaint of excessive daytime sleepiness, thus mimicking hypersomnolence. Others might adopt maladaptive behaviors such as spending excessive time in bed, a term coined clinophilia. Objective markers of hypersomnolence, such as ambulatory ad libitum polysomnography may facilitate distinguishing between conditions that mimic hypersomnolence. Our review identified several clinical targets for hypersomnolence in depression. Low-sodium oxybate, which is approved for idiopathic hypersomnia, needs additional study in patients with depression. Neuromodulation that targets prefrontal cortex anomalies should be systematically explored, while tailored light therapy protocols may mitigate light hyposensitivity. Additionally, cognitive behavioral therapy for hypersomnolence is being developed as a nonpharmacological adjunct to these treatments.

Circadian rhythm, epigenetics and disease interaction

Identifying the circadian clock first provided the genetic basis for behaviour, and our understanding of circadian rhythms has since expanded to provide molecular insight into disease and physiology. The synchronization of central and peripheral clocks and robust daily rhythms can be achieved in a wide range of physiological systems and homeostatic responses can be supplemented. The rhythmical epigenome, which works as a central regulator, determines the circadian transcription of cell types. The rhythmical epigenome imposes oscillation on biological systems that momentarily split metabolism within 24 h. Interactions between the endogenous circadian system govern blood pressure, sleep, obesity and postural variations. Human health is dependent on the circadian rhythm. It can depict disease dynamics as well as overall drug efficacy monitoring to optimize the therapy effect. Circadian rhythms can collectively drive various metabolic activities, but dietary habits, sleep patterns, and other factors can also influence the circadian rhythm. The synergy of circadian rhythm and metabolism can bring new insights and personalized analysis for disease development causes and prevention. The understanding of the molecular clock and disease relationship can be exploited to determine treatment timing as well as new therapy targets.

I "Gut" Rhythm: the microbiota as a modulator of the stress response and circadian rhythms

Modern habits are becoming more and more disruptive to health. As our days are often filled with circadian disruption and stress exposures, we need to understand how our responses to these external stimuli are shaped and how their mediators can be targeted to promote health. A growing body of research demonstrates the role of the gut microbiota in influencing brain function and behavior. The stress response and circadian rhythms, which are essential to maintaining appropriate responses to the environment, are known to be impacted by the gut microbiota. Gut microbes have been shown to alter the host's response to stress and modulate circadian rhythmicity. Although studies demonstrated strong links between the gut microbiota, circadian rhythms and the stress response, such studies were conducted in an independent manner not conducive to understanding the interface between these factors. Due to the interconnected nature of the stress response and circadian rhythms, in this review we explore how the gut microbiota may play a role in regulating the integration of stress and circadian signals in mammals and the consequences for brain health and disease.

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.

Association between sleep disorder and depression in stroke in the National Health and Nutrition Examination Surveys (NHANES) 2005 to 2014

BACKGROUND

To investigate the association between sleep disorder and depression in stroke population using data from the National Health and Nutrition Examination Surveys (NHANES) conducted between 2005 and 2014.

METHODS

Participants included stroke population who reported on sleep disorder and completed the Patient Health Questionnaire-9 (PHQ-9) to assess depressive symptom. Sleep disorder was self-reported and categorized dichotomously. Multivariate logistic regression, subgroup analysis, receiver operating characteristic curve (ROC) and restricted cubic spline (RCS) were used to explore the association between sleep disorder and depression.

RESULTS

The final sample included 566 stroke survivors (weighted n = 3,326,625). Multivariate logistic regression analysis confirmed that sleep disorder was independently associated with an increased risk of depression even after adjusting for potential confounders (OR = 2.616, 95 % CI: 2.561 to 2.599, P < 0.0001). Subgroup analysis indicated that this association was particularly strong among female stroke population (OR = 5.515). Sleep disorder as a significant predictor of depression, while the relationship between sleep time and depression is characterized by non-linearity.

CONCLUSIONS

Sleep disorder is significantly associated with an increased risk of depression in stroke. This relationship remains robust across various sociodemographic and lifestyle factors, highlighting the need for integrated interventions targeting both sleep and mood disturbances in stroke care.

Multiple-timescale dynamics, mixed mode oscillations and mixed affective states in a model of bipolar disorder

Mixed affective states in bipolar disorder (BD) is a common psychiatric condition that occurs when symptoms of the two opposite poles coexist during an episode of mania or depression. A four-dimensional model by Goldbeter (Progr Biophys Mol Biol 105:119-127, 2011; Pharmacopsychiatry 46:S44-S52, 2013) rests upon the notion that manic and depressive symptoms are produced by two competing and auto-inhibited neural networks. Some of the rich dynamics that this model can produce, include complex rhythms formed by both small-amplitude (subthreshold) and large-amplitude (suprathreshold) oscillations and could correspond to mixed bipolar states. These rhythms are commonly referred to as mixed mode oscillations (MMOs) and they have already been studied in many different contexts by Bertram (Mathematical analysis of complex cellular activity, Springer, Cham, 2015), (Petrov et al. in J Chem Phys 97:6191-6198, 1992). In order to accurately explain these dynamics one has to apply a mathematical apparatus that makes full use of the timescale separation between variables. Here we apply the framework of multiple-timescale dynamics to the model of BD in order to understand the mathematical mechanisms underpinning the observed dynamics of changing mood. We show that the observed complex oscillations can be understood as MMOs due to a so-called folded-node singularity. Moreover, we explore the bifurcation structure of the system and we provide possible biological interpretations of our findings. Finally, we show the robustness of the MMOs regime to stochastic noise and we propose a minimal three-dimensional model which, with the addition of noise, exhibits similar yet purely noise-driven dynamics. The broader significance of this work is to introduce mathematical tools that could be used to analyse and potentially control future, more biologically grounded models of BD.

Relationship between Polygenic Risk Score and the Hypnotics in Bipolar I Disorder

Objective

Bipolar disorder (BD) is marked by significant change in mood and energy levels with sleep disturbance a common feature, resulting in diminished quality of life and impaired daily functioning. This study assessed the association between BD-polygenic risk scores (PRS) and hypnotics in bipolar I disorder (BD-I) patients.

Methods

Large-sample data were collected from the genome-wide association study of a multicenter Bipolar Genomic Study, and 1,394 BD-I patients with available medication information were divided into two groups depending on whether they used hypnotics or not. The Diagnostic Interview for Genetic Studies (DIGS) score was used to assess the clinical manifestations and function of the participants and the association between the use of hypnotics and genetic risk was analyzed.

