Environmental Risk Factors for Schizophrenia and Bipolar Disorder and Their Relationship to Genetic Risk: Current Knowledge and Future Directions

Environmental pollution and extreme weather conditions: insights into the effect on mental health

Environmental pollution exposures, including air, soil, water, light, and noise pollution, are critical issues that may implicate adverse mental health outcomes. Extreme weather conditions, such as hurricanes, floods, wildfires, and droughts, may also cause long-term severe concerns. However, the knowledge about possible psychiatric disorders associated with these exposures is currently not well disseminated. In this review, we aim to summarize the current knowledge on the impact of environmental pollution and extreme weather conditions on mental health, focusing on anxiety spectrum disorders, autism spectrum disorders, schizophrenia, and depression. In air pollution studies, increased concentrations of PM2.5, NO2, and SO2 were the most strongly associated with the exacerbation of anxiety, schizophrenia, and depression symptoms. We provide an overview of the suggested underlying pathomechanisms involved. We highlight that the pathogenesis of environmental pollution-related diseases is multifactorial, including increased oxidative stress, systematic inflammation, disruption of the blood-brain barrier, and epigenetic dysregulation. Light pollution and noise pollution were correlated with an increased risk of neurodegenerative disorders, particularly Alzheimer's disease. Moreover, the impact of soil and water pollution is discussed. Such compounds as crude oil, heavy metals, natural gas, agro-chemicals (pesticides, herbicides, and fertilizers), polycyclic or polynuclear aromatic hydrocarbons (PAH), solvents, lead (Pb), and asbestos were associated with detrimental impact on mental health. Extreme weather conditions were linked to depression and anxiety spectrum disorders, namely PTSD. Several policy recommendations and awareness campaigns should be implemented, advocating for the advancement of high-quality urbanization, the mitigation of environmental pollution, and, consequently, the enhancement of residents' mental health.

Downregulation of miR-29a as a possible diagnostic biomarker for schizophrenia

BACKGROUND

MicroRNAs (miRNAs) are epigenetic factors regulating many genes involved in brain development. Dysregulation of miRNA could result in dysregulation of genes which may contribute to diseases affecting the brain and behavior (e.g., schizophrenia). miR-29 family is a miRNA family contributing to brain maturation. miR-29 knockout in animal studies is reported to correlate with psychiatric disorders very similar to those seen in schizophrenia. In this study, we aimed to evaluate the miR-29a level in patients with schizophrenia and its potential value in the diagnosis of schizophrenia.

MATERIALS AND METHODS

The serum sample of 42 patients with schizophrenia and 40 healthy subjects were obtained from the Azeri Recent onset/Acute phase psychosis Survey (ARAS) Cohort study. After preparations, the expression level of miR-29a was investigated by real-time PCR. The SPSS and GraphPad prism software were used to analyze the relation between miR-29a level and clinical parameters and its potential as a biomarker for the diagnosis of schizophrenia.

RESULTS

Our study showed a significantly lower miR-29a level in patients compared to healthy controls (p = 0.0012). Furthermore, miR-29a level was significantly lower in some types of schizophrenia (p = 0.024). miR-29a level was not related to sex, age, or heredity (p > 0.05). miR-29a also showed 80% specificity and 71.43% sensitivity in the diagnosis of schizophrenia.

CONCLUSION

Downregulation of miR-29a in schizophrenia is significantly related to the development of this illness. It might have the potential as a biomarker for schizophrenia.

Immediate and delayed effects of environmental temperature on schizophrenia admissions in Liuzhou, China, 2013-2020: a time series analysis

This study aimed to investigate the associations between environmental temperature and schizophrenia admissions in Liuzhou, China. A Poisson generalized linear model combined with a distributed lag nonlinear model was used to analyze the effects of daily mean temperature on schizophrenia admissions from 2013 to 2020 in Liuzhou. Additionally, subgroup analyses were conducted to investigate possible modifications stratified by gender, marital status, and age. In this study, 10,420 schizophrenia admissions were included. The relative risks of schizophrenia admissions increased as the temperature rose, and the lag effects of high temperature on schizophrenia admissions were observed when the daily mean temperature reached 21.65°C. The largest single effect was observed at lag0, while the largest cumulative effect was observed at lag6. The single effects of high temperatures on schizophrenia admissions were statistically significant in both males and females, but the cumulative effects were statistically significant only in males, with the greatest effect at lag0-7. The single effect of high temperatures on admissions for unmarried schizophrenics was greatest at lag5, while the maximum cumulative effect for unmarried schizophrenia was observed at lag0-7. The single effects of high temperatures on schizophrenia admissions were observed in those aged 0-20, 21-40, and 41-60. The cumulative effects for schizophrenics aged 21-40 were observed from lag0-3 to lag0-7, with the maximum effect at lag0-7. In conclusion, the risk of schizophrenia admissions increased as the environmental temperature increased. The schizophrenics who were unmarried appeared to be more vulnerable to the single and cumulative effects of high temperature.

COVID-19 pandemic and emergency department visits for psychosis: Visit volume, restraint use, medication use, psychiatric hospitalization, and length of stay

BACKGROUND

Individuals with a schizophrenia spectrum disorder were at heightened risk for interruptions in psychiatric care during the coronavirus-19 (COVID 19) pandemic. There is limited work exploring the pandemic's impact on emergency department (ED) visit volume, use of restraint and parenteral medications, inpatient psychiatric (IP) hospitalization, and ED length of stay (LOS) among this population.

METHODS

We retrospectively examined 2134 ED visits with a billing code for psychosis between March 1, 2019-February 28, 2021. We used Poisson regression analysis to compare ED visit volume between the pandemic and pre-pandemic periods. Restraint use, parenteral antipsychotic or benzodiazepine use, IP hospitalization, and ED LOS were compared between the two periods using chi-square tests and independent samples t-tests.

RESULTS

Overall volume of psychosis-related ED visits during the pandemic did not differ significantly from the prior year. Rates of restraint use (16.2 % vs 11.6 %, p < .01), parenteral antipsychotic (22.6 % vs 14.9, p < .001), and parenteral benzodiazepine (22.3 % vs 16.3 %, p < .001) use were significantly higher during the pandemic. Fewer patients had an IP hospital disposition during the pandemic than the year prior (57.8 % vs. 61.9 %, p < .05). ED LOS was longer during the pandemic compared to pre-pandemic (28.37 h vs 20.26 h, p < .001).

CONCLUSIONS

Although the volume of psychosis-related ED visits remained constant, restraint and parenteral medication use rates were significantly higher during the pandemic. ED LOS increased but fewer ED visits resulted in IP hospitalization. These findings underscore the importance of planning for increased acuity of psychosis ED presentations during public health emergencies.

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.

