Bipolar disorder and its relation to major psychiatric disorders: a family-based study in the Swedish population

Beyond the Window of Risk? The Dutch Bipolar Offspring Study: 22-Year Follow-Up

OBJECTIVE

Adolescent offspring of parents with bipolar disorder (BD) are at high risk to develop BD and other psychopathology, yet, it remains unknown how this risk continues into middle adulthood. We aim to determine the window of risk for BD and other psychopathology in offspring of parents with BD followed from adolescence into adulthood.

METHOD

This study reports on the 22-year follow-up assessment of the Dutch Bipolar Offspring Study, a fixed cohort study of 140 participants, established in 1997. Offspring (n=100; mean age of 38.28 years, SD=2.74) of parents with BD-I or BD-II were assessed at baseline, 1-, 5-, 12-, and 22-year follow-up.

RESULTS

No new BD onsets occurred since the 12-year follow-up (lifetime prevalence=11-13%; BD-I=4%; BD-II=7%). Lifetime prevalence of any mood disorder is 65%, for major depressive disorder (MDD) 36%, and for recurrent mood episodes 37%. Prevalence of MDD more than doubled in the past decade. Point prevalence of any psychopathology peaked between 20-25 years (38-46%) subsiding to 29-35% per year after age 30. Overall, 71% of offspring contacted mental health services since the last assessment.

CONCLUSION

The risk for homotypic transmission of BD in offspring of parents with BD is highest during adolescence. The heterotypic risk for mood disorder onset and recurrences continues over the life course. Severe mood disorders are often preceded by milder psychopathology, emphasizing the need for early identification and interventions. This study allows for better understanding of the onset and course of mood disorders and specific windows of risk in a familial high-risk population.

Heterogeneity in the longitudinal courses of global functioning in children at familial risk of major psychiatric disorders: Association with trauma and familial characteristics

OBJECTIVES

The extent to which heterogeneity in childhood risk trajectories may underlie later heterogeneity in schizophrenia (SZ), bipolar disorder (BP), and major depressive disorder (MDD) remains a chief question. Answers may optimally be found by studying the longitudinal trajectories of children born to an affected parent. We aimed to differentiate trajectories of global functioning and their sensitive periods from the age of 6 to 17 years in children at familial risk (FHRs).

METHODS

First, a latent class mixed model analysis (LCMM) was applied to yearly ratings of the Children's Global Assessment Scale (CGAS) from the age of 6 to 17 years in 170 FHRs born to a parent affected by DSM-IV SZ (N = 37), BP (N = 82) or MDD (N = 51). Then, we compared the obtained Classes or trajectories of FHRs in terms of sex, parental diagnosis, IQ, child clinical status, childhood trauma, polygenic risk score (PRS), and outcome in transition to illness.

RESULTS

The LCMM on yearly CGAS trajectories identified a 4-class solution showing markedly different childhood and adolescence dynamic courses and temporal vulnerability windows marked by a functioning decline and a degree of specificity in parental diagnosis. Moreover, IQ, trauma exposure, PRS level, and timing of later transition to illness differentiated the trajectories. Almost half (46%) of the FHRs exhibited a good and stable global functioning trajectory.

CONCLUSIONS

FHRs of major psychiatric disorders show heterogeneous functional decline during development associated with parental diagnosis, polygenic risk loading, and childhood trauma.

The emerging neuroimmune hypothesis of bipolar disorder: An updated overview of neuroimmune and microglial findings

Bipolar disorder (BD) is a severe and multifactorial disease, with onset usually in young adulthood, which follows a progressive course throughout life. Replicated epidemiological studies have suggested inflammatory mechanisms and neuroimmune risk factors as primary contributors to the onset and development of BD. While not all patients display overt markers of inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease and seems to be mood phase dependent, likely explaining the heterogeneity of findings observed in this population. As the brain's immune cells, microglia orchestrate the brain's immune response and play a critical role in maintaining the brain's health across the lifespan. Microglia are also highly sensitive to environmental changes and respond to physiological and pathological events by adapting their functions, structure, and molecular expression. Recently, it has been highlighted that instead of a single population of cells, microglia comprise a heterogeneous community with specialized states adjusted according to the local molecular cues and intercellular interactions. Early evidence has highlighted the contribution of microglia to BD neuropathology, notably for severe outcomes, such as suicidality. However, the roles and diversity of microglial states in this disease are still largely undermined. This review brings an updated overview of current literature on the contribution of neuroimmune risk factors for the onset and progression of BD, the most prominent neuroimmune abnormalities (including biomarker, neuroimaging, ex vivo studies) and the most recent findings of microglial involvement in BD neuropathology. Combining these different shreds of evidence, we aim to propose a unifying hypothesis for BD pathophysiology centered on neuroimmune abnormalities and microglia. Also, we highlight the urgent need to apply novel multi-system biology approaches to characterize the diversity of microglial states and functions involved in this enigmatic disorder, which can open bright perspectives for novel biomarkers and therapeutic discoveries.

Fibroblasts as an in vitro model of circadian genetic and genomic studies: A temporal analysis

Bipolar disorder (BD) is a heritable disorder characterized by shifts in mood that manifest in manic or depressive episodes. Clinical studies have identified abnormalities of the circadian system in BD patients as a hallmark of underlying pathophysiology. Fibroblasts are a well-established in vitro model for measuring circadian patterns. We set out to examine the underlying genetic architecture of circadian rhythm in fibroblasts, with the goal to assess its contribution to the polygenic nature of BD disease risk. We collected, from primary cell lines of 6 healthy individuals, temporal genomic features over a 48 hour period from transcriptomic data (RNA-seq) and open chromatin data (ATAC-seq). The RNA-seq data showed that only a limited number of genes, primarily the known core clock genes such as ARNTL, CRY1, PER3, NR1D2 and TEF display circadian patterns of expression consistently across cell cultures. The ATAC-seq data identified that distinct transcription factor families, like those with the basic helix-loop-helix motif, were associated with regions that were increasing in accessibility over time. Whereas known glucocorticoid receptor target motifs were identified in those regions that were decreasing in accessibility. Further evaluation of these regions using stratified linkage disequilibrium score regression (sLDSC) analysis failed to identify a significant presence of them in the known genetic architecture of BD, and other psychiatric disorders or neurobehavioral traits in which the circadian rhythm is affected. In this study, we characterize the biological pathways that are activated in this in vitro circadian model, evaluating the relevance of these processes in the context of the genetic architecture of BD and other disorders, highlighting its limitations and future applications for circadian genomic studies.

Key subphenotypes of bipolar disorder are differentially associated with polygenic liabilities for bipolar disorder, schizophrenia, and major depressive disorder

Bipolar disorder (BD) features heterogenous clinical presentation and course of illness. It remains unclear how subphenotypes associate with genetic loadings of BD and related psychiatric disorders. We investigated associations between the subphenotypes and polygenic risk scores (PRS) for BD, schizophrenia, and major depressive disorder (MDD) in two BD cohorts from Sweden (N = 5180) and the UK (N = 2577). Participants were assessed through interviews and medical records for inter-episode remission, psychotic features during mood episodes, global assessment of functioning (GAF, function and symptom burden dimensions), and comorbid anxiety disorders. Meta-analyses based on both cohorts showed that inter-episode remission and GAF-function were positively correlated with BD-PRS but negatively correlated with schizophrenia-PRS (SCZ-PRS) and MDD-PRS. Moreover, BD-PRS was negatively, and MDD-PRS positively, associated with the risk of comorbid anxiety disorders. Finally, SCZ-PRS was positively associated with psychotic symptoms during mood episodes. Assuming a higher PRS of certain psychiatric disorders in cases with a positive family history, we further tested the associations between subphenotypes in index BD people and occurrence of BD, schizophrenia, or MDD in their relatives using Swedish national registries. BD patients with a relative diagnosed with BD had: (1) higher GAF and lower risk of comorbid anxiety than those with a relative diagnosed with schizophrenia or MDD, (2) lower risk of psychotic symptoms than those with a relative diagnosed with schizophrenia. Our findings shed light on the genetic underpinnings of the heterogeneity in clinical manifestations and course of illness in BD, which ultimately provide insights for developing personalized approaches to the diagnosis and treatment.

Aberrant brain network topology in youth with a familial risk for bipolar disorder: a task-based fMRI connectome study

BACKGROUND

Youth with a family history of bipolar disorder (BD) may be at increased risk for mood disorders and for developing side effects after antidepressant exposure. The neurobiological basis of these risks remains poorly understood. We aimed to identify biomarkers underlying risk by characterizing abnormalities in the brain connectome of symptomatic youth at familial risk for BD.

METHODS

Depressed and/or anxious youth (n = 119, age = 14.9 ± 1.6 years) with a family history of BD but no prior antidepressant exposure and typically developing controls (n = 57, age = 14.8 ± 1.7 years) received functional magnetic resonance imaging (fMRI) during an emotional continuous performance task. A generalized psychophysiological interaction (gPPI) analysis was performed to compare their brain connectome patterns, followed by machine learning of topological metrics.