Results

Of the 1,394 total participants, 556 (40%) patients received hypnotics, mostly benzodiazepines, administered singly or in combination with other sleeping agents such as, Z-drugs, melatonin-related drugs, and trazodone. The DIGS score was significantly higher for negative categories in the group prescribed hypnotics as was the BD-PRS score, according to the four p value thresholds (p = 0.3, 0.2, 0.1, and 0.05). Logistic regression analysis confirmed a statistically significant association between the BD-PRS and hypnotic use.

Conclusion

Our results suggest an association between hypnotic use and genetic susceptibility to BD. Sleep disturbances in participants were based on the prescription status of hypnotics supporting the hypothesis that sleep disturbances may be associated with genetic aspects of BD-I. Further genetic studies on genetic overlaps between BD and specific phenotypes or medication responses are required.

Accurately predicting mood episodes in mood disorder patients using wearable sleep and circadian rhythm features

Wearable devices enable passive collection of sleep, heart rate, and step-count data, offering potential for mood episode prediction in mood disorder patients. However, current models often require various data types, limiting real-world application. Here, we develop models that predict future episodes using only sleep-wake data, easily gathered through smartphones and wearables when trained on an individual's sleep-wake history and past mood episodes. Using mathematical modeling to longitudinal data from 168 patients (587 days average clinical follow-up, 267 days wearable data), we derived 36 sleep and circadian rhythm features. These features enabled accurate next-day predictions for depressive, manic, and hypomanic episodes (AUCs: 0.80, 0.98, 0.95). Notably, daily circadian phase shifts were the most significant predictors: delays linked to depressive episodes, advances to manic episodes. This prospective observational cohort study (ClinicalTrials.gov: NCT03088657, 2017-3-23) shows sleep-wake data, combined with prior mood episode history, can effectively predict mood episodes, enhancing mood disorder management.

Are circadian rhythms more favorable with lithium than with other mood stabilizers? An exploratory actigraphy study in euthymic bipolar disorder type 1

BACKGROUND

Bipolar Disorder (BD) is associated with alterations of circadian rhythms of activity (CRA). Experimental research suggests that lithium (Li) modifies CRA, but this has been rarely explored in BD using actigraphy.

METHODS

The sample comprised 88 euthymic BD-I cases with 3 weeks of actigraphy. We used a Principal Component Analysis (PCA) to generate CRA dimensions. We then used linear regression analyses to compare these dimensions between groups of individuals defined according to prescribed mood stabilizers: Li monotherapy ("Li" group, n = 28), anticonvulsant or atypical antipsychotic monotherapy ("AC or AAP" group, n = 27) or combined treatments ("Li+AC or Li+AAP" group, n = 33). Analyses were adjusted for potential confounders (gender, age, body mass index, depressive symptoms, co-prescribed benzodiazepines and antidepressants, smoking status and past alcohol use disorder).

RESULTS

The PCA identified two dimensions: "robust CRA" (high amplitude and interdaily stability, with low intradaily variability) and "late chronotype". Univariate analyses showed higher scores for "robust CRA" in the "Li" versus the "AC or AAP" (p = 0.021) or "Li+AC or Li+AAP" groups (p = 0.047). These findings remained significant after adjustments (respectively p = 0.010 and p = 0.019). Post-hoc analyses suggested lower variability, higher stability and higher amplitude of CRA in the "Li" group. Medication groups were similar for the "late chronotype" dimension (p = 0.92).

CONCLUSIONS

This actigraphy study is the first to show more favorable CRA in BD-I individuals receiving a Li monotherapy when compared with those receiving other classes or combinations of mood stabilizers. Replications in larger samples are required. Prospective studies are also warranted to elucidate whether the introduction of Li or other mood stabilizers might influence CRA in BD-I.

Sleep and circadian disruption in bipolar disorders: From psychopathology to digital phenotyping in clinical practice

Sleep and biological rhythms are integral to mood regulation across the lifespan, particularly in bipolar disorder (BD), where alterations in sleep phase, structure, and duration occur in all mood states. These disruptions are linked to poorer quality of life, heightened suicide risk, impaired cognitive function, and increased relapse rates. This review highlights the pathophysiology of sleep disturbances in BD and aims to consolidate understanding and clinical applications of these phenomena. It also summarizes the evolution of sleep and biological rhythms assessment methods, including ecological momentary assessment (EMA) and digital phenotyping. It underscores the importance of recognizing circadian rhythm involvement in mood regulation, suggesting potential therapeutic targets. Future research directions include elucidating circadian clock gene mechanisms, understanding environmental impacts on circadian rhythms, and investigating the bidirectional relationship between sleep disturbances and mood regulation in BD. Standardizing assessment methods and addressing privacy concerns related to EMA technology and digital phenotyping are essential for advancing research. Collaborative efforts are crucial for enhancing clinical applicability and understanding the broader implications of biological rhythms in BD diagnosis and treatment. Overall, recognizing the significance of sleep and biological rhythms in BD offers promise for improved outcomes through targeted interventions and a deeper understanding of the disorder's underlying mechanisms.

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.

Pathophysiological Mechanisms of Psychosis-Induced Atrial Fibrillation: The Links between Mental Disorder and Arrhythmia

Atrial fibrillation (AF) is a common phenomenon of sustained arrhythmia leading to heart failure or stroke. Patients with mental disorders (MD), particularly schizophrenia and bipolar disorder, are at a high risk of AF triggered by the dysregulation of the autonomic nervous system, atrial stretch, oxidative stress, inflammation, and electrical or structural remodeling. Moreover, pathophysiological mechanisms underlying MD may also contribute to the genesis of AF. An overactivated hypothalamic-pituitary-adrenal axis, aberrant renin-angiotensin-aldosterone system, abnormal serotonin signaling, disturbed sleep, and genetic/epigenetic factors can adversely alter atrial electrophysiology and structural substrates, leading to the development of AF. In this review, we provide an update of our collective knowledge of the pathophysiological and molecular mechanisms that link MD and AF. Targeting the pathogenic mechanisms of MD-specific AF may facilitate the development of therapeutics that mitigate AF and cardiovascular mortality in this patient population.