Regulation of Zbp1 by miR-99b-5p in microglia controls the development of schizophrenia-like symptoms in mice

Current approaches to the treatment of schizophrenia have mainly focused on the protein-coding part of the genome; in this context, the roles of microRNAs have received less attention. In the present study, we analyze the microRNAome in the blood and postmortem brains of schizophrenia patients, showing that the expression of miR-99b-5p is downregulated in both the prefrontal cortex and blood of patients. Lowering the amount of miR-99b-5p in mice leads to both schizophrenia-like phenotypes and inflammatory processes that are linked to synaptic pruning in microglia. The microglial miR-99b-5p-supressed inflammatory response requires Z-DNA binding protein 1 (Zbp1), which we identify as a novel miR-99b-5p target. Antisense oligonucleotides against Zbp1 ameliorate the pathological effects of miR-99b-5p inhibition. Our findings indicate that a novel miR-99b-5p-Zbp1 pathway in microglia might contribute to the pathogenesis of schizophrenia.

Validation of Enhancer Regions in Primary Human Neural Progenitor Cells using Capture STARR-seq

Genome-wide association studies (GWAS) and expression analyses implicate noncoding regulatory regions as harboring risk factors for psychiatric disease, but functional characterization of these regions remains limited. We performed capture STARR-sequencing of over 78,000 candidate regions to identify active enhancers in primary human neural progenitor cells (phNPCs). We selected candidate regions by integrating data from NPCs, prefrontal cortex, developmental timepoints, and GWAS. Over 8,000 regions demonstrated enhancer activity in the phNPCs, and we linked these regions to over 2,200 predicted target genes. These genes are involved in neuronal and psychiatric disease-associated pathways, including dopaminergic synapse, axon guidance, and schizophrenia. We functionally validated a subset of these enhancers using mutation STARR-sequencing and CRISPR deletions, demonstrating the effects of genetic variation on enhancer activity and enhancer deletion on gene expression. Overall, we identified thousands of highly active enhancers and functionally validated a subset of these enhancers, improving our understanding of regulatory networks underlying brain function and disease.

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.

Efficacy of cannabinoids in neurodevelopmental and neuropsychiatric disorders among children and adolescents: a systematic review

A better understanding of the endocannabinoid system and a relaxation in regulatory control of cannabis globally has increased interest in the medicinal use of cannabinoid-based products (CBP). We provide a systematic review of the rationale and current clinical trial evidence for CBP in the treatment of neuropsychiatric and neurodevelopmental disorders in children and adolescents. A systematic search of MEDLINE, Embase, PsycINFO, and the Cochrane Central Register of Trials was performed to identify articles published after 1980 about CBP for medical purposes in individuals aged 18 years or younger with selected neuropsychiatric or neurodevelopmental conditions. Risk of bias and quality of evidence was assessed for each article. Of 4466 articles screened, 18 were eligible for inclusion, addressing eight conditions (anxiety disorders (n = 1); autism spectrum disorder (n = 5); foetal alcohol spectrum disorder (n = 1); fragile X syndrome (n = 2); intellectual disability (n = 1); mood disorders (n = 2); post-traumatic stress disorder (n = 3); and Tourette syndrome (n = 3)). Only one randomised controlled trial (RCT) was identified. The remaining seventeen articles included one open-label trial, three uncontrolled before-and-after trials, two case series and 11 case reports, thus the risk of bias was high. Despite growing community and scientific interest, our systematic review identified limited and generally poor-quality evidence for the efficacy of CBP in neuropsychiatric and neurodevelopmental disorders in children and adolescents. Large rigorous RCTs are required to inform clinical care. In the meantime, clinicians must balance patient expectations with the limited evidence available.

Gut microbial diversity moderates polygenic risk of schizophrenia

Background

Schizophrenia (SCZ) is a heritable disorder with a polygenic architecture, and the gut microbiota seems to be involved in its development and outcome. In this study, we investigate the interplay between genetic risk and gut microbial markers.

Methods

We included 159 first-episode, drug-naïve SCZ patients and 86 healthy controls. The microbial composition of feces was characterized using the 16S rRNA sequencing platform, and five microbial α-diversity indices were estimated [Shannon, Simpson, Chao1, the Abundance-based Eoverage Estimator (ACE), and a phylogenetic diversity-based estimate (PD)]. Polygenic risk scores (PRS) for SCZ were constructed using data from large-scale genome-wide association studies. Effects of microbial α-diversity, microbial abundance, and PRS on SCZ were evaluated via generalized linear models.

Results

We confirmed that PRS was associated with SCZ (OR = 2.08, p = 1.22×10-5) and that scores on the Shannon (OR = 0.29, p = 1.15×10-8) and Simpson (OR = 0.29, p = 1.25×10-8) indices were inversely associated with SCZ risk. We found significant interactions (p < 0.05) between PRS and α-diversity indices (Shannon, Simpson, and PD), with the effects of PRS being larger in those exhibiting higher diversity compared to those with lower diversity. Moreover, the PRS effects were larger in individuals with a high abundance of the genera Romboutsia, Streptococcus, and Anaerostipes than in those with low abundance (p < 0.05). All three of these genera showed protective effects against SCZ.

Conclusion

The current findings suggest an interplay between the gut microbiota and polygenic risk of SCZ that warrants replication in independent samples. Experimental studies are needed to determine the underpinning mechanisms.

Increased metabolic variability in Korean patients with new onset bipolar disorder: a nationwide cohort study

Introduction

The aim of this study was to determine associations between changes of metabolic parameters and the development of BD using nationally representative data.

Methods

We used health examination data provided by the South Korean National Health Insurance System (NHIS) (n = 8,326,953). The variability of each metabolic parameter including weight circumference, blood pressure, fasting blood glucose, high-density lipoprotein cholesterol, and triglyceride levels was caculated using variability independent of mean (VIM) indices. The presence of metabolic syndrome was associated with new onset BD. Each metabolic parameter with high variability was associated with a higher risk of new onset BD compared to those with low variability after adjusting for age, sex, smoking, alcohol drinking, regular exercise, income status, baseline diabetes, hypertension, and dyslipidemia.

Results

As the number of highly variable metabolic parameters increased, the risk for new onset depression also increased even after covariates adjustment. The associations between new onset BD and metabolic variability were greater in populations with age > 50 years. In addition, these associations remained significant after adjusting for the presence of depression prior to diagnoses of BD.

Discussion

Our results suggest possibility of metabolic variability as an independent environmental risk factor for BD even after adjusting for the presence of metabolic syndrome.

