Empirically derived subgroups of bipolar I patients with different comorbidity patterns of anxiety and substance use disorders in Han Chinese population

Usage Patterns of Traditional Chinese Medicine for Patients with Bipolar Disorder: A Population-Based Study in Taiwan

BACKGROUND

Patients with bipolar disorder (BD) receive traditional Chinese medicine (TCM) for clinical needs unmet with psychotropic medications. However, the clinical characteristics of practices and outcomes of TCM in BD are not fully understood. This cohort study investigated the clinical characteristics, principal diagnoses, TCM interventions, and TCM prescriptions in patients with BD.

METHODS

Data for a total of 12,113 patients with BD between 1996 and 2013 were withdrawn from Taiwan's longitudinal health insurance database 2000 (LHID 2000). The chi-square test was used for categorical variables, and the independent t-test was used for continuous variables. A p-value less than 0.05 indicated significance.

RESULTS

One thousand three hundred nineteen patients who visited TCM clinics after the diagnosis of BD were in the TCM group, while those who never visited TCM were in the non-TCM group (n = 1053). Compared to the non-TCM group, patients in the TCM group had younger average age, a higher percentage of female individuals, more comorbidities of anxiety and alcohol use disorders, and higher mood stabilizer usage rates. The TCM group exhibited pain-related indications, including joint pain, myalgia, myositis, headache, and sleep disturbances. Corydalis yanhusuo and Shu-Jing-Huo-Xue-Tang were the most useful single herbs and herbal formulae.

CONCLUSIONS

Physicians need to be aware of the use of TCM in patients with BD.

The detrimental effects of smoking on the course and outcome in adults with bipolar disorder-A narrative review

BACKGROUND

Smoking is a substantial and avoidable risk for physical disability and premature death. Despite a declining tobacco use in the community of developed countries, smoking remains abundant in people with mental disorders. This narrative review highlights the epidemiology, consequences and treatment options of tobacco use disorder (TUD) and nicotine dependence (ND) in people with bipolar disorder (BD).

METHODS

The authors conducted a Medline literature search from 1970 to November 2022 using MeSH terms "bipolar disorder" x "smoking" or "nicotine" or "tobacco" that retrieved 770 results. Search results were complemented by additional literature retrieved from examining cross references and by hand search in text books. Finally, 92 references were considered as essential and selected for the educational purpose of this review.

SUMMARY OF FINDINGS

Lifetime and point prevalence of smoking in people with BD is in the range of 45-70% and thus about 2-3 times more frequent in BD than in community samples. Smoking, TUD and ND have a detrimental impact both on mental and physical health as well as mortality in people with BD. In the absence of large controlled studies in comorbid BD and TUD or ND, pharmacological treatment follows the individual guidance for each disorder. Community-based psychosocial interventions for TUD and ND appear to be suitable in people with BD, too, as well as Cognitive Behavioral (CBT) or Acceptance and Commitment (ACT) based psychotherapies.

CONCLUSIONS

Smoking is a modifiable risk factor causing increased risks both for mental and physical health in BD, and deserves more attention in treatment. More treatment research into pharmacological and psychosocial interventions in comorbid BD and TUD or ND are still needed to deliver evidence-based recommendations to physicians.

The association of personality polygenic risk score, psychosocial protective factors and suicide attempt in mood disorder

Some personality traits, especially neuroticism, has been found to be associated with suicide attempt (SA) in mood disorder patients. The present study explored the association between personality traits and SA using polygenic risk scores (PRS) for personality among patients with mood disorders. We also investigated the effects of a variety of psychosocial variables on SA. Patients with bipolar disorder (BPD, N = 841) and major depressive disorder (MDD, N = 710) were recruited from hospitals in Taiwan. Lifetime SA and information on psychosocial factors was collected. We calculated the PRS of neuroticism and extraversion. A trend test for SA was performed across quartiles of the PRS for neuroticism and extraversion, and logistic regression analyses were performed to examine the associations between psychosocial factors and SA, accounting for the PRS of personality traits. The prevalence of SA was higher in MDD than in BPD patients. The risk of SA was elevated in MDD patients with a higher quintile of PRS in neuroticism and a lower quintile of PRS in extraversion. The multiple regression analysis results demonstrated that later age of onset, higher family support and resilience, and lower overall social support were protective factors against SA. From the perspective of suicide prevention efforts, strengthening family support and conducting resilience training for patients with mood disorders may be beneficial interventions in clinical settings.

The prevalence, odds, predictors, and management of tobacco use disorder or nicotine dependence among people with severe mental illness: Systematic review and meta-analysis

The prevalence, correlates, and management of tobacco use disorder (TUD) or nicotine dependence (ND) among people with severe mental illness (SMI), namely schizophrenia, bipolar disorder (BD), and major depressive disorder (MDD), remain unclear. Therefore, a systematic review and meta-analysis was conducted. Electronic databases were systematically searched from inception to July 12, 2020, for observational studies documenting the prevalence, odds, and correlates of TUD/ND among people with SMI; randomized controlled trials (RCTs) informing the management of TUD/ND in people with SMI were also included. Random-effects meta-analyses were conducted. Sources of heterogeneity were explored. Nineteen observational studies, including 7527 participants with SMI met inclusion criteria. TUD/ND co-occurred in 33.4-65% of people with SMI. Rates were higher among males. While bupropion and varenicline represent promising treatment opportunities for schizophrenia with TUD/ND, non-pharmacological interventions require further research, mainly for people with primary mood disorders. TUD/ND represent prevalent co-occurring conditions among people with SMI. Further well-designed RCTs are warranted to inform their management.