Insights into the Effect of Light Pollution on Mental Health: Focus on Affective Disorders-A Narrative Review

The presence of artificial light at night has emerged as an anthropogenic stressor in recent years. Various sources of light pollution have been shown to affect circadian physiology with serious consequences for metabolic pathways, possibly disrupting pineal melatonin production with multiple adverse health effects. The suppression of melatonin at night may also affect human mental health and contribute to the development or exacerbation of psychiatric disorders in vulnerable individuals. Due to the high burden of circadian disruption in affective disorders, it has been hypothesized that light pollution impacts mental health, mainly affecting mood regulation. Hence, the aim of this review was to critically summarize the evidence on the effects of light pollution on mood symptoms, with a particular focus on the role of circadian rhythms in mediating this relationship. We conducted a narrative review of the literature in the PubMed, Scopus, and Web of Science datasets. After the screening process, eighteen papers were eligible for inclusion. The results clearly indicate a link between light pollution and the development of affective symptoms, with a central role of sleep disturbances in the emergence of mood alterations. Risk perception also represents a crucial topic, possibly modulating the development of affective symptoms in response to light pollution. The results of this review should encourage a multidisciplinary approach to the design of healthier environments, including lighting conditions among the key determinants of human mental health.

Sleep-wake changes and incident depressive symptoms in midlife women

Our study aimed to investigate the relationship between sleep-wake changes and depressive symptoms events among midlife women. We enrolled 1579 women aged 44-56 years who had no clinically relevant depressive symptoms at baseline. Depressive symptoms were assessed at each visit using the Center for Epidemiologic Studies Depression scale. At the third and fourth follow-up visits, women reported their sleep habits. The sleep midpoint was defined as the time to fall asleep plus one-half of the sleep duration. Sleep-wake changes were determined by the difference in the midpoint of sleep between the third and fourth visits, which were 1 year apart. The median follow-up time was 7 years (range 1-7 years). Cox proportional hazard models were fitted to calculate hazard ratios and 95% confidence intervals for the incidence of depressive symptoms associated with sleep-wake changes. After adjusting for potential confounding factors, the hazard ratio (95% confidence interval) of depressive symptoms for severe sleep midpoint changes was 1.51 (1.12, 2.05) compared with mild sleep midpoint changes. This relationship remained statistically significant and changed little when additionally controlling for sleep duration, sleep quality, insomnia symptoms, use of sleep medications, use of nervous medications, glucose, insulin, lipids, dietary energy intake, and C-reactive protein. Our findings indicate that exposure to long-term severe sleep-wake changes increases the risk of depressive symptoms in midlife women.

Glycyrrhizic acid treatment ameliorates anxiety-like behaviour via GLT1 and Per1/2-dependent pathways

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese medicinal herb, Glycyrrhiza.

URALENSIS

Fisch. (licorice root, chinese name: Gancao) has a variety of medicinal values and is widely used clinically. Its main active ingredient, glycyrrhizic acid (GA), is believed to have a neuroprotective effect. However, the underlying biological mechanisms of GA on stress-induced anxiety disorders are still unclear.

AIM OF THE STUDY

To investigate the anti-anxiety effect of GA and its underlying mechanism.

METHODS

We selected the anxiety model induced by repeated chronic restraint stress (CRS) for 2 h on each of 7 consecutive days. GA (4, 20, 100 mg/kg) was injected intraperitoneally once daily for 1 week. The potential GA receptors were identified using whole-cell patches and computer-assisted docking of molecules. High-throughput RNA sequencing, adeno-associated virus-mediated gene regulation, Western blotting, and RT-qPCR were used to assess the underlying molecular pathways.

RESULTS

GA alleviate depression-like and anxiety-like behaviors in CRS mice. GA decreased synaptic transmission by facilitating glutamate reuptaking in mPFC. Meanwhile, long-term GA treatment increased the expression of clock genes Per1 and Per2. Suppressing both Per1 and Per2 abolished the anxiolytic effects of GA treatment.

CONCLUSION

Our study suggests that GA may be developed for the treatment of stress-induced anxiety disorders, and its mechanism is related to GLT1 and Per1/2-dependent pathways. This presents a novel approach to discovering potent therapeutic drugs.

Improving Social and Personal Rhythm Dysregulation in Young and Old Adults with Bipolar Disorder: Post-Hoc Analysis of a Feasibility Randomized Controlled Trial Using Virtual Reality-Based Intervention

Introduction: Rehabilitative interventions employing technology play a crucial role in bipolar disorder (BD) treatment. The study aims to appraise the virtual reality (VR)-based cognitive remediation (CR) and the interpersonal rhythm approaches to treatment outcomes of BD across different age groups. Methods: Post-hoc analysis of a 12-week randomizedcontrolled cross-over feasibility trial involving people with mood disorders (BD, DSM-IV) aged 18-75 years old: thirty-nine exposed to the experimental VR-based CR vs 25 waiting list controls. People with BD relapse, epilepsy or severe eye diseases (due to the potential VR risks exposure) were excluded. Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) was used to measure the outcome. Results: Cases and controls did not statistically significantly differ in age and sex distributions. Personal rhythm scores improved over the study follow-up in the experimental vs the control group (APC = 8.7%; F = 111.9; p < 0.0001), both in young (18-45 years) (APC = 5.5%; F = 70.46; p < 0.0001) and, to a lesser extent, older (>46 years) adults (APC = 10.5%; F = 12.110; p = 0.002). Conclusions: This study observed improved synchronization of personal and social rhythms in individuals with BD after a virtual reality cognitive remediation intervention, particularly in social activity, daily activities, and chronotype, with greater benefits in the younger population.

Social and circadian rhythm dysregulation and suicide: A systematic review and meta-analysis

This systematic review of 52 studies provides a quantitative synthesis of the empirical literature on social and circadian rhythm correlates of suicidal thoughts and behaviors (STB). Small-to-medium pooled effect sizes were observed for associations between evening chronotype and STB and suicidal ideation (SI), although the pooled effect size diminished when accounting for publication bias. Three studies employed longitudinal designs and suggested eveningness was predictive of future STB, with a small-to-medium effect size. Social rhythm irregularity was also a significant correlate of STB with pooled effect sizes in the medium range. Overall circadian rhythm disruption was not associated with STB, although certain circadian rhythm metrics, including mean daytime activity, circadian rhythm sleep-wake disorder diagnosis, and actigraphy-assessed amplitude were associated with STB. Pooled effect sizes for these indices were in the medium to large range. There is a need for additional longitudinal research on actigraphy-based circadian parameters and objective markers of circadian phase (i.e., dim-light melatonin onset) to gain a clearer understanding of associations of endogenous circadian function and STB beyond that which can be captured via self-report.