Stress, Environment and Early Psychosis

Existing literature provides extended evidence of the close relationship between stress dysregulation, environmental insults, and psychosis onset. Early stress can sensitize genetically vulnerable individuals to future stress, modifying their risk for developing psychotic phenomena. Neurobiological substrate of the aberrant stress response to hypothalamic-pituitary-adrenal axis dysregulation, disrupted inflammation processes, oxidative stress increase, gut dysbiosis, and altered brain signaling, provides mechanistic links between environmental risk factors and the development of psychotic symptoms. Early-life and later-life exposures may act directly, accumulatively, and repeatedly during critical neurodevelopmental time windows. Environmental hazards, such as pre- and perinatal complications, traumatic experiences, psychosocial stressors, and cannabis use might negatively intervene with brain developmental trajectories and disturb the balance of important stress systems, which act together with recent life events to push the individual over the threshold for the manifestation of psychosis. The current review presents the dynamic and complex relationship between stress, environment, and psychosis onset, attempting to provide an insight into potentially modifiable factors, enhancing resilience and possibly influencing individual psychosis liability.

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.

Geographical variation in treated psychotic and other mental disorders in Finland by region and urbanicity

PURPOSE

In Finland, prevalence of schizophrenia is higher in the eastern and northern regions and co-occurs with the distribution of schizophrenia polygenic risk scores. Both genetic and environmental factors have been hypothesized to contribute to this variation. We aimed to examine the prevalence of psychotic and other mental disorders by region and degree of urbanicity, and the impacts of socio-economic adjustments on these associations.

METHODS

Nationwide population registers from 2011 to 2017 and healthcare registers from 1975 to 2017. We used 19 administrative and three aggregate regions based on the distribution of schizophrenia polygenic risk scores, and a seven-level urban-rural classification. Prevalence ratios (PRs) were calculated by Poisson regression models and adjusted for gender, age, and calendar year (basic adjustments), and Finnish origin, residential history, urbanicity, household income, economic activity, and physical comorbidity (additional adjustments) on an individual level. Average marginal effects were used to visualize interaction effects between region and urbanicity.

RESULTS

A total of 5,898,180 individuals were observed. All mental disorders were slightly more prevalent (PR 1.03 [95% CI, 1.02-1.03]), and psychotic disorders (1.11 [1.10-1.12]) and schizophrenia (1.19 [1.17-1.21]) considerably more prevalent in eastern and northern than in western coastal regions. After the additional adjustments, however, the PRs were 0.95 (0.95-0.96), 1.00 (0.99-1.01), and 1.03 (1.02-1.04), respectively. Urban residence was associated with increased prevalence of psychotic disorders across all regions (adjusted PR 1.21 [1.20-1.22]).

CONCLUSION

After adjusting for socioeconomic and sociodemographic factors, the within-country distribution of mental disorders no longer followed the traditional east-west gradient. Urban-rural differences, on the other hand, persisted after the adjustments.

Sex-related differences in parental rearing patterns in young adults with bipolar disorder

The aim of this study was to examine the parenting characteristics of young patients with bipolar disorder (BD) and explore the sex differences. The parental rearing pattern of young patients with BD was measured and compared with the healthy control of young adults. The EMBU scale was used to assess parental rearing patterns. Patients with BD reported significantly higher scores in the punishment and severity index, as well as of the rejection and denial index, but lower scores in the warmth & affectionate index in the paternal rearing pattern, compared with healthy controls. In addition, patients scored higher on the punishment and severity index and rejection and patterns index in maternal rearing patterns. More importantly, we found significant sex differences in maternal rearing patterns (pBonferroni < 0.05). Specifically, in the maternal rearing patterns, male patients had higher scores on the favoring index than male controls, whereas female patients had lower scores on the warmth & affectionate index than female controls. This study shows significant differences in parental rearing patterns between patients and control subjects. Male patients were overprotective by their mothers and female patients were overlooked by their mothers during upbringing.

Dense attention network identifies EEG abnormalities during working memory performance of patients with schizophrenia

Introduction

Patients with schizophrenia typically exhibit deficits in working memory (WM) associated with abnormalities in brain activity. Alterations in the encoding, maintenance and retrieval phases of sequential WM tasks are well established. However, due to the heterogeneity of symptoms and complexity of its neurophysiological underpinnings, differential diagnosis remains a challenge. We conducted an electroencephalographic (EEG) study during a visual WM task in fifteen schizophrenia patients and fifteen healthy controls. We hypothesized that EEG abnormalities during the task could be identified, and patients successfully classified by an interpretable machine learning algorithm.

Methods

We tested a custom dense attention network (DAN) machine learning model to discriminate patients from control subjects and compared its performance with simpler and more commonly used machine learning models. Additionally, we analyzed behavioral performance, event-related EEG potentials, and time-frequency representations of the evoked responses to further characterize abnormalities in patients during WM.

Results

The DAN model was significantly accurate in discriminating patients from healthy controls, ACC = 0.69, SD = 0.05. There were no significant differences between groups, conditions, or their interaction in behavioral performance or event-related potentials. However, patients showed significantly lower alpha suppression in the task preparation, memory encoding, maintenance, and retrieval phases F(1,28) = 5.93, p = 0.022, η2 = 0.149. Further analysis revealed that the two highest peaks in the attention value vector of the DAN model overlapped in time with the preparation and memory retrieval phases, as well as with two of the four significant time-frequency ROIs.

Discussion

These results highlight the potential utility of interpretable machine learning algorithms as an aid in diagnosis of schizophrenia and other psychiatric disorders presenting oscillatory abnormalities.

Blood-Based MicroRNAs in Psychotic Disorders-A Systematic Review

Psychotic disorders are a heterogenous class of mental illness, with an intricate pathophysiology, involving genetics and environmental factors, and their interaction. The identification of accessible biomarkers in bodily systems such as blood may lead to more accurate diagnosis, and more effective treatments targeting dysfunctional pathways, and could assist in monitoring the disease evolution. This systematic review aims to highlight the dysregulated microRNAs (miRNAs) in the peripheral blood of patients with psychotic disorders. Using the PRISMA protocol, PubMed and Science Direct databases were investigated and 22 articles were included. Fifty-five different miRNAs were found differentially expressed in the blood of psychotic patients compared to controls. Seventeen miRNAs (miR-34a, miR-181b, miR-432, miR-30e, miR-21, miR-137, miR-134, miR-7, miR-92a, miR-1273d, miR-1303, miR-3064-5p, miR-3131, miR-3687, miR-4428, miR-4725-3p, and miR-5096) were dysregulated with the same trend (up- or down-regulation) in at least two studies. Of note, miR-34a and miR-181b were up-regulated in the blood of psychotic patients in seven and six studies, respectively. Moreover, the level of miR-181b in plasma was found to be positively correlated with the amelioration of negative symptoms. The panel of miRNAs identified in this review could be validated in future studies in large and well-characterized cohorts of psychotic patients.

