Neuromolecular Etiology of Bipolar Disorder: Possible Therapeutic Targets of Mood Stabilizers

Long non-coding RNAs in bipolar disorder

Bipolar disorder is characterized by alternating episodes of mania or hypomania and depression, encompassing various forms such as cyclothymia, bipolar I disorder, and bipolar II disorder. Manic periods present with increased energy and decreased sleep, whereas depressive episodes involve poor energy and extended sleep duration. Despite the availability of treatments, approximately 30% of patients with bipolar disorder are drug resistant and require alternative strategies. Recent research highlights the role of long noncoding RNAs (lncRNAs) as potential biomarkers for bipolar disorder, aiding in distinguishing it from other mood disorders and improving diagnostic accuracy. LncRNAs such as GAS5 and FOXD3-AS1 are downregulated in bipolar disorder patients, suggesting their utility as diagnostic tools. LncRNAs regulate gene expression through interactions with DNA, RNA, and proteins, influencing various biological processes. Studies have identified several lncRNAs linked to bipolar disorder, including lincRNA-p21, lincRNA-ROR, and lincRNA-PINT. These findings underscore the potential of lncRNAs as biomarkers and therapeutic targets, facilitating more personalized treatment strategies. This review explores the diagnostic and therapeutic potential of lncRNAs in bipolar disorder, aiming to enhance the current understanding and management of this condition.

Antidepressants in Bipolar Depression: From Neurotransmitter Mechanisms to Clinical Challenges

Bipolar disorder (BD) is characterized by the occurrence of manic/hypomanic and depressive episodes, with the latter having a significant impact on morbidity, mortality and overall quality of life. Current guidelines for bipolar depression provide limited treatment options, with only a few approved therapies. Despite these limitations, approximately 50-60% of individuals diagnosed with BD are prescribed antidepressants. However, the use of these medications remains controversial due to risks of manic induction, rapid cycling, and symptom destabilization. This review explores the neurotransmitter mechanisms underpinning the phases of BD, focusing on monoamines and assessing the efficacy and safety of different antidepressant medications in the treatment of bipolar depression. Norepinephrine and dopamine have been identified as neurotransmitters associated with both depressive and manic poles, with a proposed deficit in depression and an increase in mania. The evidence indicates that serotonin is deficient during depressive phases, yet its imbalance also manifests in mania. Selective serotonin reuptake inhibitors (SSRIs), which primarily increase serotonin levels, are generally safer than tricyclic antidepressants (TCAs) and show promising-though not definitive-results, especially when combined with mood stabilizers. Other newer-generation antidepressants may also have potential for the treatment of bipolar depression. The heterogeneity of mood disorders poses a significant challenge in the diagnosis of BD, which is often ambiguous and complex. The natural mood fluctuations associated with BD, in conjunction with the frequent comorbidities such as anxiety, render the treatment of this condition particularly challenging, particularly in the context of antidepressant therapy. While clinical trials are conducted with the utmost rigor, they frequently fail to account for the intricacies of the real-world context due to the strict inclusion criteria. The identification of predictors of effective antidepressant use, such as symptom severity and comorbid conditions, has the potential to enhance treatment outcomes. Future research should aim to identify individualized predictors and deepen understanding of mood disorder spectra to optimize antidepressant use in bipolar depression.

Untangling the complex relationship between bipolar disorder and anxiety: a comprehensive review of prevalence, prognosis, and therapy

Bipolar disorder (BD) frequently coexists with anxiety disorders, creating complex challenges in clinical therapy and management. This study investigates the prevalence, prognostic implications, and treatment strategies for comorbid BD and anxiety disorders. High comorbidity rates, particularly with generalized anxiety disorder, underscore the necessity of thorough clinical assessments to guide effective management. Our findings suggest that anxiety disorders may serve as precursors to BD, especially in high-risk populations, making early detection of anxiety symptoms crucial for timely intervention and prevention. We also found that comorbid anxiety can negatively affect the course of BD, increasing clinical severity, reducing treatment responsiveness, and worsening prognosis. These complexities highlight the need for caution in using antidepressants, which may destabilize mood. Alternatively, cognitive-behavioral therapy presents a promising, targeted approach for managing BD with comorbid anxiety. In summary, this study provides essential insights for clinicians and researchers, enhancing understanding of BD and anxiety comorbidity and guiding more precise diagnostics and tailored interventions to improve overall patient care.

