Common genetic determinants of schizophrenia and bipolar disorder in Swedish families: a population-based study

Monozygotic twins discordant for schizophrenia differ in maturation and synaptic transmission

Schizophrenia affects approximately 1% of the world population. Genetics, epigenetics, and environmental factors are known to play a role in this psychiatric disorder. While there is a high concordance in monozygotic twins, about half of twin pairs are discordant for schizophrenia. To address the question of how and when concordance in monozygotic twins occur, we have obtained fibroblasts from two pairs of schizophrenia discordant twins (one sibling with schizophrenia while the second one is unaffected by schizophrenia) and three pairs of healthy twins (both of the siblings are healthy). We have prepared iPSC models for these 3 groups of patients with schizophrenia, unaffected co-twins, and the healthy twins. When the study started the co-twins were considered healthy and unaffected but both the co-twins were later diagnosed with a depressive disorder. The reprogrammed iPSCs were differentiated into hippocampal neurons to measure the neurophysiological abnormalities in the patients. We found that the neurons derived from the schizophrenia patients were less arborized, were hypoexcitable with immature spike features, and exhibited a significant reduction in synaptic activity with dysregulation in synapse-related genes. Interestingly, the neurons derived from the co-twin siblings who did not have schizophrenia formed another distinct group that was different from the neurons in the group of the affected twin siblings but also different from the neurons in the group of the control twins. Importantly, their synaptic activity was not affected. Our measurements that were obtained from schizophrenia patients and their monozygotic twin and compared also to control healthy twins point to hippocampal synaptic deficits as a central mechanism in schizophrenia.

Comparing cognition in parents with schizophrenia or bipolar disorder and their 7-year-old offspring

Individuals with schizophrenia (SZ) or bipolar disorder (BP) display cognitive impairments, while their first-degree relatives perform at an intermediate level between the patient groups and controls. However, the environmental impact of having an ill relative likely varies with the type of kinship and some studies suggest that offspring may be particularly disadvantaged. The present study aimed to investigate the relationship between parent and child cognition in parents with SZ or BD and their 7-year-old offspring. A population-based cohort of 522 children (parental SZ, n = 202; parental BP, n = 120; controls, n = 200) and their parents underwent the same assessment battery covering a wide range of cognitive functions. We used Bayesian statistics to model performance. We found that performance on non-verbal tests was better in offspring than parents with SZ or BP, using the controls as reference. However, for verbal tests, there was little to no evidence for this pattern or even some evidence for the opposite in the BP group: relatively better performance in parents than offspring. The findings suggest that the offspring of parents with SZ or BP may be particularly disadvantaged in verbal abilities. Future studies will show whether this pattern persists throughout development.

Non-linear development of brain morphometry in child and adolescent offspring of individuals with bipolar disorder or schizophrenia

Offspring of parents with severe mental illness (e.g., bipolar disorder or schizophrenia) are at increased risk of developing psychopathology. Structural brain alterations have been found in child and adolescent offspring of patients with bipolar disorder and schizophrenia, but the developmental trajectories of brain anatomy in this high-familial-risk population are still unclear. 300 T1-weighted scans were obtained of 187 offspring of at least one parent diagnosed with bipolar disorder (n=80) or schizophrenia (n=53) and offspring of parents without severe mental illness (n=54). The age range was 8 to 23 years old; 113 offspring underwent two scans. Global brain measures and regional cortical thickness and surface area were computed. A generalized additive mixed model was used to capture non-linear age trajectories. Offspring of parents with schizophrenia had smaller total brain volume than offspring of parents with bipolar disorder (d=-0.20, p=0.004) and control offspring (d=-0.22, p=0.005) and lower mean cortical thickness than control offspring (d=-0.23, p<0.001). Offspring of parents with schizophrenia showed differential age trajectories of mean cortical thickness and cerebral white matter volume compared with control offspring (both p's=0.003). Regionally, offspring of parents with schizophrenia had a significantly different trajectory of cortical thickness in the middle temporal gyrus versus control offspring (p<0.001) and bipolar disorder offspring (p=0.001), which was no longer significant after correcting for mean cortical thickness. These findings suggest that particularly familial high risk of schizophrenia is related to reductions and deviating developmental trajectories of global brain structure measures, which were not driven by specific regions.

Clinical Outcomes and Cost Implications of a Community Psychosocial Rehabilitation Service for Severe and Persistent Mental Illness in Nova Scotia, Canada

Introduction: Individuals with severe and persistent mental illness (SPMI) present distinct challenges in mental healthcare due to the chronic and complex nature of their conditions. This study was conducted to assess the clinical efficacy and potential cost-effectiveness of a multidisciplinary community-based psychosocial rehabilitation team serving individuals with SPMI in Nova Scotia, Canada. Method: This study was conducted to evaluate the effects of a community-based psychosocial rehabilitation program on individuals with severe and persistent mental illness (SPMI) in Nova Scotia, Canada. This research focused on clinical outcomes and potential cost savings following a one-year intervention, offering critical insights into the benefits of community-based care for this population. A cohort of 137 clients accepted into the community rehabilitation service (Connections Dartmouth) between September 2016 and September 2020 was analyzed. Each participant received one year of community rehabilitation intervention. Using data from the Canadian Medical Service Insurance (MSI) billing system, this research compared the use of inpatient services and Emergency Department visits in the year prior to and the year following the intervention. The findings provide valuable evidence on the role of community rehabilitation in reducing healthcare utilization for individuals with SPMI. Results: The results demonstrated a statistically significant reduction in mean admission rates and length of inpatient admissions in the year following rehabilitation compared to the pre-rehabilitation year. A substantial percentage of patients experienced no inpatient admissions (88% vs. 60%) or Emergency Department visits (82% vs. 67%) in the post-rehabilitation year, compared to the pre-rehabilitation year. There was a significant reduction in inpatient days by 90%, translating into substantial cost savings. The findings highlight the potential economic benefits of community rehabilitation for people with SPMI. Conclusions: This uncontrolled study suggests that community rehabilitation is associated with positive clinical outcomes for individuals with SPMI in terms of reduced inpatient service use and associated costs. Further research, including controlled studies and cost-effectiveness studies, into the community psychosocial rehabilitation services in the Canadian setting is needed.

Analyzing language ability in first-episode psychosis and their unaffected siblings: A diffusion tensor imaging tract-based spatial statistics analysis study

Schizophrenia (SZ) is a highly heritable mental disorder, and language dysfunctions play a crucial role in diagnosing it. Although language-related symptoms such as disorganized speech were predicted by the polygenic risk for SZ which emphasized the common genetic liability for the disease, few studies investigated possible white matter integrity abnormalities in the language-related tracts in those at familial high-risk for SZ. Also, their results are not consistent. In this current study, we examined possible aberrations in language-related white matter tracts in patients with first-episode psychosis (FEP, N = 20), their siblings (SIB, N = 20), and healthy controls (CON, N = 20) by applying whole-brain Tract-Based Spatial Statistics and region-of-interest analyses. We also assessed language ability by Thought and Language Index (TLI) using Thematic Apperception Test (TAT) pictures and verbal fluency to see whether the scores of these language tests would predict the differences in these tracts. We found significant alterations in language-related tracts such as inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF) among three groups and between SIB and CON. We also proved partly their relationship with the language test as indicated by the significant correlation detected between TLI Impoverished thought/language sub-scale and ILF. We could not find any difference between FEP and CON. These results showed that the abnormalities, especially in the ILF and UF, could be important pathophysiological vulnerability indexes of schizophrenia. Further studies are required to understand better the role of language as a possible endophenotype in schizophrenia with larger samples.

Evaluating Oxidative Stress Markers in At-Risk Individuals for Bipolar Disorder: A Systematic Review and Meta-Analysis

INTRODUCTION

Bipolar disorder (BD), a mood disorder with recurrent affective episodes and a strong genetic basis is frequently associated with significant comorbidities, both physical and psychiatric, yet its neurobiology remains unclear. Recent evidence underscores oxidative stress as a pivotal factor linking BD to its comorbidities, prompting an investigation into whether this is a sign of a genetic vulnerability or a consequence of the disease. In this study, we systematically reviewed oxidative stress studies conducted on individuals at risk for BD. We performed a meta-analysis on studies examining oxidative DNA damage in these individuals.

METHODS

The literature was searched across the databases PubMed, Web of Science, Scopus, Ovid MEDLINE, and Cochrane to locate studies of oxidative stress markers in relatives of patients with BD compared with healthy controls (from 1946 to March 2024). Studies were considered for inclusion based on the following criteria: (i) involvement of first- or second-degree relatives of individuals diagnosed with BD, (ii) presence of a healthy control group, (iii) reporting of oxidative stress parameters for relatives, including mean and standard deviation or median and interquartile range (25-75%) values, and (iv) publication in the English language. Studies comparing the levels of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) or its tautomer 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) in individuals at risk for BD with healthy controls were evaluated using a meta-analysis with the random-effects method. The risk of bias was evaluated using the Risk of Bias in Non-Randomized Studies of Exposure (ROBINS-E) tool.

RESULTS

Eleven studies were included in the systematic review and four studies for the meta-analysis. The meta-analysis included 543 individuals (first-degree relatives of individuals with BD = 238, control = 305). 8-OH-dG levels were found to be increased in first-degree relatives of individuals with BD compared to healthy controls (random effects: Hedges's g = 0.53, 95% CI = 0.36-0.71, p < 0.001). Findings of oxidative stress markers other than oxidative DNA damage in relatives of individuals with BD are limited and scarce.