The relationship between biological rhythm and perceived social support, coping styles and medication adherence in patients with bipolar disorder in Türkiye

INTRODUCTION

The disruption of biological rhythm (sleep, eating patterns, hormonal secretions, activities, and social life etc.) in individuals diagnosed with bipolar disorder makes it challenging to balance the mood of the patient and facilitates recurrence. Although social support, coping with stress, and medication adherence are known to affect prognosis, no study has been found to investigate the relationship between these factors and biological rhythm.

AIM

This descriptive and correlational design study investigated the relationship between perceived social support, coping styles and medication adherence, and biological rhythm in individuals diagnosed with bipolar disorder.

METHOD

This study was conducted with 111 patients receiving treatment in the outpatient clinics of the psychiatry department of two public hospitals in Ankara, Turkey. Biological Rhythm Interview of Assessment in Neuropsychiatry (BRIAN), Multidimensional Scale of Perceived Social Support (MSPSS), Coping Style Inventory (CSI), and Morisky Medication Adherence Scale (MMAS) were used for data collection.

RESULTS

The biological rhythm total and subscales scores were significantly and negatively related to perceived social support total, and subscales scores (p < 0.005). The biological rhythm total and most of its subscales scores were significantly and negatively related to medication adherence (p < 0.005). The biological rhythm total and domain scores were significantly and negatively related to seeking social support, self-confident, and optimistic subscales of CSI while significantly and positively related to helpless and submissive (p < 0.005).

DISCUSSION

In this study, a positive relationship was found between increased perceived social support, effective coping with stress, and adherence to medication. This study highlights that these factors may be helpful for the regulation of biological rhythm.

A Systematic Review of the Molecular and Cellular Alterations Induced by Cannabis That May Serve as Risk Factors for Bipolar Disorder

BACKGROUND

Cannabis use is a risk factor of psychiatric illness, such as bipolar disorder type-I (BDI). Indeed, cannabis use strongly influences the onset and clinical course of BDI, although the biological mechanisms underlying this interaction remain unknown. Therefore, we have reviewed the biological mechanisms affected by cannabis use that may trigger BD.

METHODS

A systematic review was carried out of articles in which gene expression was studied in cannabis users or human-derived cells exposed to tetrahydrocannabinol (THC) or cannabidiol (CBD). A second systematic review was then performed to identify articles in which gene expression was studied in BDI samples, highlighting those that described alterations to the same molecular and cellular mechanisms affected by cannabis/THC/CBD.

RESULTS

The initial search identified 82 studies on cannabis and 962 on BDI. After removing duplicates and applying the inclusion/exclusion criteria, 9 studies into cannabis and 228 on BDI were retained. The molecular and cellular mechanisms altered by cannabis use or THC/CBD exposure were then identified, including neural development and function, cytoskeletal function, cell adhesion, mitochondrial biology, inflammatory related pathways, lipid metabolism, the endocannabinoid system, the hypocretin/orexin system, and apoptosis. Alterations to those activities were also described in 19 of 228 focused on BDI.

CONCLUSIONS

The biological mechanisms described in this study may be good candidates to the search for diagnostic biomarkers and therapeutic targets for BDI. Because cannabis use can trigger the onset of BD, further studies would be of interest to determine whether they are involved in the early development of the disorder, prompting early treatment.

The efficacy of a transdiagnostic sleep intervention for outpatients with sleep problems and depression, bipolar disorder, or attention deficit disorder: study protocol for a randomized controlled trial

BACKGROUND

Patients with mental disorders have a higher prevalence of sleep problems than the general population. Sleep problems may include insomnia, circadian rhythm disorders, or hypersomnia. A transdiagnostic approach combining cognitive behavioral therapy for insomnia (CBT-I) with chronotherapy addressing a broad range of sleep problems has shown promising results in a limited number of studies. The aim of the study is to investigate the efficacy of a transdiagnostic sleep intervention for patients with sleep problems comorbid to bipolar disorder, unipolar depression, or attention deficit disorders. The primary hypothesis is that the intervention improves sleep quality compared with a control group. The secondary hypotheses are that the intervention increases subjective and objective sleep efficiency, reduces sleep onset latency, wake after sleep onset, number of awakenings, and severity of insomnia; and that it improves well-being, personal recovery, work ability, and consumption of sleep medication compared with a control group.

METHODS

The study is a randomized controlled trial enrolling 88 outpatients with bipolar disorder, major depression, or attention deficit disorder with symptoms of various sleep problems (insomnia, circadian rhythm disorders, or hypersomnia). Patients are allocated to either an intervention group receiving six sessions of transdiagnostic sleep treatment or to a control group receiving a single session of sleep hygiene education. Assessments are made at baseline, at week two, and after 6 weeks in both groups. Actigraphy is performed continuously throughout the 6-week study period for all patients. The primary outcome is changes in the subjective appraisal of sleep quality (Pittsburgh Sleep Quality Index). The secondary outcomes are changes in sleep efficiency, sleep onset latency, wake after sleep onset, number of nocturnal awakenings (based on actigraph and sleep diary data), changes in insomnia severity (Insomnia Severity Index), well-being (WHO-5 Well-Being Index), personal recovery (INSPIRE-O), work ability (Work Ability Index), and consumption of sleep medication (sleep-diaries).

DISCUSSION

The study was initiated in 2022 and the inclusion period will continue until mid-2024. The results may have implications for the development and implementation of additional treatment options for patients with mental disorders and comorbid sleep problems.

TRIAL REGISTRATION

ClinicalTrials.gov. NCT05406414. Registered on June 6, 2022.

Unraveling the interplay of circadian rhythm and sleep deprivation on mood: A Real-World Study on first-year physicians

The interplay between circadian rhythms, time awake, and mood remains poorly understood in the real-world. Individuals in high-stress occupations with irregular schedules or nighttime shifts are particularly vulnerable to depression and other mood disorders. Advances in wearable technology have provided the opportunity to study these interactions outside of a controlled laboratory environment. Here, we examine the effects of circadian rhythms and time awake on mood in first-year physicians using wearables. Continuous heart rate, step count, sleep data, and daily mood scores were collected from 2,602 medical interns across 168,311 days of Fitbit data. Circadian time and time awake were extracted from minute-by-minute wearable heart rate and motion measurements. Linear mixed modeling determined the relationship between mood, circadian rhythm, and time awake. In this cohort, mood was modulated by circadian timekeeping (p<0.001). Furthermore, we show that increasing time awake both deteriorates mood (p<0.001) and amplifies mood's circadian rhythm nonlinearly. These findings demonstrate the contributions of both circadian rhythms and sleep deprivation to underlying mood and show how these factors can be studied in real-world settings using Fitbits. They underscore the promising opportunity to harness wearables in deploying chronotherapies for psychiatric illness.