RESULTS

High-risk youth showed weaker connectivity patterns that were mainly located in the default mode network (DMN) (network weight = 50.1%) relative to controls, and connectivity patterns derived from the visual network (VN) constituted the largest proportion of aberrant stronger pairs (network weight = 54.9%). Global local efficiency (Elocal , p = .022) and clustering coefficient (Cp , p = .029) and nodal metrics of the right superior frontal gyrus (SFG) (Elocal : p < .001; Cp : p = .001) in the high-risk group were significantly higher than those in healthy subjects, and similar patterns were also found in the left insula (degree: p = .004; betweenness: p = .005; age-by-group interaction, p = .038) and right hippocampus (degree: p = .003; betweenness: p = .003). The case-control classifier achieved a cross-validation accuracy of 78.4%.

CONCLUSIONS

Our findings of abnormal connectome organization in the DMN and VN may advance mechanistic understanding of risk for BD. Neuroimaging biomarkers of increased network segregation in the SFG and altered topological centrality in the insula and hippocampus in broader limbic systems may be used to target interventions tailored to mitigate the underlying risk of brain abnormalities in these at-risk youth.

Divergent epigenetic responses to perinatal asphyxia in severe mental disorders

Epigenetic modifications influenced by environmental exposures are molecular sources of phenotypic heterogeneity found in schizophrenia and bipolar disorder and may contribute to shared etiopathogenetic mechanisms of these two disorders. Newborns who experienced perinatal asphyxia have suffered reduced oxygen delivery to the brain around the time of birth, which increases the risk of later psychiatric diagnosis. This study aimed to investigate DNA methylation in blood cells for associations with a history of perinatal asphyxia, a neurologically harmful condition occurring within the biological environment of birth. We utilized prospective data from the Medical Birth Registry of Norway to identify incidents of perinatal asphyxia in 643 individuals with schizophrenia or bipolar disorder and 676 healthy controls. We performed an epigenome wide association study to distinguish differentially methylated positions associated with perinatal asphyxia. We found an interaction between methylation and exposure to perinatal asphyxia on case-control status, wherein having a history of perinatal asphyxia was associated with an increase of methylation in healthy controls and a decrease of methylation in patients on 4 regions of DNA important for brain development and function. The differentially methylated regions were observed in genes involved in oligodendrocyte survival and axonal myelination and functional recovery (LINGO3); assembly, maturation and maintenance of the brain (BLCAP;NNAT and NANOS2) and axonal transport processes and neural plasticity (SLC2A14). These findings are consistent with the notion that an opposite epigenetic response to perinatal asphyxia, in patients compared with controls, may contribute to molecular mechanisms of risk for schizophrenia and bipolar disorder.

Selective mutism and the risk of mental and neurodevelopmental disorders among siblings

The siblings of children with mental disorders are more likely to experience mental health issues themselves, but there has been a lack of sibling studies on selective mutism (SM). The aim of this population-based study was to use national registers to examine associations between children with SM and diagnoses of various mental disorder in their siblings. All singleton children born in Finland from 1987 to 2009, and diagnosed with SM from 1998 to 2012, were identified from national health registers and matched with four controls by age and sex. Their biological siblings and parents were identified using national registries and the diagnostic information on the siblings of the subjects and controls was obtained. The final analyses comprised 658 children with SM and their 1661 siblings and 2092 controls with 4120 siblings. The analyses were conducted using generalized estimating equations. Mental disorders were more common among the siblings of the children with SM than among the siblings of the controls. The strongest associations were observed for childhood emotional disorders and autism spectrum disorders after the data were adjusted for covariates and comorbid diagnoses among SM subjects. The final model showed associations between SM and a wide range of disorders in siblings, with strongest associations with disorders that usually have their onset during childhood. Our finding showed that SM clustered with other mental disorders in siblings and this requires further research, especially the association between SM and autism spectrum disorders. Strong associations with childhood onset disorders may indicate shared etiologies.

Neurite outgrowth deficits caused by rare PLXNB1 mutation in pediatric bipolar disorder

Pediatric bipolar disorder (PBD) is a severe mood dysregulation condition that affects 0.5-1% of children and teens in the United States. It is associated with recurrent episodes of mania and depression and an increased risk of suicidality. However, the genetics and neuropathology of PBD are largely unknown. Here, we used a combinatorial family-based approach to characterize cellular, molecular, genetic, and network-level deficits associated with PBD. We recruited a PBD patient and three unaffected family members from a family with a history of psychiatric illnesses. Using resting-state functional magnetic resonance imaging (rs-fMRI), we detected altered resting-state functional connectivity in the patient as compared to an unaffected sibling. Using transcriptomic profiling of patient and control induced pluripotent stem cell (iPSC)-derived telencephalic organoids, we found aberrant signaling in the molecular pathways related to neurite outgrowth. We corroborated the presence of neurite outgrowth deficits in patient iPSC-derived cortical neurons and identified a rare homozygous loss-of-function PLXNB1 variant (c.1360C>C; p.Ser454Arg) responsible for the deficits in the patient. Expression of wild-type PLXNB1, but not the variant, rescued neurite outgrowth in patient neurons, and expression of the variant caused the neurite outgrowth deficits in cortical neurons from PlxnB1 knockout mice. These results indicate that dysregulated PLXNB1 signaling may contribute to an increased risk of PBD and other mood dysregulation-related disorders by disrupting neurite outgrowth and functional brain connectivity. Overall, this study established and validated a novel family-based combinatorial approach for studying cellular and molecular deficits in psychiatric disorders and identified dysfunctional PLXNB1 signaling and neurite outgrowth as potential risk factors for PBD.

Diagnosis and management of bipolar disorders

Bipolar disorders (BDs) are recurrent and sometimes chronic disorders of mood that affect around 2% of the world's population and encompass a spectrum between severe elevated and excitable mood states (mania) to the dysphoria, low energy, and despondency of depressive episodes. The illness commonly starts in young adults and is a leading cause of disability and premature mortality. The clinical manifestations of bipolar disorder can be markedly varied between and within individuals across their lifespan. Early diagnosis is challenging and misdiagnoses are frequent, potentially resulting in missed early intervention and increasing the risk of iatrogenic harm. Over 15 approved treatments exist for the various phases of bipolar disorder, but outcomes are often suboptimal owing to insufficient efficacy, side effects, or lack of availability. Lithium, the first approved treatment for bipolar disorder, continues to be the most effective drug overall, although full remission is only seen in a subset of patients. Newer atypical antipsychotics are increasingly being found to be effective in the treatment of bipolar depression; however, their long term tolerability and safety are uncertain. For many with bipolar disorder, combination therapy and adjunctive psychotherapy might be necessary to treat symptoms across different phases of illness. Several classes of medications exist for treating bipolar disorder but predicting which medication is likely to be most effective or tolerable is not yet possible. As pathophysiological insights into the causes of bipolar disorders are revealed, a new era of targeted treatments aimed at causal mechanisms, be they pharmacological or psychosocial, will hopefully be developed. For the time being, however, clinical judgment, shared decision making, and empirical follow-up remain essential elements of clinical care. This review provides an overview of the clinical features, diagnostic subtypes, and major treatment modalities available to treat people with bipolar disorder, highlighting recent advances and ongoing therapeutic challenges.

Meta-analysis of personal and familial co-occurrence of Attention Deficit/Hyperactivity Disorder and Bipolar Disorder

BACKGROUND

Attention Deficit Disorder / Hyperactivity (ADHD) and Bipolar Disorder (BD) are highly comorbid disorders. Studies have raised the hypothesis of shared genetic, neurobiological, and clinical factors. This would entail an excess risk of co-occurrence of both disorders.

OBJECTIVE

We present the first meta-analysis of individual and familial associations between ADHD and BD.

METHODS

From 2688 references, 59 were included, with a total of 550,379 ADHD patients, 57,799 BD patients and 12,608,137 controls.

RESULTS

Personal history of ADHD increased the risk of BD (OR = 6.06), and conversely individuals with BD had an increased risk of ADHD (OR = 8.94). First-degree relatives of ADHD patients had an increased risk of BD (OR = 1.94). Offspring of individuals with BD had a higher risk for ADHD (OR = 2.33). Finally, first-degree relatives of BD patients had an increased risk of ADHD (OR = 2.71).

CONCLUSION

We show a clear epidemiological overlap between ADHD and BD, as well as a strong familial association which advocates in favor of a more systematic screening.

Neuroimaging profiling identifies distinct brain maturational subtypes of youth with mood and anxiety disorders

Mood and anxiety disorders typically begin in adolescence and have overlapping clinical features but marked inter-individual variation in clinical presentation. The use of multimodal neuroimaging data may offer novel insights into the underlying brain mechanisms. We applied Heterogeneity Through Discriminative Analysis (HYDRA) to measures of regional brain morphometry, neurite density, and intracortical myelination to identify subtypes of youth, aged 9-10 years, with mood and anxiety disorders (N = 1931) compared to typically developing youth (N = 2823). We identified three subtypes that were robust to permutation testing and sample composition. Subtype 1 evidenced a pattern of imbalanced cortical-subcortical maturation compared to the typically developing group, with subcortical regions lagging behind prefrontal cortical thinning and myelination and greater cortical surface expansion globally. Subtype 2 displayed a pattern of delayed cortical maturation indicated by higher cortical thickness and lower cortical surface area expansion and myelination compared to the typically developing group. Subtype 3 showed evidence of atypical brain maturation involving globally lower cortical thickness and surface coupled with higher myelination and neural density. Subtype 1 had superior cognitive function in contrast to the other two subtypes that underperformed compared to the typically developing group. Higher levels of parental psychopathology, family conflict, and social adversity were common to all subtypes, with subtype 3 having the highest burden of adverse exposures. These analyses comprehensively characterize pre-adolescent mood and anxiety disorders, the biopsychosocial context in which they arise, and lay the foundation for the examination of the longitudinal evolution of the subtypes identified as the study sample transitions through adolescence.

