Gene-environment interactions in schizophrenia: review of epidemiological findings and future directions

N-acetylcysteine enhances the antipsychotic effect of aripiprazole in the neurodevelopmental rat model of schizophrenia

Symptoms of schizophrenia are well characterized, but the mechanism underlying the pathogenesis of the disease still remains unknown. In addition, therapy of negative symptoms and cognitive deficits in schizophrenic patients is a serious clinical problem. Some clinical studies have shown that the atypical antipsychotic drug aripiprazole (ARI), and the antioxidant N-acetylcysteine (NAC) are effective in reducing positive and negative symptoms of schizophrenia in patients. The aim of the present study was to evaluate the influence of repeated co-treatment with low doses of ARI and NAC on the schizophrenia-like behavior in adult rats. The schizophrenia-like behavior was induced in Sprague-Dawley male pups in the neonatal days p5-p16 by repeated administration of the glutathione synthesis inhibitor L-butionine-(S,R)-sulfoximine (BSO) given together with the dopamine reuptake inhibitor 1-[2-[Bis-4(fluorophenyl)methoxy]ethyl]-4-3-(3-phenylpropyl) (GBR 12909). Adult rats received repeated co-treatment with ARI (0.1 mg/kg) and NAC (10 mg/kg) for 21 days, and their effects on schizophrenia-like behavior were assessed (on p90-91) using the social interaction test and novel object recognition test. The present data indicated that the studied drugs at higher doses: ARI (0.3 mg/kg but not 0.1 mg/kg) and NAC (30 mg/kg but not 10 mg/kg) reversed schizophrenia-like symptoms in the tested model. Moreover, repeated co-treatment with low doses of ARI with NAC also reversed schizophrenia-like behavior in the neurodevelopmental rat model of schizophrenia. The above results indicated that NAC enhanced the action of ARI in the used neurodevelopmental rat model of schizophrenia, and the mechanism of action of the used drugs in this model is discussed.

What does really matter in the premorbid background of psychosis leading to long-term disability? A 21-year follow-up cohort study of first-episode psychosis

BACKGROUND

Clinicians are currently unable to predict which patients are at higher risk of long-term disability based on premorbid factors. We aimed to determine the extent to which premorbid factors could prospectively predict long-term disability in patients with first-episode psychosis.

METHODS

We assessed 12 potential premorbid risk factors in 243 individuals with first-episode psychosis reassessed 21 years later for several domains of psychosocial disability. Hierarchical multivariate regression and Directed Acyclic Graphs (DAGs) were used sequentially to investigate independent and causal associations between risk factors and long-term disability.

RESULTS

The familial load of schizophrenia, lower parental SES, obstetric complications, early neurodevelopmental delay, childhood adversity, and poor adolescence social networks were independent predictors of long-term disability, accounting for 40.6 % of the variability. The DAGs analysis showed that both familial risk of schizophrenia and lower SES had statistically significant direct and indirect effects on later disability. The indirect effects were mediated by the variables indexing impaired development, although childhood adversity and poor adolescence social networks also had significant direct effects on disability. Early neurodevelopmental delay was the only developmental marker present in all statistically significant indirect paths from familial background factors to long-term disability, suggesting that it is a key component of the causal chain that leads to later disability.

CONCLUSIONS

In individuals with psychotic disorders, familial background factors appear to trigger a complex and multidetermined cascade of risk factors across developmental stages that interact iteratively, leading to long-term disability.

The expanding spectrum of infectious risk organisms and immunogenetic susceptibility in neuropsychiatric disorders

The spectrum of infectious risk organisms showing associations with psychiatric traits is expanding. Infectious agents can modulate the risk of psychiatric disorders at different stages of life, such as gestational, childhood, adolescent, and adult periods. Prenatal infection appears to 'prime' the developing brain, whereas infection during childhood or later periods may act as a 'second hit', and these may have synergistic effects on the risk of developing psychiatric diseases. However, neither all the individuals with antecedent infection develop psychiatric disorders, nor do infectious organisms alone lead to psychiatric phenotypes. This suggests modulatory effects of additional host factors. The host genetic background crucially determines differential susceptibility to infection and serves as an important gateway for immune activation and signalling, as well as homeostatic brain functions. Despite the presence of several immune checkpoints and effectors, the infectious organisms disrupt the balance between immune-activating and immune-compensatory mechanisms and contribute to immune dysregulation. This depends substantially on genetic loci encoding immune molecules such as Toll-like receptors, Major Histocompatibility Complex, cytokines/ chemokines and their receptors, complement proteins, and other molecules and elements such as human endogenous retroviruses and gut microbiome that have distinct roles in immune regulation and immune effector functions. Genetic variations within these loci not only influence differential susceptibility to infection but also confer risk to psychiatric disorders. This article highlights a comprehensive overview of the nexus between infections and immune function-related genes and their impact on psychiatric traits. Understanding such interactions will lead to the identification of genetic markers of susceptibility to infection and psychiatric diseases.

Aberrant aging-associated p62 autophagic cascade in biopsied olfactory neuronal cells from patients with psychosis

Sequestosome-1/p62, a key mediator in the clearance of damaged organelles and macromolecules during autophagy, serves as a marker of biological aging. We demonstrate elevated p62 in biopsied neuronal cells in patients with psychosis compared to healthy controls. In healthy controls, p62-indicated biological/autophagic age is positively correlated with chronological age over time, whereas in patients, neuronal p62-indicated biological/autophagic age shows no correlation with chronological age, being significantly higher than chronological age from the onset of the disease.

Model systems for emulating human tissue and physiology in psychiatric research

The modeling of psychiatric disorders poses significant challenges due to the complex nature of these conditions, which encompass a range of neuropsychiatric diseases such as autism spectrum disorder (ASD), schizophrenia (SCZ), bipolar disorder (BD), post-traumatic stress disorder (PTSD), anxiety disorder (AD) and depression. The rising global prevalence of mental disorders and the urgency for more effective treatments have propelled the development of innovative in vitro models. This review presents a thorough examination of two-dimensional (2D) versus three-dimensional (3D) induced pluripotent stem cell (iPSC) models of neuropsychiatric diseases, offering insights into their respective capacities to mimic neurodevelopment and cellular phenotypes observed in these conditions. Our comparative analysis reveals that while traditional 2D cultures have been instrumental in elucidating disease pathways and high-throughput drug screening, they fall short in replicating the intricate cellular architecture and environment of the human brain. On the other hand, 3D organoid models, including brain organoids, better recapitulate the spatial organization, cell-type diversity, and functional connectivity of brain tissue, offering a more physiologically relevant context for studying disease mechanisms and testing therapeutic interventions. We assess the progress in modeling ASD, SCZ, BD, PTSD, AD, and depression, highlighting the advanced understanding of disease etiology and potential treatment avenues offered by 3D iPSC technologies. Challenges remain, including the scalability, reproducibility, and maturation of organoids, but the potential for personalized medicine and the elucidation of disease ontogeny is unparalleled. The review concludes with a perspective on the future directions of psychiatric disease modeling, emphasizing the integration of 3D iPSC models with high-throughput technologies and computational approaches to enhance our understanding and treatment of these debilitating conditions.

Sample ascertainment and clinical outcome measures in the Accelerating Medicines Partnership® Schizophrenia Program

Clinical ascertainment and clinical outcome are key features of any large multisite study. In the ProNET and PRESCIENT research networks, the Accelerating Medicines Partnership® Schizophrenia (AMP®SCZ) Clinical Ascertainment and Outcome Measures Team aimed to establish a harmonized clinical assessment protocol across these two research networks and to define ascertainment criteria and primary and secondary endpoints. In addition to developing the assessment protocol, the goals of this aspect of the AMP SCZ project were: (1) to implement and monitor clinical training, ascertainment of participants, and clinical assessments; (2) to provide expert clinical input to the Psychosis Risk Evaluation, Data Integration and Computational Technologies: Data Processing, Analysis, and Coordination Center (PREDICT-DPACC) for data collection, quality control, and preparation of data for the analysis of the clinical measures; and (3) to provide ongoing support to the collection, analysis, and reporting of clinical data. This paper describes the (1) protocol clinical endpoints and outcomes, (2) rationale for the selection of the clinical measures, (3) extensive training of clinical staff, (4) preparation of clinical measures for a multisite study which includes several sites where English is not the native language; and (5) the assessment of measure stability over time in the AMP SCZ observational study comparing clinical ratings at baseline and at the 2-month follow up. Watch Dr. Jean Addington discuss her work and this article: https://vimeo.com/1040425281 .