Sleep and Postpartum Psychosis: A Narrative Review of the Existing Literature

Sleep problems are extremely common during the postpartum period. The role of sleep in the development of postpartum psychosis (PP) is, however, still under-researched. This narrative review aims to (1) provide a summary of the existing evidence for the associations between sleep problems and PP, (2) discuss the relevant risk factors associated with sleep problems and PP, and (3) suggest future lines of research in this area. Some of the existing literature suggests an association between sleep problems, specifically insomnia, sleep loss and sleep disruption during pregnancy and postpartum, and PP, with the most relevant risk factors including history of bipolar disorder and time of delivery. However, it is still unclear whether the previously mentioned sleep problems are a symptom of, or a trigger for PP. Thus, further research is needed to identify the specific role of sleep problems in PP, using longitudinal designs and more objective measures of sleep. This will allow appropriate detection, intervention and support for women experiencing and/or at risk for PP.

The engagement of autophagy in maniac disease

AIMS

Mania is a prevalent psychiatric disorder with undefined pathological mechanism. Here, we reviewed current knowledge indicating the potential involvement of autophagy dysregulation in mania and further discussed whether targeting autophagy could be a promising strategy for mania therapy.

DISCUSSIONS

Accumulating evidence indicated the involvement of autophagy in the pathology of mania. One of the most well-accepted mechanisms underlying mania, circadian dysregulation, showed mutual interaction with autophagy dysfunction. In addition, several first-line drugs for mania therapy were found to regulate neuronal autophagy. Besides, deficiencies in mitochondrial quality control, neurotransmission, and ion channel, which showed causal links to mania, were intimately associated with autophagy dysfunction.

CONCLUSIONS

Although more efforts should be made to either identify the key pathology of mania, the current evidence supported that autophagy dysregulation may act as a possible mechanism involved in the onset of mania-like symptoms. It is therefore a potential strategy to treat manic disorder by correting autophagy.

Metabolome subtyping reveals multi-omics characteristics and biological heterogeneity in major psychiatric disorders

Growing evidence suggests that major psychiatric disorders (MPDs) share common etiologies and pathological processes. However, the diagnosis is currently based on descriptive symptoms, which ignores the underlying pathogenesis and hinders the development of clinical treatments. This highlights the urgency of characterizing molecular biomarkers and establishing objective diagnoses of MPDs. Here, we collected untargeted metabolomics, proteomics and DNA methylation data of 327 patients with MPDs, 131 individuals with genetic high risk and 146 healthy controls to explore the multi-omics characteristics of MPDs. First, differential metabolites (DMs) were identified and we classified MPD patients into 3 subtypes based on DMs. The subtypes showed distinct metabolomics, proteomics and DNA methylation signatures. Specifically, one subtype showed dysregulation of complement and coagulation proteins, while the DNA methylation showed abnormalities in chemical synapses and autophagy. Integrative analysis in metabolic pathways identified the important roles of the citrate cycle, sphingolipid metabolism and amino acid metabolism. Finally, we constructed prediction models based on the metabolites and proteomics that successfully captured the risks of MPD patients. Our study established molecular subtypes of MPDs and elucidated their biological heterogeneity through a multi-omics investigation. These results facilitate the understanding of pathological mechanisms and promote the diagnosis and prevention of MPDs.

The Transdiagnostic Intervention for Sleep and Circadian Dysfunction (TranS-C) in community mental health: Comorbidity and use of modules under the microscope

Sleep and circadian problems are intertwined with serious mental illness (SMI). Thus, optimizing treatments that target comorbid sleep and circadian problems and SMI is critical. Among adults with sleep and circadian problems and SMI, the present study conducted a secondary data analysis of the Transdiagnostic Intervention for Sleep and Circadian Dysfunction (TranS-C). TranS-C targets a range of sleep and circadian problems and SMI with 15 modules, seven of which are optional. In a 'real world' sample recruited from a community setting (N=121, 52.07% female, 42.97% African American or Black), we aimed to (1) elucidate patterns of sleep and circadian problems that met criteria for full diagnoses and subdiagnostic symptoms across (a) the full sample and (b) SMI diagnoses, and (2) determine whether TranS-C optional modules were delivered as intended based on participants' sleep and circadian problems. Results indicated that most participants (> 85.0%) had full diagnoses or subdiagnostic symptoms of two or more sleep and circadian problems. Further, participants exhibited heterogenous comorbidities between sleep and circadian problems and SMI diagnoses. Specifically, participants with a schizophrenia spectrum disorder (n=50), bipolar disorder (n=35), and major depressive disorder (n=26) exhibited 25, 24, and 21 patterns of sleep and circadian comorbidity, respectively. Notably, most participants with insomnia, hypersomnia, and an advanced or delayed circadian rhythm phase disorder did not receive the intended TranS-C optional modules designed to target these problems. Results underscore sleep and circadian and SMI diagnostic complexity in the community. Additionally, findings reveal discrepancies between intended and 'real-world' use of treatment modules. Future research investigating clinician decision-making-particularly when treating patients with comorbidities or using modularized treatments-is needed.

Chronotype is associated with affective temperaments, clinical severity and worse treatment outcomes in bipolar disorders: results from a two-center, cross-sectional study

OBJECTIVE

The present study was aimed at investigating the clinical correlates of evening chronotype in a population of subjects suffering from bipolar disorders (BD).

METHODS

We assessed chronotype using the Morningness-Eveningness Questionnaire. We administered the brief Temperament Evaluation of Memphis, Pisa, and San Diego, the Barratt Impulsiveness Scale, and the Alda Scale to evaluate affective temperaments, impulsiveness, and response to mood stabilisers. We performed bivariate analyses and ran a logistic regression model to analyse clinical variables associated with evening chronotype.

RESULTS

In our sample (n = 178), subjects with an evening chronotype (n = 56, 31.5%) more often suffered from BD type I and reported higher prevalence of seasonality, antidepressant-induced mood switches, psychotic, aggressive, mixed, and anxiety features, and substance use disorders. The number of lifetime suicide attempts and mood episodes was higher in this subgroup. Depressive, cyclothymic, irritable, and anxious temperament scores were higher among evening-chronotype subjects, who also displayed greater levels of impulsiveness and worse treatment response. At the logistic regression, evening chronotype was associated with depressive and irritable temperaments.

