Immune dysregulation and autoimmunity in bipolar disorder: Synthesis of the evidence and its clinical application

Lithium and the risk of fractures in patients with bipolar disorder: A population-based cohort study

Lithium is considered to be the most effective mood stabilizer for bipolar disorder. Evolving evidence suggested lithium can also regulate bone metabolism which may reduce the risk of fractures. While there are concerns about fractures for antipsychotics and mood stabilizing antiepileptics, very little is known about the overall risk of fractures associated with specific treatments. This study aimed to compare the risk of fractures in patients with bipolar disorder prescribed lithium, antipsychotics or mood stabilizing antiepileptics (valproate, lamotrigine, carbamazepine). Among 40,697 patients with bipolar disorder from 1993 to 2019 identified from a primary care electronic health record database in the UK, 13,385 were new users of mood stabilizing agents (lithium:2339; non-lithium: 11,046). Lithium was associated with a lower risk of fractures compared with non-lithium treatments (HR 0.66, 95 % CI 0.44-0.98). The results were similar when comparing lithium with prolactin raising and sparing antipsychotics, and individual antiepileptics. Lithium use may lower fracture risk, a benefit that is particularly relevant for patients with serious mental illness who are more prone to falls due to their behaviors. Our findings could help inform better treatment decisions for bipolar disorder, and lithium's potential to prevent fractures should be considered for patients at high risk of fractures.

Pathogenesis or a response to lithium? A novel perspective for mitochondrial mass fluctuation of naïve T cells in patients with bipolar disorder

BACKGROUND

Immune imbalances are associated with the pathogenesis and pharmacological efficacy of bipolar disorder (BD). The underlying mechanisms remain largely obscure but may involve immunometabolic dysfunctions of T-lymphocytes.

METHODS

We investigated if inflammatory cytokines and the immunometabolic function of T-lymphocytes, including frequencies of subsets, mitochondrial mass (MM), and low mitochondrial membrane potential (MMPLow) differed between BD patients (n = 47) and healthy controls (HC, n = 43). During lithium treatment of hospitalized patients (n = 33), the association between weekly T-lymphocyte immune metabolism and clinical symptoms was analyzed, and preliminary explorations on possible mechanisms were conducted.

RESULTS

In comparison to HC, BD patients predominantly showed a trend toward CD4+ naïve T (Tn) activation and exhibited mitochondrial metabolic disturbances such as decreased MM and increased MMPLow. Lower CD4+ Tn-MM correlated with elevated IL-6, IL-8, and decreased IL-17 A in BD patients. With lithium treatment effective, MM of CD4+ T/Tn was negatively correlated with depression score HAMD. When lithium intolerance was present, MM of CD4+ T/Tn was positively correlated with depression score HAMD and mania score BRMS. Lithium does not mediate through the inositol depletion hypothesis, but the mRNA level of IMPA2 in peripheral blood is associated with mitochondrial function in CD8+ T cells.

LIMITATIONS

The cross-sectional design and short-term follow-up meant that we could not directly examine the causality of BD and immune dysregulation.

CONCLUSION

The altered metabolism of CD4+ Tn was strongly associated with remodeling of the inflammatory landscape in BD patients and can also be used to reflect the short-term therapeutic effects of lithium.

A composite immune and vascular stress marker in patients newly diagnosed with bipolar disorder and their unaffected first-degree relatives

AIMS

Substantial evidence emphasizes immune dysregulation in patients with bipolar disorder (BD). However, whether immune dysregulation is present already in the early illness stages of BD or even precedes development of BD is largely unknown. In this study we compared immune and vascular stress markers in patients newly diagnosed with BD, their unaffected first-degree relatives (UR) and healthy control individuals (HC) and investigated the ability a composite immune and vascular stress marker to discriminate between the three groups of participants.

METHODS

In a unique sample including 373 patients newly diagnosed with BD, 95 UR and 190 HC, we compared 47 immune and vascular stress markers at the baseline visit in the ongoing longitudinal Bipolar Illness Onset study. For comparison of individual immune and vascular stress markers between groups, we applied linear mixed models, whereas the composite immune and vascular stress marker was investigated using the SuperLearner ensemble-method.

RESULTS

Compared with HC, patients newly diagnosed with BD had higher levels of the anti-inflammatory interleukin-1 receptor antagonist (IL-1RA) and IL-10, and of the pro-inflammatory IL-6, eotaxin, monocyte chemoattractant protein-1 (MCP-1), MCP-4, Macrophage Derived Chemokine (MDC), and Thymus and Activation-Regulated Chemokine (TARC) in analyses adjusted for sex and age ranging from 26 % higher levels of IL-6 (1.26, 95 %CI: [1.12-1.43], p < 0.001, adjusted p = 0.009) and IL-10 (1.26, 95 %CI: [1.09-1.46], p = 0.002, adjusted p = 0.049), respectively, to 9 % higher eotaxin levels (1.09, 95 %CI: [1.04-1.15], p = 0.001, adjusted p = 0.024). Of these, MDC levels were 12 % higher in BD compared with UR (1.12, 95 %CI: [1.02-1.22], p = 0.001, adjusted p = 0.024). For all other markers, UR showed no difference from patients with BD or HC. Based on a data-driven model, a composite marker including all 47 immune and vascular stress markers, sex, age, BMI, smoking status, and alcohol intake, discriminated patients with BD from HC with a with an area under the receiver operating curve (AUC) of 0.76 (95 % CI: 0.75-0.77) CONCLUSIONS: Higher levels of pro-inflammatory and anti-inflammatory immune markers are present in patients newly diagnosed with BD but not in UR compared with HC, supporting immune dysregulation playing a role in the pathophysiology of BD.

xWAS analysis in neuropsychiatric disorders by integrating multi-molecular phenotype quantitative trait loci and GWAS summary data

BACKGROUND

Integrating quantitative trait loci (QTL) data related to molecular phenotypes with genome-wide association study (GWAS) data is an important post-GWAS strategic approach employed to identify disease-associated molecular features. Various types of molecular phenotypes have been investigated in neuropsychiatric disorders. However, these findings pertaining to distinct molecular features are often independent of each other, posing challenges for having an overview of the mapped genes.

METHODS

In this study, we comprehensively summarized published analyses focusing on four types of risk-related molecular features (gene expression, splicing transcriptome, protein abundance, and DNA methylation) across five common neuropsychiatric disorders. Subsequently, we conducted supplementary analyses with the latest GWAS dataset and corresponding deficient molecular phenotypes using Functional Summary-based Imputation (FUSION) and summary data-based Mendelian randomization (SMR). Based on the curated and supplemented results, novel reliable genes and their functions were explored.

RESULTS

Our findings revealed that eQTL exhibited superior ability in prioritizing risk genes compared to the other QTL, followed by sQTL. Approximately half of the genes associated with splicing transcriptome, protein abundance, and DNA methylation were successfully replicated by eQTL-associated genes across all five disorders. Furthermore, we identified 436 novel reliable genes, which enriched in pathways related with neurotransmitter transportation such as synaptic, dendrite, vesicles, axon along with correlations with other neuropsychiatric disorders. Finally, we identified ten multiple molecular involved regulation patterns (MMRP), which may provide valuable insights into understanding the contribution of molecular regulation network targeting these disease-associated genes.

CONCLUSIONS

The analyses prioritized novel and reliable gene sets related with five molecular features based on published and supplementary results for five common neuropsychiatric disorders, which were missed in the original GWAS analysis. Besides, the involved MMRP behind these genes could be given priority for further investigation to elucidate the pathogenic molecular mechanisms underlying neuropsychiatric disorders in future studies.

Periodontal conditions and association of periodontitis with oral-health-related quality of life in patients experiencing different episodes of bipolar disorder compared with healthy controls

AIM

The aim of the present cross-sectional study was to evaluate periodontal conditions and the association of periodontitis with oral-health-related quality of life (OHRQoL) in patients with a history of bipolar disorder.

MATERIALS AND METHODS

A total of 160 participants were recruited in four groups for the study: 40 patients with euthymic episodes, 40 patients with depression, 40 patients with manic episodes and 40 systemically healthy individuals. Clinical periodontal parameters were recorded. Oral Health Impact Profile (OHIP-14) was used to measure the impact of oral health on the quality of life.