Genetic Differences in Reactivity to the Environment Impact Psychotic-Like and Affective Reactivity in Daily Life

BACKGROUND AND HYPOTHESIS

Consistent with diathesis-stress models, psychosis research has focused on genetic moderation of adverse environmental exposures. In contrast, the Differential Susceptibility (DS) model suggests that the same genetic variants that increase risk-inducing effects of adverse experiences also enhance beneficial effects from positive experiences. This study examined whether individuals with high genetic susceptibility to the environment showed differential psychotic-like and affective reactivity in response to positive and negative events in daily life.

STUDY DESIGN

Experience sampling methodology assessed context (positive and stressful) and momentary levels of paranoia, psychotic-like experiences (PLE), and positive (PA) and negative affect (NA) in 217 non-clinical adults oversampled for schizotypy. Linear mixed models examined whether Polygenic Risk Scores of Environmental Sensitivity (PRS-ES) moderated the impact of current context on subsequent experiences.

STUDY RESULTS

PRS-ES moderated positive, but not stressful, context on subsequent levels of momentary paranoia, NA, and PA, but not PLE. Genetic and environmental (G × E) interactions indicated diathesis-stress at lower thresholds of PRS-ES, but a DS model at the highest threshold of the PRS-ES. Participants with elevated PRS-ES showed increased paranoia and NA and decreased PA in subsequent assessments when reporting low levels of positive situations, but also decreased paranoia and NA and increased PA when rating contexts as positive.

CONCLUSIONS

Findings support the influence of genetic sensitivity to the environment on psychotic-like and affective reactivity in daily life, particularly in response to positive contexts. This highlights the transdiagnostic protective role of positive experiences and informs ecological momentary interventions.

Viruses and psychiatric disorders: We have not crossed the borderline from hypothesis to proof yet (Review)

Most psychiatric disorders are heterogeneous and are attributed to the synergistic action of a multitude of factors. It is generally accepted that psychiatric disorders are the outcome of interactions between genetic predisposition and environmental perturbations, which involve psychosocial stress, or alterations in the physiological state of the organism. A number of hypotheses have been presented on such environmental influences that may include direct insults such as injury, malnutrition and hostile living conditions, or indirect sequelae following infection from viruses such as influenza, arboviruses, enteroviruses and several herpesviruses, or the differential expression of human endogenous retroviruses. It is known that the concept of viruses is far more extensive than their perception as mere agents of acute infections, or chronic debilitating diseases, such as AIDS or some forms of cancer. Notably, an apparent causal connection between viruses and the pathophysiology of diseases has been suggested; however, it remains unclear as to how to establish this causal connection. There are inherent difficulties in answering this question with certainty, which may be due to the multitude of genetic and environmental influences that can lead to psychopathology; the latent state of chronic infection exhibited by a number of neurotropic viruses; the late onset of psychiatric disorders with respect to the acute phase of viral infection at which detection tests would be successful; the complexity of the virome; and the existence of thousands of viral species. The present review aims to provide an outline of the conclusions that have thus far been reached regarding a possible association between viral infection and psychiatric disease, and the obstacles confronted during the quest for the truth behind the role of viruses.

Interaction between Neighborhood Exposome and Genetic Risk in Child Psychotic-like Experiences

Persistent distressing psychotic-like experiences (PLE) among children may be driven by genetics and neighborhood environmental exposures. However, the gene-environment interaction to persistent distressing PLE is unknown. The study included 6,449 participants from the Adolescent Brain and Cognitive Development Study. Genetic risk was measured by a multi-ancestry schizophrenia polygenic risk score (SCZ-PRS). Multi-dimensional neighborhood-level exposures were used to form a neighborhood exposome (NE) score. SCZ-PRS was not statistically significantly associated with odds of persistent distressing PLE (OR = 1.04, 95% CI: 0.97, 1.13, P = 0.280), whereas NE score was (OR = 1.15, 95% CI: 1.05, 1.26, P = 0.003). The association between NE score and persistent distressing PLE was statistically significantly attenuated as SCZ-PRS increased (OR for interaction = 0.92, 95% CI: 0.86, 1.00, P = 0.039). The findings indicate that persistent distressing PLE may be driven by detrimental neighborhood exposures, particularly among children with low genetic risks.

Epigenetic Control in Schizophrenia

Schizophrenia is a severe and complex psychiatric condition ranking among the top 15 leading causes of disability worldwide. Despite the well-established heritability component, a complex interplay between genetic and environmental risk factors plays a key role in the development of schizophrenia and psychotic disorders in general. This chapter covers all the clinical evidence showing how the analysis of the epigenetic modulation in schizophrenia might be relevant to understand the pathogenesis of schizophrenia as well as potentially useful to develop new pharmacotherapies.

Human stem cell-based models to study synaptic dysfunction and cognition in schizophrenia: A narrative review

Cognitive impairment is the strongest predictor of functional outcomes in schizophrenia and is hypothesized to result from synaptic dysfunction. However, targeting synaptic plasticity and cognitive deficits in patients remains a significant clinical challenge. A comprehensive understanding of synaptic plasticity and the molecular basis of learning and memory in a disease context can provide specific targets for the development of novel therapeutics targeting cognitive impairments in schizophrenia. Here, we describe the role of synaptic plasticity in cognition, summarize evidence for synaptic dysfunction in schizophrenia and demonstrate the use of patient derived induced-pluripotent stem cells for studying synaptic plasticity in vitro. Lastly, we discuss current advances and future technologies for bridging basic science research of synaptic dysfunction with clinical and translational research that can be used to predict treatment response and develop novel therapeutics.

Genetic and Neurodevelopmental Markers in Schizophrenia-Spectrum Disorders: Analysis of the Combined Role of the CNR1 Gene and Dermatoglyphics

Background: Dermatoglyphic pattern deviances have been associated with schizophrenia-spectrum disorders (SSD) and are considered neurodevelopment vulnerability markers based on the shared ectodermal origin of the epidermis and the central nervous system. The endocannabinoid system participates in epidermal differentiation, is sensitive to prenatal insults and is associated with SSD. Objective: We aimed to investigate whether the Cannabinoid Receptor 1 gene (CNR1) modulates the dermatoglyphics-SSD association. Methods: In a sample of 112 controls and 97 patients with SSD, three dermatoglyphic markers were assessed: the total palmar a-b ridge count (TABRC), the a-b ridge count fluctuating asymmetry (ABRC-FA), and the pattern intensity index (PII). Two CNR1 polymorphisms were genotyped: rs2023239-T/C and rs806379-A/T. We tested: (i) the CNR1 association with SSD and dermatoglyphic variability within groups; and (ii) the CNR1 × dermatoglyphic measures interaction on SSD susceptibility. Results: Both polymorphisms were associated with SSD. The polymorphism rs2023239 modulated the relationship between PII and SSD: a high PII score was associated with a lower SSD risk within C-allele carriers and a higher SSD risk within TT-homozygotes. This result indicates an inverse relationship between the PII and the SSD predicted probability conditional to the rs2023239 genotype. Conclusions: These novel findings suggest the endocannabinoid system's role in the development and variability of dermatoglyphic patterns. The identified interaction encourages combining genetic and dermatoglyphics to assess neurodevelopmental alterations predisposing to SSD in future studies.

Examining measures of schizotypy for gender and racial bias using item response theory and differential item functioning

Schizotypy involves schizophrenia-like traits and symptoms, with the Wisconsin Schizotypy Scales (WSS) being frequently used in previous research. There is some evidence that schizophrenia-spectrum symptom levels, including when using the WSS, might vary both by gender and by race and ethnicity. However, previous research has rarely examined to what extent the WSS show gender and racial bias. Further, this has not been previously examined for the Cognitive Slippage Scale, a measure of disorganized schizotypy. In this study, we examined biases for a subset of items from the WSS in a large sample of undergraduate students (n = 21,829). Using item response theory to test for levels of differential item functioning (DIF), we found some evidence of problematic DIF for all scales, including for negative, positive, and disorganized schizotypy scales. There was evidence of problematic DIF especially by gender and for Black and Multiracial participants. Overall, the current results suggest that gender and/or racial bias on these scales should be an important consideration in using these scales and our results could have implications for assessment of schizophrenia-spectrum symptoms.