Modeling psychotic disorders: Environment x environment interaction

Schizophrenia is a major psychotic disorder with multifactorial etiology that includes interactions between genetic vulnerability and environmental risk factors. In addition, interplay of multiple environmental adversities affects neurodevelopment and may increase the individual risk of developing schizophrenia. Consistent with the two-hit hypothesis of schizophrenia, we review rodent models that combine maternal immune activation as the first hit with other adverse environmental exposures as the second hit. We discuss the strengths and pitfalls of the current animal models of environment x environment interplay and propose some future directions to advance the field.

Bipolar disorder: Diagnosis, treatment and future directions

Bipolar disorder is a relatively common mental illness, characterised by recurrent episodes of mania (or hypomania) and major depression, and associated with a significant burden of morbidity and premature mortality. Physicians across all specialities are likely to encounter individuals with the condition within their clinical practice. This short review provides an up-to-date overview of the clinical features, epidemiology, pathophysiology, evidence-based management, prognosis and future directions for treatment and research in bipolar disorder. Aspects of cross-specialty relevance are highlighted, including the physical health burden associated with the condition, and the side effects and safety considerations of medication regimes used in bipolar disorder.

Out of their minds? Externalist challenges for using AI in forensic psychiatry

Harnessing the power of machine learning (ML) and other Artificial Intelligence (AI) techniques promises substantial improvements across forensic psychiatry, supposedly offering more objective evaluations and predictions. However, AI-based predictions about future violent behaviour and criminal recidivism pose ethical challenges that require careful deliberation due to their social and legal significance. In this paper, we shed light on these challenges by considering externalist accounts of psychiatric disorders which stress that the presentation and development of psychiatric disorders is intricately entangled with their outward environment and social circumstances. We argue that any use of predictive AI in forensic psychiatry should not be limited to neurobiology alone but must also consider social and environmental factors. This thesis has practical implications for the design of predictive AI systems, especially regarding the collection and processing of training data, the selection of ML methods, and the determination of their explainability requirements.

Disease specific brain capillary angiopathy in schizophrenia, bipolar disorder, and Alzheimer's disease

Schizophrenia (SZ) and bipolar disorder (BD), which are both psychiatric disorders, share some common clinical evidence. We recently discovered that brain capillary angiopathy is another common feature of these psychiatric disorders using fibrin accumulation in vascular endothelial cells as an indicator. This study aimed to characterize the similarities and differences in cerebral capillary injuries in various brain diseases to provide new diagnostic methods for SZ and BD and to develop new therapeutic strategies. We evaluated whether discrepancies exist in the degree of vascular damage among SZ and BD and other brain disorders (amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and Alzheimer's disease (AD)) using postmortem brains. Our results demonstrate that fibrin was strongly accumulated in the capillaries of the grey matter (GM) of brains of patients with SZ and AD and in the capillaries of the white matter (WM) in those of patients with SZ, BD, and AD when compared with control subjects without any psychiatric or neurological disease history. However, ALS and PD brains did not present a significant increase in the amount of accumulated fibrin, either in the capillaries of WM or GM. Furthermore, significant leakage of fibrin into the brain parenchyma, indicating a vascular physical disruption, was observed in the brains of patients with AD but not in the brains of other patients compared with control subjects. In conclusion, our work reveals that Fibrin-accumulation in the brain capillaries are observed in psychiatric disorders, such as SZ, BD, and AD. Furthermore, fibrin-accumulating, nonbreaking type angiopathy is characteristic of SZ and BD, even though there are regional differences between these diseases.

Assessment of Tissue Expression of the Oxytocin-Vasopressin Pathway in the Placenta of Women with a First-Episode Psychosis during Pregnancy

Psychosis refers to a mental health condition characterized by a loss of touch with reality, comprising delusions, hallucinations, disorganized thought, disorganized behavior, catatonia, and negative symptoms. A first-episode psychosis (FEP) is a rare condition that can trigger adverse outcomes both for the mother and newborn. Previously, we demonstrated the existence of histopathological changes in the placenta of pregnant women who suffer an FEP in pregnancy. Altered levels of oxytocin (OXT) and vasopressin (AVP) have been detected in patients who manifested an FEP, whereas abnormal placental expression of these hormones and their receptors (OXTR and AVPR1A) has been proven in different obstetric complications. However, the precise role and expression of these components in the placenta of women after an FEP have not been studied yet. Thus, the purpose of the present study was to analyze the gene and protein expression, using RT-qPCR and immunohistochemistry (IHC), of OXT, OXTR, AVP, and AVPR1a in the placental tissue of pregnant women after an FEP in comparison to pregnant women without any health complication (HC-PW). Our results showed increased gene and protein expression of OXT, AVP, OXTR, and AVPR1A in the placental tissue of pregnant women who suffer an FEP. Therefore, our study suggests that an FEP during pregnancy may be associated with an abnormal paracrine/endocrine activity of the placenta, which can negatively affect the maternofetal wellbeing. Nevertheless, additional research is required to validate our findings and ascertain any potential implications of the observed alterations.

SIRTUINS MODULATORS COUNTERACT MITOCHONDRIAL DYSFUNCTION IN CELLULAR MODELS OF HYPOXIA: RELEVANCE TO SCHIZOPHRENIA

Schizophrenia (SZ) is a neurodevelopmental-associated disorder strongly related to environmental factors, such as hypoxia. Because there is no cure for SZ or any pharmacological approach that could revert hypoxia-induced cellular damages, we evaluated whether modulators of sirtuins could abrogate hypoxia-induced mitochondrial deregulation as a neuroprotective strategy. Firstly, astrocytes from control (Wistar) and Spontaneously Hypertensive Rats (SHR), a model of both SZ and neonatal hypoxia, were submitted to chemical hypoxia. Then, cells were exposed to different concentrations of Nicotinamide (NAM), Resveratrol (Resv), and Sirtinol (Sir) for 48hrs. Our data indicate that sirtuins modulation reduces cell death increasing the acetylation of histone 3. This outcome is related to the rescue of loss of mitochondrial membrane potential, changes in mitochondrial calcium buffering capacity, decreased O₂^-• levels and increased expression of metabolic regulators (Nrf-1 and Nfe2l2) and mitochondrial content. Such findings are relevant not only for hypoxia-associated conditions, named pre-eclampsia but also for SZ since prenatal hypoxia is a relevant environmental factor related to this burdensome neuropsychiatric disorder.

Impact of Early-Life Factors on Risk for Schizophrenia and Bipolar Disorder

BACKGROUND AND HYPOTHESIS

Schizophrenia (SCZ) and bipolar disorder (BD) have shared genetic risk and clinical symptoms, yet the extent to which environmental risk factors are shared is not well known. We aimed to examine the associations of early-life environmental exposures with the risk of SCZ and BD.