RESULTS

Bipolar disorder groups exhibited generally higher clinical parameters compared with the control group (p < .05). OHIP-14 total score (β = 3.32, 95% confidence interval [CI]: 0.08-6.56, p = .044), functional limitation (β = .89, 95% CI: 0.27-1.49, p = .005) and physical pain (β = .64, 95% CI: 0.01-1.27, p = .046) were associated with bipolar depression episodes. Psychological discomfort was associated with the presence of generalized periodontitis (β = .76, 95% CI: 0.01-1.51, p = .047) and psychological disability was associated with the presence of stage III-IV (β = .83, 95% CI: 0.07-1.59, p = .033) and generalized (β = .75, 95% CI: 0.07-1.42, p = .029) periodontitis.

CONCLUSIONS

According to this study, a history of bipolar disorder episodes (exposure) may be associated with increased prevalence and severity of periodontitis and related reported OHRQoL impacts (outcomes). Bipolar depression episodes had a higher impact on OHRQoL than other bipolar episodes.

Genetic risk for hospitalization of African American patients with severe mental illness reveals HLA loci

Background

Mood disorders such as major depressive and bipolar disorders, along with posttraumatic stress disorder (PTSD), schizophrenia (SCZ), and other psychotic disorders, constitute serious mental illnesses (SMI) and often lead to inpatient psychiatric care for adults. Risk factors associated with increased hospitalization rate in SMI (H-SMI) are largely unknown but likely involve a combination of genetic, environmental, and socio-behavioral factors. We performed a genome-wide association study in an African American cohort to identify possible genes associated with hospitalization due to SMI (H-SMI).

Methods

Patients hospitalized for psychiatric disorders (H-SMI; n=690) were compared with demographically matched controls (n=4467). Quality control and imputation of genome-wide data were performed following the Psychiatric Genetic Consortium (PGC)-PTSD guidelines. Imputation of the Human Leukocyte Antigen (HLA) locus was performed using the HIBAG package.

Results

Genome-wide association analysis revealed a genome-wide significant association at 6p22.1 locus in the ubiquitin D (UBD/FAT10) gene (rs362514, p=9.43x10-9) and around the HLA locus. Heritability of H-SMI (14.6%) was comparable to other psychiatric disorders (4% to 45%). We observed a nominally significant association with 2 HLA alleles: HLA-A*23:01 (OR=1.04, p=2.3x10-3) and HLA-C*06:02 (OR=1.04, p=1.5x10-3). Two other genes (VSP13D and TSPAN9), possibly associated with immune response, were found to be associated with H-SMI using gene-based analyses.

Conclusion

We observed a strong association between H-SMI and a locus that has been consistently and strongly associated with SCZ in multiple studies (6p21.32-p22.1), possibly indicating an involvement of the immune system and the immune response in the development of severe transdiagnostic SMI.

The immunomodulatory effect of lithium as a mechanism of action in bipolar disorder

Bipolar disorder (BD) is a chronic mental disorder characterized by recurrent episodes of mania and depression alternating with periods of euthymia. Although environmental and genetic factors have been described, their pathogenesis is not fully understood. Much evidence suggests a role for inflammatory mediators and immune dysregulation in the development of BD. The first-line treatment in BD are mood-stabilizing agents, one of which is lithium (Li) salts. The Li mechanism of action is not fully understood, but it has been proposed that its robust immunomodulatory properties might be one of the mechanisms responsible for its effectiveness. In this article, the authors present the current knowledge about immune system changes accompanying BD, as well as the immunomodulatory effect of lithium. The results of studies describing connections between immune system changes and lithium effectiveness are often incoherent. Further research is needed to understand the connection between immune system modulation and the therapeutic action of lithium in BD.

Psychiatric polygenic risk as a predictor of COVID-19 risk and severity: insight into the genetic overlap between schizophrenia and COVID-19

Despite the high contagion and mortality rates that have accompanied the coronavirus disease-19 (COVID-19) pandemic, the clinical presentation of the syndrome varies greatly from one individual to another. Potential host factors that accompany greater risk from COVID-19 have been sought and schizophrenia (SCZ) patients seem to present more severe COVID-19 than control counterparts, with certain gene expression similarities between psychiatric and COVID-19 patients reported. We used summary statistics from the last SCZ, bipolar disorder (BD), and depression (DEP) meta-analyses available on the Psychiatric Genomics Consortium webpage to calculate polygenic risk scores (PRSs) for a target sample of 11,977 COVID-19 cases and 5943 subjects with unknown COVID-19 status. Linkage disequilibrium score (LDSC) regression analysis was performed when positive associations were obtained from the PRS analysis. The SCZ PRS was a significant predictor in the case/control, symptomatic/asymptomatic, and hospitalization/no hospitalization analyses in the total and female samples; and of symptomatic/asymptomatic status in men. No significant associations were found for the BD or DEP PRS or in the LDSC regression analysis. SNP-based genetic risk for SCZ, but not for BD or DEP, may be associated with higher risk of SARS-CoV-2 infection and COVID-19 severity, especially among women; however, predictive accuracy barely exceeded chance level. We believe that the inclusion of sexual loci and rare variations in the analysis of genomic overlap between SCZ and COVID-19 will help to elucidate the genetic commonalities between these conditions.

T cells: an emerging cast of roles in bipolar disorder

Bipolar disorder (BD) is a distinctly heterogeneous and multifactorial disorder with a high individual and social burden. Immune pathway dysregulation is an important pathophysiological feature of BD. Recent studies have suggested a potential role for T lymphocytes in the pathogenesis of BD. Therefore, greater insight into T lymphocytes' functioning in patients with BD is essential. In this narrative review, we describe the presence of an imbalance in the ratio and altered function of T lymphocyte subsets in BD patients, mainly in T helper (Th) 1, Th2, Th17 cells and regulatory T cells, and alterations in hormones, intracellular signaling, and microbiomes may be potential causes. Abnormal T cell presence explains the elevated rates of comorbid inflammatory illnesses in the BD population. We also update the findings on T cell-targeting drugs as potentially immunomodulatory therapeutic agents for BD disease in addition to classical mood stabilizers (lithium, valproic acid). In conclusion, an imbalance in T lymphocyte subpopulation ratios and altered function may be involved in the development of BD, and maintaining T cell immune homeostasis may provide an overall therapeutic benefit.

Comparison of oxidative stress parameters, thiol-disulfide homeostasis, and pro-inflammatory cytokines levels in patients with bipolar disorder and their first-degree relatives

BACKGROUND

In this study, we aimed to compare the oxidative stress parameters, thiol-disulfide homeostasis, and plasma pro-inflammatory cytokines levels of patients with bipolar disorder (BD), BD patients' first-degree relatives (FDRs), and the healthy controls (HCs).

METHODS

Thirty-five patients with BD, 35 FDRs of BD, and 35 healthy controls (HCs) were included. The individuals' ages varied from 28 to 58, and the groups were well-matched in terms of age and gender. The total thiol (TT), native thiol (NT), disulfide (DIS), total oxidant status (TOS), total antioxidant status (TAS), IL-1β, IL-6, and TNF-α concentrations were measured from serum samples. The oxidative stress index (OSI) was calculated using mathematical formulas.

RESULTS

TOS was significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons). OSI, DIS, oxidized thiol, and the ratio of thiol oxidation-reduction levels were significantly higher in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). TAS, TT, NT, and reduced thiol levels were significantly lower in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). IL-1β, IL-6, and TNF-α were significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons).

LIMITATIONS

Small sample size.

CONCLUSIONS

Early diagnosis is important for treating of bipolar disorder. TT, NT, DIS, TOS, TAS, OSI, IL1-β, IL-6, and TNF-α can be used as potential biomarkers in the early diagnosis and intervention of BD. Furthermore, oxidative/antioxidative markers and plasma pro-inflammatory cytokine parameters may guide the determination of the disease's activity and response to treatment.