Screen time and manic symptoms in early adolescents: prospective findings from the Adolescent Brain Cognitive Development Study

PURPOSE

This study aimed to examine prospective associations between screen time and manic symptoms in early adolescents, and the extent to which problematic screen use (characterized by addiction, conflict, relapse, and withdrawal) mediates the association.

METHODS

We analyzed prospective cohort data from the Adolescent Brain Cognitive Development Study (N = 9,243; ages 10-11 years in Year 1 in 2017-2019; 48.8% female; 44.0% racial/ethnic minority). Participants reported daily time spent on six different screen subtypes. Linear regression analyses were used to determine associations between typical daily screen time (Year 1; total and subtypes) and manic symptoms (Year 3, 7 Up Mania scale), adjusting for potential confounders. Sleep duration, problematic social media use, and problematic video game use (Year 2) were tested as potential mediators.

RESULTS

Adjusting for covariates, overall typical daily screen time in Year 1 was prospectively associated with higher manic symptoms in Year 3 (B = 0.05, 95% CI 0.03, 0.07, p < 0.001), as were four subtypes: social media (B = 0.20, 95% CI 0.09, 0.32, p = 0.001), texting (B = 0.18, 95%CI 0.08, 0.28, p < 0.001), videos (B = 0.14, 95% CI 0.08, 0.19, p < 0.001), and video games (B = 0.09, 95% CI 0.04, 0.14, p = 0.001). Problematic social media use, video game use, and sleep duration in Year 2 were found to be significant partial mediators (47.7%, 58.0%, and 9.0% mediation, respectively).

CONCLUSION

Results indicate significant prospective relationships between screen time and manic symptoms in early adolescence and highlight problematic screen use, video game use, and sleep duration as potential mediators. Problematic screen use may be a target for mental health prevention and early intervention efforts among adolescents.

Plausible therapeutic effects of melatonin and analogs in the dopamine-associated pathophysiology of bipolar disorder

Bipolar disorder (BD) is a significant neuropsychiatric condition characterized by marked psychological mood disturbances. Despite extensive research on the symptomatology of BD, the mechanisms underlying its development and presentation remain unknown. Consequently, potential treatments are limited, and existing medications often cause significant side effects, leading to treatment discontinuation. Dopamine (DA) has been implicated in behavioral regulation, reward systems, and mood, highlighting the importance of the dopaminergic system in BD. Elevated levels of DA and tyrosine hydroxylase are associated with the onset of manic episodes, whereas reduced levels are linked to the depressive phase. Additionally, endogenous melatonin (MEL) levels are considerably lower in patients with BD. When administered as a treatment, exogenous MEL and MEL agonists improve behavioral characteristics and significantly modulate DA-related pathophysiological pathways in BD, with minimal adverse effects achieved through MEL receptor activation. Moreover, MEL and MEL agonists offer neuroprotection by promoting physiological homeostasis during disruption. The aim of this review is to investigate and propose MEL receptors as potential novel therapeutic targets for BD. This review seeks to analyze the role of MEL and its agonists in modulating dopamine-related pathophysiological pathways, improving behavioral outcomes, and providing neuroprotection with minimal side effects.

Causality of multiple serum metabolites on emotional lability: A two-sample Mendelian randomization study

BACKGROUND

Emotional lability (EL)-a transdiagnostic feature characterized by rapid emotional shifts-contributes significantly to functional impairment across psychiatric disorders, such as depression, bipolar disorder, and schizophrenia. Despite its clinical significance, its etiology remains poorly understood, hindering effective screening and interventions. Growing evidence suggests that metabolic alterations may play a crucial role in the pathophysiology of psychiatric disorders.

METHODS

A comprehensive Mendelian randomization (MR) design incorporated summary-level data from extensive genome-wide association studies (GWAS) on serum metabolites (8299 European participants) and EL (3268 European samples) to investigate causal associations between genetically determined metabolite levels and EL. Assumptions of instrumental variables, heterogeneity, horizontal pleiotropy, and directionality were assessed alongside sensitivity analyses.