STUDY DESIGN

We conducted a Swedish register-based nested case-control study using 4184 SCZ and 18 681 BD cases diagnosed 1988-2013, individually matched to 5 population-based controls by birth year, sex and birthplace. Conditional logistic regression was used to evaluate the risk of SCZ and BD by seasonality, severe prenatal infections, and perinatal factors.

STUDY RESULTS

Seasonality had similar patterns of risk for both disorders: Higher risk for births November-December; lower risk April-June. Experiencing any perinatal factor was associated with a significantly higher risk of SCZ (incidence rate ratio [IRR] 1.19, 95%CI 1.11-1.63) and to a lesser extent BD (IRR 1.08, 95%CI 1.05-1.12). Prenatal infections were only associated with a greater risk of SCZ (IRR 1.30, 95%CI 1.04-1.63). In the mutually adjusted model, only perinatal factors were associated with outcomes. Several perinatal factors were associated with both disorders, but estimates were significantly higher for SCZ for low birth weight, low APGAR, and high parity. Congenital malformations were only associated with risk of SCZ, and jaundice with BD.

CONCLUSIONS

Adverse perinatal factors and winter birth were the risk factors for both disorders, while severe prenatal infections were only risk a factor for SCZ. Early-life exposures were associated with a higher risk of both disorders, but may play a larger role in the development of SCZ than BD.

Characterization of childhood trauma, hippocampal mediation and Cannabis use in a large dataset of psychosis and non-psychosis individuals

BACKGROUND

Cannabis use (CA) and childhood trauma (CT) independently increase the risk of earlier psychosis onset; but their interaction in relation to psychosis risk and association with endocannabinoid-receptor rich brain regions, i.e. the hippocampus (HP), remains unclear. The objective was to determine whether lower age of psychosis onset (AgePsyOnset) is associated with CA and CT through mediation by the HP volumes, and genetic risk, as measured by schizophrenia polygene scores (SZ-PGRS).

METHODS

Cross-sectional, case-control, multicenter sample from 5 metropolitan US regions. Participants (n = 1185) included 397 controls not affected by psychosis (HC); 209 participants with bipolar disorder type-1; 279 with schizoaffective disorder; and 300 with schizophrenia (DSM IV-TR). CT was assessed using the Childhood Trauma Questionnaire (CTQ); CA was assessed by self-reports and trained clinical interviewers. Assessment included neuroimaging, symptomatology, cognition and calculation of the SZ polygenic risk score (SZ-PGRS).

RESULTS

In survival analysis, CT and CA exposure interact to be associated with lower AgePsyOnset. At high CT or CA, CT or CA are individually sufficient to affect AgePsyOnset. CT relation with AgePsyOnset is mediated in part by the HP in CA users before AgePsyOnset. CA before AgePsyOnset is associated with higher SZ-PGRS and correlated with younger age at CA usage.

DISCUSSION

CA and CT interact to increase risk when moderate; while severe CT and/or CA abuse/dependence are each sufficient to affect AgePsyOnset, indicating a ceiling effect. Probands with/out CA before AgePsyOnset differ on biological variables, suggesting divergent pathways to psychosis.

FUNDING

MH077945; MH096942; MH096913; MH077862; MH103368; MH096900; MH122759.

[The nuclear receptor PPARα (peroxisome proliferator-activated receptor α) as a novel therapeutic target for schizophrenia]

Our previous study has suggested that peroxisome proliferator-activated receptor α (PPARα) plays a crucial role in the pathophysiology of schizophrenia. In the current study, we screened and identified rare variants in the PPARA gene (encoding PPARα) of schizophrenia subjects. In vitro study showed that those variants decreased activities of PPARα as a transcription factor. Ppara KO mice exhibited a deficit in the sensorimotor gating function and schizophrenia-related histological abnormalities. RNA-seq analysis revealed that PPARα regulates the expression of synaptogenesis signaling pathway-related genes in the brain. Remarkably, treatment of mice with the PPARα agonist fenofibrate alleviated an NMDA receptor antagonist, phencyclidine (PCP)-induced spine pathology and reduced sensitivity to MK-801, another NMDA receptor antagonist. In conclusion, the current study further supports the idea that perturbation in the PPARα-regulated transcriptional machinery leads to a predisposition to schizophrenia, probably by affecting synapse physiology. This study also demonstrates that PPARα can serve as a novel therapeutic target for schizophrenia.

Neuroimmune, clinical and treatment challenges in multiple sclerosis-related psychoses

In recent years, epidemiological and genetic studies have shown an association between autoimmune diseases and psychosis. The question arises whether patients with schizophrenia are more likely to develop multiple sclerosis (MS) later in life. It is well known that the immune system plays an important role in the etiopathogenesis of both disorders. Immune disturbances may be similar or very different in terms of different types of immune responses, disturbed myelination, and/or immunogenetic predispositions. A psychotic symptom may be a consequence of the MS diagnosis itself or a separate entity. In this review article, we discussed the timing of onset of psychotic symptoms and MS and whether the use of corticosteroids as therapy for acute relapses in MS is unfairly neglected in patients with psychiatric comorbidities. In addition, we discussed that the anti-inflammatory potential of antipsychotics could be useful and should be considered, especially in the treatment of psychosis that coexists with MS. Autoimmune disorders could precipitate psychotic symptoms, and in this context, autoimmune psychosis must be considered as a persistent symptomatology that requires continuous and specific treatment.

Maternal Inflammation with Elevated Kynurenine Metabolites Is Related to the Risk of Abnormal Brain Development and Behavioral Changes in Autism Spectrum Disorder

Several studies show that genetic and environmental factors contribute to the onset and progression of neurodevelopmental disorders. Maternal immune activation (MIA) during gestation is considered one of the major environmental factors driving this process. The kynurenine pathway (KP) is a major route of the essential amino acid L-tryptophan (Trp) catabolism in mammalian cells. Activation of the KP following neuro-inflammation can generate various endogenous neuroactive metabolites that may impact brain functions and behaviors. Additionally, neurotoxic metabolites and excitotoxicity cause long-term changes in the trophic support, glutamatergic system, and synaptic function following KP activation. Therefore, investigating the role of KP metabolites during neurodevelopment will likely promote further understanding of additional pathophysiology of neurodevelopmental disorders, including autism spectrum disorder (ASD). In this review, we describe the changes in KP metabolism in the brain during pregnancy and represent how maternal inflammation and genetic factors influence the KP during development. We overview the patients with ASD clinical data and animal models designed to verify the role of perinatal KP elevation in long-lasting biochemical, neuropathological, and behavioral deficits later in life. Our review will help shed light on new therapeutic strategies and interventions targeting the KP for neurodevelopmental disorders.