Association between the oral microbiome and brain resting state connectivity in schizophrenia

Recent microbiome-brain axis findings have shown evidence of the modulation of microbiome community as an environmental mediator in brain function and psychiatric illness. This work is focused on the role of the microbiome in understanding a rarely investigated environmental involvement in schizophrenia (SZ), especially in relation to brain circuit dysfunction. We leveraged high throughput microbial 16s rRNA sequencing and functional neuroimaging techniques to enable the delineation of microbiome-brain network links in SZ. N = 213 SZ and healthy control subjects were assessed for the oral microbiome. Among them, 139 subjects were scanned by resting-state functional magnetic resonance imaging (rsfMRI) to derive brain functional connectivity. We found a significant microbiome compositional shift in SZ beta diversity (weighted UniFrac distance, p = 6 × 10-3; Bray-Curtis distance p = 0.021). Fourteen microbial species involving pro-inflammatory and neurotransmitter signaling and H2S production, showed significant abundance alterations in SZ. Multivariate analysis revealed one pair of microbial and functional connectivity components showing a significant correlation of 0.46. Thirty five percent of microbial species and 87.8 % of brain functional network connectivity from each component also showed significant differences between SZ and healthy controls with strong performance in classifying SZ from healthy controls, with an area under curve (AUC) = 0.84 and 0.87, respectively. The results suggest a potential link between oral microbiome dysbiosis and brain functional connectivity alteration in relation to SZ, possibly through immunological and neurotransmitter signaling pathways and the hypothalamic-pituitary-adrenal axis, supporting for future work in characterizing the role of oral microbiome in mediating effects on SZ brain functional activity.

The effect of phencyclidine-mediated blockade of NMDA receptors in the early postnatal period on glutathione and sulfur amino acid levels in the rat brain as a potential causative factor of schizophrenia-like behavior in adulthood

BACKGROUND

Phencyclidine, an NMDA receptor antagonist, is frequently used to model behavioral and neurochemical changes correlated with schizophrenia in laboratory animals. The present study aimed to examine the effects of repeated administration of phencyclidine during early postnatal development on the contents of glutathione and sulfur-containing amino acids, as well as the activity of antioxidant enzymes in the brain of 12-day-old rats, and schizophrenia-like symptoms in adulthood.

METHODS

Male Sprague-Dawley pups were administered phencyclidine (10 mg/kg) or saline subcutaneously on the postnatal days p2, p6, p9 and p12. In 12-day-old pups, 4 h after the last dose of phencyclidine, the levels of glutathione, cysteine, methionine, and homocysteine, and the enzymatic activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR) were measured in the frontal cortex, hippocampus, and striatum. In 70-72-day-old rats, schizophrenia-like symptoms were assessed using behavioral tests.

RESULTS

Biochemical data showed that perinatal phencyclidine treatment significantly reduced glutathione and cysteine levels in all brain structures studied, methionine was diminished in the striatum, and homocysteine in both the frontal cortex and striatum. GR activity was increased in the frontal cortex while SODactivity was decreased in the hippocampus. Behaviorally, perinatal phencyclidine induced long-term deficits in social and cognitive function and a decrease in locomotor activity assessed as the time of walking. Finally, perinatal treatment with phencyclidine resulted in a significant reduction in body weight gain over time.

CONCLUSION

Our research provides further evidence for the usefulness of the phencyclidine-induced neurodevelopmental model of schizophrenia for studying the pathogenesis of schizophrenia.

The Role of Childhood Trauma in Affective Stress Recovery in Early Psychosis: An Experience Sampling Study

BACKGROUND AND HYPOTHESES

Affective recovery, operationalized as the time needed for affect to return to baseline levels after daily stressors, may be a putative momentary representation of resilience. This study aimed to investigate affective recovery in positive and negative affect across subclinical and clinical stages of psychosis and whether this is associated with exposure to childhood trauma (sexual, physical, and emotional abuse).

STUDY DESIGN

We used survival analysis to predict the time-to-recovery from a daily event-related stressor in a pooled sample of 3 previously conducted experience sampling studies including 113 individuals with first-episode psychosis, 162 at-risk individuals, and 94 controls.

STUDY RESULTS

Negative affective recovery (ie, return to baseline following an increase in negative affect) was longer in individuals with first-episode psychosis compared with controls (hazard ratio [HR] = 1.71, 95% confidence interval [CI; 1.03, 2.61], P = .04) and in at-risk individuals exposed to high vs low levels of emotional abuse (HR = 1.31, 95% CI [1.06, 1.62], P = .01). Positive affective recovery (ie, return to baseline following a decrease in positive affect) did not differ between groups and was not associated with childhood trauma.

CONCLUSIONS

Our results give first indications that negative affective recovery may be a putative momentary representation of resilience across stages of psychosis and may be amplified in at-risk individuals with prior experiences of emotional abuse. Understanding how affective recovery contributes to the development of psychosis may help identify new targets for prevention and intervention to buffer risk or foster resilience in daily life.

Overview on cognitive impairment in psychotic disorders: From impaired microcircuits to dysconnectivity

Schizophrenia's cognitive deficits, often overshadowed by positive symptoms, significantly contribute to the disorder's morbidity. Increasing attention highlights these deficits as reflections of neural circuit dysfunction across various cortical regions. Numerous connectivity alterations linked to cognitive symptoms in psychotic disorders have been reported, both at the macroscopic and microscopic level, emphasizing the potential role of plasticity and microcircuits impairment during development and later stages. However, the heterogeneous clinical presentation of cognitive impairment and diverse connectivity findings pose challenges in summarizing them into a cohesive picture. This review aims to synthesize major cognitive alterations, recent insights into network structural and functional connectivity changes and proposed mechanisms and microcircuit alterations underpinning these symptoms, particularly focusing on neurodevelopmental impairment, E/I balance, and sleep disturbances. Finally, we will also comment on some of the most recent and promising therapeutic approaches that aim to target these mechanisms to address cognitive symptoms. Through this comprehensive exploration, we strive to provide an updated and nuanced overview of the multiscale connectivity impairment underlying cognitive impairment in psychotic disorders.

Measuring interpersonal trauma: Development and validation of the German version of the victimization experience schedule (VES)

OBJECTIVE

Interpersonal victimization experiences (VEs) significantly affect mental and physical health, particularly in disorders associated with life-time adversities, like fibromyalgia syndrome (FMS) and major depressive disorder (MDD). However, assessing VEs comprehensively remains challenging due to limited tools that encompass sub-traumatic events, such as bullying or discrimination, and contextual dimensions. We aimed to address this gap by validating the Victimization Experience Schedule (VES) in German, examining its reliability, and assessing VEs in clinical populations with FMS and MDD.

METHODS

We investigated the relationship between VEs and clinical symptoms in individuals with FMS, MDD and healthy controls (N = 105) in a case-control study. We also analyzed correlations between different types of VEs and categories of early childhood abuse and posttraumatic-stress-disorder instruments. Additionally, we validated our findings in an independent sample of individuals with FMS (N = 97) from a clinical study.

RESULTS

We observed excellent inter-rater reliability (Kw = 0.90-0.99), and VEs assessed using the VES were in alignment with subcategories of early childhood abuse. The prevalence of VEs extended beyond the categories covered by traditional survey instruments and was higher in individuals with MDD (4.0 ± 2.6) and FMS (5.9 ± 3.1) compared to controls (1.5 ± 1.7). We consistently identified a significant association between the number of VEs, the associated subjective distress, and clinical scores. Furthermore, distinct correlation patterns between VEs and clinical outcomes emerged across different cohorts.

CONCLUSION

Our study emphasizes the VES's value in understanding VEs within MDD and FMS. These experiences span from traumatic to sub-traumatic and correlate with posttraumatic-stress and clinical symptoms, underscoring the VES's importance as an assessment tool.

Systematic exploration of a decade of publications on psychiatric genetics in Latin America

Psychiatric disorders have a great impact in terms of mortality, morbidity, and disability across the lifespan. Considerable effort has been devoted to understanding their complex and heterogeneous genetic architecture, including diverse ancestry populations. Our aim was to review the psychiatric genetics research published with Latin American populations from 2010 to 2019, and classify it according to country of origin, type of analysis, source of funding, and other variables. We found that most publications came from Brazil, Mexico, and Colombia. Also, local funds are generally not large enough for genome-wide studies in Latin America, with the exception of Brazil and Mexico; larger studies are often done in collaboration with international partners, mostly funded by US agencies. In most of the larger studies, the participants are individuals of Latin American ancestry living in the United States, which limits the potential for exploring the complex gene-environment interaction. Family studies, traditionally strong in Latin America, represent about 30% of the total research publications. Scarce local resources for research in Latin America have probably been an important limitation for conducting bigger and more complex studies, contributing to the reduced representation of these populations in global psychiatric genetics studies. Increasing diversity must be a goal to improve generalizability and applicability in clinical settings.