CONCLUSIONS

Subjects with evening chronotype display higher clinical severity and worse BD course. Clinicians should evaluate the presence of evening chronotype in BD subjects, especially in those with irritable or depressive temperament.Key pointsEvening chronotype is a frequent clinical feature in subjects suffering from bipolar disorders (BD);Affective temperaments, particularly depressive and irritable, are associated with evening chronotype in BD;Evening chronotype underpins higher severity of the clinical picture in BD, as well as a worse response to mood stabiliser treatment;Circadian preferences should be systematically assessed in subjects suffering from BD, with particular attention to evening preference.

Effects of Exercise on Functional Recovery in Patients with Bipolar Depression: A Study Protocol for a Randomized Controlled Trial

Treatment of bipolar disorder is prone to prolongation despite various treatments, including medication. The efficacy of exercise treatment (i.e., interventions involving physical exercise and sports intervention) for major depressive disorders has been reported for depressive symptoms, cognitive function, and sleep disturbances. However, its efficacy for bipolar disorder has yet to be established. We designed a randomized, controlled, double-blind clinical trial that includes 100 patients with bipolar disorder aged 20-65 years. This will be a cluster-randomized, two-group trial that will be conducted in ten psychiatric hospitals. The hospitals will be randomly assigned to an exercise intervention + treatment as usual (exercise) group or a placebo exercise intervention (stretching) + treatment as usual (control) group. Patients will be assessed using an extensive battery of clinical tests, physical parameters, sleep status, biological parameters (cytokines, neurotrophic factors), and genetic parameters (DNA and RNA) at baseline after a 6-week intervention period, at 10-week follow-up, and at 6-month follow-up. This innovative study may provide important evidence for the effectiveness of exercise in the treatment of bipolar depression based on clinical, biological, genetic, and physiological markers.

Chronotype and Cardiometabolic Parameters in Patients with Bipolar Disorder: Preliminary Findings

Cardiometabolic alterations are very common in bipolar disorder (BD). The aim of this study was to investigate the relationship between chronotype and cardiometabolic parameters in patients with a primary diagnosis of BD. This study is an observational clinical investigation including 170 subjects consecutively admitted to the Psychiatric Inpatient Unit of the IRCCS Ospedale Policlinico San Martino (Genoa, Italy), recruited over a period of 48 months. A psychometric tool assessing chronotype was administered and blood tests were performed. Furthermore, the atherogenic coefficient ((total cholesterol-HDL cholesterol)/HDL cholesterol), and Castelli risk index-I (total cholesterol/HDL cholesterol) and -II (LDL cholesterol/HDL cholesterol) were calculated. Patients with BD and an eveningness chronotype showed a higher body mass index, total and low-density lipotrotein cholesterol compared to patients with BD and an intermediate or morning chronotype. Furthermore, the Atherogenic Coefficient and Castelli Risk-Index I-II were found to be higher in bipolar patients with an evening chronotype. The role of chronotype in the development of obesity and cardiovascular risk is, therefore, a relationship worth being investigated, especially in the context of BD, to ameliorate the clinical and therapeutic approach, aiming at increasing the quality of life and reducing the mortality.

Microbiota-gut-brain axis mechanisms in the complex network of bipolar disorders: potential clinical implications and translational opportunities

Bipolar disorders (BD) represent a severe leading disabling mental condition worldwide characterized by episodic and often progressive mood fluctuations with manic and depressive stages. The biological mechanisms underlying the pathophysiology of BD remain incompletely understood, but it seems that there is a complex picture of genetic and environmental factors implicated. Nowadays, gut microbiota is in the spotlight of new research related to this kind of psychiatric disorder, as it can be consistently related to several pathophysiological events observed in BD. In the context of the so-called microbiota-gut-brain (MGB) axis, it is shown to have a strong influence on host neuromodulation and endocrine functions (i.e., controlling the synthesis of neurotransmitters like serotonin or mediating the activation of the hypothalamic-pituitary-adrenal axis), as well as in modulation of host immune responses, critically regulating intestinal, systemic and brain inflammation (neuroinflammation). The present review aims to elucidate pathophysiological mechanisms derived from the MGB axis disruption and possible therapeutic approaches mainly focusing on gut microbiota in the complex network of BD. Understanding the mechanisms of gut microbiota and its bidirectional communication with the immune and other systems can shed light on the discovery of new therapies for improving the clinical management of these patients. Besides, the effect of psychiatric drugs on gut microbiota currently used in BD patients, together with new therapeutical approaches targeting this ecosystem (dietary patterns, probiotics, prebiotics, and other novelties) will also be contemplated.

Exploratory study of ultraviolet B (UVB) radiation and age of onset of bipolar disorder

BACKGROUND

Sunlight contains ultraviolet B (UVB) radiation that triggers the production of vitamin D by skin. Vitamin D has widespread effects on brain function in both developing and adult brains. However, many people live at latitudes (about > 40 N or S) that do not receive enough UVB in winter to produce vitamin D. This exploratory study investigated the association between the age of onset of bipolar I disorder and the threshold for UVB sufficient for vitamin D production in a large global sample.

METHODS

Data for 6972 patients with bipolar I disorder were obtained at 75 collection sites in 41 countries in both hemispheres. The best model to assess the relation between the threshold for UVB sufficient for vitamin D production and age of onset included 1 or more months below the threshold, family history of mood disorders, and birth cohort. All coefficients estimated at P ≤ 0.001.

RESULTS

The 6972 patients had an onset in 582 locations in 70 countries, with a mean age of onset of 25.6 years. Of the onset locations, 34.0% had at least 1 month below the threshold for UVB sufficient for vitamin D production. The age of onset at locations with 1 or more months of less than or equal to the threshold for UVB was 1.66 years younger.

CONCLUSION

UVB and vitamin D may have an important influence on the development of bipolar disorder. Study limitations included a lack of data on patient vitamin D levels, lifestyles, or supplement use. More study of the impacts of UVB and vitamin D in bipolar disorder is needed to evaluate this supposition.