First Manic Episode Following SARS-CoV-2 Infection

Since the beginning of the COVID-19 pandemic, there have been reports of neuropsychiatric symptoms following infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), most notably mania and psychosis. However, despite the widely reported incidence of psychosis and mania following infection with SARS-CoV-2, a causal link between the virus and these neuropsychiatric symptoms has not been established. A myriad of confounding factors such as underlying psychiatric disorders, personal and family psychiatric histories, substance use, and treatment with steroids all have the ability to obscure a correlation between SARS-CoV-2 and subsequent psychiatric symptoms. Here we present a case of a manic episode in a 40-year-old male following a COVID-19 infection. He had no past psychiatric history, no family psychiatric history, and no history of substance use. This case is unique in that the patient lacks all these typical confounding variables. It should serve as an example of a first-time manic episode following a recent infection with SARS-CoV-2. It may contribute data to future investigations seeking to better elucidate the correlation between SARS-CoV-2 and neuropsychiatric symptoms such as mania.

Minor physical anomalies in bipolar disorder in comparison to healthy controls and schizophrenia: A systematic review and meta-analysis

Minor physical anomalies (MPAs) are markers of abnormalities in early foetal development and are well established findings in schizophrenia. It has been suggested that neurodevelopmental abnormalities might play a role not only in schizophrenia but also in bipolar disorder (BD). Therefore, according to neurodevelopmental theory of BD, one might expect increased prevalence of MPAs in BD. A meta-analysis of 11 studies was conducted to quantitatively review MPAs in BD in comparison to schizophrenia and healthy controls. The current meta-analysis compared MPA scores of 584 BD patients and 723 healthy controls, and 401 BD and 612 schizophrenia patients. Patients with BD had significantly higher MPA scores than healthy controls (g=0.47, CI=0.28-0.67). This was true both for craniofacial (g=0.57, CI=0.34-0.79) and periphery (g=0.46, CI=0.18-0.73) MPAs. BD was associated with a less severe increase in MPA score compared to schizophrenia, however, between-group difference was small (g=0.19, CI=0.05-0.33). The outcome of this meta-analysis suggests that BD is associated with medium effect size increase in MPAs which is only minimally less severe than schizophrenia. This finding supports the hypothesis that early developmental insult in brain development plays a role not only in schizophrenia but also BD. Studies investigating clinical, neurocognitive, neuroanatomical and other biological correlates of MPAs in BD might helpful in characterizing subtype (s) of BD that is associated with pronounced deviations in brain development.

The next 10 years of behavioural genomic research

Background

The explosion caused by the fusion of quantitative genetics and molecular genetics will transform behavioural genetic research in child and adolescent psychology and psychiatry.

Methods

Although the fallout has not yet settled, the goal of this paper is to predict the next 10 years of research in what could be called behavioural genomics.

Results

I focus on three research directions: the genetic architecture of psychopathology, causal modelling of gene-environment interplay, and the use of DNA as an early warning system.

Conclusion

Eventually, whole-genome sequencing will be available for all newborns, which means that behavioural genomics could potentially be applied ubiquitously in research and clinical practice.

Cross-Disorder Analysis of Genic and Regulatory Copy Number Variations in Bipolar Disorder, Schizophrenia, and Autism Spectrum Disorder

BACKGROUND

We aimed to determine the similarities and differences in the roles of genic and regulatory copy number variations (CNVs) in bipolar disorder (BD), schizophrenia (SCZ), and autism spectrum disorder (ASD).

METHODS

Based on high-resolution CNV data from 8708 Japanese samples, we performed to our knowledge the largest cross-disorder analysis of genic and regulatory CNVs in BD, SCZ, and ASD.

RESULTS

In genic CNVs, we found an increased burden of smaller (<100 kb) exonic deletions in BD, which contrasted with the highest burden of larger (>500 kb) exonic CNVs in SCZ/ASD. Pathogenic CNVs linked to neurodevelopmental disorders were significantly associated with the risk for each disorder, but BD and SCZ/ASD differed in terms of the effect size (smaller in BD) and subtype distribution of CNVs linked to neurodevelopmental disorders. We identified 3 synaptic genes (DLG2, PCDH15, and ASTN2) as risk factors for BD. Whereas gene set analysis showed that BD-associated pathways were restricted to chromatin biology, SCZ and ASD involved more extensive and similar pathways. Nevertheless, a correlation analysis of gene set results indicated weak but significant pathway similarities between BD and SCZ or ASD (r = 0.25-0.31). In SCZ and ASD, but not BD, CNVs were significantly enriched in enhancers and promoters in brain tissue.

CONCLUSIONS

BD and SCZ/ASD differ in terms of CNV burden, characteristics of CNVs linked to neurodevelopmental disorders, and regulatory CNVs. On the other hand, they have shared molecular mechanisms, including chromatin biology. The BD risk genes identified here could provide insight into the pathogenesis of BD.

Shared genetic components between metabolic syndrome and schizophrenia: Genetic correlation using multipopulation data sets

AIM

The genetic relationship between schizophrenia (SCZ) and other nonpsychiatric disorders remains largely unknown. We examined the shared genetic components between these disorders based on multipopulation data sets.

METHODS

We used two data sets for East Asian (EAS) and European (EUR) samples. SCZ data was based on the Psychiatric Genomics Consortium Asia with our own genome-wide association study for EAS and Psychiatric Genomics Consortium for EUR. Nonpsychiatric data (20 binary traits [mainly nonpsychiatric complex disorders] and 34 quantitative traits [mainly laboratory examinations and physical characteristics]) were obtained from Biobank Japan and UK Biobank for EAS and EUR samples, respectively. To evaluate genetic correlation, linkage disequilibrium score regression analysis was utilized with further meta-analysis for each result from EAS and EUR samples to obtain robust evidence. Subsequent mendelian randomization analysis was also included to examine the causal effect.

RESULTS

A significant genetic correlation between SCZ and several metabolic syndrome (MetS) traits was detected in the combined samples (meta-analysis between EAS and EUR data) (body mass index [r_g  = -0.10, q-value = 1.0 × 10^-9 ], high-density-lipoprotein cholesterol [r_g  = 0.072, q-value = 2.9 × 10^-3 ], blood sugar [r_g  = -0.068, q-value = 1.4 × 10^-2 ], triglycerides [r_g  = -0.052, q-value = 2.4 × 10^-2 ], systolic blood pressure [r_g  = -0.054, q-value = 3.5 × 10^-2 ], and C-reactive protein [r_g  = -0.076, q-value = 7.8 × 10^-5 ]. However, no causal relationship on SCZ susceptibility was detected for these traits based on the mendelian randomization analysis.

CONCLUSION

Our results indicate shared genetic components between SCZ and MetS traits and C-reactive protein. Specifically, we found it interesting that the correlation between MetS traits and SCZ was the opposite of that expected from clinical studies: this genetic study suggests that SCZ susceptibility was associated with reduced MetS. This implied that MetS in patients with SCZ was not associated with genetic components but with environmental factors, including antipsychotics, lifestyle changes, poor diet, lack of exercise, and living conditions.

Validity and utility of Hierarchical Taxonomy of Psychopathology (HiTOP): III. Emotional dysfunction superspectrum

The Hierarchical Taxonomy of Psychopathology (HiTOP) is a quantitative nosological system that addresses shortcomings of traditional mental disorder diagnoses, including arbitrary boundaries between psychopathology and normality, frequent disorder co-occurrence, substantial heterogeneity within disorders, and diagnostic unreliability over time and across clinicians. This paper reviews evidence on the validity and utility of the internalizing and somatoform spectra of HiTOP, which together provide support for an emotional dysfunction superspectrum. These spectra are composed of homogeneous symptom and maladaptive trait dimensions currently subsumed within multiple diagnostic classes, including depressive, anxiety, trauma-related, eating, bipolar, and somatic symptom disorders, as well as sexual dysfunction and aspects of personality disorders. Dimensions falling within the emotional dysfunction superspectrum are broadly linked to individual differences in negative affect/neuroticism. Extensive evidence establishes that dimensions falling within the superspectrum share genetic diatheses, environmental risk factors, cognitive and affective difficulties, neural substrates and biomarkers, childhood temperamental antecedents, and treatment response. The structure of these validators mirrors the quantitative structure of the superspectrum, with some correlates more specific to internalizing or somatoform conditions, and others common to both, thereby underlining the hierarchical structure of the domain. Compared to traditional diagnoses, the internalizing and somatoform spectra demonstrated substantially improved utility: greater reliability, larger explanatory and predictive power, and greater clinical applicability. Validated measures are currently available to implement the HiTOP system in practice, which can make diagnostic classification more useful, both in research and in the clinic.

Diagnostic progression to bipolar disorder in 17,285 adolescents and young adults with attention deficit hyperactivity disorder: A longitudinal follow-up study

OBJECTIVE

We investigated the diagnostic progression to bipolar disorder (BD) among adolescents and young adults with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Using the Taiwan National Health Insurance Research Database, we enrolled adolescents and young adults aged 10-29 years with ADHD between January 1, 2001, and December 31, 2010, who were followed up until December 31, 2011, to determine progression to BD. Cox regression analysis was used to examine candidate risk and protective factors.