Shared and distinct structural brain alterations and cognitive features in drug-naïve schizophrenia and bipolar disorder

Our study aimed to examine the shared and distinct structural brain alterations, including cortical thickness(CT) and local gyrification index(LGI), and cognitive impairments between the early course stage of drug-naïve schizophrenia(SZ) and bipolar disorder(BD) patients when compared to healthy controls(HCs), and to further explore the correlation between altered brain structure and cognitive impairments. We included 72 SZ patients, 35 BD patients and 43 HCs. The cognitive function was assessed using the MATRICS Consensus Cognitive Battery. Cerebral cortex analyses were performed with FreeSurfer. Furthermore, any structural aberrations related to cognition impairments were examined. Cognitive impairments existed in SZ and BD patients and were much more severe and widespread in SZ patients, compared to HCs. There were no significant differences in LGI among three groups. Compared to HCs, SZ had thicker cortex in left pars triangularis, and BD showed thinner CT in left postcentral gyrus. In addition, BD showed thinner cortex in left pars triangularis, left pars opercularis, left insula and right fusiform gyrus compared to SZ. Moreover, our results indicated that CT in many brain areas were significantly correlated with cognitive function in HCs, but only CT of left pars triangularis was correlated with impaired social cognition found in SZ. The findings suggest that changes of CT in the left pars triangularis and left postcentral gyrus may be potential pathophysiological mechanisms of the cognition impairments in SZ and BD, respectively, and the divergent CT of partly brain areas in BD vs. SZ may help distinguish them in early phases.

Epigenetic Targets in Schizophrenia Development and Therapy

Schizophrenia is regarded as a neurodevelopmental disorder with its course progressing throughout life. However, the aetiology and development of schizophrenia are still under investigation. Several data suggest that the dysfunction of epigenetic mechanisms is known to be involved in the pathomechanism of this mental disorder. The present article revised the epigenetic background of schizophrenia based on the data available in online databases (PubMed, Scopus). This paper focused on the role of epigenetic regulation, such as DNA methylation, histone modifications, and interference of non-coding RNAs, in schizophrenia development. The article also reviewed the available data related to epigenetic regulation that may modify the severity of the disease as a possible target for schizophrenia pharmacotherapy. Moreover, the effects of antipsychotics on epigenetic malfunction in schizophrenia are discussed based on preclinical and clinical results. The obtainable data suggest alterations of epigenetic regulation in schizophrenia. Moreover, they also showed the important role of epigenetic modifications in antipsychotic action. There is a need for more data to establish the role of epigenetic mechanisms in schizophrenia therapy. It would be of special interest to find and develop new targets for schizophrenia therapy because patients with schizophrenia could show little or no response to current pharmacotherapy and have treatment-resistant schizophrenia.

Lurasidone for the treatment of schizophrenia in adult and paediatric populations

Schizophrenia is a common debilitating disorder characterized by significant impairments in how reality is perceived, combined with behavioural changes. In this review, we describe the lurasidone development programme for adult and paediatric patients. Both the pharmacokinetic and pharmacodynamic characteristics of lurasidone are revisited. In addition, pivotal clinical studies conducted on both adults and children are summarized. Several clinical cases, which demonstrate the role of lurasidone in real-world practice, are also presented. Current clinical guidelines recommend lurasidone as the first-line treatment in the acute and long-term management of schizophrenia in both adult and paediatric populations.

Prenatal and perinatal risk factors for bipolar disorder: A systematic review and meta-analysis

BACKGROUND

Perinatal and prenatal risk factors may be implicated in the development of bipolar disorder, but literature lacks a comprehensive account of possible associations.

METHODS

We performed a systematic review and meta-analyses of observational studies detailing the association between prenatal and perinatal risk factors and bipolar disorder in adulthood by searching PubMed, Embase, Web of Science and Psycinfo for articles published in any language between January 1st, 1960 and September 20th, 2021. Meta-analyses were performed when risk factors were available in at least two studies.

FINDINGS

Twenty seven studies were included with 18 prenatal or perinatal factors reported across the literature. Peripartum asphyxia (k = 5, OR = 1.46 [1.02; 2.11]), maternal stress during pregnancy (k = 2, OR = 12.00 [3.30; 43.59]), obstetric complications (k = 6, OR = 1.41 [1.18; 1.69]), and birth weight less than 2500 g (k = 5, OR = 1.28 [1.04; 1.56]) were associated with an increased risk for bipolar disorder.

INTERPRETATION

Perinatal and prenatal risk factors are implicated in the pathogenesis of bipolar disorder, supporting a role of prenatal care in preventing the condition.

Schizophrenia, Human Leukocyte Antigen (HLA), and Herpes Viruses: Immunogenetic Associations at the Population Level

Several factors have been implicated in schizophrenia (SZ), including human herpes viruses (HHV) and the adaptive immunity Human Leukocyte Antigen (HLA) genes. Here we investigated these issues in 2 complementary ways. In one analysis, we evaluated SZ-HLA and HHV-HLA associations at the level of a single allele by computing (a) a SZ-HLA protection/susceptibility (P/S) score based on the covariance between SZ and 127 HLA allele prevalences in 14 European countries, (b) estimating in silico HHV-HLA best binding affinities for the 9 HHV strains, and (c) evaluating the dependence of P/S score on HHV-HLA binding affinities. These analyses yielded (a) a set of 127 SZ-HLA P/S scores, varying by >200× (maximum/minimum), which could not be accounted for by chance, (b) a set of 127 alleles × 9 HHV best-estimated affinities, varying by >600×, and (c) a set of correlations between SZ-HLA P/S scores and HHV-HLA binding which indicated a prominent role of HHV1. In a subsequent analysis, we extended these findings to the individual person by taking into account the fact that every individual carries 12 HLA alleles and computed (a) the average SZ-HLA P/S scores of 12 randomly chosen alleles (2 per gene), an indicator of HLA-based SZ P/S for an individual, and (b) the average of the corresponding HHV estimated affinities for those alleles, an indicator of overall effectiveness of HHV-HLA binding. We found (a) that HLA protection for SZ was significantly more prominent than susceptibility, and (b) that protective SZ-HLA scores were associated with higher HHV-HLA binding affinities, indicating that HLA binding and subsequent elimination of several HHV strains may confer protection against schizophrenia.

Schizophrenia: One Name, Many Different Manifestations

Schizophrenia is a disabling condition impacting approximately 1% of the worldwide population. Symptoms include positive symptoms (eg, hallucinations, delusions), negative symptoms (eg, avolition, anhedonia), and cognitive impairment. There are likely many different environmental and pathophysiologic etiologies involving distinct neurotransmitters and neurocircuits. Pharmacologic treatment at present consists of dopamine receptor antagonists, which are reasonably effective at treating positive symptoms, but less effective at treating cognitive and negative symptoms. Nondopaminergic medications targeting alternative receptors are under investigation. Supportive psychosocial treatments can work in tandem with antipsychotic medications and optimize patient care.