Transcranial direct current stimulation for bipolar depression: systematic reviews of clinical evidence and biological underpinnings

Despite multiple available treatments for bipolar depression (BD), many patients face sub-optimal responses. Transcranial direct current stimulation (tDCS) has been advocated in the management of different conditions, including BD, especially in treatment-resistant cases. The optimal dose and timing of tDCS, the mutual influence with other concurrently administered interventions, long-term efficacy, overall safety, and biological underpinnings nonetheless deserve additional assessment. The present study appraised the existing clinical evidence about tDCS for bipolar depression, delving into the putative biological underpinnings with a special emphasis on cellular and molecular levels, with the ultimate goal of providing a translational perspective on the matter. Two separate systematic reviews across the PubMed database since inception up to August 8^th 2022 were performed, with fourteen clinical and nineteen neurobiological eligible studies. The included clinical studies encompass 207 bipolar depression patients overall and consistently document the efficacy of tDCS, with a reduction in depression scores after treatment ranging from 18% to 92%. The RCT with the largest sample clearly showed a significant superiority of active stimulation over sham. Mild-to-moderate and transient adverse effects are attributed to tDCS across these studies. The review of neurobiological literature indicates that several molecular mechanisms may account for the antidepressant effect of tDCS in BD patients, including the action on calcium homeostasis in glial cells, the enhancement of LTP, the regulation of neurotrophic factors and inflammatory mediators, and the modulation of the expression of plasticity-related genes. To the best of our knowledge, this is the first study on the matter to concurrently provide a synthesis of the clinical evidence and an in-depth appraisal of the putative biological underpinnings, providing consistent support for the efficacy, safety, and tolerability of tDCS.

Long-Term Lithium Therapy and Thyroid Disorders in Bipolar Disorder: A Historical Cohort Study

Lithium has been a cornerstone treatment for bipolar disorder (BD). Despite descriptions in the literature regarding associations between long-term lithium therapy (LTLT) and development of a thyroid disorder (overt/subclinical hypo/hyperthyroidism, thyroid nodule, and goiter) in BD, factors such as time to onset of thyroid abnormalities and impact on clinical outcomes in the course of illness have not been fully characterized. In this study we aimed to compare clinical characteristics of adult BD patients with and without thyroid disorders who were on LTLT. We aimed to identify the incidence of thyroid disorders in patients with BD on LTLT and response to lithium between patients with and without thyroid disorders in BD. The Cox proportional model was used to find the median time to the development of a thyroid disorder. Our results showed that up to 32% of patients with BD on LTLT developed a thyroid disorder, of which 79% developed hypothyroidism, which was corrected with thyroid hormone replacement. We did not find significant differences in lithium response between patients with or without thyroid disorders in BD. Findings from this study suggest that patients with BD and comorbid thyroid disorders when adequately treated have a response to lithium similar to patients with BD and no thyroid disorders.

Expression analysis of NF-ƙB-related long non-coding RNAs in bipolar disorder

Bipolar disorder (BD) is a mental disorder that leads to abnormal swings in mood, energy, activity level, attention, and the capability to accomplish daily tasks. Several long non-coding RNAs (lncRNAs) are dysregulated in BD patients. We have compared expression levels of five NF-κB-associated lncRNAs, namely ANRIL, CEBPA-DT, H19, NKILA and HNF1A-AS1 in blood samples of BD patients compared with controls. While ANRIL, CEBPA-DT and HNF1-AS1 were significantly under-expressed in BD patients compared with controls, NKILA levels were higher in patients versus controls. Among differentially expressed genes, HFN1A-AS1 exhibited the best diagnostic parameters in the separation of patients from controls (AUC ± SD = 0.86 ± 0.03, sensitivity = 0.82, specificity = 0.82, P value < 0.0001). AUC values for NKILA, ANRIL and CEBPA-DT were 0.71, 0.68 and 0.65, respectively. In accordance with the previously reported participation of NF-ƙB in the pathophysiology of BD, the current study provides evidence for dysregulation of NF-κB-associated lncRNAs in BD.

Forgetful, sad and old: Do vascular cognitive impairment and depression share a common pre-disease network and how is it impacted by ageing?

Vascular cognitive impairment (VCI) and depression frequently coexist in geriatric populations and reciprocally increase disease risks. We assert that a shared pre-disease state of the psycho-immune-neuroendocrine (PINE) network model mechanistically explains bidirectional associations between VCI and depression. Five pathophysiological sub-networks are identified that are shared by VCI and depression: neuroinflammation, kynurenine pathway imbalance, hypothalamic-pituitary-adrenal (HPA) axis overactivity, impaired neurotrophic support and cerebrovascular dysfunction. These do not act independently, and their complex interactions necessitate a systems biology approach to better define disease pathogenesis. The PINE network is already established in the context of non-communicable diseases (NCDs) such as depression, hypertension, atherosclerosis, coronary heart disease and type 2 diabetes mellitus. We build on previous literature to specifically explore mechanistic links between MDD and VCI in the context of PINE pathways and discuss key mechanistic commonalities linking these comorbid conditions and identify a common pre-disease state which precedes transition to VCI and MDD. We expand the model to incorporate bidirectional interactions with biological ageing. Diathesis factors for both VCI and depression feed into this network and the culmination of shared mechanisms (on an ageing substrate) lead to a critical network transition to one or both disease states. A common pre-disease state underlying VCI and depression can provide clinicians a unique opportunity for early risk assessment and intervention in disease development. Establishing the mechanistic elements and systems biology of this network can reveal early warning or predictive biomarkers together with novel therapeutic targets. Integrative studies are recommended to elucidate the dynamic networked biology of VCI and depression over time.

Complexities of cooccurrence of catatonia and autoimmune thyroiditis in bipolar disorder: A case series and selective review

In recent years the neurobiological underpinnings of catatonia have been an emerging area of interest. Catatonia is frequently encountered in mood disorders, neurological disorders and systemic illnesses. Furthermore, the manifestation of catatonia in autoimmune disorders such as NMDA receptor antibody encephalitis and thyroiditis reinforces its neuropsychiatric nature. Irrespective of cause benzodiazepines and electroconvulsive therapy remain the standard treatments for catatonia, although a proportion fail to respond to the same. This report describes three women with pre-existing bipolar disorder presenting in catatonia. Interestingly in all three, while benzodiazepines and electroconvulsive therapy failed, a dramatic resolution of catatonia with corticosteroids was noted following the detection of Hashimoto's thyroiditis. Hashimoto's encephalopathy presenting as catatonia has been reported, but our patients' profile differed in having had an a priory diagnosis of bipolar disorder. Given that both catatonia and thyroid dysfunction are frequently encountered in bipolar disorder, Hashimoto's encephalopathy as a potential cause for this concurrent manifestation in bipolar disorder may be overlooked. Therefore, it is essential to suspect Hashimoto's encephalopathy when catatonia manifests in bipolar disorder. A timely evaluation would be prudent as they may fail to respond to standard treatments for catatonia but respond remarkably to corticosteroids, saving much time and angst. Recent evidence implicates immune system dysfunction, with neuroinflammation and peripheral immune dysregulation contributing to the pathophysiology of bipolar disorder as well as catatonia. Findings from this study reaffirm the role of immune system dysfunction common to the etiopathogenesis of all these disorders, highlighting the complex interplay between catatonia, thyroiditis and bipolar disorder.

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Catatonia is common in bipolar disorder and also noted in autoimmune disorders.

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Thyroiditis in bipolar disorder may be overlooked due to frequent occurrence of thyroid dysfunction.

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Catatonia in bipolar disorder may result from Hashimoto's encephalopathy.

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Hashimoto's related catatonia in bipolar disorder may poorly respond to standard treatment.

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Autoimmune thyroiditis and catatonia highlight the immune dysfunction hypothesis of bipolar disorder.

Co-Expression Networks Unveiled Long Non-Coding RNAs as Molecular Targets of Drugs Used to Treat Bipolar Disorder

Long non-coding RNAs (lncRNAs) may play a role in psychiatric diseases including bipolar disorder (BD). We investigated mRNA-lncRNA co-expression patterns in neuronal-like cells treated with widely prescribed BD medications. The aim was to unveil insights into the complex mechanisms of BD medications and highlight potential targets for new drug development. Human neuronal-like (NT2-N) cells were treated with either lamotrigine, lithium, quetiapine, valproate or vehicle for 24 h. Genome-wide mRNA expression was quantified for weighted gene co-expression network analysis (WGCNA) to correlate the expression levels of mRNAs with lncRNAs. Functional enrichment analysis and hub lncRNA identification was conducted on key co-expressed modules associated with the drug response. We constructed lncRNA-mRNA co-expression networks and identified key modules underlying these treatments, as well as their enriched biological functions. Processes enriched in key modules included synaptic vesicle cycle, endoplasmic reticulum-related functions and neurodevelopment. Several lncRNAs such as GAS6-AS1 and MIR100HG were highlighted as driver genes of key modules. Our study demonstrates the key role of lncRNAs in the mechanism(s) of action of BD drugs. Several lncRNAs have been suggested as major regulators of medication effects and are worthy of further investigation as novel drug targets to treat BD.