RESULTS

Out of 1400 metabolites and ratios analyzed, 30 metabolites demonstrated causal associations with an increased risk of EL based on the inverse-variance weighted method. Sensitivity analyses identified three potential causal metabolites: hydrocinnamate (OR: 1.277, CI: 1.071-1.522, P = 0.0063), which is associated with an increased risk, while glycolithocholate (OR: 0.779, CI: 0.667-0.911, P = 0.0017) and 3β-hydroxy-5-cholenoic acid (OR: 0.857, CI: 0.756-0.971, P = 0.015) are associated with a decreased risk.

CONCLUSION

This MR study supports a causal link between hydrocinnamate, glycolithocholate, and 3β-hydroxy-5-cholenoic acid levels and the incidence of EL, offering potential metabolic biomarkers and therapeutic targets for EL in psychiatric disorders.

Understanding immune system dysfunction and its context in mood disorders: psychoneuroimmunoendocrinology and clinical interventions

Mood disorders include a set of psychiatric manifestations of increasing prevalence in our society, being mainly represented by major depressive disorder (MDD) and bipolar disorder (BD). The etiopathogenesis of mood disorders is extremely complex, with a wide spectrum of biological, psychological, and sociocultural factors being responsible for their appearance and development. In this sense, immune system dysfunction represents a key mechanism in the onset and pathophysiology of mood disorders, worsening mainly the central nervous system (neuroinflammation) and the periphery of the body (systemic inflammation). However, these alterations cannot be understood separately, but as part of a complex picture in which different factors and systems interact with each other. Psychoneuroimmunoendocrinology (PNIE) is the area responsible for studying the relationship between these elements and the impact of mind-body integration, placing the immune system as part of a whole. Thus, the dysfunction of the immune system is capable of influencing and activating different mechanisms that promote disruption of the psyche, damage to the nervous system, alterations to the endocrine and metabolic systems, and disruption of the microbiota and intestinal ecosystem, as well as of other organs and, in turn, all these mechanisms are responsible for inducing and enhancing the immune dysfunction. Similarly, the clinical approach to these patients is usually multidisciplinary, and the therapeutic arsenal includes different pharmacological (for example, antidepressants, antipsychotics, and lithium) and non-pharmacological (i.e., psychotherapy, lifestyle, and electroconvulsive therapy) treatments. These interventions also modulate the immune system and other elements of the PNIE in these patients, which may be interesting to understand the therapeutic success or failure of these approaches. In this sense, this review aims to delve into the relationship between immune dysfunction and mood disorders and their integration in the complex context of PNIE. Likewise, an attempt will be made to explore the effects on the immune system of different strategies available in the clinical approach to these patients, in order to identify the mechanisms described and their possible uses as biomarkers.

Association of early- and late-life bipolar disorder with incident dementia. A Danish cohort study

BACKGROUND

This study aimed to explore the association between bipolar disorder and the risk of developing dementia, and whether the risk varies with age at the onset of bipolar disorder.

METHODS

In this study, 37,084 individuals with a first-time diagnosis of bipolar disorder diagnosed between 1969 and 2018 and a reference population (n = 189,662) matched on sex, birth year and time of bipolar diagnosis (index date) were followed in nationwide registries for incident dementia until October 2020. Associations were analysed using Cox proportional hazard regression with adjustment for sex, education level, alcohol or drug abuse, traumatic brain injury, ischemic heart disease, stroke and diabetes mellitus.

RESULTS

In total, 6.6 % of individuals with bipolar disorder and 4.0 % in the reference population developed dementia during the mean follow-up of 13.1 years. Compared to the reference population, individuals with bipolar disorder had a higher incidence of dementia during follow-up after adjusting for potential confounders (HR: 2.66, 95 % CI [2.53-2.79]). The strength of this association did not vary among individuals diagnosed with bipolar disorder before and after age 45.