CONCLUSION

In this meta-analysis, which consists of a limited number of studies, oxidative DNA damage seems to be a trait marker for BD. This finding could be associated with increased comorbidity and a higher risk of premature aging in individuals at risk for BD. However, further studies with larger sample sizes and longitudinal designs are warranted to confirm findings. Clarifying the changes in these markers from individuals at risk for the disorder throughout the course of the illness would help bridge the gap in understanding the role of oxidative pathways in the risk of BD.

Involvement of CXCL10 rs4256246, CXCR4 rs2228014, CCR2 rs1799864 and CXCL16 rs2277680 in the Predisposition to Schizophrenia

Chemokine ligands and their receptors have acquired less attention than pro- and anti-inflammatory cytokines in schizophrenia (SCZ). Thus, we aimed to examine the impact of functional polymorphisms of the chemokine genes CXCL10, CXCL16, CXCR4, and CCR2 in the development of SCZ. Using PCR-RFLP, we analyzed the selected polymorphisms in a Tunisian cohort composed of 200 patients with SCZ and 200 healthy controls. Our preliminary data suggest that the minor allele A of CXCL10 rs4256246 is significantly associated with likelihood of SCZ (PAdjusted = 0.00002) and more precisely to paranoid patients with late-onset SCZ (PAdjusted = 0.0007). However, the mutated allele T of CXCR4 rs2228014 showed a significant protective impact against SCZ (PAdjusted = 0.000007) and especially to male sex (PAdjusted = 0.000003). This effect persists among the undifferentiated patients with early-onset SCZ (PAdjusted = 0.002). Following the stratified analyses, CCR2 rs1799864 and CXCL16 rs2277680 were significantly correlated with the clinical symptoms among disorganized patients. As regards haplotype analysis, we noted that GATG haplotype was associated with protection against SCZ (PAdjusted = 0.0087) but the AGCG haplotype was correlated with susceptibility to this disease (PAdjusted = 0.014). Our preliminary results suggested that CXCL10 rs4256246 enhanced susceptibility to SCZ, while CXCR4 rs2228014 seemed to be protective factor. Furthermore, we identified a substantial correlation between CCR2 rs1799864 and CXCL16 rs2277680 with the clinical signs of the disorder. To validate these results and clarify the functional significance of the targeted polymorphisms in SCZ, more independent research is needed.

Polygenic scores for psychiatric disorders associate with year of first bipolar disorder diagnosis: A register-based study between 1972 and 2016

The diagnostic criteria of bipolar disorder (BD) have changed over time. To test if these changes are reflected in the polygenic profile in BD, we studied the association between first BD diagnosis year (during 1972-2016) and polygenic scores (PGS) for psychiatric disorders in BD patients (N = 3,818). We found significant associations between diagnosis year and PGS for BD, depression, and attention deficit hyperactivity disorder (ADHD). The PGS remained largely stable over time in BD type 1, while changes were observed in BD type 2. These findings bear significance not only for genetic research but also for clinical practise, as shifts in patient characteristics can influence treatment response.

Accelerated Cortical Thinning in Schizophrenia Is Associated With Rare and Common Predisposing Variation to Schizophrenia and Neurodevelopmental Disorders

BACKGROUND

Schizophrenia is a highly heritable disorder characterized by increased cortical thinning throughout the life span. Studies have reported a shared genetic basis between schizophrenia and cortical thickness. However, no genes whose expression is related to abnormal cortical thinning in schizophrenia have been identified.

METHODS

We conducted linear mixed models to estimate the rates of accelerated cortical thinning across 68 regions from the Desikan-Killiany atlas in individuals with schizophrenia compared with healthy control participants from a large longitudinal sample (ncases = 169 and ncontrols = 298, ages 16-70 years). We studied the correlation between gene expression data from the Allen Human Brain Atlas and accelerated thinning estimates across cortical regions. Finally, we explored the functional and genetic underpinnings of the genes that contribute most to accelerated thinning.

RESULTS

We found a global pattern of accelerated cortical thinning in individuals with schizophrenia compared with healthy control participants. Genes underexpressed in cortical regions that exhibit this accelerated thinning were downregulated in several psychiatric disorders and were enriched for both common and rare disrupting variation for schizophrenia and neurodevelopmental disorders. In contrast, none of these enrichments were observed for baseline cross-sectional cortical thickness differences.

CONCLUSIONS

Our findings suggest that accelerated cortical thinning, rather than cortical thickness alone, serves as an informative phenotype for neurodevelopmental disruptions in schizophrenia. We highlight the genetic and transcriptomic correlates of this accelerated cortical thinning, emphasizing the need for future longitudinal studies to elucidate the role of genetic variation and the temporal-spatial dynamics of gene expression in brain development and aging in schizophrenia.

Schizophrenia genomics: genetic complexity and functional insights

Determining the causes of schizophrenia has been a notoriously intractable problem, resistant to a multitude of investigative approaches over centuries. In recent decades, genomic studies have delivered hundreds of robust findings that implicate nearly 300 common genetic variants (via genome-wide association studies) and more than 20 rare variants (via whole-exome sequencing and copy number variant studies) as risk factors for schizophrenia. In parallel, functional genomic and neurobiological studies have provided exceptionally detailed information about the cellular composition of the brain and its interconnections in neurotypical individuals and, increasingly, in those with schizophrenia. Taken together, these results suggest unexpected complexity in the mechanisms that drive schizophrenia, pointing to the involvement of ensembles of genes (polygenicity) rather than single-gene causation. In this Review, we describe what we now know about the genetics of schizophrenia and consider the neurobiological implications of this information.

Polygenic Risk Scores and Twin Concordance for Schizophrenia and Bipolar Disorder

Importance

Schizophrenia and bipolar disorder are highly heritable psychiatric disorders with strong genetic and phenotypic overlap. Twin and molecular methods can be leveraged to predict the shared genetic liability to these disorders.

Objective

To investigate whether twin concordance for psychosis depends on the level of polygenic risk score (PRS) for psychosis and zygosity and compare PRS from cases and controls from several large samples and estimate the twin heritability of psychosis.

Design, Setting, and Participants

In this case-control study, psychosis PRS were generated from a genome-wide association study (GWAS) combining schizophrenia and bipolar disorder into a single psychosis phenotype and compared between cases and controls from the Schizophrenia and Bipolar Twin Study in Sweden (STAR) project. Further tests were conducted to ascertain if twin concordance for psychosis depended on the mean PRS for psychosis. Structural equation modeling was used to estimate heritability. This study constituted an analysis of existing clinical and population datasets with genotype and/or twin data. Included were twins from the STAR cohort and from the Swedish Twin Registry. Data were collected during the 2006 to 2013 period and analyzed from March 2023 to June 2024.

Exposures

PRS for psychosis based on the most recent GWAS of combined schizophrenia/bipolar disorder.

Main Outcomes and Measures

Psychosis case status was assessed by clinical interviews and/or Swedish National Register data.

Results

The final cohort comprised 87 pairs of twins with 1 or both affected and 59 unaffected pairs from the STAR project (for a total of 292 twins) as well as 443 pairs with 1 or both affected and 20 913 unaffected pairs from the Swedish Twin Registry. Among the 292 twins (mean [SD] birth year, 1960 [10.8] years; 158 female [54.1%]; 134 male [45.9%]), 134 were monozygotic twins, and 158 were dyzygotic twins. PRS for psychosis was higher in cases than in controls and associated with twin concordance for psychosis (1-SD increase in PRS, odds ratio [OR], 2.12; 95% CI, 1.23-3.87 on case status in monozygotic twins and OR, 2.74; 95% CI, 1.56-5.30 in dizygotic twins). The association between PRS for psychosis and concordance was not modified by zygosity. The twin heritability was estimated at 0.73 (95% CI, 0.30-1.00), which overlapped with the estimate in the full Swedish Twin Registry (0.69; 95% CI, 0.43-0.85).

Conclusions and Relevance

In this case-control study, using the natural experiment of twins, results suggest that twins with greater inherited liability for psychosis were more likely to have an affected co-twin. Results from twin and molecular designs largely aligned. Even as illness vulnerability is not solely genetic, PRS carried predictive power for psychosis even in a modest sample size.

Multitrait Genetic Analysis Identifies Novel Pleiotropic Loci for Depression and Schizophrenia in East Asians

BACKGROUND AND HYPOTHESIS

While genetic correlations, pleiotropic loci, and shared genetic mechanisms of psychiatric disorders have been extensively studied in European populations, the investigation of these factors in East Asian populations has been relatively limited.

STUDY DESIGN

To identify novel pleiotropic risk loci for depression and schizophrenia (SCZ) in East Asians. We utilized the most comprehensive dataset available for East Asians and quantified the genetic overlap between depression, SCZ, and their related traits via a multitrait genome-wide association study. Global and local genetic correlations were estimated by LDSC and ρ-HESS. Pleiotropic loci were identified by the multitrait analysis of GWAS (MTAG).

STUDY RESULTS

Besides the significant correlation between depression and SCZ, our analysis revealed genetic correlations between depression and obesity-related traits, such as weight, BMI, T2D, and HDL. In SCZ, significant correlations were detected with HDL, heart diseases and use of various medications. Conventional meta-analysis of depression and SCZ identified a novel locus at 1q25.2 in East Asians. Further multitrait analysis of depression, SCZ and related traits identified ten novel pleiotropic loci for depression, and four for SCZ.

CONCLUSIONS

Our findings demonstrate shared genetic underpinnings between depression and SCZ in East Asians, as well as their associated traits, providing novel candidate genes for the identification and prioritization of therapeutic targets specific to this population.