Identification of Psychosis Risk and Diagnosis of First-Episode Psychosis: Advice for Clinicians

Early detection of psychotic-spectrum disorders among adolescents and young adults is crucial, as the initial years after psychotic symptom onset encompass a critical period in which psychosocial and pharmacological interventions are most effective. Moreover, clinicians and researchers in recent decades have thoroughly characterized psychosis-risk syndromes, in which youth are experiencing early warning signs indicative of heightened risk for developing a psychotic disorder. These insights have created opportunities for intervention even earlier in the illness course, ideally culminating in the prevention or mitigation of psychosis onset. However, identification and diagnosis of early signs of psychosis can be complex, as clinical presentations are heterogeneous, and psychotic symptoms exist on a continuum. When a young person presents to a clinic, it may be unclear whether they are experiencing common, mild psychotic-like symptoms, early warning signs of psychosis, overt psychotic symptoms, or symptoms better accounted for by a non-psychotic disorder. Therefore, the purpose of this review is to provide a framework for clinicians, including those who treat non-psychotic disorders and those in primary care settings, for guiding identification and diagnosis of early psychosis within the presenting clinic or via referral to a specialty clinic. We first provide descriptions and examples of first-episode psychosis (FEP) and psychosis-risk syndromes, as well as assessment tools used to diagnose these conditions. Next, we provide guidance as to the differential diagnosis of conditions which have phenotypic overlap with psychotic disorders, while considering the possibility of co-occurring symptoms in which case transdiagnostic treatments are encouraged. Finally, we conclude with an overview of early detection screening and outreach campaigns, which should be further optimized to reduce the duration of untreated psychosis among youth.

Association between urban upbringing and functional brain connectivity in schizophrenia

Background

Environmental factors considerably influence the development of the human cortex during the perinatal period, early childhood, and adolescence. Urban upbringing in the first 15 years of life is a known risk factor for schizophrenia (SCZ). Though the risk of urban birth and upbringing is well-examined from an epidemiological perspective, the biological mechanisms underlying urban upbringing remain unknown. The effect of urban birth and upbringing on functional brain connectivity in SCZ patients is not yet examined.

Methods

This is a secondary data analysis of three studies that included 87 patients with SCZ and 70 healthy volunteers (HV) aged 18 to 50 years. We calculated the developmental urbanicity index using a validated method in earlier studies. Following standard pre-processing of resting functional magnetic resonance imaging (fMRI) scans, seed-return on investment (ROI) functional connectivity analysis was performed.

Results

The results showed a significant association between urban birth and upbringing on functional connectivity in SCZ patients and HV (P < 0.05). In SCZ patients, connections from the right caudate, anterior cingulate cortex, left and right intracalcarine cortices, left and right lingual gyri, left posterior parahippocampal cortex to the cerebellum, fusiform gyri, lateral occipital cortex, and amygdala were significantly associated with the urbanicity index (P < 0.05).

Conclusions

These study findings suggest a significant association between urban birth and upbringing on functional brain connectivity in regions involved in reward processing and social cognition in SCZ. Assessment of social cognition could have implications in developing an in-depth understanding of this impairment in persons with SCZ.

Biomarkers for Psychosis: Are We There Yet? Umbrella Review of 1478 Biomarkers

Background and Hypothesis

This umbrella review aims to comprehensively synthesize the evidence of association between peripheral, electrophysiological, neuroimaging, neuropathological, and other biomarkers and diagnosis of psychotic disorders.

Study Design

We selected systematic reviews and meta-analyses of observational studies on diagnostic biomarkers for psychotic disorders, published until February 1, 2018. Data extraction was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Evidence of association between biomarkers and psychotic disorders was classified as convincing, highly suggestive, suggestive, weak, or non-significant, using a standardized classification. Quality analyses used the Assessment of Multiple Systematic Reviews (AMSTAR) tool.

Study Results

The umbrella review included 110 meta-analyses or systematic reviews corresponding to 3892 individual studies, 1478 biomarkers, and 392 210 participants. No factor showed a convincing level of evidence. Highly suggestive evidence was observed for transglutaminase autoantibodies levels (odds ratio [OR] = 7.32; 95% CI: 3.36, 15.94), mismatch negativity in auditory event-related potentials (standardized mean difference [SMD] = 0.73; 95% CI: 0.5, 0.96), P300 component latency (SMD = -0.6; 95% CI: -0.83, -0.38), ventricle-brain ratio (SMD = 0.61; 95% CI: 0.5, 0.71), and minor physical anomalies (SMD = 0.99; 95% CI: 0.64, 1.34). Suggestive evidence was observed for folate, malondialdehyde, brain-derived neurotrophic factor, homocysteine, P50 sensory gating (P50 S2/S1 ratio), frontal N-acetyl-aspartate, and high-frequency heart rate variability. Among the remaining biomarkers, weak evidence was found for 626 and a non-significant association for 833 factors.

Conclusions

While several biomarkers present highly suggestive or suggestive evidence of association with psychotic disorders, methodological biases, and underpowered studies call for future higher-quality research.

Association between the oral microbiome and brain resting state connectivity in schizophrenia

Recent microbiome-brain axis findings have shown evidence of the modulation of microbiome community as an environmental mediator in brain function and psychiatric illness. This work is focused on the role of the microbiome in understanding a rarely investigated environmental involvement in schizophrenia (SZ), especially in relation to brain circuit dysfunction. We leveraged high throughput microbial 16s rRNA sequencing and functional neuroimaging techniques to enable the delineation of microbiome-brain network links in SZ. N=213 SZ and healthy control (HC) subjects were assessed for the oral microbiome. Among them, 139 subjects were scanned by resting-state functional magnetic resonance imaging (rsfMRI) to derive brain functional connectivity. We found a significant microbiome compositional shift in SZ beta diversity (weighted UniFrac distance, p= 6×10 -3 ; Bray-Curtis distance p = 0.021). Fourteen microbial species involving pro-inflammatory and neurotransmitter signaling and H 2 S production, showed significant abundance alterations in SZ. Multivariate analysis revealed one pair of microbial and functional connectivity components showing a significant correlation of 0.46. Thirty five percent of microbial species and 87.8% of brain functional network connectivity from each component also showed significant differences between SZ and HC with strong performance in classifying SZ from HC, with an area under curve (AUC) = 0.84 and 0.87, respectively. The results suggest a potential link between oral microbiome dysbiosis and brain functional connectivity alteration in relation to SZ, possibly through immunological and neurotransmitter signaling pathways and the hypothalamic-pituitary-adrenal axis, supporting for future work in characterizing the role of oral microbiome in mediating effects on SZ brain functional activity.

Unraveling the Link between Olfactory Deficits and Neuropsychiatric Disorders

Smell loss has caught public attention during the recent COVID-19 pandemic. Research on olfactory function in health and disease gains new momentum. Smell deficits have long been recognized as an early clinical sign associated with neuropsychiatric disorders. Here we review research on the associations between olfactory deficits and neuropathological conditions, focusing on recent progress in four areas: (1) human clinical studies of the correlations between smell deficits and neuropsychiatric disorders; (2) development of olfactory mucosa-derived tissue and cell models for studying the molecular pathologic mechanisms; (3) recent findings in brain imaging studies of structural and functional connectivity changes in olfactory pathways in neuropsychiatric disorders; and (4) application of preclinical animal models to validate and extend the findings from human subjects. Together, these studies have provided strong evidence of the link between the olfactory system and neuropsychiatric disorders, highlighting the relevance of deepening our understanding of the role of the olfactory system in pathophysiological processes. Following the lead of studies reviewed here, future research in this field may open the door to the early detection of neuropsychiatric disorders, personalized treatment approaches, and potential therapeutic interventions through nasal administration techniques, such as nasal brush or nasal spray.