Latent class analysis of bipolar disorder symptoms and suicidal ideation and behaviors

Individuals with bipolar disorder are at increased risk of dying by suicide compared to healthy controls and those with unipolar depression. Previous studies show that depressive symptoms and mixed episodes of mania and depression are related to suicide. However, most of these studies adopt a variable-centered approach to understanding how specific symptoms relate to suicidal ideation, without addressing how these symptoms and symptom profiles relate to suicidal behaviors.

OBJECTIVES

Using latent class analysis, this study adopts a person-centered approach to examine whether subtypes of patients with bipolar disorder differ in their levels of suicidal ideation and behaviors.

METHODS

A total of 150 patients from a behavioral health outpatient clinic were recruited. Latent classes were generated based on self reports of their depressive and manic symptoms.

RESULTS

Five classes of patients with bipolar disorder were identified, namely, a minimal symptom, mania, moderately depressed, severely depressed, and mixed depression-mania subtypes. Those in the severely depressed and mixed depression-mania groups reported significantly higher levels of suicidal ideation and behaviors compared to the other groups.

CONCLUSIONS

Our findings provide further support for the strong relationship between depressive symptoms and suicidality. These findings are significant as they shed light on the different suicide risk profiles among a heterogenous group of patients with bipolar disorder. Name of clinical trial: Suicidal Behavior in Patients Diagnosed with Bipolar Disorder: The Roles of Biological and Childhood and Adult Environmental Risk Factors. ClinicalTrials.gov Identifier: NCT02604277.

Differential Co-Occurring Patterns Between Depressive Symptomatology and Sleep-Wake-Related Disturbances in Mood Disorders

PURPOSE

This study aimed to elucidate the various co-occurring patterns of depressive symptomatology and sleep-wake-related disturbances (SWRDs) in patients with mood disorders.

PATIENTS AND METHODS

Individuals in non-acute states of major depressive disorder or bipolar disorder were recruited. The Beck Depression Inventory II (BDI-II) was utilized to evaluate depressive symptoms. BDI-II items were classified into three domains: cognitive, affective, and somatic. Between-domain differences with various SWRDs were examined. Latent class analysis was used to empirically classify participants using BDI-II items as indicator variables. Co-occurring patterns between domains of BDI-II items and SWRDs were re-examined in each subgroup to elucidate inter-individual differences.

RESULTS

In total, 657 participants were enrolled. Of participants, 66.8% were female, and 52.4% were diagnosed with major depressive disorder. Each BDI-II domain exhibited different co-occurring patterns. The somatic domain was most likely to co-occur with various SWRDs. Three subgroups were derived from latent class analysis and were designated as poor sleep quality and high insomnia (n=150), poor sleep quality and moderate insomnia (n=248), and poor sleep quality and low insomnia (n=159). The group with more severe insomnia presented with more severe depressive and anxiety symptoms. The three subgroups further differed in co-occurring patterns. From the low insomnia to high insomnia group, the associations with various SWRDs appeared in the sequence of somatic, affective, and cognitive domains.

CONCLUSION

Co-occurring patterns between domains of depressive symptomatology with various SWRDs differ and may vary among individuals.

Alcohol misuse in bipolar disorder. A systematic review and meta-analysis of comorbidity rates

Aims:

To assess the comorbidity rates of alcohol use disorders (AUDs) in bipolar disorder (BD) and to explore possible sources of heterogeneity.

Methods:

Studies were identified through database searches. Meta-analytic techniques were employed to aggregate data on lifetime comorbidity and to explore possible sources of heterogeneity. Funnel plots were used to detect publication bias.

Results:

In clinical studies, AUDs affected more than one in three subjects with BD. Significant heterogeneity was found, which was largely explained by the geographical location of study populations and gender ratio of participants. AUDs affected more than one in five women and two in five men.

Conclusion:

AUDs are highly prevalent in BD. Our study revealed a substantial heterogeneity across studies. Further research including control groups is needed. Patients with BD should be assessed for current and previous AUDs.

Subgrouping Poor Sleep Quality in Community-Dwelling Older Adults with Latent Class Analysis - The Yilan Study, Taiwan

The manifestation of older adults with poor sleep quality is heterogeneous. Using data-driven classifying methods, the study aims to subgroup community-dwelling older adults with poor sleep quality. Adults aged 65 and older participated in the Yilan study. Poor sleep quality was defined using the Pittsburgh Sleep Quality Index. Latent class analysis with the 7 subscores of the Pittsburgh Sleep Quality Index as the indicators was used to generate empirical subgroups. Differences in comorbidity patterns between subgroups were compared. A total of 2622 individuals, of which 1011 (38.6%) had Pittsburgh Sleep Quality Index -defined poor sleep quality, participated. Three groups for poor sleep quality were specified in the latent class analysis: High Insomnia (n = 191, 7.3%), Mild Insomnia (n = 574, 21.9%), and High Hypnotics (n = 246, 9.4%). The High Insomnia and Mild Insomnia groups shared similar profiles but different severities in the 7 domains of the Pittsburgh Sleep Quality Index. In contrast, the High Hypnotics group had the lowest Pittsburgh Sleep Quality Index total scores and insomnia severity but had similar mental and physical comorbid patterns as the High Insomnia group. This finding suggests that poor sleep quality in community-dwelling older adults had various feature-based subgroups. It also implicates the development of group-centered interventions.