Therapeutic Interventions to Mitigate Mitochondrial Dysfunction and Oxidative Stress–Induced Damage in Patients with Bipolar Disorder

Bipolar disorder (BD) is characterized by mood changes, including recurrent manic, hypomanic, and depressive episodes, which may involve mixed symptoms. Despite the progress in neurobiological research, the pathophysiology of BD has not been extensively described to date. Progress in the understanding of the neurobiology driving BD could help facilitate the discovery of therapeutic targets and biomarkers for its early detection. Oxidative stress (OS), which damages biomolecules and causes mitochondrial and dopamine system dysfunctions, is a persistent finding in patients with BD. Inflammation and immune dysfunction might also play a role in BD pathophysiology. Specific nutrient supplements (nutraceuticals) may target neurobiological pathways suggested to be perturbed in BD, such as inflammation, mitochondrial dysfunction, and OS. Consequently, nutraceuticals may be used in the adjunctive treatment of BD. This paper summarizes the possible roles of OS, mitochondrial dysfunction, and immune system dysregulation in the onset of BD. It then discusses OS-mitigating strategies that may serve as therapeutic interventions for BD. It also analyzes the relationship between diet and BD as well as the use of nutritional interventions in the treatment of BD. In addition, it addresses the use of lithium therapy; novel antipsychotic agents, including clozapine, olanzapine, risperidone, cariprazine, and quetiapine; and anti-inflammatory agents to treat BD. Furthermore, it reviews the efficacy of the most used therapies for BD, such as cognitive–behavioral therapy, bright light therapy, imagery-focused cognitive therapy, and electroconvulsive therapy. A better understanding of the roles of OS, mitochondrial dysfunction, and inflammation in the pathogenesis of bipolar disorder, along with a stronger elucidation of the therapeutic functions of antioxidants, antipsychotics, anti-inflammatory agents, lithium therapy, and light therapies, may lead to improved strategies for the treatment and prevention of bipolar disorder.

Bipolar spectrum disorders in neurologic disorders

Psychiatric symptoms frequently predate or complicate neurological disorders, such as neurodegenerative diseases. Symptoms of bipolar spectrum disorders (BSD), like mood, behavioral, and psychotic alterations, are known to occur - individually or as a syndromic cluster - in Parkinson's disease and in the behavioral variant of frontotemporal dementia (FTD). Nonetheless, due to shared pathophysiological mechanisms, or genetic predisposition, several other neurological disorders show significant, yet neglected, clinical and biological overlaps with BSD like neuroinflammation, ion channel dysfunctions, neurotransmission imbalance, or neurodegeneration. BSD pathophysiology is still largely unclear, but large-scale network dysfunctions are known to participate in the onset of mood disorders and psychotic symptoms. Thus, functional alterations can unleash BSD symptoms years before the evidence of an organic disease of the central nervous system. The aim of our narrative review was to illustrate the numerous intersections between BSD and neurological disorders from a clinical-biological point of view and the underlying predisposing factors, to guide future diagnostic and therapeutical research in the field.

Bipolar Patients and Bullous Pemphigoid after Risperidone Long-Acting Injectable: A Case Report and a Review of the Literature

Neuropsychiatric disorders are found to be associated with bullous pemphigoid (BP), an autoimmune subepidermal blistering disease. Antipsychotics have emerged as possible inducing factors of BP. However, large sample studies concerning BP associated with antipsychotics, as well as with specific mental disorders, are still lacking. Our review retrieved a few clinical studies and case reports on the topic, producing controversial results. We report for the first time a bipolar patient case presenting BP following five-month therapy with risperidone long-acting injectable (LAI). We hypothesize that the dermatological event is associated with the medication administered. The issue emerged during psychiatric consultation and was confirmed by histological examination, direct and indirect immunofluorescence studies, plus positive plasma and cutaneous BP180 and BP230 IgG. Neurodegeneration or neuroinflammation might represent a primary process leading to a cross-reactive immune response between neural and cutaneous antigens and contributing to self-tolerance failure. Furthermore, the time sequence of the shared biological mechanisms leading to clinical manifestations of the neuropsychiatric disorder and BP remains undefined. BP comorbid with bipolar disorder might occasionally represent a serious health risk and affect patients' physical and psychosocial quality of life. Thus, clinicians treating psychiatric patients should consider BP as a possible adverse effect of psychotropic medications.

Repurposing Immunomodulatory Imide Drugs (IMiDs) in Neuropsychiatric and Neurodegenerative Disorders

Neuroinflammation represents a common trait in the pathology and progression of the major psychiatric and neurodegenerative disorders. Neuropsychiatric disorders have emerged as a global crisis, affecting 1 in 4 people, while neurological disorders are the second leading cause of death in the elderly population worldwide (WHO, 2001; GBD 2016 Neurology Collaborators, 2019). However, there remains an immense deficit in availability of effective drug treatments for most neurological disorders. In fact, for disorders such as depression, placebos and behavioral therapies have equal effectiveness as antidepressants. For neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, drugs that can prevent, slow, or cure the disease have yet to be found. Several non-traditional avenues of drug target identification have emerged with ongoing neurological disease research to meet the need for novel and efficacious treatments. Of these novel avenues is that of neuroinflammation, which has been found to be involved in the progression and pathology of many of the leading neurological disorders. Neuroinflammation is characterized by glial inflammatory factors in certain stages of neurological disorders. Although the meta-analyses have provided evidence of genetic/proteomic upregulation of inflammatory factors in certain stages of neurological disorders. Although the mechanisms underpinning the connections between neuroinflammation and neurological disorders are unclear, and meta-analysis results have shown high sensitivity to factors such as disorder severity and sample type, there is significant evidence of neuroinflammation associations across neurological disorders. In this review, we summarize the role of neuroinflammation in psychiatric disorders such as major depressive disorder, generalized anxiety disorder, post-traumatic stress disorder, and bipolar disorder, as well as in neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease, and introduce current research on the potential of immunomodulatory imide drugs (IMiDs) as a new treatment strategy for these disorders.

Case Report: Psychopathological Syndromes in the Course of Lupus Erythematosus and the Co-occurrence of Lupus Erythematous With Mental Disorders

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease that leads to a chronic inflammatory process in tissues and organs. The neuropsychiatric systemic lupus erythematosus (NPSLE) is a set of neuropsychiatric symptoms that derive from the central and peripheral nervous system and are observed in the course of SLE. Case Report and Final Diagnostic and Therapeutic Results: A diagnostic and therapeutic process in a patient with the signs and symptoms of SLE and bipolar disorder (BD) has been described. Bipolar disorder has been diagnosed as a primary disorder while SLE as a comorbid disease. Discussion: Common immunological mechanisms in BD and SLE are the reason for difficulties in diagnosing BD with co-occurring SLE. It should be determined whether BD is a primary disorder or a secondary component of a clinical picture of SLE (NPSLE) or whether mood and/or psychotic disorders are the result of steroid therapy in the course of SLE (steroid-induced mood and psychotic disorders, SIMPD). Conclusion and the Patient's Perspective: The presented case report is a unique description of a patient with a primary diagnosis of BD with comorbid SLE.

Risk of bipolar disorder in patients with endometriosis: A nationwide population-based cohort study

BACKGROUND

Women with endometriosis (EM) have increased vulnerability to certain psychiatric disorders, including depression and anxiety, as well as bipolar disorder (BD). This study investigates the risk of BD development in EM patients. Also, the impact of EM treatment on the risk of developing BD is examined.

METHODS

A total of 17,832 EM patients and 17,832 non-EM controls matched by age, index year, and Charlson Comorbidity Index (CCI) score were included between 2000-2012 and followed to the end of 2013. Participants newly diagnosed as BD by board-certified psychiatrist were defined as incidents. Cox regression analysis was used to calculate the hazard ratio (HR) with 95% confidence interval (CI) of the BD incidence rate between two studied groups.

RESULTS

EM patients were associated with an increased risk of BD development compared with non-EM controls after adjusting for age, CCI score, and different treatment options (1.04 versus 0.56 per 1,000 person-years, HR: 2.34, 95% CI: 1.75-3.12). Also, there was no significant difference in the risk estimate between different hormonal or surgical treatment groups, suggesting a limited impact of EM treatment on the risk of BD development.