Trends in socioeconomic inequalities in incidence of severe mental illness - A population-based linkage study using primary and secondary care routinely collected data between 2000 and 2017

OBJECTIVE

In 2008, the UK entered a period of economic recession followed by sustained austerity measures. We investigate changes in inequalities by area deprivation and urbanicity in incidence of severe mental illness (SMI, including schizophrenia-related disorders and bipolar disorder) between 2000 and 2017.

METHODS

We analysed 4.4 million individuals from primary and secondary care routinely collected datasets (2000-2017) in Wales and estimated the incidence of SMI by deprivation and urbanicity measured by the Welsh Index of Multiple Deprivation (WIMD) and urban/rural indicator respectively. Using linear modelling and joinpoint regression approaches, we examined time trends of the incidence and incidence rate ratios (IRR) of SMI by the WIMD and urban/rural indicator adjusted for available confounders.

RESULTS

We observed a turning point of time trends of incidence of SMI at 2008/2009 where slope changes of time trends were significantly increasing. IRRs by deprivation/urbanicity remained stable or significantly decreased over the study period except for those with bipolar disorder sourced from secondary care settings, with increasing trend of IRRs (increase in IRR by deprivation after 2010: 1.6 % per year, 95 % CI: 1.0 %-2.2 %; increase in IRR by urbanicity 1.0 % per year, 95 % CI: 0.6 %-1.3 %).

CONCLUSIONS

There was an association between recession/austerity and an increase in the incidence of SMI over time. There were variations in the effects of deprivation/urbanicity on incidence of SMI associated with short- and long-term socioeconomic change. These findings may support targeted interventions and social protection systems to reduce incidence of SMI.

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.

Polygenic risk, familial liability and stress reactivity in psychosis: an experience sampling study

BACKGROUND

There is evidence for a polygenic contribution to psychosis. One targetable mechanism through which polygenic variation may impact on individuals and interact with the social environment is stress sensitization, characterized by elevated reactivity to minor stressors in daily life. The current study aimed to investigate whether stress reactivity is modified by polygenic risk score for schizophrenia (PRS) in cases with enduring non-affective psychotic disorder, first-degree relatives of cases, and controls.

METHODS

We used the experience sampling method to assess minor stressors, negative affect, positive affect and psychotic experiences in 96 cases, 79 first-degree relatives, i.e. siblings, and 73 controls at wave 3 of the Dutch Genetic Risk and Outcome of Psychosis (GROUP) study. Genome-wide data were collected at baseline to calculate PRS.

RESULTS

We found that associations of momentary stress with psychotic experiences, but not with negative and positive affect, were modified by PRS and group (all pFWE<0.001). In contrast to our hypotheses, siblings with high PRS reported less intense psychotic experiences in response to momentary stress compared to siblings with low PRS. No differences in magnitude of these associations were observed in cases with high v. low level of PRS. By contrast, controls with high PRS showed more intense psychotic experiences in response to stress compared to those with low PRS.

CONCLUSIONS

This tentatively suggests that polygenic risk may operate in different ways than previously assumed and amplify reactivity to stress in unaffected individuals but operate as a resilience factor in relatives by attenuating their stress reactivity.

Genome-Environment Interactions and Psychiatric Disorders

Environmental factors are known to interact with the genome by altering epigenetic mechanisms regulating gene expression and contributing to the pathogenesis of psychiatric disorders. This article is a narrative review of how the major environmental factors contribute to the pathogenesis of common psychiatric disorders such as schizophrenia, bipolar disorder, major depressive disorder, and anxiety disorder this way. The cited articles were published between 1 January 2000 and 31 December 2022 and were obtained from PubMed and Google Scholar. The search terms used were as follows: gene or genetic; genome; environment; mental or psychiatric disorder; epigenetic; and interaction. The following environmental factors were found to act epigenetically on the genome to influence the pathogenesis of psychiatric disorders: social determinants of mental health, maternal prenatal psychological stress, poverty, migration, urban dwelling, pregnancy and birth complications, alcohol and substance abuse, microbiota, and prenatal and postnatal infections. The article also discusses the ways by which factors such as drugs, psychotherapy, electroconvulsive therapy, and physical exercise act epigenetically to alleviate the symptoms of psychiatric disorders in affected patients. These data will be useful information for clinical psychiatrists and those researching the pathogenesis and treatment of psychiatric disorders.

Differential effects of parental socioeconomic status on cortical thickness in patients with schizophrenia spectrum disorders and healthy controls

OBJECTIVES

Widespread changes in cortical thickness (CT) have been repeatedly reported in schizophrenia (SZ). The nature of the pathophysiologic process underlying such changes remains to be elucidated. The aims of the present study were to measure the CT; evaluate parent socioeconomic status (pSES), childhood trauma (ChT) and premorbid adjustment (PA) in patients with schizophrenia spectrum disorders (SSDs); and investigate group differences in CT (i.e., SSD vs. healthy controls (HCs)), pSES, PA, and/or ChT, as well as the interactions among these factors.

METHODS

164 patients with SSD and 245 age-, sex- and education-matched healthy controls have participated. The pSES, ChT and PA were evaluated using Korean version of Polyenvironmental Risk Score, Early Trauma Inventory Self Report-Short Form and Premorbid Adjustment Scale, respectively. Vertex-wise measure of CT was estimated using the FreeSurfer. To investigate the main effects and interactions, multilevel regression was employed.

RESULTS

We found widespread cortical thinning in patients with SSDs compared to HCs. The cortical thinning was associated with ChT, symptom severity and chlorpromazine equivalent dose and duration of illness in patients. In multilevel regression, main effects of group and pSES and interaction between group and pSES were found whereas a significant interaction between ChT and CPZ equivalent was found in patients.

CONCLUSION

Our findings indicate that compared to HCs, patients with SSDs have cortical structural abnormalities, and that group and pSES interaction determines CT. Further studies are needed to explore the effects of psychosocial factors on brain structural and functional abnormalities in SZ.

Cumulative Environmental Risk in Early Life: Associations With Schizotypy in Childhood

BACKGROUND AND HYPOTHESIS

Psychotic disorders are associated with a growing number of recognized environmental exposures. Cumulative exposure to multiple environmental risk factors in childhood may contribute to the development of different patterns of schizotypy evident in early life. Hypotheses were that distinct profiles of schizotypy would have differential associations with a cumulative score of environmental risk factors.

STUDY DESIGN

We prospectively examined the relationship between 19 environmental exposures (which had demonstrated replicated associations with psychosis) measured from the prenatal period through to age 11 years, and 3 profiles of schizotypy in children (mean age = 11.9 years, n = 20 599) that have been established in population data from the New South Wales-Child Development Study. Multinomial logistic regression was used to examine associations between membership in each of 3 schizotypy profiles (true schizotypy, introverted schizotypy, and affective schizotypy) and exposure to a range of 19 environmental risk factors for psychosis (both individually and summed as a cumulative environmental risk score [ERS]), relative to children showing no risk.

RESULTS

Almost all environmental factors were associated with at least 1 schizotypy profile. The cumulative ERS was most strongly associated with the true schizotypy profile (OR = 1.61, 95% CI = 1.52-1.70), followed by the affective (OR = 1.33, 95% CI = 1.28-1.38), and introverted (OR = 1.32, 95% CI = 1.28-1.37) schizotypy profiles.

CONCLUSIONS

Consistent with the cumulative risk hypothesis, results indicate that an increased number of risk exposures is associated with an increased likelihood of membership in the 3 schizotypy profiles identified in middle childhood, relative to children with no schizotypy profile.

Neurodevelopmental disturbances in schizophrenia: evidence from genetic and environmental factors

Since more than 3 decades, schizophrenia (SZ) has been regarded as a neurodevelopmental disorder. The neurodevelopmental hypothesis proposes that SZ is associated with genetic and environmental risk factors, which influence connectivity in neuronal circuits during vulnerable developmental periods. We carried out a non-systematic review of genetic/environmental factors that increase SZ risk in light of its neurodevelopmental hypothesis. We also reviewed the potential impact of SZ-related environmental and genetic risk factors on grey and white matter pathology and brain function based on magnetic resonance imaging and post-mortem studies. Finally, we reviewed studies that have used patient-derived neuronal models to gain knowledge of the role of genetic and environmental factors in early developmental stages. Taken together, these studies indicate that a variety of environmental factors may interact with genetic risk factors during the pre- or postnatal period and/or during adolescence to induce symptoms of SZ in early adulthood. These risk factors induce disturbances of macro- and microconnectivity in brain regions involving the prefrontal, temporal and parietal cortices and the hippocampus. On the molecular and cellular level, a disturbed synaptic plasticity, loss of oligodendrocytes and impaired myelination have been shown in brain regions of SZ patients. These cellular/histological phenotypes are related to environmental risk factors such as obstetric complications, maternal infections and childhood trauma and genetic risk factors identified in recent genome-wide association studies. SZ-related genetic risk may contribute to active processes interfering with synaptic plasticity in the adult brain. Advances in stem cell technologies are providing promising mechanistic insights into how SZ risk factors impact the developing brain. Further research is needed to understand the timing of the different complex biological processes taking place as a result of the interplay between genetic and environmental factors.