RESULTS

At the 11-year follow-up, the progression rate from ADHD to BD was 5.12%. Of the participants who progressed, 62.16% (322/518) progressed within the first 3 years. Risk factors for progression were as follows: older age (hazard ratio [HR], 1.058; 95% confidence interval [CI], 1.033-1.084), comorbidity with autistic spectrum disorder (HR, 1.839; 95% CI, 1.415-2.391), disruptive behavior disorder (HR, 1.434; 95% CI, 1.132-1.816), intelligence disability (HR, 1.744; 95% CI, 1.399-2.176), depressive disorder (HR, 1.978; 95% CI, 1.577-2.482), alcohol use disorder (HR, 1.705; 95% CI, 1.057-2.751), cluster A (HR, 2.508; 95% CI, 1.167-5.391) or B (HR, 2.718; 95% CI, 1.974-3.741) personality disorder, and a family history of BD (HR, 2.618; 95% CI, 1.823-3.758) Identified protective factors were male sex (HR, 0.771; 95% CI, 0.630-0.943) and cluster C personality disorder (HR, 0.278; 95% CI, 0.086-0.898).

CONCLUSION

The study demonstrated the specific risk and protective factors for BD progression among adolescents and young adults with ADHD. It is important for clinician and mental health care providers to recognize identified factors to focus on early detection and prompt intervention.

Familial and genetic associations between autism spectrum disorder and other neurodevelopmental and psychiatric disorders

BACKGROUND

Familial and genetic associations between autism spectrum disorder (ASD) and other neurodevelopmental and psychiatric disorders have been reported, sometimes with conflicting results. We estimated familial and genetic associations between ASD and nine disorder groups, and explored differences in these associations for ASD in the context of intellectual disability, epilepsy, chromosomal abnormalities, and congenital malformations.

METHODS

Individuals born between 1985 and 2009 living in Sweden on their seventh birthday were linked to their biological parents in order to identify different types of relatives. We retrieved information on all the disorders considered from the National Patient Register. Logistic regression was used to estimate the familial association between ASD and other neurodevelopmental and psychiatric disorders in the different groups of relatives. Structural equation modeling was used to estimate phenotypic (r_p ) and genetic associations (r_g ), as well as the contribution of genetic influences to r_p .

RESULTS

The study included 2,398,608 individuals. Among relatives of individuals diagnosed with ASD, there was an increased risk of the disorders considered, compared to relatives of individuals who were not diagnosed with ASD. Stronger associations were detected for ASD without any additional diagnosis of intellectual disability, epilepsy, chromosomal abnormalities, and congenital malformations. The strongest genetic correlation was estimated between ASD and other neurodevelopmental disorders (r_g  = 0.73; 95% CI = 0.66-0.79). Moderate genetic correlations were estimated for anxiety disorders (r_g  = 0.47; 95% CI = 0.33-0.61), depression (r_g  = 0.52; 95% CI = 0.37-0.66), and intentional self-harm (r_g  = 0.54; 95% CI = 0.36-0.71).

CONCLUSIONS

ASD shows familial and genetic association not only with other neurodevelopmental disorders, but also with other psychiatric disorders, such as anxiety, depression, and intentional self-harm. Family history of ASD comorbid with intellectual disability, epilepsy, congenital malformations, or chromosomal abnormalities is less related to other psychiatric disorders, potentially suggesting a different etiology for this subgroup of patients.

Insights into attention-deficit/hyperactivity disorder from recent genetic studies

Attention-deficit/hyperactivity disorder (ADHD) is a common and highly heritable neurodevelopmental disorder (NDD). In this narrative review, we summarize recent advances in quantitative and molecular genetic research from the past 5-10 years. Combined with large-scale international collaboration, these advances have resulted in fast-paced progress in understanding the etiology of ADHD and how genetic risk factors map on to clinical heterogeneity. Studies are converging on a number of key insights. First, ADHD is a highly polygenic NDD with a complex genetic architecture encompassing risk variants across the spectrum of allelic frequencies, which are implicated in neurobiological processes. Second, genetic studies strongly suggest that ADHD diagnosis shares a large proportion of genetic risks with continuously distributed traits of ADHD in the population, with shared genetic risks also seen across development and sex. Third, ADHD genetic risks are shared with those implicated in many other neurodevelopmental, psychiatric and somatic phenotypes. As sample sizes and the diversity of genetic studies continue to increase through international collaborative efforts, we anticipate further success with gene discovery, characterization of how the ADHD phenotype relates to other human traits and growing potential to use genomic risk factors for understanding clinical trajectories and for precision medicine approaches.

Genetic contributions to bipolar disorder: current status and future directions

Bipolar disorder (BD) is a highly heritable mental disorder and is estimated to affect about 50 million people worldwide. Our understanding of the genetic etiology of BD has greatly increased in recent years with advances in technology and methodology as well as the adoption of international consortiums and large population-based biobanks. It is clear that BD is also highly heterogeneous and polygenic and shows substantial genetic overlap with other psychiatric disorders. Genetic studies of BD suggest that the number of associated loci is expected to substantially increase in larger future studies and with it, improved genetic prediction of the disorder. Still, a number of challenges remain to fully characterize the genetic architecture of BD. First among these is the need to incorporate ancestrally-diverse samples to move research away from a Eurocentric bias that has the potential to exacerbate health disparities already seen in BD. Furthermore, incorporation of population biobanks, registry data, and electronic health records will be required to increase the sample size necessary for continued genetic discovery, while increased deep phenotyping is necessary to elucidate subtypes within BD. Lastly, the role of rare variation in BD remains to be determined. Meeting these challenges will enable improved identification of causal variants for the disorder and also allow for equitable future clinical applications of both genetic risk prediction and therapeutic interventions.

SERINC2 increases the risk of bipolar disorder in the Chinese population

BACKGROUND

Although common variants in a large collection of patients are associated with increased risk for bipolar disorder (BD), studies have only been able to predict 25%-45% of risks, suggesting that lots of variants that contribute to the risk for BD haven't been identified. Our study aims to identify novel BD risk genes.

METHODS

We performed whole-exome sequencing of 27 individuals from 6 BD multi-affected Chinese families to identify candidate variants. Targeted sequencing of one of the novel risk genes, SERINC2, in additional sporadic 717 BD patients and 312 healthy controls (HC) validated the association. Magnetic resonance imaging (MRI) were performed to evaluate the effect of the variant to brain structures from 213 subjects (4 BD subjects from a multi-affected family, 130 sporadic BD subjects and 79 HC control).

RESULTS

BD pedigrees had an increased burden of uncommon variants in extracellular matrix (ECM) and calcium ion binding. By large-scale sequencing we identified a novel recessive BD risk gene, SERINC2, which plays a role in synthesis of sphingolipid and phosphatidylserine (PS). MRI image results show the homozygous nonsense variant in SERINC2 affects the volume of white matter in cerebellum.

CONCLUSIONS

Our study identified SERINC2 as a risk gene of BD in the Chinese population.

Genome-wide association study of more than 40,000 bipolar disorder cases provides new insights into the underlying biology

Bipolar disorder is a heritable mental illness with complex etiology. We performed a genome-wide association study of 41,917 bipolar disorder cases and 371,549 controls of European ancestry, which identified 64 associated genomic loci. Bipolar disorder risk alleles were enriched in genes in synaptic signaling pathways and brain-expressed genes, particularly those with high specificity of expression in neurons of the prefrontal cortex and hippocampus. Significant signal enrichment was found in genes encoding targets of antipsychotics, calcium channel blockers, antiepileptics and anesthetics. Integrating expression quantitative trait locus data implicated 15 genes robustly linked to bipolar disorder via gene expression, encoding druggable targets such as HTR6, MCHR1, DCLK3 and FURIN. Analyses of bipolar disorder subtypes indicated high but imperfect genetic correlation between bipolar disorder type I and II and identified additional associated loci. Together, these results advance our understanding of the biological etiology of bipolar disorder, identify novel therapeutic leads and prioritize genes for functional follow-up studies.

Additive effect of glutathione S-transferase T1 active genotype and infection with Toxoplasma gondii for increasing the risk of schizophrenia

PURPOSE

To determine if Toxoplasma gondii (T. gondii) infection may play a role in the development of schizophrenia in genetically susceptible persons with regard to genes encoding glutathione S-transferase T1 (GSTT1) and M1 (GSTM1).

METHODS

A total of 78 cases with psychiatric diagnosis of schizophrenia were compared with 91 healthy controls. For detection of IgG antibodies, enzyme-linked immunosorbent assay was used. Genotyping of GSTM1 and GSTT1 was performed by multiplex PCR. Chi-square and logistic regression were used for statistical analyses.

RESULTS

A higher frequency of the GSTT1 active gene in schizophrenic patients was observed. When risk categories based on the combination of T. gondii status and GSTs polymorphisms were compared, risk of schizophrenia increased in T. gondii positive/GSTT1 absent subjects (OR = 4.75, p = 0.05) compared with T. gondii negative/GSTT1 absent group. When T. gondii positive subjects had the GSTT1 active genotype, the risk increased linearly (OR = 10.20, p < 0.001). Odds ratio in T. gondii positive groups were almost the same in combination with the GSTM1 active genotype (OR = 4.45, p = 0.003) or null genotype (OR = 4.37, p = 0.006).