Transcriptome Changes in Relation to Manic Episode

Bipolar disorder (BD) is highly heritable and well known for its recurrent manic and depressive episodes. The present study focused on manic episode in BD patients and aimed to investigate state-specific transcriptome alterations between acute episode and remission, including messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs), and micro-RNAs (miRNAs), using microarray and RNA sequencing (RNA-Seq) platforms. BD patients were enrolled with clinical information, and peripheral blood samples collected at both acute and remission status spanning for at least 2 months were confirmed by follow-ups. Symptom severity was assessed by Young Mania Rating Scale. We enrolled six BD patients as the discovery samples and used the Affymetrix Human Transcriptome Array 2.0 to capture transcriptome data at the two time points. For replication, expression data from Gene Expression Omnibus that consisted of 11 BD patients were downloaded, and we performed a mega-analysis for microarray data of 17 patients. Moreover, we conducted RNA sequencing (RNA-Seq) in additional samples of 7 BD patients. To identify intraindividual differentially expressed genes (DEGs), we analyzed data using a linear model controlling for symptom severity. We found that noncoding genes were of majority among the top DEGs in microarray data. The expression fold change of coding genes among DEGs showed moderate to high correlations (∼0.5) across platforms. A number of lncRNAs and two miRNAs (MIR181B1 and MIR103A1) exhibited high levels of gene expression in the manic state. For coding genes, we reported that the taste function-related genes, including TAS2R5 and TAS2R3, may be mania state-specific markers. Additionally, four genes showed a nominal p-value of less than 0.05 in all our microarray data, mega-analysis, and RNA-Seq analysis. They were upregulated in the manic state and consisted of MS4A14, PYHIN1, UTRN, and DMXL2, and their gene expression patterns were further validated by quantitative real-time polymerase chain reaction (PCR) (qRT-PCR). We also performed weight gene coexpression network analysis to identify gene modules for manic episode. Genes in the mania-related modules were different from the susceptible loci of BD obtained from genome-wide association studies, and biological pathways in relation to these modules were mainly related to immune function, especially cytokine-cytokine receptor interaction. Results of the present study elucidated potential molecular targets and genomic networks that are involved in manic episode. Future studies are needed to further validate these biomarkers for their roles in the etiology of bipolar illness.

Factors predicting re-hospitalization for inpatients with bipolar mania--A naturalistic cohort

Patients with bipolar mania often require re-hospitalization, which can be a social-economic burden. This study aimed to investigate the factors affecting time to re-hospitalization for inpatients with acute bipolar mania. In this 6-year naturalistic study we reviewed the charts of inpatients with acute bipolar mania. Potential dichotomous factors including sex, family history of affective disorder, suicide history, and discharge against medical advice, involuntary admission, psychotic features, substance use disorder, and remission at discharge were recorded. Continuous variables including age, age at onset of affective episodes, and number of previous hospitalizations were also recorded. We used survival analysis with a univariate Cox proportional hazard regression model, along with forward multivariate model, to identify the potential factors. Of the 165 patients, 23% achieved symptomatic remission at discharge. In the forward Cox model, psychotic features, discharge against medical advice and higher number of previous hospitalizations were significant risk factors for re-admission. Remission at discharge was significantly associated with preventing re-hospitalization. We identified several predictors for re-hospitalization among inpatients with bipolar mania. Further studies are needed in other real-world settings to validate our results.

Risk profiles of personality traits for suicidality among mood disorder patients and community controls

OBJECTIVE

To examine the associations between personality traits and suicidal ideation (SI) and attempt (SA) in mood disorder patients and community controls.

METHOD

We recruited 365 bipolar, 296 major depressive disorder patients, and 315 community controls to assess their lifetime suicidality. Participants filled out self-reported personality questionnaires to collect data of personality traits, including novelty seeking (NS), harm avoidance (HA), extraversion (E), and neuroticism (N). We used logistic regression models adjusted for diagnoses to analyze combinational effects of personality traits on the risk of suicide. Additionally, radar charts display personality profiles for suicidal behaviours by groups.

RESULTS

All personality traits were associated with the risk of suicidality with various effect size, except for E that showed protective effect. High N or HA had prominent and independent risk effects on SI and SA. Combinations of high N and low E, or high HA and NS were the risk personality profiles for suicidality. Higher N scores further distinguished SA from SI in mood disorder patients.

CONCLUSION

Introvert personality traits showed independent risk effects on suicidality regardless of diagnosis status. Among high-risk individuals with suicidal thoughts, higher neuroticism tendency is further associated with increased risk of suicide attempt.