LIMITATIONS

This study deals with the duration of hormonal treatment, whether operated or not, which reduces the chances of showing the effect of individual EM treatment on the risk of BD development.

CONCLUSION

This study shows that EM patients are associated with an increased risk of BD development. Further studies would be needed to elucidate the mechanism linking the EM and BD.

Chronic Periodontitis Is Associated with the Risk of Bipolar Disorder: A Population-Based Cohort Study

Bipolar disorder (BD) is a psychiatric mood disturbance manifested by manic, hypomanic, or major depressive periods. Chronic inflammation was evidenced as an important etiologic factor of BD. Chronic periodontitis (CP) is an inflammatory disease triggered by bacterial products, leading to the destruction of periodontium. The relationship between BD and CP is of interest to investigate. Therefore, a nationwide population-based cohort study was used to investigate the risk of BD and CP exposure from 2001 to 2012. We identified 61,608 patients with CP from the Taiwanese National Health Insurance Research Database (NHIRD). The 123,216 controls were randomly captured and matched by age, sex, index year, and co-morbidities. The association between CP exposure and BD risk was examined by Cox proportional hazards regression models. In this study, 61,608 CP patients and 123,216 controls were followed up for 7.45 and 7.36 years, respectively. In total, 138 BD patients were identified in the CP cohort and 187 BD cases were found in the non-CP cohort. The incidence rate of BD was significantly higher in the CP cohort than in the non-CP cohort (adjusted HR: 1.46, 95% CI: 1.17–1.81) according to the multivariate Cox regression analysis. Females had a 1.47-fold increased risk (95% CI: 1.16–1.86) for BD compared to males. Taken together, CP may be associated with an increased risk of subsequent BD in Taiwan.

The association between systemic lupus erythematosus and bipolar disorder – a big data analysis

Background:

Systemic lupus erythematosus (SLE) is a chronic, autoimmune disease that has a wide variety of physical manifestations, including neuropsychiatric features. Bipolar disorder (BD) is a chronic, episodic illness, that may present as depression or as mania. The objective of this study was to investigate the association between SLE and BD using big data analysis methods.

Methods:

Patients with SLE were compared with age- and sex-matched controls regarding the prevalence of BD in a cross-sectional study. Chi-square and t-tests were used for univariate analysis and a logistic regression model was used for multivariate analysis, adjusting for confounders. The study was performed utilizing the chronic disease registry of Clalit Health Services medical database.

Results:

The study included 5018 SLE patients and 25,090 matched controls. BD was found in a higher prevalence among SLE patients compared to controls (0.62% vs. 0.26%, respectively, P < 0.001). BD patients had a greater prevalence of smokers compared to non-BD patients (62.5% vs 23.5%, respectively, P < 0.001). In a multivariate analysis, smoking and SLE were both found to be significantly associated with BD.

Conclusions:

SLE was found to be independently associated with BD. These findings may imply that an autoimmune process affecting the central nervous system among SLE patients facilitates the expression of concomitant BD.

Patients with rheumatoid arthritis have a higher risk of bipolar disorder: A systematic review and meta-analysis

The current study was conducted with the aim to investigate the relationship between rheumatoid arthritis (RA) and bipolar disorder (BD). Potentially eligible studies were identified from Medline and EMBASE databases from inception to May 2019. Eligible cohort studies must include patients with RA and comparators without RA, follow them for incident BD and report the relative risk, hazard risk ratio or standardized incidence ratio and associated 95% confidence intervals (CI) comparing the incidence of BD between the two groups. Eligible case-control studies must include cases with BD and controls without BD, explore prior history of RA and report the odds ratio and associated 95% CI for this association. Point estimates with standard errors were extracted from individual study and were combined together using random-effect model, generic inverse variance method. A total of six studies fulfilled the inclusion criteria and were included into the meta-analysis. The risk of developing BD was significantly higher among patients with RA than individuals without RA with the pooled relative risk of 2.06 (95% CI, 1.34-3.17; I² 86%). Chronic inflammation is a potential mechanism and could be a modifiable risk factor of BD. However, further studies are still required to confirm this.

Peripheral Oxidative Stress Markers in Patients with Bipolar Disorder during Euthymia and in Siblings

AIMS

Oxidative stress is increased during the acute phases of bipolar disorder (BD). Our aim here was to analyze oxidative stress biomarkers in patients with BD during euthymia and their siblings.

METHOD

A cross-sectional study was performed in euthymic patients with BD-I (n=48), unaffected siblings (n=23) and genetically unrelated healthy controls (n=21). Protein carbonyl content (PCC), total antioxidant capacity (TRAP), lipid peroxidation (TBARS) and uric acid were measured as biomarkers of oxidative stress in blood.

RESULTS

The antioxidant capacity (TRAP) was lower (p<0.001) in patients with BD compared to their siblings and controls, whereas no differences were observed in PCC, TBARS or uric acid. In patients, the concentrations of TRAP and TBARS were positively associated with the dose of valproic acid (p<0.05 and p<0.001, respectively). The concentrations of these biomarkers were not significantly associated with any of socio-demographic and clinical variables.

CONCLUSION

A selective reduction in antioxidant capacity is present in BD during euthymia state, whereas other markers of oxidative stress are unaltered during euthymia. Siblings did not show any alterations in oxidative stress biomarkers. Oxidative stress might represent a state-dependent marker in BD. The association between treatment with valproic acid and oxidative stress markers in euthymia deserves further studies.

Insulin-like growth factor binding protein 2 in bipolar disorder: An expression study in peripheral tissues

OBJECTIVES

Insulin-like growth factor binding protein 2 (IGFBP2) is a member of the family of high-affinity binding proteins (IGFBP1-6) and appears to play a governing role in insulin-like growth factor (IGF) regulation in the central nervous system. This study aimed to investigate the putative involvement of IGFBP2 in mood disorder pathogenesis by measuring its expression levels in patient peripheral tissues.

METHODS

IGFBP2 protein and mRNA levels were measured in the serum of 93 controls, 41 bipolar disorder (BD) and 43 major depressive disorder (MDD) patients and in the skin fibroblasts from 15 controls, 12 BD and 23 MDD patients.

RESULTS

The results indicated reduced expression of IGFBP2 in both tissues of BD patients, whereas no difference was found in MDD patients compared with controls.

CONCLUSIONS

Our findings in peripheral tissues are consistent with previous results in the brain and support a downregulation of IGFBP2 expression that is specific for BD, suggesting a role for this protein in the alterations in neurodevelopment and neuroprotection observed in the disorder. Further studies in independent and larger cohorts are warranted to confirm the involvement of IGFBP2 in BD.

SJ. Genetic correlations among psychiatric and immune-related phenotypes based on genome-wide association data

Individuals with psychiatric disorders have elevated rates of autoimmune comorbidity and altered immune signaling. It is unclear whether these altered immunological states have a shared genetic basis with those psychiatric disorders. The present study sought to use existing summary-level data from previous genome-wide association studies to determine if commonly varying single nucleotide polymorphisms are shared between psychiatric and immune-related phenotypes. We estimated heritability and examined pair-wise genetic correlations using the linkage disequilibrium score regression (LDSC) and heritability estimation from summary statistics methods. Using LDSC, we observed significant genetic correlations between immune-related disorders and several psychiatric disorders, including anorexia nervosa, attention deficit-hyperactivity disorder, bipolar disorder, major depression, obsessive compulsive disorder, schizophrenia, smoking behavior, and Tourette syndrome. Loci significantly mediating genetic correlations were identified for schizophrenia when analytically paired with Crohn's disease, primary biliary cirrhosis, systemic lupus erythematosus, and ulcerative colitis. We report significantly correlated loci and highlight those containing genome-wide associations and candidate genes for respective disorders. We also used the LDSC method to characterize genetic correlations among the immune-related phenotypes. We discuss our findings in the context of relevant genetic and epidemiological literature, as well as the limitations and caveats of the study.