CONCLUSIONS

Our results showed an additive effect for T. gondii and GSTT1 active genotype as risk factors for schizophrenia in Iranian population. This is a small pilot study and replicating the study with larger groups of patients in multinational investigation to clarify these findings is recommended.

Examining the association between childhood autistic traits and adolescent hypomania: a longitudinal twin study

BACKGROUND

There is evidence that autism spectrum disorders (ASDs) co-occur with bipolar disorder (BD) relatively frequently. Individuals with BD often report symptoms of mania and hypomania during adolescence, prior to the age of onset for BD. It is unknown whether these symptoms are associated with ASDs. We examined whether diagnoses of ASDs and autistic traits were associated with hypomania in a large, population-based Swedish twin sample.

METHODS

Parental structured interviews assessed autistic traits, and were used to assign screening diagnoses of ASDs, when twins were aged 9 or 12 (N = 13 533 pairs). Parents then completed questionnaires assessing hypomania when the twins were aged 15 and 18 (N = 3852 pairs at age 15, and 3013 pairs at age 18). After investigating the phenotypic associations between these measures, we used the classical twin design to test whether genetic and environmental influences on autistic traits influence variation in adolescent hypomania.

RESULTS

Autistic traits and ASD diagnoses in childhood were associated with elevated scores on the measures of adolescent hypomania. Twin analyses indicated that 6-9% of the variance in hypomania was explained by genetic influences that were shared with autistic traits in childhood. When repeating these analyses for specific autistic trait domains, we found a stronger association between social interaction difficulties and hypomania than for other autistic trait domains.

CONCLUSIONS

These results indicate a genetic link between autistic traits and hypomania in adolescence. This adds to the growing evidence base of genetic factors associated with ASDs showing links with psychiatric outcomes across childhood and into adulthood.

A nationwide population-based longitudinal study mapping psychiatric disorders during lifetime in siblings to patients with bipolar disorder

OBJECTIVE

The aim was to map rates and cumulative incidences of psychiatric disorders during lifetime for siblings to patients with a diagnosis of bipolar disorder compared with the general population.

METHODS

Danish nationwide population-based longitudinal register linkage study including 13,923 unaffected siblings to 19,955 patients with bipolar disorder and 278,460 unaffected control individuals from the general population matched according to year of birth and sex. Follow-up covered 22 years from 1995 to 2017.

RESULTS

Rates of 'any psychiatric disorder' among siblings compared with control individuals were constantly around twofold increased throughout lifespan whereas there was a bimodal age distribution of hazard ratios of bipolar disorder, unipolar disorder and use of alcohol or psychoactive drugs with the highest hazard ratios up to age 20 and above 60 years of age. Cumulative incidences from age 15 years of any psychiatric disorder were 44.2% at age 80 years for siblings versus 27.6% for control individuals and the corresponding numbers for bipolar disorder was 8.7% for siblings compared with 1.6% for control individuals.

CONCLUSION

Strategies to prevent onset of psychiatric illness in individuals with a first-generation family history of bipolar disorder should not be limited to adolescence and early adulthood but should be lifetime, likely with differentiated age-specific strategies.

Bipolar multiplex families have an increased burden of common risk variants for psychiatric disorders

Multiplex families with a high prevalence of a psychiatric disorder are often examined to identify rare genetic variants with large effect sizes. In the present study, we analysed whether the risk for bipolar disorder (BD) in BD multiplex families is influenced by common genetic variants. Furthermore, we investigated whether this risk is conferred mainly by BD-specific risk variants or by variants also associated with the susceptibility to schizophrenia or major depression. In total, 395 individuals from 33 Andalusian BD multiplex families (166 BD, 78 major depressive disorder, 151 unaffected) as well as 438 subjects from an independent, BD case/control cohort (161 unrelated BD, 277 unrelated controls) were analysed. Polygenic risk scores (PRS) for BD, schizophrenia (SCZ), and major depression were calculated and compared between the cohorts. Both the familial BD cases and unaffected family members had higher PRS for all three psychiatric disorders than the independent controls, with BD and SCZ being significant after correction for multiple testing, suggesting a high baseline risk for several psychiatric disorders in the families. Moreover, familial BD cases showed significantly higher BD PRS than unaffected family members and unrelated BD cases. A plausible hypothesis is that, in multiplex families with a general increase in risk for psychiatric disease, BD development is attributable to a high burden of common variants that confer a specific risk for BD. The present analyses demonstrated that common genetic risk variants for psychiatric disorders are likely to contribute to the high incidence of affective psychiatric disorders in the multiplex families. However, the PRS explained only part of the observed phenotypic variance, and rare variants might have also contributed to disease development.

Culture and psychopathology: An attempt at reconsidering the role of social learning

This paper proposes a model for developmental psychopathology that is informed by recent research suggestive of a single model of mental health disorder (the p factor) and seeks to integrate the role of the wider social and cultural environment into our model, which has previously been more narrowly focused on the role of the immediate caregiving context. Informed by recently emerging thinking on the social and culturally driven nature of human cognitive development, the ways in which humans are primed to learn and communicate culture, and a mentalizing perspective on the highly intersubjective nature of our capacity for affect regulation and social functioning, we set out a cultural-developmental approach to psychopathology.

Association Between Inflammatory Bowel Disease and Psychiatric Morbidity and Suicide: A Swedish Nationwide Population-Based Cohort Study With Sibling Comparisons

BACKGROUND AND AIMS

Inflammatory bowel disease [IBD] is linked to psychiatric morbidity, but few studies have assessed general population comparators. We aimed to investigate the risk of psychiatric morbidity and suicide in adult-onset IBD patients.

METHODS

We used a nationwide population-based cohort study in Sweden [1973-2013]. We studied the risk of psychiatric disorders and suicide in 69,865 adult-onset IBD patients [ulcerative colitis, UC: n = 43,557; Crohn's disease, CD: n = 21,245; and IBD-unclassified: n = 5063] compared to 3,472,913 general population references and 66 292 siblings.

RESULTS

During a median follow-up of 11 years, we found 7465 [10.7%] first psychiatric disorders in IBD [incidence rate, IR/1000 person-years 8.4] and 306 911 [9.9%] in the general population [IR 6.6], resulting in 1.8 extra psychiatric morbidity per 100 patients followed-up for 10 years and a hazard ratio [HR] of 1.3 [95% confidence interval, 95%CI = 1.2-1.3]. The highest risk of overall psychiatric morbidity was seen in the first year after IBD diagnosis [HR = 1.4, 95%CI = 1.2-1.6] and in patients with extraintestinal manifestations [HR = 1.6, 95%CI = 1.5-1.7]. Psychiatric morbidity was more common in all IBD subtypes [HR 1.3-1.5]. An increased risk of suicide attempts was observed among all IBD types [HR = 1.2-1.4], whereas completed suicide was explicitly associated with CD [HR = 1.5] and elderly-onset [diagnosed at the age of > 60 years] IBD [HR = 1.7].

CONCLUSION

Adult-onset IBD was associated with an increased risk of psychiatric disorders and suicide attempts. Psychological follow-up should be provided to patients with IBD, especially those with extraintestinal manifestations and elderly-onset IBD. This follow-up should be within the first year after IBD diagnosis.

Familial aggregation of anxiety disorder subtypes and anxious temperament in the NIMH Family Study of Affective Spectrum Disorders

BACKGROUND

Evidence from family and twin studies suggests that mood and anxiety disorders, and related temperamental factors may share common etiologic factors. We examine the familial aggregation and coaggregation of anxiety disorder subtypes and anxiety-related temperamental traits, and their association with mood disorders.

METHODS

A total of 477 probands and 549 first-degree adult relatives from a large community based family study of affective spectrum disorders completed semi-structured diagnostic interviews and self-reported assessments of temperamental traits including: negative affectivity on the 'Positive and Negative Affect Schedule' (PANAS), neuroticism anxiety on the 'Zuckerman-Kuhlman Personality Questionnaire' (ZKPQ), and anxiety sensitivity on the 'Anxiety Sensitivity Index' (ASI).

RESULTS

The anxiety-related temperamental traits of negative affectivity, neuroticism anxiety and anxiety sensitivity had significant familial specificity, even after controlling for comorbid mood and anxiety disorders in probands and relatives. Yet, these traits in probands did not predict anxiety disorders in relatives. Although some anxiety subtypes were familial, there were no longer familial links between anxiety disorder subtypes (generalized anxiety disorder, social anxiety or panic disorder) after controlling for mood disorder subtypes in probands and relatives.

LIMITATIONS

Cross-sectional interviews were used to estimate disorders, and self-report measures were used for temperamental traits.

CONCLUSIONS

These results confirm previous research regarding familial overlap between anxiety subtypes and mood disorders, however their shared liability cannot be fully explained by anxiety-related temperamental traits. These findings suggest that anxiety-related temperamental traits may indicate a vulnerability for mood and anxiety disorders or a potential consequence of these conditions.

Comorbidity of ADHD and adult bipolar disorder: A systematic review and meta-analysis

Attention-deficit / hyperactivity disorder (ADHD) and Bipolar Disorder (BD) are common mental disorders with a high degree of comorbidity. However, no systematic review with meta-analysis has aimed to quantify the degree of comorbidity between both disorders. To this end we performed a systematic search of the literature in October 2020. In a meta-analysis of 71 studies with 646,766 participants from 18 countries, it was found that about one in thirteen adults with ADHD was also diagnosed with BD (7.95 %; 95 % CI: 5.31-11.06), and nearly one in six adults with BD had ADHD (17.11 %; 95 % CI: 13.05-21.59 %). Substantial heterogeneity of comorbidity rates was present, highlighting the importance of contextual factors: Heterogeneity could partially be explained by diagnostic system, sample size and geographical location. Age of BD onset occurred earlier in patients with comorbid ADHD (3.96 years; 95 % CI: 2.65-5.26, p < 0.001). Cultural and methodological differences deserve attention for evaluating diagnostic criteria and clinicians should be aware of the high comorbidity rates to prevent misdiagnosis and provide optimal care for both disorders.