Prevalence and Associated Features of Anxiety Disorder Comorbidity in Bipolar Disorder: A Meta-Analysis and Meta-Regression Study

Objective: Bipolar disorder is highly comorbid with anxiety disorders, however current and lifetime comorbidity patterns of each anxiety disorder and their associated features are not well studied. Here, we aimed to conduct a meta-analysis and meta-regression study of current evidence. Method: We searched PubMed to access relevant articles published until September 2015, using the keywords "Bipolar disorder" or "Affective Psychosis" or "manic depressive" separately with "generalized anxiety," "panic disorder," "social phobia," "obsessive compulsive," and "anxiety." Variables for associated features and prevalence of anxiety disorders were carefully extracted. Results: Lifetime any anxiety disorder comorbidity in BD was 40.5%; panic disorder (PD) 18.1%, generalized anxiety disorder (GAD) 13.3%, social anxiety disorder (SAD) 13.5% and obsessive compulsive disorder (OCD) 9.7%. Current any anxiety disorder comorbidity in BD is 38.2%; GAD is 15.2%, PD 13.3%, SAD 11.7%, and OCD 9.9%. When studies reporting data about comorbidities in BDI or BDII were analyzed separately, lifetime any anxiety disorder comorbidity in BDI and BDII were 38% and 34%, PD was 15% and 15%, GAD was 14% and 16.6%, SAD was 8% and 13%, OCD was 8% and 10%, respectively. Current any DSM anxiety disorder comorbidity in BDI or BDII were 31% and 37%, PD was 9% and 13%, GAD was 8% and 12%, SAD was 7% and 11%, and OCD was 8% and 7%, respectively. The percentage of manic patients and age of onset of BD tended to have a significant impact on anxiety disorders. Percentage of BD I patients significantly decreased the prevalence of panic disorder and social anxiety disorder. A higher rate of substance use disorder was associated with greater BD-SAD comorbidity. History of psychotic features significantly affected current PD and GAD. Conclusions: Anxiety disorder comorbidity is high in BD with somewhat lower rates in BDI vs BDII. Age of onset, substance use disorders, and percentage of patients in a manic episode or with psychotic features influences anxiety disorder comorbidity.

Evaluation of the interaction between genetic variants of GAD1 and miRNA in bipolar disorders

BACKGROUND

Glutamic acid dehydrogenase 1 (GAD1) serves as the rate-limiting enzyme for synthesizing GABA, and is reported to be associated with several psychiatric disorders. The present study examined the effects of GAD1 genetic variants on bipolar disorder (BD) and its subtypes. Moreover, we investigated functional interactions between genetic variants and miRNAs via algorithm prediction and experimental validation.

METHODS

A case-control study was conducted with 280 BD patients and 200 healthy controls. Eight tag SNPs in GAD1 were genotyped. For associated markers, we performed in silico prediction for their potential functions through SNP-miRNA interactions by establishing a scoring system to combine information from several miRNA predictive algorithms. We then tested allelic expression differences using Dual-Glo luciferase reporter assays for the selected SNP-miRNA pair. Lastly, we examined the associations of the GAD1 gene and BD in two additional independent datasets with a few thousand samples for replication.

RESULTS

Marker rs3749034 was associated with BD, in particular the BD-II subtype. According to our scoring system, several candidate miRNAs were predicted to interact with rs3749034, and hsa-miR-504 had the highest score. Findings from an in vitro experiment revealed a non-statistically significant trend for lower gene expression level with the A allele of rs3749034 compared with the G allele. The association between rs3749034 and BD was not replicated in either of the independent datasets. Instead, other rarer genetic variants in GAD1 showed suggestive signals (e.g. rs575441409, p-value = 3.8*10^-4, D' = 1 with rs3749034) with BD in the Taiwanese dataset.

LIMITATIONS

The present study considered common genetic variants only. In addition, we only used a 293T cell-line in conducting luciferase reporter assays, as no primary cell-lines from patient samples were available to differentiate the effects between BD subtypes.

CONCLUSIONS

Our results demonstrate a weak effect of the GAD1 gene on the risk of bipolar illness, and the associated marker might represent a proxy for real signals of rare variants.

Substance use disorders in adolescent and young adult relatives of probands with bipolar disorder: What drives the increased risk?

BACKGROUND

Adults with bipolar disorder (BD) have higher rates of substance use disorders (SUDs) compared to the general population. SUD rates in young offspring/relatives of BD probands, as well as factors which drive those rates, are not as well-characterized.

METHODS

We aimed to examine SUD prevalence among adolescent/young adult offspring and relatives of probands with and without BD. Data were collected from five sites in the US and Australia during 2006-2011. Youth offspring/relatives ("Relatives of BD probands;" n=267; mean age=16.8years; ±2.9S.D.), identified through a proband family member with DSM-IV BD (Type I or II), were compared to offspring/relatives of control probands ("relatives of control probands;" n=149; mean age=17.4years; ±2.9S.D.). Logistic regression with generalized estimating equations was used to compare the groups across a range of substance use and SUD variables. Odds ratios were calculated for lifetime prevalence of substance outcomes.

RESULTS

Bivariate analyses showed DSM-IV SUDs were more prevalent among relatives of BD probands than among relatives of control probands (29% vs. 18%; p=0.01). Generalized estimating equation models showed BD mood and childhood-onset externalizing disorders in adolescent and young adult relatives to each significantly increase the odds (OR=2.80-3.17; p<0.02) for the development of several substance variables among all relatives, whereas the risk of SUDs in relatives was not increased when the relatives had no mood or externalizing disorders themselves.

CONCLUSION

Relatives of BD probands with lifetime mood and externalizing disorders report more substance use/SUDs than relatives of control probands. In contrast, SUD outcomes in relatives of BD probands without mood or externalizing disorders were no different from control relatives without psychopathology. Early recognition and treatment of psychiatric disorders may lead to less substance use in this highly vulnerable population.