LIMITATIONS

The higher risk of dementia identified for individuals with bipolar disorder could be influenced by detection bias and, despite a large cohort, some of the age-stratified analyses were still affected by lack of statistical power.

CONCLUSION

Individuals with bipolar disorder have a higher risk of developing dementia compared to a reference population without bipolar disorder, independent of the age at the onset of bipolar disorder.

Unlocking new avenues for neuropsychiatric disease therapy: the emerging potential of Peroxisome proliferator-activated receptors as promising therapeutic targets

RATIONALE

Peroxisome proliferator-activated receptors (PPARs) are transcription factors that regulate various physiological processes such as inflammation, lipid metabolism, and glucose homeostasis. Recent studies suggest that targeting PPARs could be beneficial in treating neuropsychiatric disorders by modulating neuronal function and signaling pathways in the brain. PPAR-α, PPAR-δ, and PPAR-γ have been found to play important roles in cognitive function, neuroinflammation, and neuroprotection. Dysregulation of PPARs has been associated with neuropsychiatric disorders like bipolar disorder, schizophrenia, major depression disorder, and autism spectrum disorder. The limitations and side effects of current treatments have prompted research to target PPARs as a promising novel therapeutic strategy. Preclinical and clinical studies have shown the potential of PPAR agonists and antagonists to improve symptoms associated with these disorders.

OBJECTIVE

This review aims to provide an overview of the current understanding of PPARs in neuropsychiatric disorders, their potential as therapeutic targets, and the challenges and future directions for developing PPAR-based therapies.

METHODS

An extensive literature review of various search engines like PubMed, Medline, Bentham, Scopus, and EMBASE (Elsevier) databases was carried out with the keywords "PPAR, Neuropsychiatric disorders, Oxidative stress, Inflammation, Bipolar Disorder, Schizophrenia, Major depression disorder, Autism spectrum disorder, molecular pathway".

RESULT & CONCLUSION

Although PPARs present a hopeful direction for innovative therapeutic approaches in neuropsychiatric conditions, additional research is required to address obstacles and convert this potential into clinically viable and individualized treatments.

BI-REAL: A 12-session DBT skills group intervention adapted for bipolar disorder - A feasibility randomised pilot trial

International guidelines endorse psychological treatment for Bipolar Disorder (BD); however, the absence of a recognised gold-standard intervention requires further research. A Dialectical Behaviour Therapy (DBT) skills group intervention with 12 sessions was developed. This pilot randomised controlled trial (RCT) aims to evaluate the feasibility, acceptability, and outcomes variance of Bi-REAL - Respond Effectively, Assertively, and Live mindfully, tailored for individuals with BD, in preparation for a future RCT.

METHODS

52 participants (female = 62.7 %; mean age = 43.2 ± 11.1) with BD were randomised by blocks to either the experimental group (EG; n = 26; Bi-REAL + Treatment as Usual, TAU) receiving 12 weekly 90-minutes sessions, or the control group (CG; n = 26, TAU). Feasibility and acceptability were assessed with a multimethod approach (qualitative interviews, semi-structured clinical interviews and a battery of self-report questionnaires - candidate main outcomes Bipolar Recovery Questionnaire (BRQ) and brief Quality of Life for Bipolar Disorder (QoL.BD)). All participants were evaluated at baseline (T0), post-intervention (T1) and 3-month follow-up (T2).

RESULTS

Acceptability was supported by participants' positive feedback and ratings of the sessions and programme overall, as well as the treatment attendance (86.25 % of sessions attended). The trial overall retention rate was 74.5 %, with CG having a higher dropout rate across the 3-timepoints (42.31 %). A significant Time × Group interaction effect was found for BRQ and QoL.BD favouring the intervention group (p < .05).

LIMITATIONS

The assessors were not blind at T1 (only at T2). Recruitment plan was impacted due to COVID-19 restrictions and replication is questionable. High attrition rates in the CG.

CONCLUSIONS

The acceptability of Bi-REAL was sustained, and subsequent feasibility testing will be necessary to establish whether the retention rates of the overall trial improve and if feasibility is confirmed, before progressing to a definitive trial.