Future directions in personality pathology

This article suggests two areas of future development in the realm of personality pathology. First, a reconceptualization of personality pathology in the context of research evidence suggestive of a single model for psychopathology. Recent work on the 'p factor', in combination with findings from clinical research, behavior genetics, molecular biology, and neurobiological models are considered in relation to this reconceptualization of personality pathology. Second, a cultural-developmental model for personality pathology is proposed, based on Gergely and Csibra's work on natural pedagogy, Tomasello's work on joint attention and intentionality, and our recent work on epistemic trust and the social-communicative nature of psychopathology.

Familial aggregation analysis of cognitive performance in early-onset bipolar disorder

We analysed the familial aggregation (familiality) of cognitive dimensions and explored their role as liability markers for early-onset bipolar disorder (EOBD). The sample comprised 99 subjects from 26 families, each with an offspring diagnosed with EOBD. Four cognitive dimensions were assessed: reasoning skills; attention and working memory; memory; and executive functions. Their familiality was investigated in the total sample and in a subset of healthy relatives. The intra-family resemblance score (IRS), a family-based index of the similarity of cognitive performance among family members, was calculated. Familiality was detected for the attention and working memory (AW) dimension in the total sample (ICC = 0.37, p = 0.0004) and in the subsample of healthy relatives (ICC = 0.37, p = 0.016). The IRS reflected that there are families with similar AW mean scores (either high or low) and families with heterogeneous scores. Families with the most common background for the AW dimension (IRS > 0) were selected and dichotomized in two groups according to the mean family AW score. This allowed differentiating families whose members had similar high scores than those with similar low scores: both patients (t = - 4.82, p = 0.0005) and relatives (t = - 5.04, p < 0.0001) of the two groups differed in their AW scores. AW dimension showed familial aggregation, suggesting its putative role as a familial vulnerability marker for EOBD. The IRS estimation allowed the identification of families with homogeneous scores for this dimension. This represents a first step towards the investigation of the underlying mechanisms of AW dimension and the identification of etiological subgroups.

Comorbidity and patterns of familial aggregation in attention-deficit/hyperactivity disorder and bipolar disorder in a family study of affective and anxiety spectrum disorders

The aim of this study is to examine the familial aggregation of Attention-deficit/hyperactivity disorder (ADHD) and its cross-transmission with bipolar disorder (BD) in a community-based family study of mood spectrum disorders. A clinically-enriched community sample of 562 probands recruited from the greater Washington, DC metropolitan area and their 698 directly interviewed relatives were included in analyses. Inclusion criteria were English speaking and consent to contact at least two first-degree relatives. Standard family study methodology was used and DSM-IV classified mental disorders were ascertained through a best-estimate procedure based on direct semi-structured interviews and multiple family history reports. There was specificity of familial aggregation of both bipolar I disorder (BD I) and bipolar II disorder (BD II) (i.e., BD I OR = 6.08 [1.66, 22.3]; BD II OR = 2.98 [1.11, 7.96]) and ADHD (ADHD OR = 2.13 [1.16, 3.95]). However, there was no evidence for cross-transmission of BD and ADHD in first degree relatives (i.e., did not observe increased rates of BD in relatives of those with ADHD and vice versa; all ps > 0.05). The specificity of familial aggregation of ADHD and BD alongside the absence of shared familial risk are consistent with the notion that the comorbidity between ADHD and BD may be attributable to diagnostic artifact, could represent a distinct BD suptype characterized by childhood-onset symptoms, or the possibility that attention problems serve as a precursor or consequence of BD.

Insights into the genomics of affective disorders

Affective disorders, or mood disorders, are a group of neuropsychiatric illnesses that are characterized by a disturbance of mood or affect. Most genetic research in this field to date has focused on bipolar disorder and major depression. Symptoms of major depression include a depressed mood, reduced energy, and a loss of interest and enjoyment. Bipolar disorder is characterized by the occurrence of (hypo)manic episodes, which generally alternate with periods of depression. Formal and molecular genetic studies have demonstrated that affective disorders are multifactorial diseases, in which both genetic and environmental factors contribute to disease development. Twin and family studies have generated heritability estimates of 58–85 % for bipolar disorder and 40 % for major depression.

Large genome-wide association studies have provided important insights into the genetics of affective disorders via the identification of a number of common genetic risk factors. Based on these studies, the estimated overall contribution of common variants to the phenotypic variability (single-nucleotide polymorphism [SNP]-based heritability) is 17–23 % for bipolar disorder and 9 % for major depression. Bioinformatic analyses suggest that the associated loci and implicated genes converge into specific pathways, including calcium signaling. Research suggests that rare copy number variants make a lower contribution to the development of affective disorders than to other psychiatric diseases, such as schizophrenia or the autism spectrum disorders, which would be compatible with their less pronounced negative impact on reproduction. However, the identification of rare sequence variants remains in its infancy, as available next-generation sequencing studies have been conducted in limited samples. Future research strategies will include the enlargement of genomic data sets via innovative recruitment strategies; functional analyses of known associated loci; and the development of new, etiologically based disease models. Researchers hope that deeper insights into the biological causes of affective disorders will eventually lead to improved diagnostics and disease prediction, as well as to the development of new preventative, diagnostic, and therapeutic strategies. Pharmacogenetics and the application of polygenic risk scores represent promising initial approaches to the future translation of genomic findings into psychiatric clinical practice.

Using the tools of genetic epidemiology to understand sex differences in neuropsychiatric disorders

Many neuropsychiatric disorders exhibit differences in prevalence, age of onset, symptoms or course of illness between males and females. For the most part, the origins of these differences are not well understood. In this article, we provide an overview of sex differences in psychiatric disorders including autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), anxiety, depression, alcohol and substance abuse, schizophrenia, eating disorders and risk of suicide. We discuss both genetic and nongenetic mechanisms that have been hypothesized to underlie these differences, including ascertainment bias, environmental stressors, X‐ or Y‐linked risk loci, and differential liability thresholds in males and females. We then review the use of twin, family and genome‐wide association approaches to study potential genetic mechanisms of sex differences and the extent to which these designs have been employed in studies of psychiatric disorders. We describe the utility of genetic epidemiologic study designs, including classical twin and family studies, large‐scale studies of population registries, derived recurrence risks, and molecular genetic analyses of genome‐wide variation that may enhance our understanding sex differences in neuropsychiatric disorders.

The Amygdala in Schizophrenia and Bipolar Disorder: A Synthesis of Structural MRI, Diffusion Tensor Imaging, and Resting-State Functional Connectivity Findings

Frequently implicated in psychotic spectrum disorders, the amygdala serves as an important hub for elucidating the convergent and divergent neural substrates in schizophrenia and bipolar disorder, the two most studied groups of psychotic spectrum conditions. A systematic search of electronic databases through December 2017 was conducted to identify neuroimaging studies of the amygdala in schizophrenia and bipolar disorder, focusing on structural MRI, diffusion tensor imaging (DTI), and resting-state functional connectivity studies, with an emphasis on cross-diagnostic studies. Ninety-four independent studies were selected for the present review (49 structural MRI, 27 DTI, and 18 resting-state functional MRI studies). Also selected, and analyzed in a separate meta-analysis, were 33 volumetric studies with the amygdala as the region-of-interest. Reduced left, right, and total amygdala volumes were found in schizophrenia, relative to both healthy controls and bipolar subjects, even when restricted to cohorts in the early stages of illness. No volume abnormalities were observed in bipolar subjects relative to healthy controls. Shape morphometry studies showed either amygdala deformity or no differences in schizophrenia, and no abnormalities in bipolar disorder. In contrast to the volumetric findings, DTI studies of the uncinate fasciculus tract (connecting the amygdala with the medial- and orbitofrontal cortices) largely showed reduced fractional anisotropy (a marker of white matter microstructure abnormality) in both schizophrenia and bipolar patients, with no cross-diagnostic differences. While decreased amygdalar-orbitofrontal functional connectivity was generally observed in schizophrenia, varying patterns of amygdalar-orbitofrontal connectivity in bipolar disorder were found. Future studies can consider adopting longitudinal approaches with multimodal imaging and more extensive clinical subtyping to probe amygdalar subregional changes and their relationship to the sequelae of psychotic disorders.

Shared Genetic Loci Between Body Mass Index and Major Psychiatric Disorders: A Genome-wide Association Study

Importance

People with major psychiatric disorders (MPDs) have a 10- to 20-year shorter life span than the rest of the population, and this difference is mainly due to comorbid cardiovascular diseases. Genome-wide association studies have identified common variants involved in schizophrenia (SCZ), bipolar disorder (BIP), and major depression (MD) and body mass index (BMI), a key cardiometabolic risk factor. However, genetic variants jointly influencing MPD and BMI remain largely unknown.

Objective

To assess the extent of the overlap between the genetic architectures of MPDs and BMI and identify genetic loci shared between them.