Prevalence of comorbid bipolar and substance use disorders in clinical settings, 1990-2015: Systematic review and meta-analysis

BACKGROUND

Comorbidity between substance use disorders (SUDs) and bipolar disorder (BD) is highly prevalent to the extent it may almost be regarded the norm. This systematic review and meta-analysis aimed to estimate the prevalence rates of SUDs in treatment seeking patients diagnosed with BD in both inpatient and outpatient settings.

METHODS

A comprehensive literature search of Medline, EMBASE, psychINFO and CINAHL databases was conducted from 1990 to 2015. Prevalence of co-morbid SUDs and BD were extracted and odds ratios (ORs) were calculated using random effects meta-analysis.

RESULTS

There were 151 articles identified by electronic searches that yielded 22 large, multi-site studies and 56 individual studies describing comorbid rates of SUDs amongst community dwelling, BD inpatients or outpatients. The SUDs with the highest prevalence in BD were alcohol use (42%) followed by cannabis use (20%) and other illicit drug use (17%). Meta-analysis showed males had higher lifetime risks of SUDs compared to females. BD and comorbid SUDS were associated with earlier age of onset and slightly more hospitalisations than non-users.

LIMITATIONS

The results do not take into account the possibility that individuals may have more than one comorbid disorder, such as having more than one SUD, anxiety disorder, or other combination. Some of the meta-analyses were based on relatively few studies with high rates of heterogeneity. Most included studies were cross-sectional and therefore causality cannot be inferred.

CONCLUSIONS

This systematic review shows comorbidity between SUDs and bipolar illness is highly prevalent in hospital and community-based samples. The prevalence of SUDs was similar in patients with bipolar I and bipolar II disorders. This study adds to the literature demonstrating that SUDs are common in BD and reinforces the need to provide better interventions and properly conducted treatment trials to reduce the burden conferred by comorbid SUD and BD.

Prevalence, impact and treatment of generalised anxiety disorder in bipolar disorder: a systematic review and meta-analysis

QUESTION

Recent data suggest that anxiety disorders are as often comorbid with bipolar disorder (BD) as with unipolar depression; however, less attention has been paid to comorbidity of anxiety disorders with BD. Generalised anxiety disorder (GAD) is one of the most prevalent anxiety disorders that is highly comorbid with other mental disorders. We carried out a systematic review and meta-analysis to assess the degree of comorbidity between GAD and BD.

STUDY SELECTION AND ANALYSIS

We searched for all studies, which included primary data concerning the existence of GAD in patients with BD. The literature search strategy, selection of publications and the reporting of results have been conducted with PRISMA guidelines. The meta-analysis calculated prevalence estimates using the variance-stabilising Freeman-Tukey double arcsine transformation. We applied the inverse variance method using both fixed-effects and random-effects models to estimate summary effects for all combined studies. Heterogeneity was assessed and measured with Cochran's Q and I(2) statistics, respectively.

FINDINGS

The current meta-analysis analysed data from 28 independent studies and a total of 2975 patients from point prevalence studies and 4919 patients from lifetime studies. The overall random-effects point prevalence of GAD in patients with BD was 12.2% (95% CI 10.9% to 13.5%) and the overall random-effects lifetime estimate was 15.1% (95% CI 9.7% to 21.5%). Both estimates reported significant heterogeneity (94.0% and 94.7%, respectively).

CONCLUSIONS

Published studies report prevalence rates with high heterogeneity and consistently higher than those typically reported in the general population. It is believed that comorbid GAD might be associated with a more severe BD course and increased suicidality, and it is unknown how best to treat such conditions. The current meta-analysis confirms that GAD is highly prevalent in BD and the rate is higher in comparison to those in the general population.

Identification of Susceptible Loci and Enriched Pathways for Bipolar II Disorder Using Genome-Wide Association Studies

BACKGROUND

This study aimed to identify susceptible loci and enriched pathways for bipolar disorder subtype II.

METHODS

We conducted a genome-wide association scan in discovery samples with 189 bipolar disorder subtype II patients and 1773 controls, and replication samples with 283 bipolar disorder subtype II patients and 500 controls in a Taiwanese Han population using Affymetrix Axiom Genome-Wide CHB1 Array. We performed single-marker and gene-based association analyses, as well as calculated polygeneic risk scores for bipolar disorder subtype II. Pathway enrichment analyses were employed to reveal significant biological pathways.

RESULTS

Seven markers were found to be associated with bipolar disorder subtype II in meta-analysis combining both discovery and replication samples (P<5.0×10^-6), including markers in or close to MYO16, HSP90AB3P, noncoding gene LOC100507632, and markers in chromosomes 4 and 10. A novel locus, ETF1, was associated with bipolar disorder subtype II (P<6.0×10^-3) in gene-based association tests. Results of risk evaluation demonstrated that higher genetic risk scores were able to distinguish bipolar disorder subtype II patients from healthy controls in both discovery (P=3.9×10^-4~1.0×10^-3) and replication samples (2.8×10^-4~1.7×10^-3). Genetic variance explained by chip markers for bipolar disorder subtype II was substantial in the discovery (55.1%) and replication (60.5%) samples. Moreover, pathways related to neurodevelopmental function, signal transduction, neuronal system, and cell adhesion molecules were significantly associated with bipolar disorder subtype II.

CONCLUSION

We reported novel susceptible loci for pure bipolar subtype II disorder that is less addressed in the literature. Future studies are needed to confirm the roles of these loci for bipolar disorder subtype II.