Progress and Implications from Genetic Studies of Bipolar Disorder

With the advancements in gene sequencing technologies, including genome-wide association studies, polygenetic risk scores, and high-throughput sequencing, there has been a tremendous advantage in mapping a detailed blueprint for the genetic model of bipolar disorder (BD). To date, intriguing genetic clues have been identified to explain the development of BD, as well as the genetic association that might be applied for the development of susceptibility prediction and pharmacogenetic intervention. Risk genes of BD, such as CACNA1C, ANK3, TRANK1, and CLOCK, have been found to be involved in various pathophysiological processes correlated with BD. Although the specific roles of these genes have yet to be determined, genetic research on BD will help improve the prevention, therapeutics, and prognosis in clinical practice. The latest preclinical and clinical studies, and reviews of the genetics of BD, are analyzed in this review, aiming to summarize the progress in this intriguing field and to provide perspectives for individualized, precise, and effective clinical practice.

The Intergenerational Transfer of Mental Disorders: A Population-Based Multigenerational Linkage Study: Le transfert intergénérationnel des troubles mentaux : une étude sur les liens multigénérationnels basée sur la population

OBJECTIVES

The aetiology of mental disorders involves genetic and environmental factors, both reflected in family health history. We examined the intergenerational transmission of multiple mental disorders from parents and grandparents using population-based, objectively measured family histories.

METHODS

This population-based retrospective cohort study used administrative healthcare databases in Manitoba, Canada and included adults living in Manitoba from 1977 to 2020 with linkages to at least one parent and one grandparent. Index date was when individuals turned 18 or 1 April 1977, whichever occurred later. Mental disorder diagnoses (mood and anxiety, substance use and psychotic disorders) were identified in individuals, parents and grandparents from hospitalization and outpatient records. Cox proportional hazards regression models included sociodemographic characteristics, individual's comorbidity and mental disorder history in a grandparent, mother and father.

RESULTS

Of 109,359 individuals with no mental disorder prior to index date, 47.1% were female, 36.3% had a mental disorder during follow-up, and 90.9% had a parent or grandparent with a history of a mental disorder prior to the index date. Both paternal and maternal history of a mental disorder increased the risk of the disorder in individuals. Psychotic disorders had the strongest association with parental history and were mostly influenced by paternal (hazards ratio [HR] 3.73, 95% confidence interval [CI] 2.99 to 4.64) compared to maternal history (HR 2.23, 95% CI, 1.89 to 2.64). Grandparent history was independently associated with the risk of all mental disorders but had the strongest influence on substance use disorders (HR 1.42, 95% CI, 1.34 to 1.50).

CONCLUSIONS

Parental history of mental disorders was associated with an increased risk of all mental disorders. Grandparent history of mental disorders was associated with a small risk increase of the disorders above and beyond parental history influence. This three-generation study further highlights the need for family-based interventional programs in families affected by mental disorders.

PLAIN LANGUAGE SUMMARY TITLE

The Intergenerational Transfer of Mental Illnesses.

TLR4 Polymorphisms (T399I/D299G) Association with Schizophrenia and Bipolar Disorder in a Tunisian Population

Immune dysregulation has been widely described in the pathophysiology of schizophrenia (SCZ) and bipolar disorder (BD). Particularly, TLR4-altered activation was proposed as one of the underlying processes of psychosis onset. Since TLR4 activation was altered by T399I and D299G polymorphisms, we hypothesized that those variants could present common genetic factors of SCZ and BD. A total of 293 healthy volunteers and 335 psychotic patients were genotyped using PCR-RFLP. Genotype, allele, and haplotype distribution between controls and patients were evaluated according to clinical parameters. Statistical analyses were adjusted by logistic regression. In dominant model, T399I CT + TT and allele frequency were significantly higher in controls compared to psychotic population (p = 0.004, p = 0.002, respectively), SCZ (p = 0.02, p = 0.01, respectively), and BD (p = 0.03, p = 0.02, respectively). Similarly, D299G AG + GG and allele frequency were significantly higher in controls compared to psychotic population (p = 0.04, p = 0.04, respectively) and SCZ (p = 0.04, p = 0.03, respectively). T399I CT + TT and T allele were overrepresented in controls compared to paranoid subgroup (Padjusted = 0.04, p = 0.04, respectively) and type I BD (p = 0.04). Moreover, T399I and D299G were less prevalent in SCZ late-onset age (p = 0.03, p = 0.02, respectively). TA haplotype was associated with protection from psychoses (p = 0.02) and particularly from schizophrenia (p = 0.04). In conclusion, TLR4 polymorphisms could present a preventive genetic background against psychoses onset in a Tunisian population. While T399I could be associated with protection against SCZ and BD, presenting an overlapping genetic factor between those psychoses, D299G was suggested to be associated with protection only from schizophrenia.

Integrative ceRNA network analysis identifies unique and shared molecular signatures in Bipolar Disorder and Schizophrenia

Bipolar Disorder (BPD) and Schizophrenia (SCZ) are complex psychiatric disorders with shared symptomatology and genetic risk factors. Understanding the molecular mechanisms underlying these disorders is crucial for refining diagnostic criteria and guiding targeted treatments. In this study, publicly available RNA-seq data from post-mortem samples of the basal ganglia's striatum were analyzed using an integrative computational approach to identify differentially expressed (DE) transcripts associated with SCZ and BPD. The analysis aimed to reveal both shared and distinct genes and long non-coding RNAs (lncRNAs) and to construct competitive endogenous RNA (ceRNA) networks within the striatum. Furthermore, the functional implications of these identified transcripts are explored, alongside their presence in established databases such as BipEx and SCHEMA. A significant outcome of our analysis was the identification of 21 DEmRNAs and 1 DElncRNA shared between BPD and SCZ across the Caudate, Putamen, and Nucleus Accumbens. Another noteworthy finding was the identification of Hub nodes within the ceRNA networks that were linked to major psychosis. Particularly, MED19, HNRNPC, MAGED4B, KDM5A, GOLGA7, CHASERR, hsa-miR-4778-3p, hsa-miR-4739, and hsa-miR-4685-5p emerged as potential biomarkers. These findings shed light on the common and unique molecular signatures underlying BPD and SCZ, offering significant potential for the advancement of diagnostic and therapeutic strategies tailored to these psychiatric disorders.

Psychiatric Diagnoses in Parents and Psychiatric, Behavioral, and Psychosocial Outcomes in Their Offspring: A Swedish Population-Based Register Study

OBJECTIVE

Associations were examined between six psychiatric diagnoses in parents and a broad range of psychiatric and nonpsychiatric outcomes in their offspring.

METHODS

All individuals born in Sweden between 1970 and 2000 were linked to their biological parents (N=3,286,293) through Swedish national registers. A matched cohort design, with stratified Cox regression and conditional logistic regression analyses, was used examine associations between six psychiatric diagnoses in the parents and 32 outcomes in their offspring. All children, including those exposed and those not exposed to parents with psychiatric diagnoses, were followed from their date of birth to the date of emigration from Sweden, death, or December 31, 2013, when the offspring were 14-44 years old.

RESULTS

In terms of absolute risk, most children who had parents with psychiatric diagnoses were not diagnosed in specialist care themselves, and the proportion of offspring having any of the 16 types of psychiatric conditions ranged from 22.17% (of offspring exposed to parental depression) to 25.05% (of offspring exposed to parental drug-related disorder) at the end of follow-up. Nevertheless, in terms of relative risk, exposure to any of the six parental psychiatric diagnoses increased probabilities of the 32 outcomes among the offspring, with hazard ratios that ranged from 1.03 to 8.46 for time-to-event outcomes and odds ratios that ranged from 1.29 to 3.36 for binary outcomes. Some specificities were observed for parental diagnoses of psychosis and substance-related disorders, which more strongly predicted psychotic-like and externalizing-related outcomes, respectively, in the offspring.

CONCLUSIONS

The intergenerational transmission of parental psychiatric conditions appeared largely transdiagnostic and extended to nonpsychiatric outcomes in offspring. Given the broad spectrum of associations with the outcomes, service providers (e.g., psychiatrists, teachers, and social workers) should consider clients' broader psychiatric family history when predicting prognosis and planning interventions or treatment.

Polygenic risk for schizophrenia and bipolar disorder in relation to cardiovascular biomarkers

Individuals with schizophrenia and bipolar disorder are at an increased risk of cardiovascular disease (CVD), and a range of biomarkers related to CVD risk have been found to be abnormal in these patients. Common genetic factors are a putative underlying mechanism, alongside lifestyle factors and antipsychotic medication. However, the extent to which the altered CVD biomarkers are related to genetic factors involved in schizophrenia and bipolar disorder is unknown. In a sample including 699 patients with schizophrenia, 391 with bipolar disorder, and 822 healthy controls, we evaluated 8 CVD risk biomarkers, including BMI, and fasting plasma levels of CVD biomarkers from a subsample. Polygenic risk scores (PGRS) were obtained from genome-wide associations studies (GWAS) of schizophrenia and bipolar disorder from the Psychiatric Genomics Consortium. The CVD biomarkers were used as outcome variables in linear regression models including schizophrenia and bipolar disorder PGRS as predictors, age, sex, diagnostic category, batch and 10 principal components as covariates, controlling for multiple testing by Bonferroni correction for the number of independent tests. Bipolar disorder PGRS was significantly (p = 0.03) negatively associated with BMI after multiple testing correction, and schizophrenia PGRS was nominally negatively associated with BMI. There were no other significant associations between bipolar or schizophrenia PGRS, and other investigated CVD biomarkers. Despite a range of abnormal CVD risk biomarkers in psychotic disorders, we only found a significant negative association between bipolar disorder PGRS and BMI. This has previously been shown for schizophrenia PGRS and BMI, and warrants further exploration.