The effect of childhood trauma on blood transcriptome expression in major depressive disorder

Childhood trauma (CT) increases the likelihood of developing severe mental illnesses, such as major depressive disorder (MDD), during adulthood. Several studies have suggested an inflammatory immune system dysregulation as a biological mediator; however, the molecular mechanisms underlying this relationship remain largely undetermined. Moreover, different types of CT, in particular, emotional abuse and neglect, confer a higher risk of developing MDD, and recent meta-analyses showed that each CT can be associated with different pro-inflammatory biomarkers. However, no studies using a hypothesis-free approach have been performed. For this reason, we carried out a reanalysis of transcriptome data from a large mRNA sequencing dataset to investigate different types of CT in MDD patients. Gene expression analysis followed by principal component and gene-set enrichment analyses were carried out to identify genes and pathways differentially expressed in 368 patients who experienced four different types of CT (sexual abuse, physical abuse, emotional abuse and neglect). Expression analysis of single genes revealed a significant association between the neglect CT and the MED22 gene (p = 1.11 × 10^-6; FDR = 0.016). Furthermore, analyses of the principal components of expression data support a dysregulation of cytokine system pathways, such as interferon (IFN) α/β and γ signaling, as a consequence of emotional abuse in depressed patients. Our results corroborate the hypothesis that specific types of CT affect distinct molecular pathways, and in particular, emotional abuse and neglect exert the strongest impact on gene expression in MDD.

Bipolar Disorder Associated with Another Autoimmune Disease-Pemphigus: A Population-based Study

OBJECTIVES

Recent evidence suggests a notable role for inflammation and immune dysregulation in the neuroprogression of bipolar disorders (BD). Several autoimmune comorbidities have been reported in association with BD. However, the epidemiological relationship between pemphigus and BD has not yet been elucidated. We aimed to estimate the association between pemphigus and BD using a large-scale, real-life computerized database.

METHODS

Data for this study were retrieved from the database of the Clalit Health Services, the largest, state-mandated, health service organization in Israel. This study was designed as a cross-sectional study. The proportion of patients with BD was compared between patients diagnosed with pemphigus and age-, sex-, and ethnicity-matched control subjects. A logistic regression model was performed to estimate how pemphigus and other covariates contributed as risk factors for BD.

RESULTS

A total of 1,985 pemphigus cases and 9,874 controls were included in the study. The prevalence of BD was greater in cases with pemphigus than in controls (1.0% v. 0.5%, respectively; P = 0.023). This coexistence was more prominent among patients of Jewish ethnicity. After controlling for confounders, such as age, sex, ethnicity, socioeconomic status, drug abuse, alcohol abuse, smoking, healthcare utilization, and comorbidities, pemphigus demonstrated a substantial independent association with BD (OR, 1.7; 95% CI, 1.0 to 2.9).

CONCLUSIONS

Pemphigus is significantly associated with BD. Patients with pemphigus should be assessed for comorbid BD. Experimental research is needed to better recognize the biological mechanisms underlying this observation.

Association of viral hepatitis and bipolar disorder: a nationwide population-based study

Background

Bipolar disorder (BD), a type of psychiatric mood disorder, is manifested by chronic and recurrent mood fluctuations. This study aims to determine whether hepatitis B virus (HBV) or hepatitis C virus (HCV) infection is a risk factor for BD.

Methods

A total of 48,215 patients with newly diagnosed viral hepatitis from 2000 to 2010 were identified and frequency-matched with 192,860 people without hepatitis. Both groups were followed until diagnosis with BD, withdrawal from the national health insurance program, or the end of 2011. Patients with viral hepatitis were grouped into 3 cohorts: HBV infection, HCV infection, and HBV/HCV coinfection. The association between viral hepatitis and BD were examined using Cox proportional hazards regression models.

Results

The incidence of BD was higher in HBV/HCV coinfection than in the control group, with an adjusted hazard ratio of 2.16 (95% confidence interval 1.06–4.41) when adjusted for sex, age, and comorbidity. After further adjustment, we noted that an age more than 65 years and female may be associated with an increased risk of BD in patients with chronic hepatitis B and C.

Conclusion

Viral hepatitis may be associated with increased risk of subsequent BD.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1542-3) contains supplementary material, which is available to authorized users.

Add-On Memantine Treatment for Bipolar II Disorder Comorbid with Alcohol Dependence: A 12-Week Follow-Up Study

BACKGROUND

Bipolar disorder (BD), especially BD-II, is frequently comorbid with alcohol dependence. Because BD-II and alcohol dependence are neurodegenerative disorders, agents with anti-inflammatory and neurotrophic effects might provide effective therapy. We investigated whether add-on memantine to regular valproic acid treatment ameliorated clinical symptoms, reduced alcohol use, and cytokine levels, and increased plasma brain-derived neurotrophic factor (BDNF) in BD-II patients with comorbid alcohol dependence.

METHODS

In a single-arm 12-week clinical trial, BD-II patients with comorbid alcohol dependence (n = 45) undergoing regular valproic acid treatments were given add-on memantine (5 mg/d). Symptom severity, alcohol use, cytokine (plasma tumor necrosis factor-α and C-reactive protein [CRP], transforming growth factor-β1 [TGF-β1], interleukin-8 [IL-8], IL-10), and plasma BDNF levels were regularly assessed.

RESULTS

Mean within-group decreases in Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) scores, alcohol use, CRP, BDNF, and IL-8 levels were significantly different from baseline after 12 weeks of treatment. We found no significant correlation between alcohol use levels and changes in HDRS or YMRS scores. The correlation between reduced alcohol use and reduced TGF-β1 level was significant (B = 0.003, p = 0.019).

CONCLUSIONS

BD-II comorbid with alcohol dependence might benefit from add-on memantine treatment, which significantly reduced clinical severity, alcohol use, and plasma cytokine levels, and increased BDNF levels.

Heritability enrichment of specifically expressed genes identifies disease-relevant tissues and cell types

We introduce an approach to identify disease-relevant tissues and cell types by analyzing gene expression data together with genome-wide association study (GWAS) summary statistics. Our approach uses stratified linkage disequilibrium (LD) score regression to test whether disease heritability is enriched in regions surrounding genes with the highest specific expression in a given tissue. We applied our approach to gene expression data from several sources together with GWAS summary statistics for 48 diseases and traits (average N = 169,331) and found significant tissue-specific enrichments (false discovery rate (FDR) < 5%) for 34 traits. In our analysis of multiple tissues, we detected a broad range of enrichments that recapitulated known biology. In our brain-specific analysis, significant enrichments included an enrichment of inhibitory over excitatory neurons for bipolar disorder, and excitatory over inhibitory neurons for schizophrenia and body mass index. Our results demonstrate that our polygenic approach is a powerful way to leverage gene expression data for interpreting GWAS signals.

Systemic autoimmune diseases are associated with an increased risk of bipolar disorder: A nationwide population-based cohort study

BACKGROUND

Studies suggested autoimmunity plays a role in the etiology of bipolar disorder (BD). This study aimed to investigate the association between systemic autoimmune diseases (SADs) and the subsequent development of BD, and examine the potential risk factors for developing BD.

METHODS

Patients with SADs were identified in the Taiwan National Health Insurance Program (NHIP). A comparison cohort was created by matching patients without SADs with age. The SADs cohort consisted of 65,498 while the comparison cohort consisted of 261,992 patients. The incidence of BD was evaluated in both cohorts.

RESULTS

The major finding was the discovery of a higher incidence of subsequent BD among patients with SADs (adjusted hazard ratio: 1.98). Specifically, the risk of BD was observed to be significant increase in systemic lupus erythematosus, rheumatoid arthritis, autoimmune vasculitis, Sicca syndrome and Crohn's disease. Furthermore, our study revealed some potential risk factors for developing BD including female, younger age and patients who lived in eastern Taiwan. Also, some comorbidities including dyslipidemia, chronic obstructive pulmonary disease, diabetes mellitus, asthma, cerebrovascular disease, alcohol used disorder, liver cirrhosis, and malignancies were potential risk factors for incident BD.

LIMITATIONS

The diagnosis of SADs was based on the catastrophic illness certificate defined by Taiwanese NHIP. Thus, not every form of SADs was explored for subsequent developing BD.

CONCLUSION

This study confirms that SADs are associated with higher incidence of BD, suggesting that abnormal autoimmune process is associated with increased expression of psychiatric disturbances.

Pathophysiology in the comorbidity of Bipolar Disorder and Alzheimer's Disease: pharmacological and stem cell approaches

Neuropsychiatric disorders involve various pathological mechanisms, resulting in neurodegeneration and brain atrophy. Neurodevelopmental processes have shown to be critical for the progression of those disorders, which are based on genetic and epigenetic mechanisms as well as on extrinsic factors. We review here common mechanisms underlying the comorbidity of Bipolar Disorders and Alzheimer's Disease, such as aberrant neurogenesis and neurotoxicity, reporting current therapeutic approaches. The understanding of these mechanisms precedes stem cell-based strategies as a new therapeutic possibility for treatment and prevention of Bipolar and Alzheimer's Disease progression. Taking into account the difficulty of studying the molecular basis of disease progression directly in patients, we also discuss the importance of stem cells for effective drug screening, modeling and treating psychiatric diseases, once in vitro differentiation of patient-induced pluripotent stem cells provides relevant information about embryonic origins, intracellular pathways and molecular mechanisms.