Pharmacological Mechanism of Herbal Interventions for Bipolar Disorder

Bipolar disorder is a neuropsychiatric disease characterized by an abundance of undesired ideas and thoughts associated with recurrent episodes of mania or hypomania and depression. Alterations in the circuits, including the prefrontal cortex, striatum, and limbic system, regulate mood and cause variation in several crucial neurotransmitters, including serotonin, dopamine, GABA, and glutamate. Imbalances in dopamine levels have been implicated in the manic phase, while variance in serotonin is linked to depressive episodes. The precise pathophysiology of bipolar disorder is still unknown. Though different treatments are available, like lithium, risperidone, valproic acid, etc., which are widely used, they come with certain limitations, including narrow therapeutic index, hypothyroidism, weight gain, extrapyramidal symptoms, etc. The interest in herbal- based treatments for bipolar disorder arises from the desire for alternative, potentially more natural, and holistic approaches with fewer side effects. The current review focuses on the potential effects of herbal drugs and their derivatives to alleviate the symptoms of bipolar disorder.

Detection of bipolar disorder in the prodromal phase: A systematic review of assessment instruments

BACKGROUND

Early detection of prodromal symptoms may contribute to improving the prognosis of patients with bipolar disorder (BD). The main objective of this systematic review is to present the different procedures for the identification of initial and relapse prodromes in these patients.

METHODS

PsycINFO, Web of Science and PubMed databases were searched using a predetermined strategy, until January 4, 2022. Then, by means of a regulated process, studies that used a BD prodrome detection procedure, in English-language and all ages participants were selected. Quantitative and qualitative studies were assessed using a modified version of the Newcastle-Ottawa Scale and by Critical Appraisals Skills Programme checklist, respectively.

RESULTS

Forty-five studies were selected. Of these, 26 used procedures for identifying initial prodromes (n = 8014) and 19 used procedures for detecting relapse prodromes (n = 1136). The interview was the most used method in the detection of both types of prodromes (k = 30 papers, n = 4068). It was variable in its degree of structure. Mobile applications and digital technologies are gaining importance in the detection of the relapse prodromes.

LIMITATIONS

A retrospective design in most papers, small samples sizes, existence of persistent subsyndromal symptoms and difficulty to identify the end of the prodrome and the onset of the disorder.

CONCLUSIONS

There is a wide variety of assessment instruments to detect prodromes in BD, among which the clinical interview is most frequently used. Future research should consider development of a brief tool to be applied in different formats to patients and family members.

Psychometric Properties of the Korean Version of Functioning Assessment Short Test in Bipolar Disorder

Objective

The Functioning Assessment Short Test (FAST) is a relatively specific test for bipolar disorders designed to assess the main functioning problems experienced by patients. This brief instrument includes 24 items assessing impairment or disability in 6 domains of functioning: autonomy, occupational functioning, cognitive functioning, financial issues, interpersonal relationships, and leisure time. It has already been translated into standardized versions in several languages. The aim of this study is to measure the validity and reliability of the Korean version of FAST (K-FAST).

Methods

A total of 209 bipolar disorder patients were recruited from 14 centers in Korea. K-FAST, Young Mania Rating Scale (YMRS), Bipolar Depression Rating Scale (BDRS), Global Assessment of Functioning (GAF) and the World Health Organization Quality of Life Assessment Instrument Brief Form (WHOQOL-BREF) were administered, and psychometric analysis of the K-FAST was conducted.

Results

The internal consistency (Cronbach's alpha) of the K-FAST was 0.95. Test-retest reliability analysis showed a strong correlation between the two measures assessed at a 1-week interval (ICC = 0.97; p < 0.001). The K-FAST exhibited significant correlations with GAF (r = -0.771), WHOQOL-BREF (r = -0.326), YMRS (r = 0.509) and BDRS (r = 0.598). A strong negative correlation with GAF pointed to a reasonable degree of concurrent validity. Although the exploratory factor analysis showed four factors, the confirmatory factor analysis of questionnaires had a good fit for a six factors model (CFI = 0.925; TLI = 0.912; RMSEA = 0.078).

Conclusion

The K-FAST has good psychometric properties, good internal consistency, and can be applicable and acceptable to the Korean context.