Candidate biomarkers in psychiatric disorders: state of the field

The field of psychiatry is hampered by a lack of robust, reliable and valid biomarkers that can aid in objectively diagnosing patients and providing individualized treatment recommendations. Here we review and critically evaluate the evidence for the most promising biomarkers in the psychiatric neuroscience literature for autism spectrum disorder, schizophrenia, anxiety disorders and post-traumatic stress disorder, major depression and bipolar disorder, and substance use disorders. Candidate biomarkers reviewed include various neuroimaging, genetic, molecular and peripheral assays, for the purposes of determining susceptibility or presence of illness, and predicting treatment response or safety. This review highlights a critical gap in the biomarker validation process. An enormous societal investment over the past 50 years has identified numerous candidate biomarkers. However, to date, the overwhelming majority of these measures have not been proven sufficiently reliable, valid and useful to be adopted clinically. It is time to consider whether strategic investments might break this impasse, focusing on a limited number of promising candidates to advance through a process of definitive testing for a specific indication. Some promising candidates for definitive testing include the N170 signal, an event-related brain potential measured using electroencephalography, for subgroup identification within autism spectrum disorder; striatal resting-state functional magnetic resonance imaging (fMRI) measures, such as the striatal connectivity index (SCI) and the functional striatal abnormalities (FSA) index, for prediction of treatment response in schizophrenia; error-related negativity (ERN), an electrophysiological index, for prediction of first onset of generalized anxiety disorder, and resting-state and structural brain connectomic measures for prediction of treatment response in social anxiety disorder. Alternate forms of classification may be useful for conceptualizing and testing potential biomarkers. Collaborative efforts allowing the inclusion of biosystems beyond genetics and neuroimaging are needed, and online remote acquisition of selected measures in a naturalistic setting using mobile health tools may significantly advance the field. Setting specific benchmarks for well-defined target application, along with development of appropriate funding and partnership mechanisms, would also be crucial. Finally, it should never be forgotten that, for a biomarker to be actionable, it will need to be clinically predictive at the individual level and viable in clinical settings.

Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation

Delayed sleep-wake phase disorder (DSWPD) is a sleep disorder in which the habitual sleep-wake timing is delayed, resulting in difficulty in falling asleep and waking up at the desired time. Patients with DSWPD frequently experience fatigue, impaired concentration, sleep deprivation during weekdays, and problems of absenteeism, which may be further complicated by depressive symptoms. DSWPD is typically prevalent during adolescence and young adulthood. Although there are no studies comparing internationally, the prevalence of DSWPD is estimated to be approximately 3% with little racial differences between Caucasians and Asians. The presence of this disorder is associated with various physiological, genetic and psychological as well as behavioral factors. Furthermore, social factors are also involved in the mechanism of DSWPD. Recently, delayed sleep phase and prolonged sleep duration in the young generation have been reported during the period of COVID-19 pandemic-related behavioral restrictions. This phenomenon raises a concern about the risk of a mismatch between their sleep-wake phase and social life that may lead to the development of DSWPD after the removal of these restrictions. Although the typical feature of DSWPD is a delay in circadian rhythms, individuals with DSWPD without having misalignment of objectively measured circadian rhythm markers account for approximately 40% of the cases, wherein the psychological and behavioral characteristics of young people, such as truancy and academic or social troubles, are largely involved in the mechanism of this disorder. Recent studies have shown that DSWPD is frequently comorbid with psychiatric disorders, particularly mood and neurodevelopmental disorders, both of which have a bidirectional association with the pathophysiology of DSWPD. Additionally, patients with DSWPD have a strong tendency toward neuroticism and anxiety, which may result in the aggravation of insomnia symptoms. Therefore, future studies should address the effectiveness of cognitive-behavioral approaches in addition to chronobiological approaches in the treatment of DSWPD.

Gut microbiota and circadian rhythm in Alzheimer's disease pathophysiology: a review and hypothesis on their association

Alzheimer's disease (AD) is the most common neurodegenerative disease and the leading cause of dementia worldwide. Different pathologic changes have been introduced to be involved in its progression. Although amyloid-β (Aβ) deposition and tau hyperphosphorylation and aggregation are mainly considered the main characterizations of AD, several other processes are involved. In recent years, several other changes, including alterations in gut microbiota proportion and circadian rhythms, have been noticed due to their role in AD progression. However, the exact mechanism indicating the association between circadian rhythms and gut microbiota abundance has not been investigated yet. This paper aims to review the role of gut microbiota and circadian rhythm in AD pathophysiology and introduces a hypothesis to explain their association.

Association of 24 h Behavior Rhythm with Non-Alcoholic Fatty Liver Disease among American Adults with Overweight/Obesity

Emerging evidence suggests that in addition to metabolic, genetic and environmental factors, circadian rhythm also plays a role in non-alcoholic fatty liver disease (NAFLD). This study aimed to explore the association of 24 h behavior rhythm (activity-rest and feeding-fasting rhythm) with NAFLD. A total of 4502 adult participants with overweight/obesity from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 were included in the current study. The behavior rhythm indices were calculated and divided into quintiles for logistic regression models. Compared to those in the lowest quintile, participants in the highest quintile of relative amplitude (RA) had a lower risk of NAFLD (OR = 0.71, 95% CI, 0.55-0.91); participants in the highest quintile of the average activity of the least active continuous 5 h period (L5) were associated with a higher risk of NAFLD (OR = 1.35, 95% CI, 1.07-1.71). Additionally, participants in the highest quintile of fasting duration and feeding rhythm score were associated with a lower risk of NAFLD relative to those in the lowest quintile (OR = 0.76, 95% CI, 0.59-0.98 for fasting duration, OR = 0.74, 95% CI, 0.58-0.95 for feeding rhythm score). The associations were stronger among participants with obesity. No significant associations were found in the relationship of other behavior rhythm indices with NAFLD. This study indicated a significant association of 24 h behavior rhythm with NAFLD among American adults with overweight/obesity.

Biological rhythms disruption mediates the association between mother's diagnosis of bipolar disorder and offspring's emotional/behavioral problems

OBJECTIVE

The current study assesses whether the association between diagnosis of Bipolar Disorder (BD) in mothers and emotional and behavioral problems (EBP) in their offspring is mediated by a disruption in the offspring's biological rhythms.

METHODS

A probabilistic sample of 492 public school children (ages 7-8, 48 % female) were assessed for biological rhythms disruption and EBP using the Biological Rhythms Interview for Assessment in Neuropsychiatry for Kids and the Strengths and Difficulties Questionnaire, respectively. Mothers' mental health (BD = 64) was evaluated using a standardized clinical interview. A mediation analysis was conducted to assess the effect of the mother's diagnosis of BD on the EBP of their offspring in relation to the offspring's biological rhythms disruptions.

RESULTS

When compared to offspring of mothers without BD, offspring of mothers with BD showed greater difficulty in maintaining biological rhythms and higher prevalence of EBP. Using the presence of EBP as the outcome, 75 % of the effect of mother's BD diagnosis was mediated by offspring's biological rhythms disruption.