Whole genome sequencing study of identical twins discordant for psychosis

Monozygotic (MZ) twins are often thought to have identical genomes, but recent work has shown that early post-zygotic events can result in a spectrum of DNA variants that are different between MZ twins. Such variants may explain phenotypic discordance and contribute to disease etiology. Here we performed whole genome sequencing in 17 pairs of MZ twins discordant for a psychotic disorder (schizophrenia, schizoaffective disorder or bipolar disorder). We examined various classes of rare variants that are discordant within a twin pair. We identified four genes harboring rare, predicted deleterious missense variants that were private to an affected individual in the cohort. Variants in FOXN1 and FLOT2 would have been categorized as damaging from recent schizophrenia and bipolar exome sequencing studies. Additionally, we identified four rare genic copy number variants (CNVs) private to an affected sample, two of which overlapped genes that have shown evidence for association with schizophrenia or bipolar disorder. One such CNV was a 3q29 duplication previously implicated in autism and developmental delay. We have performed the largest MZ twin study for discordant psychotic phenotypes to date. These findings warrant further investigation using other analytical approaches.

A functional schizophrenia-associated genetic variant near the TSNARE1 and ADGRB1 genes

Recent collaborative genome-wide association studies (GWAS) have identified >200 independent loci contributing to risk for schizophrenia (SCZ). The genes closest to these loci have diverse functions, supporting the potential involvement of multiple relevant biological processes, yet there is no direct evidence that individual variants are functional or directly linked to specific genes. Nevertheless, overlap with certain epigenetic marks suggest that most GWAS-implicated variants are regulatory. Based on the strength of association with SCZ and the presence of regulatory epigenetic marks, we chose one such variant near TSNARE1 and ADGRB1, rs4129585, to test for functional potential and assay differences that may drive the pathogenicity of the risk allele. We observed that the variant-containing sequence drives reporter expression in relevant neuronal populations in zebrafish. Next, we introduced each allele into human induced pluripotent cells and differentiated four isogenic clones homozygous for the risk allele and five clones homozygous for the non-risk allele into neural progenitor cells. Employing RNA sequencing, we found that the two alleles yield significant transcriptional differences in the expression of 109 genes at a false discovery rate (FDR) of <0.05 and 259 genes at a FDR of <0.1. We demonstrate that these genes are highly interconnected in pathways enriched for synaptic proteins, axon guidance, and regulation of synapse assembly. Exploration of genes near rs4129585 suggests that this variant does not regulate TSNARE1 transcripts, as previously thought, but may regulate the neighboring ADGRB1, a regulator of synaptogenesis. Our results suggest that rs4129585 is a functional common variant that functions in specific pathways likely involved in SCZ risk.

Environmental risk factors for schizophrenia and bipolar disorder from childhood to diagnosis: a Swedish nested case-control study

BACKGROUND

Shared genetic risk between schizophrenia (SCZ) and bipolar disorder (BD) is well-established, yet the extent to which they share environmental risk factors remains unclear. We compare the associations between environmental exposures during childhood/prior to disorder onset with the risk of developing SCZ and BD.

METHODS

We conducted a Swedish register-based nested case-control study using 4184 SCZ cases and 18 681 BD cases diagnosed 1988-2013. Cases were matched to five controls by birth year, birth region, and sex. Conditional logistic regression was used to estimate incidence rate ratios (IRR) for SCZ and BD for each exposure (severe childhood infections, adverse childhood experiences (ACEs), substance use disorders (SUDs), urban birth/longest residence).

RESULTS

All SUD types were associated with very high risk (IRR 4.9-25.5), and all forms of ACEs with higher risk (IRR 1.5-4.3) for both disorders. In the mutually adjusted models, ACEs demonstrated slightly higher risk for BD (SCZ IRR 1.30, 1.19-1.42; BD IRR 1.49, 1.44-1.55), while for SUD, risk was higher for SCZ (SCZ IRR 9.43, 8.15-10.92; BD IRR 5.50, 5.15-5.88). Infections were associated with increased risk of BD (IRR 1.21, 1.17-1.26) but not SCZ. Urban birth and urban longest residence were associated with higher risk of SCZ (IRR 1.19, 1.03-1.37), while only the combination of urban birth and rural longest residence showed higher risk for BD (IRR 1.24, 1.13-1.35).

CONCLUSIONS

There were both shared and unique environmental risk factors: SUDs and ACEs were risk factors for both disorders, while infections were more strongly associated with BD and urbanicity with SCZ.

Family-based genetic analysis in schizophrenia by whole-exome sequence to identify rare pathogenic variants

Schizophrenia (SCZ) is influenced by a combination of genetic and environmental factors. Although several studies have been conducted to identify the causative loci and genes, few of these loci or genes can be repeated due to the high phenotypic and genetic heterogeneity of disease, and their mechanisms are not fully understood. There may be some "missing heritability" that has not yet been found. In order to investigate the deleterious heritable mutations, whole-exome sequencing (WES) in pedigrees with SCZ was used in the current work. Two unrelated pedigrees with SCZ were recruited to perform WES. Genetic analysis was next performed to find potential variants in accordance with the prioritized strategy. Followed by genetic analysis to detect candidate variants according to the prioritized strategy. Next, a series of algorithms was used to predict the pathogenicity of variants. Sanger sequencing was finally conducted to verify the co-segregation. Recessive mutations in six genes (TFEB, SNAI2, TFAP2B, PRKDC, ST18 in Pedigree 1 and PKHD1L1 in Pedigree 2) that co-segregated with SCZ in two families were discovered through genetic analysis by WES. Sanger sequencing verified that all of the mutations in the affected siblings were homozygous. These results corroborated the hypothesis that SCZ exhibits strong heterogeneity and complex inheritance patterns. The newly discovered homozygous variations deepen our understanding of the mutation spectrum and offer more proof for the involvement of TFEB, SNAI2, TFAP2B, PRKDC, ST18, and PKHD1L1 in the development of SCZ.

Transdiagnostic dimensions of symptoms and experiences associated with immune proteins in the continuity of psychosis

BACKGROUND

There is limited evidence as to whether the immune protein profile is associated with a particular symptomatology pattern across the psychosis continuum.

METHODS

We estimated two bifactor models of general and specific dimensions of psychotic experiences in unaffected siblings of patients (n = 52) and community controls (n = 200), and of psychotic symptoms in first-episode psychosis (FEP) patients (n = 110). We evaluated associations between these transdiagnostic dimensions and trait (TNF-α, IFN-γ), state (IL-6, IL-1β), and regulatory (TGF-β, IL-10, IL-4) cytokines. We explored whether schizophrenia genetic liability (schizophrenia polygenic risk score; SZ-PRS) modified the associations.

RESULTS

High levels of trait marker IFN-γ were associated with the severity of general psychosis dimension in the unaffected siblings and community controls, expanding to the depressive dimension in siblings and to the manic dimension in FEP. High TNF-α levels were associated with more positive psychotic experiences in unaffected siblings and manic symptoms in FEP. Low levels of state markers IL-6 and IL-1β were observed in unaffected siblings presenting more depressive experiences. Still, high levels of IL-6 and IL-1β were associated with the severity of the depressive and negative symptom dimensions at FEP. The severity of transdiagnostic dimension scores across the three groups was associated with lower regulatory cytokines. Exploratory analysis suggested that a high SZ-PRS contributed mostly to associations with psychotic dimensions.

CONCLUSIONS

IFN-γ mapped onto the multidimensional expression of psychosis, reinforcing the trait concept. State markers IL-6 and IL-1β may fluctuate along the spectrum. Dysfunction in the regulatory arm may disinhibit the inflammatory system. Associations with psychotic dimensions may be more prone to SZ-PRS susceptibility.

Diagnostic value of regional homogeneity and fractional amplitude of low-frequency fluctuations in the classification of schizophrenia and bipolar disorders

Schizophrenia (SCZ) and bipolar disorders (BD) show significant neurobiological and clinical overlap. In this study, we wanted to identify indexes of intrinsic brain activity that could differentiate these disorders. We compared the diagnostic value of the fractional amplitude of low-frequency fluctuations (fALFF) and regional homogeneity (ReHo) estimated from resting-state functional magnetic resonance imaging in a support vector machine classification of 59 healthy controls (HC), 40 individuals with SCZ, and 43 individuals with BD type I. The best performance, measured by balanced accuracy (BAC) for binary classification relative to HC was achieved by a stacking model (87.4% and 90.6% for SCZ and BD, respectively), with ReHo performing better than fALFF, both in SCZ (86.2% vs. 79.4%) and BD (89.9% vs. 76.9%). BD were better differentiated from HC by fronto-temporal ReHo and striato-temporo-thalamic fALFF. SCZ were better classified from HC using fronto-temporal-cerebellar ReHo and insulo-tempo-parietal-cerebellar fALFF. In conclusion, we provided evidence of widespread aberrancies of spontaneous activity and local connectivity in SCZ and BD, demonstrating that ReHo features exhibited superior discriminatory power compared to fALFF and achieved higher classification accuracies. Our results support the complementarity of these measures in the classification of SCZ and BD and suggest the potential for multivariate integration to improve diagnostic precision.