Introducing a Stable Bootstrap Validation Framework for Reliable Genomic Signature Extraction

The application of machine learning methods for the identification of candidate genes responsible for phenotypes of interest, such as cancer, is a major challenge in the field of bioinformatics. These lists of genes are often called genomic signatures and their linkage to phenotype associations may form a significant step in discovering the causation between genotypes and phenotypes. Traditional methods that produce genomic signatures from DNA Microarray data tend to extract significantly different lists under relatively small variations of the training data. That instability hinders the validity of research findings and raises skepticism about the reliability of such methods. In this study, a complete framework for the extraction of stable and reliable lists of candidate genes is presented. The proposed methodology enforces stability of results at the validation step and as a result, it is independent of the feature selection and classification methods used. Furthermore, two different statistical tests are performed in order to assess the statistical significance of the observed results. Moreover, the consistency of the signatures extracted by independent executions of the proposed method is also evaluated. The results of this study highlight the importance of stability issues in genomic signatures, beyond their prediction capabilities.

Thyroid autoimmunity in bipolar disorder: A systematic review

BACKGROUND

Accumulating evidence points to the pathophysiological relevance between immune dysfunction and mood disorders. High rates of thyroid dysfunction have been found in patients with bipolar disorder (BD), compared to the general population. A systematic review of the relationship between BD and thyroid autoimmunity was performed.

METHODS

Pubmed, EMBASE and PsycINFO databases were searched up till January 28th, 2017. This review has been conducted according to the PRISMA statements. Observational studies clearly reporting data among BD patients and the frequency of autoimmune thyroid pathologies were included.

RESULTS

11 original studies met inclusion criteria out of 340 titles first returned from the global search. There is evidence of increased prevalence of circulating thyroid autoantibodies in depressed and mixed BD patients, while there is no evidence showing a positive relationship between BD and specific autoimmune thyroid diseases. There is a controversy about the influence of lithium exposure on circulating thyroid autoantibodies, even if most of studies seem not to support this association. A study conducted on bipolar twins suggests that autoimmune thyroiditis is related to the genetic vulnerability to develop BD rather than to the disease process itself. Females are more likely to develop thyroid autoimmunity.

LIMITATIONS

The samples, study design and outcomes were heterogeneous.

CONCLUSION

Thyroid autoimmunity has been suggested to be an independent risk factor for bipolar disorder with no clear association with lithium exposure and it might serve as an endophenotype for BD.

Structural and functional correlates of serum soluble IL-6 receptor level in patients with bipolar disorder

OBJECTIVES

Inflammation is reported to play a crucial role in the pathogenesis of bipolar disorder (BD). Higher serum levels of soluble interleukin-6 receptor (sIL-6R), which forms a ligand-receptor complex with the potent proinflammatory cytokine IL-6, have been consistently observed in patients with BD. However, the effect of sIL-6R on neural structure and function remains unclear. This study investigated the association between serum sIL-6R levels and the structural and functional connectivity (FC) of the brain in patients with BD.

METHODS

Seventy-four stable patients with BD-I or BD-II were enrolled from the outpatient clinic. Structural and resting functional MRI and clinical evaluations were performed in all participants, and serum sIL-6R levels were measured. We used an automated surface-based method (FreeSurfer) to measure cortical thickness and a seed-based FC analysis to derive the FC map of the medial prefrontal cortex (mPFC), a key region implicated in the fronto-limbic disconnection hypothesis of BD. Brain-wise regression analyses of cortical thickness and FC mapping on IL-6 levels were performed using a general linear model.

RESULTS

Higher sIL-6R levels were associated with a thinner cortex in the right middle temporal gyrus. Furthermore, higher sIL-6R levels were associated with increased FC between the mPFC and amygdala, pallidum, putamen, and insula and decreased FC between the mPFC and subgenual anterior cingulate cortex and frontal pole.

CONCLUSION

The results evidence that higher serum inflammatory marker levels are associated with a severer deficit in structural and connectivity abnormalities implicated in BD.

Clinical staging and serum cytokines in bipolar patients during euthymia

AIMS

Changes in serum cytokines and altered neutrophin concentration have been associated with bipolar disorder (BD). Our aim here was to analyze peripheral blood biomarkers according to the clinical stages of BD.

METHOD

Euthymic BD-I patients were grouped according to their level of functioning in early-stage (n=25) and late-stage (n=23), and compared to healthy siblings (n=23) and genetically unrelated healthy controls (n=21). Neurotrophin (neurotrophin-3 and BDNF) concentration and biomarkers of inflammation, including cytokines (IL-6, IL-10 and TNF-α), leukocytes count and acute phase proteins, were measured.

RESULTS

IL-10 concentration was significantly increased in early-stage patients compared to late-stage patients, healthy siblings and controls whereas TNF-α concentration was significantly increased in late-stage patients compared to controls. Total leukocytes, neutrophil and monocyte count were significantly increased in late-stage patients compared to healthy siblings and controls. The concentration of IL-6, neurotrophin-3 and BDNF was unchanged in euthymia. Healthy siblings did not show significant changes in any biomarker.

CONCLUSIONS

The concentration of IL-10, TNF-α, neutrophil and monocytes subtype count in blood is altered in patients with BD during euthymic state. The link between peripheral inflammation and different stages in BD deserves further studies.

Is there any association between Toxoplasma gondii infection and bipolar disorder? A systematic review and meta-analysis

BACKGROUND

The relationship between Toxoplasma gondii infection and the development of bipolar disorder (BD) has long been investigated, yet to date it is still poorly understood and documented. The aim of this review is to derive a summary estimate of the strength of the association between infection with T. gondii and BD from the available published studies.

METHODS

A systematic review was performed using PubMed, LILACS, PsycINFO, and Embase databases. Studies which included a proportion of seropositive BD patients and controls were further examined in a meta-analysis.

RESULTS

One hundred eighteen citations were initially retrieved. Thirteen studies were included in our systematic review. Eight out of these thirteen studies were included in our meta-analysis. Statistical analyses showed that T. gondii infection is associated with with BD (OR=1.26).

LIMITATIONS

Small sample size was the major limitation among the studies that carried out serological analyses. In addition, the available studies did not have enough information on disease status/severity or type of bipolar disorder. Also, it was not possible to analyze pregnancy status or perinatal infection. Future studies addressing the aforementioned topics are clearly needed.

CONCLUSIONS

Despite heterogeneous results, patients with BD are more likely to be infected by T. gondii than controls. Early T. gondii infection might predispose the development of BD. T.gondii infection is becoming clinically relevant in psychiatric disorders and future mechanistic studies are required to elucidate the underlying pathophysiological mechanisms.

Beyond the therapeutic shackles of the monoamines: New mechanisms in bipolar disorder biology

Multiple novel biological mechanisms putatively involved in the etiology of bipolar disorders are being explored. These include oxidative stress, altered glutamatergic neurotransmission, mitochondrial dysfunction, inflammation, cell signaling, apoptosis and impaired neurogenesis. Important clinical translational potential exists for such mechanisms to help underpin development of novel therapeutics - much needed given limitations of current therapies. These new mechanisms also help improve our understanding of how current therapeutics might exert their effects. Lithium, for example, appears to have antioxidant, immunomodulatory, signaling, anti-apoptotic and neuroprotective properties. Similar properties have been attributed to other mood stabilizers such as valproate, lamotrigine, and quetiapine. Perhaps of greatest translational value has been the recognition of such mechanisms leading to the emergence of novel therapeutics for bipolar disorders. These include the antioxidant N-acetylcysteine, the anti-inflammatory celecoxib, and ketamine - with effects on the glutamatergic system and microglial inhibition. We review these novel mechanisms and emerging therapeutics, and comment on next steps in this space.