Early cognitive comorbidities before disease onset: A common symptom towards prevention of related brain diseases?

Brain diseases are very heterogeneous; however they also display multiple common risk factors and comorbidities. With a paucity of disease-modifying therapies, prevention became a health priority. Towards prevention, one strategy is to focus on similar symptoms of brain diseases occurring before disease onset. Cognitive deficits are a promising candidate as they occur across brain diseases before disease onset. Based on recent research, this review highlights the similarity of brain diseases and discusses how early cognitive deficits can be exploited to tackle disease prevention. After briefly introducing common risk factors, I review common comorbidities across brain diseases, with a focus on cognitive deficits before disease onset, reporting both experimental and clinical findings. Next, I describe network abnormalities associated with early cognitive deficits and discuss how these abnormalities can be targeted to prevent disease onset. A scenario on brain disease etiology with the idea that early cognitive deficits may constitute a common symptom of brain diseases is proposed.

Environmental Influences on the Relation between the 22q11.2 Deletion Syndrome and Mental Health: A Literature Review

22q11.2 deletion syndrome (22q11DS) is a clinically heterogeneous genetic syndrome, associated with a wide array of neuropsychiatric symptoms. The clinical presentation is likely to be influenced by environmental factors, yet little is known about this. Here, we review the available research literature on the role of the environment in 22q11DS. We find that within-patient design studies have mainly investigated the role of parental factors, stress, and substance use, reporting significant effects of these factors on the clinical profile. Case-control studies have been less successful, with almost no reports of significant moderating effects of the environment. We go on to hypothesize which specific environmental measures are most likely to interact with the 22q11 deletion, based on the genes in this region and their involvement in molecular pathways. We end by discussing potential reasons for the limited findings so far, including modest sample sizes and limited availability of environmental measures, and make recommendations how to move forward.

Deficits in adolescent social functioning, dysfunctional family processes and genetic risk for schizophrenia spectrum disorders as risk factors for later psychiatric morbidity of adoptees

Social functioning deficits during adolescence are associated with later psychiatric morbidity, particularly in offspring at high genetic risk for schizophrenia spectrum disorders. However, a shortcoming of earlier study findings is the lack of control of the impact of the family rearing environment. The study was aimed to examine the association of adoptees' social functioning during adolescence, adoptive family functioning, and adoptees' high (HR) or low (LR) genetic risk for schizophrenia spectrum disorders with adoptees' later psychiatric morbidity. The present subsample from the nationwide Finnish Adoptive Family Study of Schizophrenia included 57 HR and 60 LR adoptees. Adolescent social functioning was assessed using UCLA Social Attainment Survey (UCLA SAS). Adoptive family functioning was based on Global Family Ratings (GFRs) and psychiatric disorders on DSM-III-R criteria. The results indicated that, after controlling for adoptive family functioning and genetic risk for schizophrenia spectrum disorders, deficits in peer relationships during adolescence were associated with an increased likelihood of psychiatric morbidity of adoptees. Our findings highlight social functioning deficits during adolescence, specifically in peer relationships, as plausible independent risk factors for later psychiatric disorders. These results can be utilized in identifying possible at-risk groups and targets for prevention and in developing preventive strategies.

Gene-environment interaction using polygenic scores: Do polygenic scores for psychopathology moderate predictions from environmental risk to behavior problems?

The DNA revolution has energized research on interactions between genes and environments (GxE) by creating indices of G (polygenic scores) that are powerful predictors of behavioral traits. Here, we test the extent to which polygenic scores for attention-deficit/hyperactivity disorder and neuroticism moderate associations between parent reports of their children's environmental risk (E) at ages 3 and 4 and teacher ratings of behavior problems (hyperactivity/inattention, conduct problems, emotional symptoms, and peer relationship problems) at ages 7, 9 and 12. The sampling frame included up to 6687 twins from the Twins Early Development Study. Our analyses focused on relative effect sizes of G, E and GxE in predicting behavior problems. G, E and GxE predicted up to 2%, 2% and 0.4%, respectively, of the variance in externalizing behavior problems (hyperactivity/inattention and conduct problems) across ages 7, 9 and 12, with no clear developmental trends. G and E predictions of emotional symptoms and peer relationship problems were weaker. A quarter (12 of 48) of our tests of GxE were nominally significant (p = .05). Increasing the predictive power of G and E would enhance the search for GxE.

Using animal models for the studies of schizophrenia and depression: The value of translational models for treatment and prevention

Animal models of psychiatric disorders have been highly effective in advancing the field, identifying circuits related to pathophysiology, and identifying novel therapeutic targets. In this review, we show how animal models, particularly those based on development, have provided essential information regarding circuits involved in disorders, disease progression, and novel targets for intervention and potentially prevention. Nonetheless, in recent years there has been a pushback, largely driven by the US National Institute of Mental Health (NIMH), to shift away from animal models and instead focus on circuits in normal subjects. This has been driven primarily from a lack of discovery of new effective therapeutic targets, and the failure of targets based on preclinical research to show efficacy. We discuss why animal models of complex disorders, when strongly cross-validated by clinical research, are essential to understand disease etiology as well as pathophysiology, and direct new drug discovery. Issues related to shortcomings in clinical trial design that confound translation from animal models as well as the failure to take patient pharmacological history into account are proposed to be a source of the failure of what are likely effective compounds from showing promise in clinical trials.

Low income and schizophrenia risk: a narrative review

Despite decades of research, the precise etiology of schizophrenia is not fully understood. Ample evidence indicates that the disorder derives from a complex interplay of genetic and environmental factors during vulnerable stages of brain maturation. Among the plethora of risk factors investigated, stress, pre- and perinatal insults, and cannabis use have been repeatedly highlighted as crucial environmental risk factors for schizophrenia. Compelling findings from population-based longitudinal studies suggest low income as an additional risk factor for future schizophrenia diagnosis, but underlying mechanisms remain unclear. In this narrative review, we 1) summarize the literature in support of a relationship between low (parental) income and schizophrenia risk, and 2) explore the mediating role of chronic stress, pre- and perinatal factors, and cannabis use as established risk factors for schizophrenia. Our review describes how low income facilitates the occurrence and severity of these established risk factors and thus contributes to schizophrenia liability. The broadest influence of low income was identified for stress, as low income was found to be associated with exposure to a multitude of severe psychological and physiological stressors. This narrative review adds to the growing literature reporting a close relationship between income and mental health.