Psychosocial factors associated with the risk of developing psychosis in a Mexican general population sample

Epidemiological evidence has linked an array of sociodemographic and psychosocial factors with an increased risk of developing psychosis. However, research in samples from low- and middle-income countries is still scarce. This study used a Mexican sample to explore (i) sociodemographic and psychosocial differences between individuals with and without a positive screen for Clinical High-Risk for psychosis (CHR), and (ii) sociodemographic and psychosocial factors associated with screening positive for CHR. The sample consisted of 822 individuals from the general population who completed an online survey. Of the participants, 17.3% (n = 142) met the CHR screening criteria. Comparisons between those who screened positive (CHR-positive group) and those who did not (Non-CHR group) showed that participants in the CHR-positive group were younger, had a lower educational level, and reported more mental health problems than the Non-CHR group. Furthermore, relative to the Non-CHR group, the CHR-positive group had a greater prevalence of medium/high risk associated with cannabis use, a higher prevalence of adverse experiences (bullying, intimate partner violence, and experiencing a violent or unexpected death of a relative or friend), as well as higher levels of childhood maltreatment, poorer family functioning, and more distress associated with the COVID-19 pandemic. Groups did not differ in sex, marital/relationship status, occupation, and socio-economic status. Finally, when examined in multivariate analyses, the variables associated with screening positive for CHR were: having an unhealthy family functioning (OR = 2.75, 95%CI 1.69-4.46), a higher risk associated with cannabis use (OR = 2.75, 95%CI 1.63-4.64), a lower level of education (OR = 1.55, 95%CI 1.003-2.54), having experienced a major natural disaster (OR = 1.94, 95%CI 1.18-3.16), having experienced a violent or unexpected death of a relative or friend (OR = 1.85, 95%CI 1.22-2.81), higher levels of childhood emotional abuse (OR = 1.88, 95%CI 1.09-3.25), physical neglect (OR = 1.68, 95%CI 1.08-2.61), and physical abuse (OR = 1.66, 95%CI 1.05-2.61), and higher COVID-related distress (OR = 1.10, 95%CI 1.01-1.20). An older age was a protective factor for screening positive for CHR (OR = 0.96, 95%CI 0.92-0.99). Overall, the findings highlight the importance of examining potential psychosocial contributors to psychosis vulnerability across different sociocultural contexts to delineate risk and protective processes relevant to specific populations and better target preventive intervention efforts.

Methamphetamine-induced locomotor sensitization in mice is not associated with deficits in a range of cognitive, affective and social behaviours: interaction with brain-derived neurotrophic factor Val66Met genotype

Chronic methamphetamine (Meth) abuse may induce psychosis similar to that observed in schizophrenia. Brain-derived neurotrophic factor (BDNF) has been implicated in the development of psychosis. We have previously shown long-term protein expression changes in mice treated chronically with Meth depending on BDNF Val66Met genotype. The aim of this study was to investigate if these protein expression changes were associated with differential changes in a range of behavioural paradigms for cognition, anxiety, social and other behaviours. Male and female Val/Val, Val/Met and Met/Met mice were treated with an escalating Meth dose protocol from 6 to 9 weeks of age, with controls receiving saline injections. Several overlapping cohorts were tested in the Y-maze for short-term spatial memory, novel-object recognition test, context and cued fear conditioning, sociability and social preference, elevated plus maze for anxiety-like behaviour and prepulse inhibition (PPI) of acoustic startle. Finally, the animals were assessed for spontaneous exploratory locomotor activity and acute Meth-induced locomotor hyperactivity. Acute Meth caused significantly greater locomotor hyperactivity in mice previously treated with the drug than in saline-pretreated controls. Meth-pretreated female mice showed a mild increase in spontaneous locomotor activity. There were no Meth-induced deficits in any of the other behavioural tests. Val/Met mice showed higher overall social investigation time and lower PPI compared with the Val/Val genotype independent of pretreatment. These results show limited long-term effects of chronic Meth on a range of cognitive, affective and social behaviours despite marked drug-induced locomotor sensitization in mice. There was no interaction with BDNF Val66Met genotype.

DNA methylation signature aberration as potential biomarkers in treatment-resistant schizophrenia: Constructing a methylation risk score using a machine learning method

Treatment-resistant schizophrenia (TRS) is defined as a non-response to at least two trials of antipsychotic medication with an adequate dose and duration. We aimed to evaluate the discriminant abilities of DNA methylation probes and methylation risk score between treatment-resistant schizophrenia and non-treatment-resistant schizophrenia. This study recruited 96 schizophrenia patients (TRS and non-TRS) and 56 healthy controls (HC). Participants were divided into a discovery set and a validation set. In the discovery set, we conducted genome-wide methylation analysis (human MethylationEPIC 850K BeadChip) on the subject's blood DNA and discriminated significant methylation signatures, then verified these methylation signatures in the validation set. Based on genome-wide scans of TRS versus non-TRS, thirteen differentially methylated probes were identified at FDR <0.05 and >20% differences in DNA methylation β-values. Next, we selected six probes within gene coding regions (LOC404266, LOXL2, CERK, CHMP7, and SLC17A9) to conduct verification in the validation set using quantitative methylation-specific PCR (qMSP). These six methylation probes showed satisfactory discrimination between TRS patients and non-TRS patients, with an AUC ranging from 0.83 to 0.92, accuracy ranging from 77.8% to 87.3%, sensitivity ranging from 80% to 90%, and specificity ranging from 65.6% to 85%. This methylation risk score model showed satisfactory discrimination between TRS patients and non-TRS patients, with an accuracy of 88.3%. These findings support that methylation signatures may be used as an indicator of TRS vulnerability and provide a model for the clinical use of methylation to identify TRS.

Are the epigenetic changes predictive of therapeutic efficacy for psychiatric disorders? A translational approach towards novel drug targets

The etiopathogenesis of mental disorders is not fully understood and accumulating evidence support that clinical symptomatology cannot be assigned to a single gene mutation, but it involves several genetic factors. More specifically, a tight association between genes and environmental risk factors, which could be mediated by epigenetic mechanisms, may play a role in the development of mental disorders. Several data suggest that epigenetic modifications such as DNA methylation, post-translational histone modification and interference of microRNA (miRNA) or long non-coding RNA (lncRNA) may modify the severity of the disease and the outcome of the therapy. Indeed, the study of these mechanisms may help to identify patients particularly vulnerable to mental disorders and may have potential utility as biomarkers to facilitate diagnosis and treatment of psychiatric disorders. This article summarizes the most relevant preclinical and human data showing how epigenetic modifications can be central to the therapeutic efficacy of antidepressant and/or antipsychotic agents, as possible predictor of drugs response.

The critical periods of cerebral plasticity: A key aspect in a dialog between psychoanalysis and neuroscience centered on the psychopathology of schizophrenia

Through research into the molecular and cellular mechanisms that occur during critical periods, recent experimental neurobiological data have brought to light the importance of early childhood. These have demonstrated that childhood and early environmental stimuli play a part not only in our subjective construction, but also in brain development; thus, confirming Freud's intuition regarding the central role of childhood and early experiences of the environment in our psychological development and our subjective outcomes. "Critical periods" of cerebral development represent temporal windows that mark favorable, but also circumscribed, moments in developmental cerebral plasticity. They also vary between different cortical areas. There are, therefore, strictly defined temporal periods for learning language, music, etc., after which this learning becomes more difficult, or even impossible, to acquire. Now, research into these critical periods can be seen as having a significant part to play in the interdisciplinary dialog between psychoanalysis and neurosciences with regard to the role of early experiences in the etiology of some psychopathological conditions. Research into the cellular and molecular mechanisms controlling the onset and end of these critical periods, notably controlled by the maturation of parvalbumin-expressing basket cells, have brought to light the presence of anomalies in the maturation of these neurons in patients with schizophrenia. Starting from these findings we propose revisiting the psychoanalytic theories on the etiology of psychosis from an interdisciplinary perspective. Our study works from the observation, common to both psychoanalysis and neurosciences, that experience leaves a trace; be it a "psychic" or a "synaptic" trace. Thus, we develop a hypothesis for an "absence of trace" in psychosis; reexamining psychosis through the prism of the biological theory of critical periods in plasticity.