Increased risk of fracture in patients with bipolar disorder: a nationwide cohort study

OBJECTIVES

Bipolar disorder (BD) is a systemic inflammatory disease, and disrupted bone metabolism due to the inflammatory process can cause fracture. Despite evidence of an association between lower bone mineral density and an increased risk of fracture among patients with depression, schizophrenia, and anorexia nervosa, whether BD is a risk factor for subsequent fracture is unknown. To determine the association between BD and fracture and to examine the risk factors for fracture among patients with BD.

METHODS

In this study, we enrolled patients diagnosed with BD from the Taiwan National Health Insurance Research Database. Patients newly diagnosed with BD (ICD-9-CM 296) from 2001 to 2008 were included in the BD cohort, and the date of the initial diagnosis of BD was used as the index date. The comparison cohort, comprising participants without BD, was frequency matched to the BD cohort by age, sex, and index year, and the occurrence of fracture was evaluated in both cohorts.

RESULTS

The BD and comparison cohorts were comprised of 47,271 patients with BD and 1,89,084 frequency-matched participants without BD, respectively. The incidence of fracture was higher among patients with BD than among the controls. Cox models showed that BD was an independent risk factor for fracture irrespective of comorbidities [hazard ratio (HR) = 1.79, 95 % confidence interval (CI) = 1.73-1.84, p < .001].

CONCLUSION

Our study showed that patients with BD have a higher risk of subsequent fracture. Additional prospective clinical studies investigating the relationship between BD and fracture are warranted.

Mast cell activation disease and the modern epidemic of chronic inflammatory disease

A large and growing portion of the human population, especially in developed countries, suffers 1 or more chronic, often quite burdensome ailments which either are overtly inflammatory in nature or are suspected to be of inflammatory origin, but for which investigations to date have failed to identify specific causes, let alone unifying mechanisms underlying the multiple such ailments that often afflict such patients. Relatively recently described as a non-neoplastic cousin of the rare hematologic disease mastocytosis, mast cell (MC) activation syndrome-suspected to be of greatly heterogeneous, complex acquired clonality in many cases-is a potential underlying/unifying explanation for a diverse assortment of inflammatory ailments. A brief review of MC biology and how aberrant primary MC activation might lead to such a vast range of illness is presented.

Does CRP predict outcome in bipolar disorder in regular outpatient care?

BACKGROUND

The association between inflammation and the course of mood disorders is receiving increased attention. This study aims to investigate whether a sub-group of patients with BD can be identified for which a higher CRP (C-reactive protein) level at baseline is associated with an unfavorable prognosis.

METHODS

This is a historic cohort study using CRP at baseline, with 15-month follow-up of mood status and medication. Cross-sectional analyses include boxplots, one-way ANOVA, receiver operating characteristics (ROC) curve and Chi square test, and the longitudinal analysis using multivariate Cox-regression.

RESULTS

Eighty-four bipolar disorder patients were included in the analyses. Cross-sectionally, no statistically significant difference was found in CRP distribution across mood states (p = 0.372) or rapid cycling state (p = 0.656). Also, no CRP cut-off level was distinguished between euthymic and non-euthymic patients according to the ROC curve (p = 0.449, AUC = 0.452, 95 % CI 0.327, 0.576), and a literature-derived cut-off value (3 mg/L) again demonstrated no difference (p = 0.530). Longitudinally, no association was found between CRP and prognosis of disease neither in euthymic [-2 log likelihood = 120.460; CRP: p = 0.866, B = -0.011, OR = 0.989 (95 % CI 0.874-1.120)] nor non-euthymic patients [(-2 log likelihood = 275.028; CRP: p = 0.802, B = 0.010, OR = 1.010 (95 % CI 0.937-1.088)]. Medication use did not affect these associations.

CONCLUSIONS

We found no statistically significant association between CRP and a more unfavorable BD prognosis, suggesting that the application of CRP as a practical biomarker to predict outcome in a naturalistic outpatient care setting is not as straightforward as it may seem.

The role of macrophage polarization on bipolar disorder: Identifying new therapeutic targets

OBJECTIVE

Bipolar disorder is a chronic, severe and disabling disease; however, its pathophysiology remains poorly understood. Recent evidence has suggested that inflammation and immune dysregulation play a significant role in the pathophysiology of bipolar disorder. This review is aimed to highlight the importance of systemic inflammation in modulating the inflammatory response of microglia and hence its potential involvement with bipolar disorder. We also discuss novel therapeutic strategies that emerge from this new research.

METHOD

This article presents a theoretical synthesis of the effects of systemic inflammation on the immune response of the central nervous system in bipolar disorder. The complex relationship between stress, pro-inflammatory cytokines and microglial dysfunction is summarized, emphasizing the role of the kynurenine pathway in this process and, consequently, their effects on neuronal plasticity.

RESULTS

Bipolar patients demonstrate increased serum levels of pro-inflammatory cytokines (interleukin-1β, interleukin-6 and tumor necrosis factor-α) and lower hypothalamic-pituitary-adrenal axis sensitivity. This imbalance in the immune system promotes a change in blood-brain barrier permeability, leading to an inflammatory signal spread in the central nervous system from the periphery, through macrophages activation (M1 polarization). Chronic microglial activation can result in neuronal apoptosis, neurogenesis inhibition, hippocampal volume reduction, lower neurotransmitters synthesis and cytotoxicity, by increasing glutamate production and kynurenine metabolism.

CONCLUSIONS

This review provides an overview of the mechanisms involved in the immune system imbalance and its potential involvement in the pathophysiology of bipolar disorder. Consequently, new strategies that normalize the immune-inflammatory pathways may provide a valuable therapeutic target for the treatment of these disorders.

Bipolar disorder associated with rheumatoid arthritis: A case-control study

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with systemic comorbidities. Recent data suggests that patients with RA have increased prevalence of the bipolar disorder. The current study investigates the association between RA and bipolar disorder.

METHODS

A case-control study was conducted as Patients with RA were compared with age- and gender-matched controls regarding the prevalence of bipolar disorder. Pearson χ(2) test was used for univariate analysis and a logistic regression model was used for multivariate analysis. The study was performed utilizing the medical database of Clalit Health Services.

RESULTS

The study included 11,782 patients with RA and 57,973 age- and gender-matched controls. The prevalence of Bipolar disorder in patients with RA was increased compared with the prevalence in controls (0.6% and 0.4% respectively, p=0.036). However, in a multivariate analysis the association between RA and Bipolar disorder was not significant, whereas smoking is positively correlated with Bipolar disorder (p<0.001).

CONCLUSIONS

By univariate analysis our data implied that patients with RA have a greater prevalence of bipolar disorder than matched controls. However, our analysis suggests that this association may have been confounded by smoking status. Further research is warranted before making inferences about this association in the level of clinical practice.

Activated immune-inflammatory pathways are associated with long-standing depressive symptoms: Evidence from gene-set enrichment analyses in the Young Finns Study

We used genome wide expression (GWE) data of circulating blood cells and pathway analysis to investigate the inflammatory and other molecular pathways that may be associated with long-standing depressive symptoms. Participants were 607 women and 316 men (mean age 42 years) from the Young Finns Study who participated in three consecutive study phases in 2001, 2007 and 2012. Using Gene-set enrichment analyses (GSEA) we focused our analyses to pathways (available in MSigDB database) that are likely to affect immunological and inflammatory processes. GSEA were performed for blood cell GWE data in 2012. Depressive symptoms were assessed using a modified 21-item Beck Depression Inventory in each of the three study phases. Participants who scored in the top quartile of depressive symptoms in each of the three measurement points (n = 191) differed from other participants (n = 732) in several gene-set pathways related to inflammatory processes or immune-inflammatory signaling including interleukin (IL-1) pathway, and pathways related to various immuno-inflammatory processes, such as toll-like, the NEF protein, the nuclear factor kB, the kinase AKT and the mature B cell antigen receptor pathway (false discovery rates, FDRs<0.12). The results provide novel genome wide molecular evidence that support the association between chronic depressive symptoms and altered immune-inflammatory regulation.

The andrologist's contribution to a better life for ageing men: part 2

The long-term intake of a judiciously composed nutriceutical containing low-dose vitamins, antioxidants, minerals and particular herbal preparations seems justified for older persons who take medication, or who consume an unbalanced diet, or who are exposed to environmental toxins. Recent reports suggest these nutriceuticals may delay age-related diseases and the occurrence of cancer, and reduce mortality in apparently healthy ageing men. Food supplementation with a nutriceutical that was formulated particularly for ageing men should result in an increase of at least one quality-adjusted life year and may lower the financial and social burden of disease in elderly people.