A Lifetime Prevalence of Comorbidity Between Bipolar Affective Disorder and Anxiety Disorders: A Meta-analysis of 52 Interview-based Studies of Psychiatric Population

BACKGROUND

Bipolar affective disorder has a high rate of comorbidity with a multitude of psychiatric disorders and medical conditions. Among all the potential comorbidities, co-existing anxiety disorders stand out due to their high prevalence.

AIMS

To determine the lifetime prevalence of comorbid anxiety disorders in bipolar affective disorder under the care of psychiatric services through systematic review and meta-analysis.

METHOD

Random effects meta-analyses were used to calculate the lifetime prevalence of comorbid generalised anxiety disorder, panic disorder, social anxiety disorder, specific phobia, agoraphobia, obsessive compulsive disorder and posttraumatic stress disorder in bipolar affective disorder.

RESULTS

52 studies were included in the meta-analysis. The rate of lifetime comorbidity was as follows: panic disorder 16.8% (95% CI 13.7-20.1), generalised anxiety disorder 14.4% (95% CI 10.8-18.3), social anxiety disorder13.3% (95% CI 10.1-16.9), post-traumatic stress disorder 10.8% (95% CI 7.3-14.9), specific phobia 10.8% (95% CI 8.2-13.7), obsessive compulsive disorder 10.7% (95% CI 8.7-13.0) and agoraphobia 7.8% (95% CI 5.2-11.0). The lifetime prevalence of any anxiety disorders in bipolar disorder was 42.7%.

CONCLUSIONS

Our results suggest a high rate of lifetime concurrent anxiety disorders in bipolar disorder. The diagnostic issues at the interface are particularly difficult because of the substantial symptom overlap. The treatment of co-existing conditions has clinically remained challenging.

Alcohol use in bipolar disorder: A neurobiological model to help predict susceptibility, select treatments and attenuate cortical insult

In a series of neurophysiological and neuroimaging studies we investigated the neurobiology related to alcohol use in young people with bipolar disorder. Impairments were identified across frontal and temporal representations of event-related potential and proton magnetic resonance spectroscopy markers; mismatch negativity and in vivo glutathione, respectively. We propose these findings reflect impairments in the N-methyl-D-aspartate receptor and antioxidant capacity. This review seeks to place these findings within the broader literature in the context of two propositions: 1. Pathophysiological impairments in N-methyl-D-aspartate receptor functioning in bipolar disorder contribute to susceptibility toward developing alcohol problems. 2. Alcohol aggravates bipolar disorder neuroprogression via oxidative stress. A neurobiological model that incorporates these propositions is presented, with a focus on the potential for N-methyl-D-aspartate receptor antagonism and glutathione augmentation as potential adjunctive pharmacotherapies to treat the comorbidity. While this review highlights the importance of alcohol monitoring and reduction strategies in the treatment of bipolar disorder, the clinical impact of the proposed model remains limited by the lack of controlled trials of novel pharmacological interventions.

The Potential Role of the NLRP3 Inflammasome as a Link between Mitochondrial Complex I Dysfunction and Inflammation in Bipolar Disorder

Mitochondrial dysfunction and activation of the inflammatory system are two of the most consistently reported findings in bipolar disorder (BD). More specifically, altered levels of inflammatory cytokines and decreased levels of mitochondrial complex I subunits have been found in the brain and periphery of patients with BD, which could lead to increased production of mitochondrial reactive oxygen species (ROS). Recent studies have shown that mitochondrial production of ROS and inflammation may be closely linked through a redox sensor known as nod-like receptor pyrin domain-containing 3 (NLRP3). Upon sensing mitochondrial release of ROS, NLRP3 assembles the NLRP3 inflammasome, which releases caspase 1 to begin the inflammatory cascade. In this review, we discuss the potential role of the NLRP3 inflammasome as a link between complex I dysfunction and inflammation in BD and its therapeutic implications.

Investigation of associations between NR1D1, RORA and RORB genes and bipolar disorder

Several genes that are involved in the regulation of circadian rhythms are implicated in the susceptibility to bipolar disorder (BD). The current study aimed to investigate the relationships between genetic variants in NR1D1 RORA, and RORB genes and BD in the Han Chinese population. We conducted a case-control genetic association study with two samples of BD patients and healthy controls. Sample I consisted of 280 BD patients and 200 controls. Sample II consisted of 448 BD patients and 1770 healthy controls. 27 single nucleotide polymorphisms in the NR1D1, RORA, and RORB genes were genotyped using GoldenGate VeraCode assays in sample I, and 492 markers in the three genes were genotyped using Affymetrix Genome-Wide CHB Array in sample II. Single marker and gene-based association analyses were performed using PLINK. A combined p-value for the joining effects of all markers within a gene was calculated using the rank truncated product method. Multifactor dimensionality reduction (MDR) method was also applied to test gene-gene interactions in sample I. All markers were in Hardy-Weinberg equilibrium (P>0.001). In sample I, the associations with BD were observed for rs4774388 in RORA (OR = 1.53, empirical p-value, P = 0.024), and rs1327836 in RORB (OR = 1.75, P = 0.003). In Sample II, there were 45 SNPs showed associations with BD, and the most significant marker in RORA was rs11639084 (OR = 0.69, P = 0.002), and in RORB was rs17611535 (OR = 3.15, P = 0.027). A combined p-value of 1.6×10−6, 0.7, and 1.0 was obtained for RORA, RORB and NR1D1, respectively, indicting a strong association for RORA with the risk of developing BD. A four way interaction was found among markers in NR1D1, RORA, and RORB with the testing accuracy 53.25% and a cross-validation consistency of 8 out of 10. In sample II, 45 markers had empirical p-values less than 0.05. The most significant markers in RORA and RORB genes were rs11639084 (OR = 0.69, P = 0.002), and rs17611535 (OR = 3.15, P = 0.027), respectively. Gene-based association was significant for RORA gene (P = 0.0007). Our results support for the involvement of RORs genes in the risk of developing BD. Investigation of the functional properties of genes in the circadian pathway may further enhance our understanding about the pathogenesis of bipolar illness.