Factor analysis of lifetime psychopathology and its brain morphometric and genetic correlates in a transdiagnostic sample

There is a lack of knowledge regarding the relationship between proneness to dimensional psychopathological syndromes and the underlying pathogenesis across major psychiatric disorders, i.e., Major Depressive Disorder (MDD), Bipolar Disorder (BD), Schizoaffective Disorder (SZA), and Schizophrenia (SZ). Lifetime psychopathology was assessed using the OPerational CRITeria (OPCRIT) system in 1,038 patients meeting DSM-IV-TR criteria for MDD, BD, SZ, or SZA. The cohort was split into two samples for exploratory and confirmatory factor analyses. All patients were scanned with 3-T MRI, and data was analyzed with the CAT-12 toolbox in SPM12. Psychopathological factor scores were correlated with gray matter volume (GMV) and cortical thickness (CT). Finally, factor scores were used for exploratory genetic analyses including genome-wide association studies (GWAS) and polygenic risk score (PRS) association analyses. Three factors (paranoid-hallucinatory syndrome, PHS; mania, MA; depression, DEP) were identified and cross-validated. PHS was negatively correlated with four GMV clusters comprising parts of the hippocampus, amygdala, angular, middle occipital, and middle frontal gyri. PHS was also negatively associated with the bilateral superior temporal, left parietal operculum, and right angular gyrus CT. No significant brain correlates were observed for the two other psychopathological factors. We identified genome-wide significant associations for MA and DEP. PRS for MDD and SZ showed a positive effect on PHS, while PRS for BD showed a positive effect on all three factors. This study investigated the relationship of lifetime psychopathological factors and brain morphometric and genetic markers. Results highlight the need for dimensional approaches, overcoming the limitations of the current psychiatric nosology.

Whole-exome sequencing in a Chinese sample provides preliminary evidence for the link between rare/low-frequency immune-related variants and early-onset schizophrenia

Rare and low-frequency variants contribute to schizophrenia (SCZ), and may influence its age-at-onset (AAO). We examined the association of rare or low-frequency deleterious coding variants in Chinese patients with SCZ. We collected DNA samples in 197 patients with SCZ spectrum disorder and 82 healthy controls (HC), and performed exome sequencing. The AAO variable was ascertained in the majority of SCZ participants for identify the early-onset (EOS, AAO<=18) and adult-onset (AOS, AAO>18) subgroups. We examined the overall association of rare/low-frequency, damaging variants in SCZ versus HC, EOS versus HC, and AOS versus HC at the gene and gene-set levels using Sequence Kernel Association Test. The quantitative rare-variant association test of AAO was conducted. Resampling was used to obtain empirical p-values and to control for family-wise error rate (FWER). In binary-trait association tests, we identified 5 potential candidate risk genes and 10 gene ontology biological processes (GOBP) terms, among which PADI2 reached FWER-adjusted significance. In quantitative rare-variant association tests, we found marginally significant correlations of AAO with alterations in 4 candidate risk genes, and 5 GOBP pathways. Together, the biological and functional profiles of these genes and gene sets supported the involvement of perturbations of neural systems in SCZ, and altered immune functions in EOS.

Copy number deletion of PLA2G4A affects the susceptibility and clinical phenotypes of schizophrenia

Phospholipase A2(PLA2) superfamily is recognized as being involved in the pathogenesis of schizophrenia by affecting lipid homeostasis in cell membranes. We hypothesized that PLA2 gene copy number variation (CNV) may affect PLA2 enzyme expression and be associated with schizophrenia risk. This study indicated that in the discovery stage, an increased copy number of PLA2G6 and the deletion of PLA2G3, PLA2G4A, PLA2G4F and PLA2G12F was associated with increased risk of schizophrenia. CNV segments involving six PLA2 genes were detected in publicly available datasets, including two deletion segments specific to the PLA2G4A gene. The relationship between the deletion of PLA2G4A and susceptibility to schizophrenia was then reaffirmed in the validation group of 806 individuals. There was a significant correlation between PLA2G4A deletion and the symptoms of poverty of thought in male patients and erotomanic delusion in females. Furthermore, ELISA results demonstrate a significant decrease in peripheral blood cytosolic PLA2(cPLA2) levels in patients with the PLA2G4A deletion genotype compared to those with normal and copy number duplicate genotypes. These data suggest that the functional copy number deletion in the PLA2G4A gene is associated with the risk of schizophrenia and clinical phenotypes by reducing the expression of cPLA2, which may be an indicator of susceptibility to schizophrenia.

Structural characterization of a polymorphic repeat at the CACNA1C schizophrenia locus

Genetic variation within intron 3 of the CACNA1C calcium channel gene is associated with schizophrenia and bipolar disorder, but analysis of the causal variants and their effect is complicated by a nearby variable-number tandem repeat (VNTR). Here, we used 155 long-read genome assemblies from 78 diverse individuals to delineate the structure and population variability of the CACNA1C intron 3 VNTR. We categorized VNTR sequences into 7 Types of structural alleles using sequence differences among repeat units. Only 12 repeat units at the 5' end of the VNTR were shared across most Types, but several Types were related through a series of large and small duplications. The most diverged Types were rare and present only in individuals with African ancestry, but the multiallelic structural polymorphism Variable Region 2 was present across populations at different frequencies, consistent with expansion of the VNTR preceding the emergence of early hominins. VR2 was in complete linkage disequilibrium with fine-mapped schizophrenia variants (SNPs) from genome-wide association studies (GWAS). This risk haplotype was associated with decreased CACNA1C gene expression in brain tissues profiled by the GTEx project. Our work suggests that sequence variation within a human-specific VNTR affects gene expression, and provides a detailed characterization of new alleles at a flagship neuropsychiatric locus.

New clues for the role of cerebellum in schizophrenia and the associated cognitive impairment

Schizophrenia (SZ) is a complex neuropsychiatric disorder associated with severe cognitive dysfunction. Although research has mainly focused on forebrain abnormalities, emerging results support the involvement of the cerebellum in SZ physiopathology, particularly in Cognitive Impairment Associated with SZ (CIAS). Besides its role in motor learning and control, the cerebellum is implicated in cognition and emotion. Recent research suggests that structural and functional changes in the cerebellum are linked to deficits in various cognitive domains including attention, working memory, and decision-making. Moreover, cerebellar dysfunction is related to altered cerebellar circuit activities and connectivity with brain regions associated with cognitive processing. This review delves into the role of the cerebellum in CIAS. We initially consider the major forebrain alterations in CIAS, addressing impairments in neurotransmitter systems, synaptic plasticity, and connectivity. We then focus on recent findings showing that several mechanisms are also altered in the cerebellum and that cerebellar communication with the forebrain is impaired. This evidence implicates the cerebellum as a key component of circuits underpinning CIAS physiopathology. Further studies addressing cerebellar involvement in SZ and CIAS are warranted and might open new perspectives toward understanding the physiopathology and effective treatment of these disorders.

Stable neural underpinnings of emotional cognition subgroups in patients newly diagnosed with bipolar disorder: A prospective fMRI study

OBJECTIVES

This study aimed to investigate the neural underpinnings of emotional cognition subgroups in recently diagnosed patients with bipolar disorder (BD) and change over time over a 15-month follow-up period.

METHODS

Patients and healthy controls (HC) underwent emotional and nonemotional cognitive assessments and functional magnetic resonance imaging (fMRI) at the baseline (BD n = 87; HC n = 65) and at 15-month follow-up (BD n = 44; HC n = 38). Neural activity during emotion reactivity and regulation in response to aversive pictures was assessed during fMRI. Patients were clustered into subgroups based on their emotional cognition and, with HC, were compared longitudinally on cognition and neural activity during emotion reactivity and regulation.

RESULTS

Patients were optimally clustered into two subgroups: Subgroup 1 (n = 40, 46%) was characterized by heightened emotional reactivity in negative social scenarios, which persisted over time, but were otherwise cognitively intact. This subgroup exhibited stable left amygdala hyper-activity over time during emotion reactivity compared to subgroup 2. Subgroup 2 (n = 47, 54%) was characterized by global emotional cognitive impairments, including stable difficulties with emotion regulation over time. During emotion regulation across both time points, this group exhibited hypo-activity in the left dorsolateral prefrontal cortex. Additionally, patients in subgroup 2 had poorer nonemotional cognition, had more psychiatric hospital admissions and history of psychotic episodes than those in subgroup 1.

CONCLUSIONS

Broad impairments in emotional cognition in approximately half of BD patients and associated nonemotional cognitive deficits may originate from insufficient recruitment of prefrontal resources, contributing to poorer clinical outcomes.

Bipolar disorders and schizophrenia: discrete disorders?

Background

With similarities in heritability, neurobiology and symptomatology, the question has been raised whether schizophrenia and bipolar disorder are truly distinctive disorders or belong to a continuum. This narrative review summarizes common and distinctive findings from genetics, neuroimaging, cognition and clinical course that may help to solve this ethiopathogenetic puzzle.

Methods

The authors conducted a literature search for papers listed in PubMed and Google Scholar, using the search terms "schizophrenia" and "bipolar disorder" combined with different terms such as "genes", "neuroimaging studies", "phenomenology differences", "cognition", "epidemiology". Articles were considered for inclusion if they were written in English or Spanish, published as full articles, if they compared subjects with schizophrenia and bipolar disorder, or subjects with either disorder with healthy controls, addressing differences between groups.

Results

Several findings support the hypothesis that schizophrenia and bipolar disorder are discrete disorders, yet some overlapping of findings exists. The evidence for heritability of both SZ and BD is obvious, as well as the environmental impact on individual manifestations of both disorders. Neuroimaging studies support subtle differences between disorders, it appears to be rather a pattern of irregularities than an unequivocally unique finding distinguishing schizophrenia from bipolar disorder. The cognitive profile displays differences between disorders in certain domains, such as premorbid intellectual functioning and executive functions. Finally, the timing and trajectory of cognitive impairment in both disorders also differs.