Effect of stressful life events on subclinical psychotic symptoms in first-degree relatives and healthy controls

Exposure to Stressful Life Events (SLEs) has been linked to psychosis. However, the combined effect of SLEs and familial risk on subclinical psychotic symptoms over time remains unknown. The objective of the present study was to investigate the effect of SLEs on the level of subclinical psychotic symptoms in individuals with and without familial vulnerability for psychosis. Data were collected from siblings of individuals diagnosed with psychotic disorder and healthy controls at baseline (N = 293) and three years later at follow-up (N = 928). We assessed self-reported and observer-rated subclinical positive, negative, and depressive psychotic symptoms. Participants reported the number of SLEs in the preceding 6 months. A multilevel multivariate regression analysis revealed a positive association between the retrospectively assessed number of SLEs and symptom levels, regardless of vulnerability status (p < .001 for all outcomes). The prospective analysis demonstrated that exposure to SLEs at baseline predicted higher levels of subclinical psychotic symptoms at follow-up. However, after controlling for the level of symptoms at baseline, these associations were no longer significant. Again, the vulnerability status did not modify these results. Nevertheless, siblings in our sample were approximating the end of the critical period for the development of psychotic disorder (mean age at baseline M = 29 and follow-up M = 34). The findings partly support the vulnerability-stress model of psychosis, yet do not confirm the role of familial risk in this association. SLEs may represent a risk factor for psychosis at a population level, thus supporting the continuity of the psychosis spectrum in terms of associated risk factors.

Positive Affective Recovery in Daily Life as a Momentary Mechanism Across Subclinical and Clinical Stages of Mental Disorder: Experience Sampling Study

BACKGROUND

Identifying momentary risk and protective mechanisms may enhance our understanding and treatment of mental disorders. Affective stress reactivity is one mechanism that has been reported to be altered in individuals with early and later stages of mental disorder. Additionally, initial evidence suggests individuals with early and enduring psychosis may have an extended recovery period of negative affect in response to daily stressors (ie, a longer duration until affect reaches baseline levels after stress), but evidence on positive affective recovery as a putative protective mechanism remains limited.

OBJECTIVE

This study aimed to investigate trajectories of positive affect in response to stress across the continuum of mental disorder in a transdiagnostic sample.

METHODS

Using the Experience Sampling Method, minor activity-, event-, and overall stress and positive affect were assessed 10 times a day, with time points approximately 90 minutes apart on six consecutive days in a pooled data set including 367 individuals with a mental disorder, 217 individuals at risk for a severe mental disorder, and 227 controls. Multilevel analysis and linear contrasts were used to investigate trajectories of positive affect within and between groups.

RESULTS

Baseline positive affect differed across groups, and we observed stress reactivity in positive affect within each group. We found evidence for positive affective recovery after reporting activity- or overall stress within each group. While controls recovered to baseline positive affect about 90 minutes after stress, patients and at-risk individuals required about 180 minutes to recover. However, between-group differences in the affective recovery period fell short of significance (all P>.05).

CONCLUSIONS

The results provide first evidence that positive affective recovery may be relevant within transdiagnostic subclinical and clinical stages of mental disorder, suggesting that it may be a potential target for mobile health interventions fostering resilience in daily life.

Early trauma and schizophrenia onset: preliminary results of an outpatient cohort in Brazil

OBJECTIVES

To assess the prevalence of early trauma in individuals with onset of schizophrenia (SZ) at early (≤ 18 years) and adult (> 18 years) ages (EOP and AOP, respectively) and explore relationships between the onset of disease and clinical variables including traumatic events and psychotic and mood symptoms.

METHODS

Subjects with SZ (n = 71) and EOP and AOP were compared for history of psychological trauma, sexual abuse, and physical punishment using the Early Trauma Inventory Self Report - Short Form (ETISR-SF). They were also compared for history of comorbidities and affective disorders using the Diagnostic Interview for Psychosis and Affective Disorders, the Positive and Negative Syndrome Scale, the Liebowitz Social Anxiety Scale, and the Calgary Depression Scale for Schizophrenia. Coefficients were calculated for correlations between scale results and disease duration.

RESULTS

Early trauma was significantly associated with an early onset psychotic episode (r = -0.315, p < 0.01). General trauma and depressive symptoms in adulthood were also associated (r = 0.442, p < 0.01), as were social anxiety symptoms and early trauma (r = 0.319, p < 0.01). Total ETISR-SF scores and the physical abuse item were significantly higher in EOP than in AOP. In the hierarchical regression, PANSS scores were best predicted by a model including the duration of disease and age of first psychotic episode (R = 0.303).

CONCLUSIONS

Our results support the hypothesis that early trauma, including physical abuse, may play a relevant role in schizophrenia symptoms, such as an earlier psychotic occurrence, as well as features of other psychiatric disorders, such as greater severity of social anxiety and depression.

Advancing translational research in neuroscience through multi-task learning

Translational research in neuroscience is increasingly focusing on the analysis of multi-modal data, in order to account for the biological complexity of suspected disease mechanisms. Recent advances in machine learning have the potential to substantially advance such translational research through the simultaneous analysis of different data modalities. This review focuses on one of such approaches, the so-called "multi-task learning" (MTL), and describes its potential utility for multi-modal data analyses in neuroscience. We summarize the methodological development of MTL starting from conventional machine learning, and present several scenarios that appear particularly suitable for its application. For these scenarios, we highlight different types of MTL algorithms, discuss emerging technological adaptations, and provide a step-by-step guide for readers to apply the MTL approach in their own studies. With its ability to simultaneously analyze multiple data modalities, MTL may become an important element of the analytics repertoire used in future neuroscience research and beyond.

Modelling the temporal interplay between stress and affective disturbances in pathways to psychosis: an experience sampling study

BACKGROUND

One putative psychological mechanism through which momentary stress impacts on psychosis in individuals with increased liability to the disorder is via affective disturbance. However, to date, this has not been systematically tested. We aimed to investigate whether (i) cross-sectional and temporal effects of momentary stress on psychotic experiences via affective disturbance, and (ii) the reverse pathway of psychotic experiences on stress via affective disturbance were modified by familial liability to psychosis.

METHODS

The Experience Sampling Method was used in a pooled data set of six studies with three groups of 245 individuals with psychotic disorder, 165 unaffected first-degree relatives, and 244 healthy control individuals to index familial liability. Multilevel moderated mediation models were fitted to investigate indirect effects across groups cross-sectionally and multilevel cross-lagged panel models to investigate temporal effects in the proposed pathways across two measurement occasions.

RESULTS

Evidence on indirect effects from cross-sectional models indicated that, in all three groups, effects of stress on psychotic experiences were mediated by negative affect and, vice versa, effects of psychotic experiences on stress were mediated by negative affect, with all indirect effects being weakest in relatives. Longitudinal modelling of data provided no evidence of temporal priority of stress in exerting its indirect effects on psychotic experiences via affective disturbance or, vice versa.

CONCLUSIONS

Our findings tentatively suggest a rapid vicious cycle of stress impacting psychotic experiences via affective disturbances, which does, however, not seem to be consistently modified by familial liability to psychosis.