Design, Setting, and Participants

Using a conditional false discovery rate statistical framework, independent genome-wide association study data on individuals with SCZ (n = 82 315), BIP (n = 51 710), MD (n = 480 359), and BMI (n = 795 640) were analyzed. The UK Biobank cohort (n = 29 740) was excluded from the MD data set to avoid sample overlap. Data were collected from August 2017 to May 2018, and analysis began July 2018.

Main Outcomes and Measures

The primary outcomes were a list of genetic loci shared between BMI and MPDs and their functional pathways.

Results

Genome-wide association study data from 1 380 284 participants were analyzed, and the genetic correlation between BMI and MPDs varied (SCZ: r for genetic = -0.11, P = 2.1 × 10-10; BIP: r for genetic = -0.06, P = .0103; MD: r for genetic = 0.12, P = 6.7 × 10-10). Overall, 63, 17, and 32 loci shared between BMI and SCZ, BIP, and MD, respectively, were analyzed at conjunctional false discovery rate less than 0.01. Of the shared loci, 34% (73 of 213) in SCZ, 52% (36 of 69) in BIP, and 57% (56 of 99) in MD had risk alleles associated with higher BMI (conjunctional false discovery rate <0.05), while the rest had opposite directions of associations. Functional analyses indicated that the overlapping loci are involved in several pathways including neurodevelopment, neurotransmitter signaling, and intracellular processes, and the loci with concordant and opposite association directions pointed mostly to different pathways.

Conclusions and Relevance

In this genome-wide association study, extensive polygenic overlap between BMI and SCZ, BIP, and MD were found, and 111 shared genetic loci were identified, implicating novel functional mechanisms. There was mixture of association directions in SCZ and BMI, albeit with a preponderance of discordant ones.

The genetics of bipolar disorder

Bipolar disorder (BD) is one of the most heritable mental illnesses, but the elucidation of its genetic basis has proven to be a very challenging endeavor. Genome-Wide Association Studies (GWAS) have transformed our understanding of BD, providing the first reproducible evidence of specific genetic markers and a highly polygenic architecture that overlaps with that of schizophrenia, major depression, and other disorders. Individual GWAS markers appear to confer little risk, but common variants together account for about 25% of the heritability of BD. A few higher-risk associations have also been identified, such as a rare copy number variant on chromosome 16p11.2. Large scale next-generation sequencing studies are actively searching for other alleles that confer substantial risk. As our understanding of the genetics of BD improves, there is growing optimism that some clear biological pathways will emerge, providing a basis for future studies aimed at molecular diagnosis and novel therapeutics.

Traumatic experiences, family functioning, and mood disorder development in bipolar offspring

Objectives

Studies in children of patients affected with bipolar disorder (BD; bipolar offspring) are at high risk to develop mood disorders. Our aim is to investigate how environmental factors such as childhood trauma and family functioning relate to the development of mood disorders in offspring at familial risk for BD.

Design

The current study is part of a longitudinal prospective cohort study among offspring of parents with BD.

Methods

The current study is part of the Dutch Bipolar Offspring Study, an ongoing prospective cohort study among adolescent offspring of a parent with BD. Bipolar offspring were psychiatrically evaluated at baseline and at 1‐, 5‐, and 12‐year follow‐up. Complete follow‐up data over de 12‐year follow‐up were available for 102 offspring. Childhood trauma was measured with the Childhood Trauma Questionnaire (CTQ) and filled out by the offspring. Family functioning was reported by the mother with the 130‐item Questionnaire for Family Problems (QFP).

Results

Emotional maltreatment was significantly associated (HR = 1.82, CI 1.18–2.82, p = .007) with mood disorder onset in bipolar offspring. No association was found with the family functioning total score (HR = 1.04, CI 0.94–15, p = .085) nor its subscales.

Conclusions

The current study suggests that emotional maltreatment is associated with mood disorder development in bipolar offspring. Remarkably, the association of offspring‐reported emotional maltreatment and mood disorder onset was not reflected in parent‐reported family functioning (e.g., support and communication, openness or involvement). Possible explanations are discussed and warrant further study.

Practitioner points

Offspring of bipolar patients are at increased risk of developing mood disorders across the life‐time.

Emotional trauma contributes to the likelihood of developing mood disorders in bipolar offspring.

In the daily treatment of bipolar patients having children, attention should be given to parental style and difficulties.

Further research using multiple informant methods on childhood trauma an family functioning is needed to further disentangle the effects of these variables on the onset of psychopathology in bipolar offspring.

A comprehensive assessment of personality traits and psychosocial functioning in parents with bipolar disorder and their intimate partners

Background

Individuals with bipolar disorder (BD) often possess maladaptive traits and present with various difficulties in psychosocial functioning. However, little is known about the intimate partners of adults with bipolar disorder (BD) and how mental illnesses other than BD within couples may further complicate the picture. Such knowledge is needed to inform both couple and family interventions.

Methods

Participants were parents whose children were enrolled in a prospective study: 55 with BD and their partners, and 47 healthy control couples. All completed diagnostic interviews, and questionnaires describing personality traits, negative life events, coping skills, social support, marital adjustment and inter-partner verbal aggression. Parents with BD and healthy control parents were compared, as were the intimate partners. A series of exploratory analyses focused on the average measures within couples, with and without BD, and took account of comorbid personality disorders among those with BD and major depressive disorder among their partners.

Results

Intimate partners of adults with BD, relative to healthy control partners, presented with more mental disorders, higher neuroticism, lower extraversion, more emotion-focused coping, smaller social networks, less satisfaction with their social networks, and little, satisfying social contact. Additionally, they reported less consensus and satisfaction in their marital relationships, and engaged in more verbal aggression towards their partners. Participants with BD showed similar, more extreme, characteristics. Marital distress and verbal aggression were greatest among couples with an adult having BD and a comorbid personality disorder or a partner with major depressive disorder.

Conclusion

This study contributes to the literature by demonstrating that both parents with BD and their intimate partners exhibit high levels of mental illness, maladaptive personality traits and psychosocial difficulties, thus limiting their partners’ ability to provide support and stability in the these high risk families. Moreover, mental illnesses other than BD may contribute to marital problems within couples. Some statistical analyses, particularly those involving comorbid conditions, were under-powered in this study. As clinical implications, the current study suggests that both individuals with BD and their partners could benefit from interventions aimed at lowering emotionality and verbal aggression, and increasing social support and effective coping skills.

Genome-wide study of immune biomarkers in cerebrospinal fluid and serum from patients with bipolar disorder and controls

Bipolar disorder is a common, chronic psychiatric disorder. Despite high heritability, there is a paucity of identified genetic risk factors. Immune biomarkers are under more direct genetic influence than bipolar disorder. To explore the genetic associations with immune biomarker levels in cerebrospinal fluid (CSF) and blood serum which previously showed differences in bipolar disorder, we performed a study involving 291 individuals (184 bipolar disorder patients and 107 controls). The biomarkers assayed in both CSF and serum were: chitinase-3-like protein-1 (YKL-40), monocyte chemoattractant protein-1 (MCP-1), soluble cluster of differentiation (sCD14), tissue inhibitor of metalloproteinases-1 and 2 (TIMP-1 and TIMP-2). C-reactive protein (CRP) was only quantified in serum, and interleukin 8 (IL-8) measures were only available in CSF. Genome-wide association studies were conducted using PLINK for each of three genotyping waves and incorporated covariates for population substructure, age, sex, and body mass index (BMI). Results were combined by meta-analysis. Genome-wide significant associations were detected for all biomarkers except TIMP-1 and TIMP-2 in CSF. The strongest association in CSF was found for markers within the CNTNAP5 gene with YKL-40 (rs150248456, P = 2.84 × 10^-10). The strongest association in serum was also for YKL-40 but localized to the FANCI gene (rs188263039, P = 5.80 × 10^-26). This study revealed numerous biologically plausible genetic associations with immune biomarkers in CSF and blood serum. Importantly, the genetic variants regulating immune biomarker levels in CSF and blood serum differ. These results extend our knowledge of how biomarkers showing alterations in bipolar disorder are genetically regulated.

Whole-exome sequencing of 81 individuals from 27 multiply affected bipolar disorder families

Bipolar disorder (BD) is a highly heritable neuropsychiatric disease characterized by recurrent episodes of depression and mania. Research suggests that the cumulative impact of common alleles explains 25-38% of phenotypic variance, and that rare variants may contribute to BD susceptibility. To identify rare, high-penetrance susceptibility variants for BD, whole-exome sequencing (WES) was performed in three affected individuals from each of 27 multiply affected families from Spain and Germany. WES identified 378 rare, non-synonymous, and potentially functional variants. These spanned 368 genes, and were carried by all three affected members in at least one family. Eight of the 368 genes harbored rare variants that were implicated in at least two independent families. In an extended segregation analysis involving additional family members, five of these eight genes harbored variants showing full or nearly full cosegregation with BD. These included the brain-expressed genes RGS12 and NCKAP5, which were considered the most promising BD candidates on the basis of independent evidence. Gene enrichment analysis for all 368 genes revealed significant enrichment for four pathways, including genes reported in de novo studies of autism (p_adj < 0.006) and schizophrenia (p_adj = 0.015). These results suggest a possible genetic overlap with BD for autism and schizophrenia at the rare-sequence-variant level. The present study implicates novel candidate genes for BD development, and may contribute to an improved understanding of the biological basis of this common and often devastating disease.