Conclusion

The question whether SZ and BD belong to a continuum or are separate disorders remains a challenge for further research. Currently, our research tools may be not precise enough to carve out distinctive, unique and undisputable differences between SZ and BD, but current evidence favors separate disorders. Given that differences are subtle, a way to overcome diagnostic uncertainties in the future could be the application of artificial intelligence based on BigData.

Limitations

Despite the detailed search, this article is not a full and complete review of all available studies on the topic. The search and selection of papers was also limited to articles in English and Spanish. Selection of papers and conclusions may be biased by the personal view and clinical experience of the authors.

Adverse childhood experiences differently affect Theory of Mind brain networks in schizophrenia and healthy controls

Patients with schizophrenia (SZ) show impairments in both affective and cognitive dimensions of theory of mind (ToM). SZ are also particularly vulnerable to detrimental effect of adverse childhood experiences (ACE), influencing the overall course of the disorder and fostering poor social functioning. ACE associate with long-lasting detrimental effects on brain structure, function, and connectivity in regions involved in ToM. Here, we investigated whether ToM networks are differentially affected by ACEs in healthy controls (HC) and SZ, and if these effects can predict the disorder clinical outcome. 26 HC and 33 SZ performed a ToM task during an fMRI session. Whole-brain functional response and connectivity (FC) were extracted, investigating the interaction between ACEs and diagnosis. FC values significantly affected by ACEs were entered in a cross-validated LASSO regression predicting Positive and Negative Syndrome Scale (PANSS), Interpersonal Reactivity Index (IRI), and task performance. ACEs and diagnosis showed a widespread interaction at both affective and cognitive tasks, including connectivity between vmPFC, ACC, precentral and postcentral gyri, insula, PCC, precuneus, parahippocampal gyrus, temporal pole, thalamus, and cerebellum, and functional response in the ACC, thalamus, parahippocampal gyrus and putamen. FC predicted the PANSS score, the fantasy dimension of IRI, and the AToM response latency. Our results highlight the crucial role of early stress in differentially shaping ToM related brain networks in HC and SZ. These effects can also partially explain the clinical and behavioral outcomes of the disorder, extending our knowledge of the effects of ACEs.

From Alzheimer's Disease to Anxiety, Epilepsy to Schizophrenia: A Comprehensive Dive Into Neuro-Psychiatric Disorders

This comprehensive narrative review endeavors to dissect the intricate web of neuropsychiatric disorders that significantly impact cognition, emotion regulation, behavior, and mental health. With a keen focus on Alzheimer's disease (AD), anxiety disorders, epilepsy, schizophrenia, and autism spectrum disorder (ASD), this article delves into their underlying mechanisms, clinical presentations, diagnostic challenges, and therapeutic interventions. Highlighting the considerable disability and societal costs that these conditions impose, it reflects on the over six million individuals grappling with Alzheimer's, the 19 million American adults living with anxiety disorders, the three million with epilepsy, and the global reach of schizophrenia affecting approximately 20 million people. Furthermore, it examines the emerging landscape of ASD, noting the escalating diagnosis rates and the pressing need for innovative treatments and equitable healthcare access. Through a detailed exploration of current research, technological innovations, and the promise of personalized medicine, this review aims to illuminate the complexities of these conditions, advocate for early intervention strategies, and call for a unified approach to tackling the multifaceted challenges they present. The ultimate goal is to inform and inspire healthcare professionals, researchers, and policymakers to foster advancements that improve outcomes and quality of life for individuals affected by these profound neuropsychiatric disorders, steering towards a future where these conditions are no longer insurmountable.

Hemorrhoidal disease and its genetic association with depression, bipolar disorder, anxiety disorders, and schizophrenia: a bidirectional mendelian randomization study

BACKGROUND

Hemorrhoids and psychiatric disorders exhibit high prevalence rates and a tendency for relapse in epidemiological studies. Despite this, limited research has explored their correlation, and these studies are often subject to reverse causality and residual confounding. We conducted a Mendelian randomization (MR) analysis to comprehensively investigate the association between several mental illnesses and hemorrhoidal disease.

METHODS

Genetic associations for four psychiatric disorders and hemorrhoidal disease were obtained from large consortia, the FinnGen study, and the UK Biobank. Genetic variants associated with depression, bipolar disorder, anxiety disorders, schizophrenia, and hemorrhoidal disease at the genome-wide significance level were selected as instrumental variables. Screening for potential confounders in genetic instrumental variables using PhenoScanner V2. Bidirectional MR estimates were employed to assess the effects of four psychiatric disorders on hemorrhoidal disease.

RESULTS

Our analysis revealed a significant association between genetically predicted depression and the risk of hemorrhoidal disease (IVW, OR=1.20,95% CI=1.09 to 1.33, P <0.001). We found no evidence of associations between bipolar disorder, anxiety disorders, schizophrenia, and hemorrhoidal disease. Inverse MR analysis provided evidence for a significant association between genetically predicted hemorrhoidal disease and depression (IVW, OR=1.07,95% CI=1.04 to 1.11, P <0.001).

CONCLUSIONS

This study offers MR evidence supporting a bidirectional causal relationship between depression and hemorrhoidal disease.

Additive effects of a family history of schizophrenia spectrum disorders and an environmental risk score for the outcome of patients with non-affective first-episode psychosis

BACKGROUND

First-episode psychotic disorders comprise a heterogeneous phenotype with a complex etiology involving numerous common small-effect genetic variations and a wide range of environmental exposures. We examined whether a family of schizophrenia spectrum disorder (FH-Sz) interacts with an environmental risk score (ERS-Sz) regarding the outcome of patients with non-affective first episode psychosis (NAFEP).

METHODS

We included 288 patients with NAFEP who were evaluated after discharge from an intensive 2-year program. We evaluated three outcome measures: symptomatic remission, psychosocial functioning, and personal recovery. We analyzed the main and joint associations of a FH-Sz and the ERS-Sz on the outcomes by using the relative excess risk due to interaction (RERI) approach.

RESULTS

A FH-Sz showed a significant association with poor symptomatic remission and psychosocial functioning outcomes, although there was no significant interaction between a FH-Sz and the ERS-Sz on these outcomes. The ERS-Sz did not show a significant association with poor symptomatic remission and psychosocial functioning outcomes, even though the magnitude of the interaction between ERS-Sz and FH-Sz with the later outcome was moderate (RERI = 6.89, 95% confidence interval -16.03 to 29.81). There was no association between a FH-Sz and the ERS-Sz and personal recovery.

CONCLUSIONS

Our results provide further empirical support regarding the contribution of FH-Sz to poor symptomatic remission and poor psychosocial functioning outcomes in patients with NAFEP.

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

Background

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

Methods

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

Results

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

Conclusion

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

A diagnostic model based on bioinformatics and machine learning to differentiate bipolar disorder from schizophrenia and major depressive disorder

Bipolar disorder (BD) showed the highest suicide rate of all psychiatric disorders, and its underlying causative genes and effective treatments remain unclear. During diagnosis, BD is often confused with schizophrenia (SC) and major depressive disorder (MDD), due to which patients may receive inadequate or inappropriate treatment, which is detrimental to their prognosis. This study aims to establish a diagnostic model to distinguish BD from SC and MDD in multiple public datasets through bioinformatics and machine learning and to provide new ideas for diagnosing BD in the future. Three brain tissue datasets containing BD, SC, and MDD were chosen from the Gene Expression Omnibus database (GEO), and two peripheral blood datasets were selected for validation. Linear Models for Microarray Data (Limma) analysis was carried out to identify differentially expressed genes (DEGs). Functional enrichment analysis and machine learning were utilized to identify. Least absolute shrinkage and selection operator (LASSO) regression was employed for identifying candidate immune-associated central genes, constructing protein-protein interaction networks (PPI), building artificial neural networks (ANN) for validation, and plotting receiver operating characteristic curve (ROC curve) for differentiating BD from SC and MDD and creating immune cell infiltration to study immune cell dysregulation in the three diseases. RBM10 was obtained as a candidate gene to distinguish BD from SC. Five candidate genes (LYPD1, HMBS, HEBP2, SETD3, and ECM2) were obtained to distinguish BD from MDD. The validation was performed by ANN, and ROC curves were plotted for diagnostic value assessment. The outcomes exhibited the prediction model to have a promising diagnostic value. In the immune infiltration analysis, Naive B, Resting NK, and Activated Mast Cells were found to be substantially different between BD and SC. Naive B and Memory B cells were prominently variant between BD and MDD. In this study, RBM10 was found as a candidate gene to distinguish BD from SC; LYPD1, HMBS, HEBP2, SETD3, and ECM2 serve as five candidate genes to distinguish BD from MDD. The results obtained from the ANN network showed that these candidate genes could perfectly distinguish BD from SC and MDD (76.923% and 81.538%, respectively).