CONCLUSIONS

Biological rhythms disruption in children fully mediates the effect of the mother's diagnosis of BD on the child's EBP. These data encourage the development of further studies to find effective strategies to prevent and treat biological rhythms disruption in offspring of mothers with BD.

Habitual light exposure and circadian activity rhythms in bipolar disorder: A cross-sectional analysis of the APPLE cohort

BACKGROUND

Circadian activity rhythm disruption is a core feature in bipolar disorder. We investigated whether light exposure in daily life is associated with circadian activity rhythms in patients with bipolar disorder.

METHODS

In a cross-sectional study, we enrolled 194 outpatients with bipolar disorder who were participants of the Association between Pathology of Bipolar Disorder and Light Exposure in Daily Life (APPLE) cohort study. The participants' physical activity and daytime illuminance were measured using an actigraph over 7 consecutive days. Nighttime illuminance in the bedroom was measured using a portable photometer. Circadian activity rhythm parameters were calculated using cosinor analysis and a nonparametric circadian rhythm analysis.

RESULTS

The median daytime illuminance and nighttime illuminance were 224.5 lx (interquartile range, 154.5-307.5 lx) and 2.3 lx (0.3-9.4 lx), respectively. Multivariable linear regression analysis, adjusted for potential confounding factors, showed that higher daytime illuminance was significantly associated with higher amplitude and most active continuous 10-hour period, advanced acrophase, higher interdaily stability, and lower intradaily variability. Higher nighttime illuminance was significantly associated with lower relative amplitude, delayed onset of the least active continuous 5-hour period, and higher intradaily variability.

LIMITATIONS

As this was a cross-sectional study, the results do not necessarily imply that light exposure alters circadian activity rhythms.

CONCLUSIONS

Daytime light exposure was associated with a positive effect and nighttime light exposure with a negative effect on circadian activity rhythms in bipolar disorder.

Circadian rhythm disruptions: A possible link of bipolar disorder and endocrine comorbidities

Epidemiological studies have demonstrated an association between bipolar disorder (BP) and endocrine diseases. Further, circadian rhythm disruptions may be a potential common pathophysiological mechanism of both disorders. This review provides a brief overview of the molecular mechanisms of circadian rhythms, as well as roles circadian rhythms play in BP and common endocrine comorbidities such as diabetes and thyroid disease. Treatments targeting the circadian system, both pharmacological and non-pharmacological, are also discussed. The hope is to elicit new interest to the importance of circadian system in BP and offer new entry points and impetus to the development of medicine.

The relationship between physical activity states and depressive symptoms: Using ambulatory assessment to characterize day-to-day associations among individuals with and without bipolar spectrum disorder

INTRODUCTION

The role of activation in the pathogenesis of bipolar spectrum disorders (BSD) is of growing interest. Physical activity is known to improve mood, but it is unclear whether low activity levels contribute to inter-episode depressive symptoms observed in BSD. This study examined whether sedentary and vigorous activity, as well as the timing of the activity, were differentially associated with next-day depressive symptoms for individuals at low risk for BSD, high-risk for BSD, and diagnosed with BSD.

METHODS

Young adults (n = 111, ages 18-27) from three groups (low BSD risk, high BSD risk, and BSD diagnosis), participated in a 20-day ecological momentary assessment study. Physical activity was measured via wrist actigraphy counts. The percentage of time awake spent in sedentary, light, moderate, and vigorous activity states was calculated, as was the percentage of morning hours and evening hours in each activity state. Multilevel models examined whether the BSD risk group moderated associations between sedentary and vigorous activity and depressive symptoms, which were assessed three times daily.

RESULTS

There were no between-group differences in time spent in each activity state, nor were there main effects of sedentary or vigorous activity on depression. Increased time spent engaging in vigorous activity was associated with a greater reduction in subsequent depressive symptoms for the BSD group. An increase in the evening, but not morning, vigorous activity was significantly associated with a reduction in subsequent depressive symptoms for the BSD group after controlling for chronotype.

CONCLUSIONS

Interventions targeting physical activity may effectively help regulate inter-episode mood disturbances in BSD.

Cognitive profiles in bipolar I disorder and associated risk factors: Using Wechsler adult intelligence scale—IV

Background

Despite the growing evidence of cognitive impairments in bipolar disorder (BD), little work has evaluated cognitive performances utilizing the latest version of the Wechsler Intelligence Scale-IV (WAIS-IV), which is one of the most widely used neurocognitive assessments in clinical settings. Furthermore, clinical characteristics or demographic features that negatively affect the cognitive functioning of BD were not systematically compared or evaluated. Accordingly, the present study aimed to examine the cognitive profile of bipolar I disorder (BD-I) patients and associated risk factors.

Methods

Participants included 45 patients, diagnosed with BD-I, current or most recent episode manic, and matching 46 healthy controls (HC). Cognitive performance was evaluated via WAIS-IV, and clinical characteristics of the BD-I group were examined via multiple self- and clinician-report questionnaires.

Results

Multivariate analysis of covariance (MANCOVA) results indicated that the BD-I group demonstrated significantly poorer performance compared to the HC group in subtests and indexes that reflect working memory and processing speed abilities. Redundancy analysis revealed that overall symptom severity, manic symptom severity, and anxiety were significant predictors of cognitive performance in BD-I, while age of onset, past mood disorder history, depression severity, and impulsiveness showed comparatively smaller predictive values.

Conclusion

The current study suggests cognitive deterioration in the cognitive proficiency area while generalized ability, including verbal comprehension and most of the perceptual reasoning skills, remain intact in BD-I. The identified risk factors of cognitive performance provide specific clinical recommendations for intervention and clinical decision-making.

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.

The Microbiota-Gut-Brain Axis in Psychiatric Disorders

Modulating the gut microbiome and its influence on human health is the subject of intense research. The gut microbiota could be associated not only with gastroenterological diseases but also with psychiatric disorders. The importance of factors such as stress, mode of delivery, the role of probiotics, circadian clock system, diet, and occupational and environmental exposure in the relationship between the gut microbiota and brain function through bidirectional communication, described as "the microbiome-gut-brain axis", is especially underlined. In this review, we discuss the link between the intestinal microbiome and the brain and host response involving different pathways between the intestinal microbiota and the nervous system (e.g., neurotransmitters, endocrine system, immunological mechanisms, or bacterial metabolites). We review the microbiota alterations and their results in the development of psychiatric disorders, including major depressive disorder (MDD), schizophrenia (SCZ), bipolar disorder (BD), autism spectrum disorder (ASD), and attention-deficit hyperactivity disorder (ADHD).