Toxoplasmosis in a Cohort of Italian Patients With Bipolar and Psychotic Disorders: How Infection May Affect Clinical Features?

This study investigated the seroprevalence of Toxoplasma gondii in a cohort of 101 Italian inpatients affected by mood or schizophrenia-spectrum disorders and compared clinical features between seronegative and seropositive subjects. Patients diagnosed according to DSM-5 criteria underwent clinical assessments and blood collection to test parasite-specific IgG/IgM serum levels. Twenty-eight patients (27.7%) had IgG anti-T. gondii, and none had IgM antibodies. We found higher prevalence rate in patients aged 40 years or older, as compared with younger. No significant association was detected between T. gondii and a specific diagnostic category; however, bipolar disorder (BD)-II showed the highest positivity rate (40.9%). The seropositive status was significantly associated with a lower presence of psychotic symptoms, higher number of total episodes of predominant excitatory polarity, longer illness duration, and lower severity of current episode, particularly anxiety, depressive, and withdrawal/retardation symptoms. These preliminary results seem to point out an association between chronic toxoplasmosis and a specific subtype of BD.

Redefining phenotypes to advance psychiatric genetics: Implications from hierarchical taxonomy of psychopathology

Genetic discovery in psychiatry and clinical psychology is hindered by suboptimal phenotypic definitions. We argue that the hierarchical, dimensional, and data-driven classification system proposed by the Hierarchical Taxonomy of Psychopathology (HiTOP) consortium provides a more effective approach to identifying genes that underlie mental disorders, and to studying psychiatric etiology, than current diagnostic categories. Specifically, genes are expected to operate at different levels of the HiTOP hierarchy, with some highly pleiotropic genes influencing higher order psychopathology (e.g., the general factor), whereas other genes conferring more specific risk for individual spectra (e.g., internalizing), subfactors (e.g., fear disorders), or narrow symptoms (e.g., mood instability). We propose that the HiTOP model aligns well with the current understanding of the higher order genetic structure of psychopathology that has emerged from a large body of family and twin studies. We also discuss the convergence between the HiTOP model and findings from recent molecular studies of psychopathology indicating broad genetic pleiotropy, such as cross-disorder SNP-based shared genetic covariance and polygenic risk scores, and we highlight molecular genetic studies that have successfully redefined phenotypes to enhance precision and statistical power. Finally, we suggest how to integrate a HiTOP approach into future molecular genetic research, including quantitative and hierarchical assessment tools for future data-collection and recommendations concerning phenotypic analyses. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Association of Genetic and Environmental Risks for Attention-Deficit/Hyperactivity Disorder With Hypomanic Symptoms in Youths

IMPORTANCE

Attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder are highly comorbid, with significantly associated symptoms. The mechanisms that account for their co-occurrence are not known.

OBJECTIVE

To examine the degree to which genetic and environmental risk factors for ADHD traits, across childhood and adolescence, are associated with adolescent hypomanic symptoms.

DESIGN, SETTING, AND PARTICIPANTS

This study used data on 13 532 twin pairs from the Child and Adolescent Twin Study in Sweden, a prospective, longitudinal twin study. Their parents provided ADHD data when children were 9 or 12 years of age. Of those who reached 15 years of age, 3784 participated. Of those who reached 18 years of age, 3013 participated. The study was performed from December 20, 2017, to December 5, 2018. Data analysis was performed at the Department of Medical Epidemiology & Biostatistics, Karolinska Institutet, Stockholm, Sweden, from March 1, 2018, to October 31, 2018.

MAIN OUTCOMES AND MEASURES

Attention-deficit/hyperactivity disorder traits and hypomanic symptoms were assessed using parent-rated instruments. Associations between ADHD and adolescent hypomanic symptoms across childhood and adolescence were investigated using generalized estimating equations. Multivariate twin models were used to examine the extent to which genetic and environmental risk factors for ADHD were associated with hypomania.

RESULTS

Among 3784 15-year-old twin pairs and 3013 18-year-old twin pairs, ADHD and hypomanic symptoms were significantly associated (age 15 years: β = 0.30; 95% CI, 0.24-0.34; P < .001; age 18 years: β = 0.19; 95% CI, 0.16-0.22; P < .001), especially for the hyperactivity-impulsivity ADHD symptom domain (age 15 years: β = 0.53; 95% CI, 0.46-0.60; P < .001; age 18 years: β = 0.36; 95% CI, 0.30-0.42; P < .001) compared with the inattention domain (age 15 years: β = 0.40; 95% CI, 0.34-0.47; P < .001; age 18 years: β = 0.24; 95% CI, 0.19-0.29; P < .001). Between 13% and 29% of the genetic risk factors for hypomania were also associated with ADHD, with higher estimates detected for symptoms of hyperactivity-impulsivity (10%-25%) compared with inattention (6%-16%). Environmental factors played a negligible role in the associations. Genetic factors unique to adolescent hypomania were associated with 25% to 42% of its variance, suggesting some etiologic distinction between these forms of psychopathology.

CONCLUSIONS AND RELEVANCE

More than a quarter of the genetic risk factors for adolescent hypomanic traits were also associated with ADHD symptoms in childhood and adolescence, with hypomania-specific genetic risk factors detected. These findings suggest that ADHD and hypomanic symptoms are associated with shared genetic factors, which should be the focus of further research.

Risk and coaggregation of major psychiatric disorders among first-degree relatives of patients with bipolar disorder: a nationwide population-based study

BACKGROUND

Bipolar disorder is a highly heritable mental illness that transmits intergeneratively. Previous studies supported that first-degree relatives (FDRs), such as parents, offspring, and siblings, of patients with bipolar disorder, had a higher risk of bipolar disorder. However, whether FDRs of bipolar patients have an increased risk of schizophrenia, major depressive disorder (MDD), autism spectrum disorder (ASD), and attention deficit hyperactivity disorder (ADHD) remains unclear.

METHODS

Among the entire population in Taiwan, 87 639 patients with bipolar disorder and 188 290 FDRs of patients with bipolar disorder were identified in our study. The relative risks (RRs) of major psychiatric disorders were assessed among FDRs of patients with bipolar disorder.

RESULTS

FDRs of patients with bipolar disorder were more likely to have a higher risk of major psychiatric disorders, including bipolar disorder (RR 6.12, 95% confidence interval (CI) 5.95-6.30), MDD (RR 2.89, 95% CI 2.82-2.96), schizophrenia (RR 2.64, 95% CI 2.55-2.73), ADHD (RR 2.21, 95% CI 2.13-2.30), and ASD (RR 2.10, 95% CI 1.92-2.29), than the total population did. These increased risks for major psychiatric disorders were consistent across different familial kinships, such as parents, offspring, siblings, and twins. A dose-dependent relationship was also found between risk of each major psychiatric disorder and numbers of bipolar patients.

CONCLUSIONS

Our study was the first study to support the familial coaggregation of bipolar disorder with other major psychiatric disorders, including schizophrenia, MDD, ADHD, and ASD, in a Taiwanese (non-Caucasian) population. Given the elevated risks of major psychiatric disorders, the public health government should pay more attention to the mental health of FDRs of patients with bipolar disorder.

A population-based heritability estimate of bipolar disorder - In a Swedish twin sample

Twin- and family studies have shown variations in the heritability estimates of bipolar disorder (BPD). The current study uses an updated statistical methodology for heritability estimation in BPD by taking available time of follow-up into account while controlling for co-variates. We identified monozygotic and dizygotic same and different sex twins with BPD (n = 804) or unaffected from BPD (n = 91,604) from the Swedish Twin Register and the National Patient Register. We applied structural equational modeling with inversed probability weighting to estimate the heritability, taking into account censoring and truncation of data. Sex-limitation models were constructed to analyze qualitative or quantitative sex-differences in BPD. Heritability for BPD was 60.4% (95% Confidence Interval: 50.3-70.5) after age, sex, left-hand truncation and censoring of the data was taken into account. A larger proportion of females were affected from BPD (females 62.2%; males 37.8%, p < 0.001), but no sex-difference in BPD heritability was found, nor any sex-specific genetic effects. We demonstrated a robust 60% heritability for BPD with no evidence of sex-specific genetic effects on disease liability.

Clinical phenotype and genetic risk factors for bipolar disorder with binge eating: an update

Introduction: Clinical and genetic study of psychiatric conditions has underscored the co-occurrence of complex phenotypes and the need to refine them. Bipolar Disorder (BD) and Binge Eating (BE) behavior are common psychiatric conditions that have high heritability and high co-occurrence, such that at least one quarter of BD patients have BE (BD + BE). Genetic studies of BD alone and of BE alone suggest complex polygenic risk models, with many genetic risk loci yet to be identified. Areas covered: We review studies of the epidemiology of BD+BE, its clinical features (cognitive traits, psychiatric comorbidity, and role of obesity), genomic studies (of BD, eating disorders (ED) defined by BE, and BD + BE), and therapeutic implications of BD + BE. Expert opinion: Subphenotyping of complex psychiatric disorders reduces heterogeneity and increases statistical power and effect size; thus, it enhances our capacity to find missing genetic (and other) risk factors. BD + BE has a severe clinical picture and genetic studies suggests a distinct genetic architecture. Differential therapeutic interventions may be needed for patients with BD + BE compared with BD patients without BE. Recognizing the BD + BE subphenotype is an example of moving towards more precise clinical and genetic entities.