Emergence of Extracellular Vesicles as "Liquid Biopsy" for Neurological Disorders: Boom or Bust

Extracellular vesicles (EVs) have emerged as an attractive liquid biopsy approach in the diagnosis and prognosis of multiple diseases and disorders. The feasibility of enriching specific subpopulations of EVs from biofluids based on their unique surface markers has opened novel opportunities to gain molecular insight from various tissues and organs, including the brain. Over the past decade, EVs in bodily fluids have been extensively studied for biomarkers associated with various neurological disorders, such as Alzheimer's disease, Parkinson's disease, schizophrenia, bipolar disorder, major depressive disorders, substance use disorders, human immunodeficiency virus-associated neurocognitive disorder, and cancer/treatment-induced neurodegeneration. These studies have focused on the isolation and cargo characterization of either total EVs or brain cells, such as neuron-, astrocyte-, microglia-, oligodendrocyte-, pericyte-, and endothelial-derived EVs from biofluids to achieve early diagnosis and molecular characterization and to predict the treatment and intervention outcomes. The findings of these studies have demonstrated that EVs could serve as a repetitive and less invasive source of valuable molecular information for these neurological disorders, supplementing existing costly neuroimaging techniques and relatively invasive measures, like lumbar puncture. However, the initial excitement surrounding blood-based biomarkers for brain-related diseases has been tempered by challenges, such as lack of central nervous system specificity in EV markers, lengthy protocols, and the absence of standardized procedures for biological sample collection, EV isolation, and characterization. Nevertheless, with rapid advancements in the EV field, supported by improved isolation methods and sensitive assays for cargo characterization, brain cell-derived EVs continue to offer unparallel opportunities with significant translational implications for various neurological disorders. SIGNIFICANCE STATEMENT: Extracellular vesicles present a less invasive liquid biopsy approach in the diagnosis and prognosis of various neurological disorders. Characterizing these vesicles in biofluids holds the potential to yield valuable molecular information, thereby significantly impacting the development of novel biomarkers for various neurological disorders. This paper has reviewed the methodology employed to isolate extracellular vesicles derived from various brain cells in biofluids, their utility in enhancing the molecular understanding of neurodegeneration, and the potential challenges in this research field.

Identifying novel chemical-related susceptibility genes for five psychiatric disorders through integrating genome-wide association study and tissue-specific 3'aQTL annotation datasets

The establishment of 3'aQTLs comprehensive database provides an opportunity to help explore the functional interpretation from the genome-wide association study (GWAS) data of psychiatric disorders. In this study, we aim to search novel susceptibility genes, pathways, and related chemicals of five psychiatric disorders via GWAS and 3'aQTLs datasets. The GWAS datasets of five psychiatric disorders were collected from the open platform of Psychiatric Genomics Consortium (PGC, https://www.med.unc.edu/pgc/ ) and iPSYCH ( https://ipsych.dk/ ) (Demontis et al. in Nat Genet 51(1):63-75, 2019; Grove et al. in Nat Genet 51:431-444, 2019; Genomic Dissection of Bipolar Disorder and Schizophrenia in Cell 173: 1705-1715.e1716, 2018; Mullins et al. in Nat Genet 53: 817-829; Howard et al. in Nat Neurosci 22: 343-352, 2019). The 3'untranslated region (3'UTR) alternative polyadenylation (APA) quantitative trait loci (3'aQTLs) summary datasets of 12 brain regions were obtained from another public platform ( https://wlcb.oit.uci.edu/3aQTLatlas/ ) (Cui et al. in Nucleic Acids Res 50: D39-D45, 2022). First, we aligned the GWAS-associated SNPs of psychiatric disorders and datasets of 3'aQTLs, and then, the GWAS-associated 3'aQTLs were identified from the overlap. Second, gene ontology (GO) and pathway analysis was applied to investigate the potential biological functions of matching genes based on the methods provided by MAGMA. Finally, chemical-related gene-set analysis (GSA) was also conducted by MAGMA to explore the potential interaction of GWAS-associated 3'aQTLs and multiple chemicals in the mechanism of psychiatric disorders. A number of susceptibility genes with 3'aQTLs were found to be associated with psychiatric disorders and some of them had brain-region specificity. For schizophrenia (SCZ), HLA-A showed associated with psychiatric disorders in all 12 brain regions, such as cerebellar hemisphere (P = 1.58 × 10-36) and cortex (P = 1.58 × 10-36). GO and pathway analysis identified several associated pathways, such as Phenylpropanoid Metabolic Process (GO:0009698, P = 6.24 × 10-7 for SCZ). Chemical-related GSA detected several chemical-related gene sets associated with psychiatric disorders. For example, gene sets of Ferulic Acid (P = 6.24 × 10-7), Morin (P = 4.47 × 10-2) and Vanillic Acid (P = 6.24 × 10-7) were found to be associated with SCZ. By integrating the functional information from 3'aQTLs, we identified several susceptibility genes and associated pathways especially chemical-related gene sets for five psychiatric disorders. Our results provided new insights to understand the etiology and mechanism of psychiatric disorders.

Exploring the relationship between attributional style measured in virtual reality and bullying among children at familial high risk of schizophrenia or bipolar disorder compared with controls

BACKGROUND

Children of parents with severe mental illness report bullying more often compared with controls. We hypothesized that deviations in attributional styles may explain the increased prevalence of bullying experiences. We aimed to assess real-time responses to standardized ambiguous social situations, bullying experiences by children, their primary caregivers, and teachers, and to investigate potential associations between attributional styles and bullying.

METHOD

The study included 465 children aged 11-12, born to parents with schizophrenia, N =179, bipolar disorder, N = 105, or population-based controls, N = 181. Attributional style was evaluated using virtual reality environments depicting ambiguous social everyday situations. We created a tailored assessment since no suitable assessments were found. Bullying was assessed through self-reports and reports from primary caregivers and teachers.

RESULTS

We observed no group differences in the attributional style of the children. Reports from children, primary caregivers, and teachers revealed that compared with controls, children born to parents with schizophrenia were more likely to perceive bullying victimization, with high consistency among reports. No associations were found between bullying reports and attributional style.

CONCLUSIONS

Children of parents with schizophrenia consistently experienced more bullying, as reported by the children themselves, primary caregivers, and teachers. No differences in attributional style were found, indicating that attributional style did not explain the increased prevalence of bullying reports. While it cannot be ruled out that our virtual environments were insufficient to trigger a sense of social exclusion, the results suggest that the observed differences in reported bullying are genuine and not a result of the child's attributional style.

The neuropsychopharmacology of acetyl-L-carnitine (LAC): basic, translational and therapeutic implications

Mitochondrial metabolism can contribute to nuclear histone acetylation among other epigenetic mechanisms. A central aspect of this signaling pathway is acetyl-L-carnitine (LAC), a pivotal mitochondrial metabolite best known for its role in fatty acid oxidation. Work from our and other groups suggested LAC as a novel epigenetic modulator of brain plasticity and a therapeutic target for clinical phenotypes of depression linked to childhood trauma. Aberrant mitochondrial metabolism of LAC has also been implicated in the pathophysiology of Alzheimer's disease. Furthermore, mitochondrial dysfunction is linked to other processes implicated in the pathophysiology of both major depressive disorders and Alzheimer's disease, such as oxidative stress, inflammation, and insulin resistance. In addition to the rapid epigenetic modulation of glutamatergic function, preclinical studies showed that boosting mitochondrial metabolism of LAC protects against oxidative stress, rapidly ameliorates insulin resistance, and reduces neuroinflammation by decreasing proinflammatory pathways such as NFkB in hippocampal and cortical neurons. These basic and translational neuroscience findings point to this mitochondrial signaling pathway as a potential target to identify novel mechanisms of brain plasticity and potential unique targets for therapeutic intervention targeted to specific clinical phenotypes.

Advances in the understanding of the pathophysiology of schizophrenia and bipolar disorder through induced pluripotent stem cell models

The pathophysiology of schizophrenia and bipolar disorder involves a complex interaction between genetic and environmental factors that begins in the early stages of neurodevelopment. Recent advancements in the field of induced pluripotent stem cells (iPSCs) offer a promising tool for understanding the neurobiological alterations involved in these disorders and, potentially, for developing new treatment options. In this review, we summarize the results of iPSC-based research on schizophrenia and bipolar disorder, showing disturbances in neurodevelopmental processes, imbalance in glutamatergic-GABAergic transmission and neuromorphological alterations. The limitations of the reviewed literature are also highlighted, particularly the methodological heterogeneity of the studies, the limited number of studies developing iPSC models of both diseases simultaneously, and the lack of in-depth clinical characterization of the included samples. Further studies are needed to advance knowledge on the common and disease-specific pathophysiological features of schizophrenia and bipolar disorder and to promote the development of new treatment options.

Familial Risk for Schizophrenia vs Bipolar Disorder and Task-Based Neural Activation: A functional Magnetic Resonance Imaging Meta-Analysis

BACKGROUND AND HYPOTHESIS

Individuals at familial risk for developing schizophrenia (FRSZ) or bipolar disorder (FRBD) have shared and unique genetic risks. Few studies have compared neural activation between these two groups. Therefore, the present meta-analysis investigated functional brain similarities and differences between FRSZ and FRBD individuals.

STUDY DESIGN

A systematic literature review was conducted of articles that compared FRSZ or FRBD individuals to healthy controls (31 FRSZ and 22 FRBD). Seed-based d mapping was used to conduct the meta-analysis. Analyses included comparisons of FRSZ to controls, FRBD to controls, and both relative groups to each other.

STUDY RESULTS

Using a highly conservative family-wise error rate correction, there were no significant findings. Using a less conservative threshold, FRSZ compared to controls had lower activation in the left precuneus (Puncorrected = .02) across all studies and in the left middle frontal gyrus (Puncorrected = .03) in nonsocial cognition studies. FRBD compared to controls had lower activation in the left superior parietal gyrus (Puncorrected = .03) and right angular gyrus (Puncorrected = .03) in nonsocial cognition studies, and higher activation in the left superior frontal gyrus (Puncorrected = .01) in social tasks. Differences between FRSZ and FRBD were not significant.

CONCLUSIONS

There were few robust differences between FRSZ or FRBD compared to controls. This suggests only weak support for neural activation differences between individuals at genetic risk for schizophrenia or bipolar disorder and controls. The tentative findings observed were in different brain regions for FRSZ and FRBD, with no strong evidence for shared effects between schizophrenia and bipolar genetic risk on neural activation.