Allostatic load and systemic comorbidities in psychiatric disorders

Psychiatric disorders are complex, disabling, and chronic conditions that are often accompanied by one or more systemic medical comorbidities. In this narrative review, we provide an overview of the allostatic load concept, which represents a multi-system dysregulation in response to chronic stress and link it to systemic comorbidities associated with psychiatric disorders. We synthesized published literature gathered using Medline (Ovid), Scopus, and PsychInfo and identified a high frequency of systemic comorbidities for both mood and psychotic disorders. The identified cardiovascular, metabolic, and immune comorbidities may represent the result of chronic wear and tear caused by a complex interaction between chronic psychosocial stress, health risk behaviors, pharmacological stressors, and the biological systems involved in the development of allostatic load. These findings support the notion that psychiatric disorders should be re-conceptualized as systemic disorders, affecting the brain and systemic biological pathways in an interconnected fashion to result in systemic comorbidities. We suggest that the multi-systemic and multi-dimensional approach that drives the allostatic load concept should be considered for understanding comorbidities in vulnerable psychiatric patients.

Dissecting schizophrenia phenotypic variation: the contribution of genetic variation, environmental exposures, and gene-environment interactions

Schizophrenia is among the leading causes of disability worldwide. Prior studies have conclusively demonstrated that the etiology of schizophrenia contains a strong genetic component. However, the understanding of environmental contributions and gene-environment interactions have remained less well understood. Here, we estimated the genetic and environmental contributions to schizophrenia risk using a unique combination of data sources and mathematical models. We used the administrative health records of 481,657 U.S. individuals organized into 128,989 families. In addition, we employed rich geographically specific measures of air, water, and land quality across the United States. Using models of progressively increasing complexity, we examined both linear and non-linear contributions of genetic variation and environmental exposures to schizophrenia risk. Our results demonstrate that heritability estimates differ significantly when gene-environment interactions are included in the models, dropping from 79% for the simplest model, to 46% in the best-fit model which included the full set of linear and non-linear parameters. Taken together, these findings suggest that environmental factors are an important source of explanatory variance underlying schizophrenia risk. Future studies are warranted to further explore linear and non-linear environmental contributions to schizophrenia risk and investigate the causality of these associations.

Brain vasculature disturbance in schizophrenia

PURPOSE OF REVIEW

The vascular hypothesis of schizophrenia (SZ) postulates that brain endothelial dysfunction contributes to brain pathophysiology. This review discusses recent evidence for and against this hypothesis, including data related to blood-brain barrier (BBB), brain endothelium, and brain blood supply, to provide a critical weighed update.

RECENT FINDINGS

Different studies report a consistent proportion of SZ patients showing increased BBB permeability, reflected by higher levels of albumin in the cerebral spinal fluid. Of note, this was not a result of antipsychotic medication. The high inflammatory profile observed in some SZ patients is strongly associated with increased BBB permeability to circulating immune cells, and with more severe cognitive deficiencies. Also, sex was found to interact with BBB integrity and permeability in SZ. The strongest independent genetic association with SZ has been identified in FZD1, a hypoxia-response gene that is 600-fold higher expressed in early development endothelium as compared to adult brain endothelium. Regarding brain blood supply, there is evidence to suggest alterations in proper brain perfusion in SZ. Nonetheless, ex-vivo experiments suggested that widely used antipsychotics favor vasoconstriction; thus, alterations in cerebral perfusion might be related to the patients' medication.

SUMMARY

In some patients with SZ, a vulnerable brain endothelium may be interacting with environmental stressors, such as inflammation or hypoxia, converging into a more severe SZ symptomatology. Gene expression and performance of human brain endothelium could vary along with development and the establishment of the BBB; therefore, we encourage to investigate its possible contribution to SZ considering this dynamic context.

The Variants at APOA1 and APOA4 Contribute to the Susceptibility of Schizophrenia With Inhibiting mRNA Expression in Peripheral Blood Leukocytes

Objective: Abnormal lipid metabolism has a close link to the pathophysiology of schizophrenia (SZ). This study mainly aimed to evaluate the association of variants at apolipoprotein A1 (APOA1) and APOA4 with SZ in a Chinese Han population.

Methods: The rs5072 of APOA1 and rs1268354 of APOA4 were examined in a case–control study involving 2,680 patients with SZ from the hospital and 2,223 healthy controls screened by physical examination from the community population. The association was estimated with the odds ratio (OR) and 95% confidence intervals (95% CIs) by logistic regression. The APOA1 and APOA4 messenger RNA (mRNA) in peripheral blood leukocytes were measured by real-time PCR and compared between SZ cases and controls. Serum apoA1 levels were detected by turbidimetric inhibition immunoassay and high-density lipoprotein cholesterol (HDL-C) levels were detected by the homogeneous method.

Results: Both of the rs5072 of APOA1 and rs1268354 of APOA4 had statistically significant associations with SZ. After adjustment for age and sex, ORs (95% CIs) of the additive model of rs5072 and rs1268354 were 0.82 (0.75–0.90) and 1.120 (1.03–1.23), and p-values were 3.22 × 10⁻⁵ and 0.011, respectively. The association of rs5072 with SZ still presented statistical significance even after Bonferroni correction (p-value×6). SZ patients during the episode presented lower levels of apoA1, HDL-C, mRNA of APOA1 common variants and transcript variant 4, and APOA4 mRNA than controls (p < 0.01) while SZ patients in remission showed a significantly decreased APOA1 transcript variant 3 expression level and increased APOA4 mRNA expression level (p < 0.01). mRNA expression levels of APOA1 transcript variant 4 significantly increased with the variations of rs5072 in SZ during the episode (p_trend = 0.017). After the SZ patients received an average of 27.50 ± 9.90 days of antipsychotic treatment, the median (interquartile) of serum apoA1 in the SZ episode significantly increased from 1.03 (1.00.1.20) g/L to 1.08 (1.00.1.22) g/L with the p-value of 0.044.

Conclusion: Our findings suggest that the genetic variations of APOA1 rs5072 and APOA4 rs1268354 contribute to the susceptibility of SZ, and the expression levels of APOA1 and APOA4 mRNA of peripheral blood leukocytes decreased in SZ patients during the episode while APOA4 increased after antipsychotic treatment.

Gene-Environment Interactions in Schizophrenia: A Literature Review

Schizophrenia is a devastating mental illness with a strong genetic component that is the subject of extensive research. Despite the high heritability, it is well recognized that non-genetic factors such as certain infections, cannabis use, psychosocial stress, childhood adversity, urban environment, and immigrant status also play a role. Whenever genetic and non-genetic factors co-exist, interaction between the two is likely. This means that certain exposures would only be of consequence given a specific genetic makeup. Here, we provide a brief review of studies reporting evidence of such interactions, exploring genes and variants that moderate the effect of the environment to increase risk of developing psychosis. Discovering these interactions is crucial to our understanding of the pathogenesis of complex disorders. It can help in identifying individuals at high risk, in developing individualized treatments and prevention plans, and can influence clinical management.