The effects of ethnic, social and cultural factors on axis I comorbidity of bipolar disorder: results from the clinical setting in Korea

OBJECTIVE

Ethnic, social and cultural factors contribute to axis I comorbid conditions in bipolar disorder (BPD). Korea has strict laws against illicit drugs and a relatively permissive prevailing attitude toward alcohol. The present study aimed to explore the lifetime axis I comorbidity rate in patients with BPD in Korea.

METHODS

Clinically stable patients with bipolar I (n=222) and bipolar II (n=194) disorders were recruited from four tertiary medical centers in Korea. The subjects׳ diagnoses and axis I comorbid conditions were evaluated using the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID) and the Korean version of the Diagnostic Interview for Genetic Studies (K-DIGS). The lifetime prevalence of anxiety disorders, substance use disorders and eating disorders was explored. The prevalence of these axis I comorbid conditions was compared with data from prior studies in other countries and to data concerning the general Korean population.

RESULTS

A total of 45.1% of all subjects had at least one axis I comorbid condition. Anxiety disorders (30.2%) were the most common comorbidity, followed by alcohol use disorders (16.8%). Males with BPD showed a higher rate of alcohol dependence compared to the general male population and females with BPD showed a greater risk of having alcohol use disorder compared to the general female population. The rate of drug use disorder was extremely low (1.7%), and only one subject had an illicit-drug-related problem.

LIMITATION

Cross-sectional studies.

CONCLUSION

Comorbid conditions of Korean patients with BPD showed a distinct pattern, which is associated with the ethnic, social and cultural characteristics in Korea.

Prevalence and clinical correlates of alcohol use disorders among bipolar disorder patients: results from the Brazilian Bipolar Research Network

OBJECTIVES

To investigate prevalence rates and clinical correlates of alcohol use disorders (AUD) among bipolar disorder (BD) patients in a large sample from the Brazilian Bipolar Research Network.

METHODS

Four hundred and eighty-three DSM-IV BD patients, divided according to the presence or absence of a lifetime AUD diagnosis (BD-AUD vs. BD-nonAUD), were included. Demographic and clinical characteristics of these two groups were compared. Logistic regression was performed to identify which characteristics were most strongly associated with a lifetime AUD diagnosis.

RESULTS

Nearly 23% presented a lifetime AUD diagnosis. BD-AUD patients were more likely to be male, to present rapid cycling, post-traumatic stress disorder (PTSD), anorexia, other substance use disorders (SUD), family history of SUD, any substance misuse during the first mood episode, history of psychosis, suicide attempts, and younger age at onset of illness than BD-nonAUD patients. Logistic regression showed that the variables most strongly associated with a lifetime AUD diagnosis were SUD (non-alcohol), any substance misuse during the first mood episode, PTSD, male gender, suicide attempt, family history of SUD, and younger age at onset of BD.

CONCLUSIONS

BD-AUD patients begin their mood disorder earlier and present more suicidal behaviors than BD-nonAUD patients. Personal and family history of SUD may be good predictors of comorbid AUD among BD patients. These variables are easily assessed in the clinical setting and may help to identify a particularly severe subgroup of BD patients.

Identification of novel loci for bipolar I disorder in a multi-stage genome-wide association study

OBJECTIVE

Identification of genetic variants that influence bipolar I disorder (BPD-I) through genome-wide association (GWA) studies is limited in Asian populations. The current study aimed to identify novel common variants for BPD-I in an ethnically homogeneous Taiwanese sample using a multi-stage GWA study design.

METHOD

At the discovery stage, 200 BPD-I patients and 200 controls that combined to form 16 pools were genotyped with 1 million markers. Utilizing a newly developed rank-based method, top-ranked markers were selected. After validation with individual genotyping, a fine-mapping association study was conducted to identify associated loci using 240 patients and 240 controls. At the last stage, independent samples were collected (351 cases and 341 controls) for replication.

RESULTS

Among the top-ranked markers from the discovery stage, eight genes and 15 individual SNPs were evaluated in the fine-mapping stage. At this stage, rs7619173, which is not in a gene coding region, showed the most significant association (P = 2 ∗ 10(-5)) with BPD-I. Four genes had empirical P-values<0.05, including KCNH7 (P = 0.0047), MYST4 (P = 0.0047), NRXN3 (P = 0.0095), and SEMA3D (P = 0.037). For markers genotyped in replication samples, rs7619173 exhibited a significant association (P(combined) = 2 ∗ 10(-4)) after multiple testing correction, while markers rs11001178 (MYST4) and rs2217887 (NRXN3) showed weak associations (P(combined) = 0.02) with BPD-I.

CONCLUSION

A multi-stage GWA design has the potential to uncover the underlying pathogenesis of a complex trait. Findings in the present study highlight three loci that warrant further investigation for bipolar.