Rediscovering tandem repeat variation in schizophrenia: challenges and opportunities

Tandem repeats (TRs) are prevalent throughout the genome, constituting at least 3% of the genome, and often highly polymorphic. The high mutation rate of TRs, which can be orders of magnitude higher than single-nucleotide polymorphisms and indels, indicates that they are likely to make significant contributions to phenotypic variation, yet their contribution to schizophrenia has been largely ignored by recent genome-wide association studies (GWAS). Tandem repeat expansions are already known causative factors for over 50 disorders, while common tandem repeat variation is increasingly being identified as significantly associated with complex disease and gene regulation. The current review summarizes key background concepts of tandem repeat variation as pertains to disease risk, elucidating their potential for schizophrenia association. An overview of next-generation sequencing-based methods that may be applied for TR genome-wide identification is provided, and some key methodological challenges in TR analyses are delineated.

A Functional Schizophrenia-associated genetic variant near the TSNARE1 and ADGRB1 genes

Recent collaborative genome wide association studies (GWAS) have identified >200 independent loci contributing to risk for schizophrenia (SCZ). The genes closest to these loci have diverse functions, supporting the potential involvement of multiple relevant biological processes; yet there is no direct evidence that individual variants are functional or directly linked to specific genes. Nevertheless, overlap with certain epigenetic marks suggest that most GWAS-implicated variants are regulatory. Based on the strength of association with SCZ and the presence of regulatory epigenetic marks, we chose one such variant near TSNARE1 and ADGRB1, rs4129585, to test for functional potential and assay differences that may drive the pathogenicity of the risk allele. We observed that the variant-containing sequence drives reporter expression in relevant neuronal populations in zebrafish. Next, we introduced each allele into human induced pluripotent cells and differentiated 4 isogenic clones homozygous for the risk allele and 5 clones homozygous for the non-risk allele into neural precursor cells. Employing RNA-seq, we found that the two alleles yield significant transcriptional differences in the expression of 109 genes at FDR <0.05 and 259 genes at FDR <0.1. We demonstrate that these genes are highly interconnected in pathways enriched for synaptic proteins, axon guidance, and regulation of synapse assembly. Exploration of genes near rs4129585 suggests that this variant does not regulate TSNARE1 transcripts, as previously thought, but may regulate the neighboring ADGRB1, a regulator of synaptogenesis. Our results suggest that rs4129585 is a functional common variant that functions in specific pathways likely involved in SCZ risk.

Transition of allele-specific DNA hydroxymethylation at regulatory loci is associated with phenotypic variation in monozygotic twins discordant for psychiatric disorders

BACKGROUND

Major psychiatric disorders such as schizophrenia (SCZ) and bipolar disorder (BPD) are complex genetic mental illnesses. Their non-Mendelian features, such as those observed in monozygotic twins discordant for SCZ or BPD, are likely complicated by environmental modifiers of genetic effects. 5-Hydroxymethylcytosine (5hmC) is an important epigenetic mark in gene regulation, and whether it is linked to genetic variants that contribute to non-Mendelian features remains largely unexplored.

METHODS

We combined the 5hmC-selective chemical labeling method (5hmC-seq) and whole-genome sequencing (WGS) analysis of peripheral blood DNA obtained from monozygotic (MZ) twins discordant for SCZ or BPD to identify allelic imbalances in hydroxymethylome maps, and examined association of allele-specific hydroxymethylation (AShM) transition with disease susceptibility based on Bayes factors (BF) derived from the Bayesian generalized additive linear mixed model. We then performed multi-omics integrative analysis to determine the molecular pathogenic basis of those AShM sites. We finally employed luciferase reporter, CRISPR/Cas9 technology, electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), PCR, FM4-64 imaging analysis, and RNA sequencing to validate the function of interested AShM sites in the human neuroblastoma SK-N-SH cells and human embryonic kidney 293T (HEK293T) cells.

RESULTS

We identified thousands of genetic variants associated with AShM imbalances that exhibited phenotypic variation-associated AShM changes at regulatory loci. These AShM marks showed plausible associations with SCZ or BPD based on their effects on interactions among transcription factors (TFs), DNA methylation levels, or other epigenomic marks and thus contributed to dysregulated gene expression, which ultimately increased disease susceptibility. We then validated that competitive binding of POU3F2 on the alternative allele at the AShM site rs4558409 (G/T) in PLLP-enhanced PLLP expression, while the hydroxymethylated alternative allele, which alleviated the POU3F2 binding activity at the rs4558409 site, might be associated with the downregulated PLLP expression observed in BPD or SCZ. Moreover, disruption of rs4558409 promoted neural development and vesicle trafficking.

CONCLUSION

Our study provides a powerful strategy for prioritizing regulatory risk variants and contributes to our understanding of the interplay between genetic and epigenetic factors in mediating SCZ or BPD susceptibility.

Factors associated with suicide attempts in the antecedent illness trajectory of bipolar disorder and schizophrenia

BACKGROUND

Factors associated with suicide attempts during the antecedent illness trajectory of bipolar disorder (BD) and schizophrenia (SZ) are poorly understood.

METHODS

Utilizing the Rochester Epidemiology Project, individuals born after 1985 in Olmsted County, MN, presented with first episode mania (FEM) or psychosis (FEP), subsequently diagnosed with BD or SZ were identified. Patient demographics, suicidal ideation with plan, self-harm, suicide attempts, psychiatric hospitalizations, substance use, and childhood adversities were quantified using the electronic health record. Analyses pooled BD and SZ groups with a transdiagnostic approach given the two diseases were not yet differentiated. Factors associated with suicide attempts were examined using bivariate methods and multivariable logistic regression modeling.

RESULTS

A total of 205 individuals with FEM or FEP (BD = 74, SZ = 131) were included. Suicide attempts were identified in 39 (19%) patients. Those with suicide attempts during antecedent illness trajectory were more likely to be female, victims of domestic violence or bullying behavior, and have higher rates of psychiatric hospitalizations, suicidal ideation with plan and/or self-harm, as well as alcohol, drug, and nicotine use before FEM/FEP onset. Based on multivariable logistic regression, three factors remained independently associated with suicidal attempts: psychiatric hospitalization (OR = 5.84, 95% CI 2.09-16.33, p < 0.001), self-harm (OR = 3.46, 95% CI 1.29-9.30, p = 0.014), and nicotine use (OR = 3.02, 95% CI 1.17-7.76, p = 0.022).

CONCLUSION

Suicidal attempts were prevalent during the antecedents of BD and SZ and were associated with several risk factors before FEM/FEP. Their clinical recognition could contribute to improve early prediction and prevention of suicide during the antecedent illness trajectory of BD and SZ.

Significance of an altered lncRNA landscape in schizophrenia and cognition: clues from a case-control association study

Genetic etiology of schizophrenia is poorly understood despite large genome-wide association data. Long non-coding RNAs (lncRNAs) with a probable regulatory role are emerging as important players in neuro-psychiatric disorders including schizophrenia. Prioritising important lncRNAs and analyses of their holistic interaction with their target genes may provide insights into disease biology/etiology. Of the 3843 lncRNA SNPs reported in schizophrenia GWASs extracted using lincSNP 2.0, we prioritised n = 247 based on association strength, minor allele frequency and regulatory potential and mapped them to lncRNAs. lncRNAs were then prioritised based on their expression in brain using lncRBase, epigenetic role using 3D SNP and functional relevance to schizophrenia etiology. 18 SNPs were finally tested for association with schizophrenia (n = 930) and its endophenotypes-tardive dyskinesia (n = 176) and cognition (n = 565) using a case-control approach. Associated SNPs were characterised by ChIP seq, eQTL, and transcription factor binding site (TFBS) data using FeatSNP. Of the eight SNPs significantly associated, rs2072806 in lncRNA hsaLB_IO39983 with regulatory effect on BTN3A2 was associated with schizophrenia (p = 0.006); rs2710323 in hsaLB_IO_2331 with role in dysregulation of ITIH1 with tardive dyskinesia (p < 0.05); and four SNPs with significant cognition score reduction (p < 0.05) in cases. Two of these with two additional variants in eQTL were observed among controls (p < 0.05), acting likely as enhancer SNPs and/or altering TFBS of eQTL mapped downstream genes. This study highlights important lncRNAs in schizophrenia and provides a proof of concept of novel interactions of lncRNAs with protein-coding genes to elicit alterations in immune/inflammatory pathways of schizophrenia.

The molecular cytoarchitecture of the adult mouse brain

The function of the mammalian brain relies upon the specification and spatial positioning of diversely specialized cell types. Yet, the molecular identities of the cell types and their positions within individual anatomical structures remain incompletely known. To construct a comprehensive atlas of cell types in each brain structure, we paired high-throughput single-nucleus RNA sequencing with Slide-seq1,2-a recently developed spatial transcriptomics method with near-cellular resolution-across the entire mouse brain. Integration of these datasets revealed the cell type composition of each neuroanatomical structure. Cell type diversity was found to be remarkably high in the midbrain, hindbrain and hypothalamus, with most clusters requiring a combination of at least three discrete gene expression markers to uniquely define them. Using these data, we developed a framework for genetically accessing each cell type, comprehensively characterized neuropeptide and neurotransmitter signalling, elucidated region-specific specializations in activity-regulated gene expression and ascertained the heritability enrichment of neurological and psychiatric phenotypes. These data, available as an online resource ( www.BrainCellData.org ), should find diverse applications across neuroscience, including the construction of new genetic tools and the prioritization of specific cell types and circuits in the study of brain diseases.