Exploring the associations between genetic variants in genes encoding for subunits of calcium channel and subtypes of bipolar disorder

BACKGROUND

Associations of two voltage-gated calcium channel (Cav) genes, CACNA1C and CACNB2, were identified for bipolar disorder (BP) in different ethnic groups in recent genome-wide association studies. The current study aimed to evaluate the associations of several Cav genes and subtypes of BP in genetically more homogeneous Taiwanese samples. Additionally, we tested interaction effects among genes that encode for α1, β and γ-subunits of calcium channel.

METHODS

8 Cav genes were selected based on evidence in prior association studies and significant linkage regions for BP. 280 BP patients and 200 controls were recruited. Multifactor dimensionality reduction was performed for interaction testing in these discovery samples. Replication was conducted for two markers using additional 495 Taiwanese cases and 1341 controls.

RESULTS

Weak associations for CACNA1C (rs10848635), CACNA1E (rs10848635), CACNB2 (rs11013860), and CACNG2 (rs2284018) genes were observed. Joint analysis of four markers revealed higher accumulative risk with increasing numbers of risk genotypes an individual endorsed for BP-I (Ptrend=0.006) and BP-II (Ptrend=0.017) disorders. Combined analysis with independent replication samples further supported the association of rs11013860 in CACNB2 with BP subtype I (P=1×10(-6)). Suggestive interactions were found between genes encoded for different subunits of calcium channel (α1, β, and γ).

LIMITATIONS

Moderate sample size and incomplete markers coverage for the chosen Cav genes.

CONCLUSIONS

Our results support the involvement of different calcium channel genes in bipolar illness, in particular the beta-subunit in the Asian population. Further investigation of functional property of these genes can contribute on understanding the etiological mechanisms of bipolar illness.

Identifying Potential Regions of Copy Number Variation for Bipolar Disorder

Bipolar disorder is a complex psychiatric disorder with high heritability, but its genetic determinants are still largely unknown. Copy number variation (CNV) is one of the sources to explain part of the heritability. However, it is a challenge to estimate discrete values of the copy numbers using continuous signals calling from a set of markers, and to simultaneously perform association testing between CNVs and phenotypic outcomes. The goal of the present study is to perform a series of data filtering and analysis procedures using a DNA pooling strategy to identify potential CNV regions that are related to bipolar disorder. A total of 200 normal controls and 200 clinically diagnosed bipolar patients were recruited in this study, and were randomly divided into eight control and eight case pools. Genome-wide genotyping was employed using Illumina Human Omni1-Quad array with approximately one million markers for CNV calling. We aimed at setting a series of criteria to filter out the signal noise of marker data and to reduce the chance of false-positive findings for CNV regions. We first defined CNV regions for each pool. Potential CNV regions were reported based on the different patterns of CNV status between cases and controls. Genes that were mapped into the potential CNV regions were examined with association testing, Gene Ontology enrichment analysis, and checked with existing literature for their associations with bipolar disorder. We reported several CNV regions that are related to bipolar disorder. Two CNV regions on chromosome 11 and 22 showed significant signal differences between cases and controls (p < 0.05). Another five CNV regions on chromosome 6, 9, and 19 were overlapped with results in previous CNV studies. Experimental validation of two CNV regions lent some support to our reported findings. Further experimental and replication studies could be designed for these selected regions.

Allostasis as a conceptual framework linking bipolar disorder and addiction

Bipolar disorders (BDs) and addictions constitute reciprocal risk factors and are best considered under a unitary perspective. The concepts of allostasis and allostatic load (AL) may contribute to the understanding of the complex relationships between BD and addictive behaviors. Allostasis entails the safeguarding of reward function stability by recruitment of changes in the reward and stress system neurocircuitry and it may help to elucidate neurobiological underpinnings of vulnerability to addiction in BD patients. Conceptualizing BD as an illness involving the cumulative build-up of allostatic states, we hypothesize a progressive dysregulation of reward circuits clinically expressed as negative affective states (i.e., anhedonia). Such negative affective states may render BD patients more vulnerable to drug addiction, fostering a very rapid transition from occasional drug use to addiction, through mechanisms of negative reinforcement. The resulting addictive behavior-related ALs, in turn, may contribute to illness progression. This framework could have a heuristic value to enhance research on pathophysiology and treatment of BD and addiction comorbidity.

The relationship of family characteristics and bipolar disorder using causal-pie models

Many family characteristics were reported to increase the risk of bipolar disorder (BPD). The development of BPD may be mediated through different pathways, involving diverse risk factor profiles. We evaluated the associations of family characteristics to build influential causal-pie models to estimate their contributions on the risk of developing BPD at the population level. We recruited 329 clinically diagnosed BPD patients and 202 healthy controls to collect information in parental psychopathology, parent-child relationship, and conflict within family. Other than logistic regression models, we applied causal-pie models to identify pathways involved with different family factors for BPD. The risk of BPD was significantly increased with parental depression, neurosis, anxiety, paternal substance use problems, and poor relationship with parents. Having a depressed mother further predicted early onset of BPD. Additionally, a greater risk for BPD was observed with higher numbers of paternal/maternal psychopathologies. Three significant risk profiles were identified for BPD, including paternal substance use problems (73.0%), maternal depression (17.6%), and through poor relationship with parents and conflict within the family (6.3%). Our findings demonstrate that different aspects of family characteristics elicit negative impacts on bipolar illness, which can be utilized to target specific factors to design and employ efficient intervention programs.