Attenuated transcriptional response to pro-inflammatory cytokines in schizophrenia hiPSC-derived neural progenitor cells

Maternal immune activation (MIA) during prenatal development is an environmental risk factor for psychiatric disorders including schizophrenia (SZ). Converging lines of evidence from human and animal model studies suggest that elevated cytokine levels in the maternal and fetal compartments are an important indication of the mechanisms driving this association. However, there is variability in susceptibility to the psychiatric risk conferred by MIA, likely influenced by genetic factors. How MIA interacts with a genetic profile susceptible to SZ is challenging to test in animal models. To address this gap, we examined whether differential gene expression responses occur in forebrain-lineage neural progenitor cells (NPCs) derived from human induced pluripotent stem cells (hiPSC) generated from three individuals with a diagnosis of schizophrenia and three healthy controls. Following acute (24 h) treatment with either interferon-gamma (IFNγ; 25 ng/μl) or interleukin (IL)-1β (10 ng/μl), we identified, by RNA sequencing, 3380 differentially expressed genes (DEGs) in the IFNγ-treated control lines (compared to untreated controls), and 1980 DEGs in IFNγ-treated SZ lines (compared to untreated SZ lines). Out of 4137 genes that responded significantly to IFNγ across all lines, 1223 were common to both SZ and control lines. The 2914 genes that appeared to respond differentially to IFNγ treatment in SZ lines were subjected to a further test of significance (multiple testing correction applied to the interaction effect between IFNγ treatment and SZ diagnosis), yielding 359 genes that passed the significance threshold. There were no differentially expressed genes in the IL-1β-treatment conditions after Benjamini-Hochberg correction. Gene set enrichment analysis however showed that IL-1β impacts immune function and neuronal differentiation. Overall, our data suggest that a) SZ NPCs show an attenuated transcriptional response to IFNγ treatment compared to controls; b) Due to low IL-1β receptor expression in NPCs, NPC cultures appear to be less responsive to IL-1β than IFNγ; and c) the genes differentially regulated in SZ lines - in the face of a cytokine challenge - are primarily associated with mitochondrial, "loss-of-function", pre- and post-synaptic gene sets. Our findings particularly highlight the role of early synaptic development in the association between maternal immune activation and schizophrenia risk.

Immune Activation in Pregnant Rats Affects Brain Glucose Consumption, Anxiety-like Behaviour and Recognition Memory in their Male Offspring

PURPOSE

Prenatal infection during pregnancy is a risk factor for schizophrenia, as well as for other developmental psychiatric disorders, such as autism and bipolar disorder. Schizophrenia patients were reported to have altered brain metabolism and neuroinflammation. However, the link between prenatal infection, altered brain inflammation and metabolism, and schizophrenia remains unclear. In this project, we aimed to evaluate whether there are changes in brain glucose consumption and microglia activation in the offspring of pregnant rats exposed to maternal immune activation (MIA), and if so, whether these changes occur before or after the initiation of schizophrenia-like behaviour.

PROCEDURES

Pregnant rats were treated with the viral mimic polyinosinic-polycytidylic acid (MIA group) or saline (control group) on gestational day 15. Static PET scans of the male offspring were acquired on postnatal day (PND) 21, 60, and 90, using [11C]-PK11195 and deoxy-2-[18F]fluoro-D-glucose ([18F]-FDG) as tracers to measure TSPO expression in activated microglia and brain glucose consumption, respectively. On PND60 and PND90, anxiety-like behaviour, recognition memory, and sensorimotor gating were measured using the open field test (OFT), novel object recognition test (NOR), and prepulse inhibition test (PPI).

RESULTS

[18F]-FDG PET demonstrated that MIA offspring displayed higher brain glucose consumption in the whole brain after weaning (p = 0.017), and in the frontal cortex during late adolescence (p = 0.001) and adulthood (p = 0.037) than control rats. [11C]-PK11195 PET did not reveal any changes in TSPO expression in MIA offspring. Prenatal infection induced age-related behavioural alterations. Adolescent MIA offspring displayed a more anxious state in the OFT than controls (p = 0.042). Adult MIA offspring showed recognition memory deficits in the NOR (p = 0.003). Our study did not show any PPI deficits.

CONCLUSIONS

Our results suggest that prenatal immune activation changed neurodevelopment, resulting in increased brain glucose consumption, but not in microglia activation. The increased brain glucose consumption in the frontal cortex of MIA offspring remained until adulthood and was associated with increased anxiety-like behaviour during adolescence and recognition memory deficits in adulthood.

Schizophrenia Polygenic Risk and Experiences of Childhood Adversity: A Systematic Review and Meta-analysis

BACKGROUND AND HYPOTHESIS

Schizophrenia has been robustly associated with multiple genetic and environmental risk factors. Childhood adversity is one of the most widely replicated environmental risk factors for schizophrenia, but it is unclear if schizophrenia genetic risk alleles contribute to this association.

STUDY DESIGN

In this systematic review and meta-analysis, we assessed the evidence for gene-environment correlation (genes influence likelihood of environmental exposure) between schizophrenia polygenic risk score (PRS) and reported childhood adversity. We also assessed the evidence for a gene-environment interaction (genes influence sensitivity to environmental exposure) in relation to the outcome of schizophrenia and/or psychosis. This study was registered on PROSPERO (CRD42020182812). Following PRISMA guidelines, a search for relevant literature was conducted using Cochrane, MEDLINE, PsycINFO, Web of Science, and Scopus databases until February 2022. All studies that examined the association between schizophrenia PRS and childhood adversity were included.

STUDY RESULTS

Seventeen of 650 identified studies met the inclusion criteria and were assessed against the Newcastle-Ottawa Scale for quality. The meta-analysis found evidence for gene-environment correlation between schizophrenia PRS and childhood adversity (r = .02; 95% CI = 0.01, 0.03; P = .001), but the effect was small and therefore likely to explain only a small proportion of the association between childhood adversity and psychosis. The 4 studies that investigated a gene-environment interaction between schizophrenia PRS and childhood adversity in increasing risk of psychosis reported inconsistent results.

CONCLUSIONS

These findings suggest that a gene-environment correlation could explain a small proportion of the relationship between reported childhood adversity and psychosis.

Prognostic accuracy and clinical utility of psychometric instruments for individuals at clinical high-risk of psychosis: a systematic review and meta-analysis

Accurate prognostication of individuals at clinical high-risk for psychosis (CHR-P) is an essential initial step for effective primary indicated prevention. We aimed to summarise the prognostic accuracy and clinical utility of CHR-P assessments for primary indicated psychosis prevention. Web of Knowledge databases were searched until 1st January 2022 for longitudinal studies following-up individuals undergoing a psychometric or diagnostic CHR-P assessment, reporting transition to psychotic disorders in both those who meet CHR-P criteria (CHR-P + ) or not (CHR-P-). Prognostic accuracy meta-analysis was conducted following relevant guidelines. Primary outcome was prognostic accuracy, indexed by area-under-the-curve (AUC), sensitivity and specificity, estimated by the number of true positives, false positives, false negatives and true negatives at the longest available follow-up time. Clinical utility analyses included: likelihood ratios, Fagan's nomogram, and population-level preventive capacity (Population Attributable Fraction, PAF). A total of 22 studies (n = 4 966, 47.5% female, age range 12-40) were included. There were not enough meta-analysable studies on CHR-P diagnostic criteria (DSM-5 Attenuated Psychosis Syndrome) or non-clinical samples. Prognostic accuracy of CHR-P psychometric instruments in clinical samples (individuals referred to CHR-P services or diagnosed with 22q.11.2 deletion syndrome) was excellent: AUC = 0.85 (95% CI: 0.81-0.88) at a mean follow-up time of 34 months. This result was driven by outstanding sensitivity (0.93, 95% CI: 0.87-0.96) and poor specificity (0.58, 95% CI: 0.50-0.66). Being CHR-P + was associated with a small likelihood ratio LR + (2.17, 95% CI: 1.81-2.60) for developing psychosis. Being CHR-P- was associated with a large LR- (0.11, 95%CI: 0.06-0.21) for developing psychosis. Fagan's nomogram indicated a low positive (0.0017%) and negative (0.0001%) post-test risk in non-clinical general population samples. The PAF of the CHR-P state is 10.9% (95% CI: 4.1-25.5%). These findings consolidate the use of psychometric instruments for CHR-P in clinical samples for primary indicated prevention of psychosis. Future research should improve the ability to rule in psychosis risk.

Schizophrenia-associated differential DNA methylation in brain is distributed across the genome and annotated to MAD1L1, a locus at which DNA methylation and transcription phenotypes share genetic variation with schizophrenia risk

DNA methylation (DNAm), the addition of a methyl group to a cytosine in DNA, plays an important role in the regulation of gene expression. Single-nucleotide polymorphisms (SNPs) associated with schizophrenia (SZ) by genome-wide association studies (GWAS) often influence local DNAm levels. Thus, DNAm alterations, acting through effects on gene expression, represent one potential mechanism by which SZ-associated SNPs confer risk. In this study, we investigated genome-wide DNAm in postmortem superior temporal gyrus from 44 subjects with SZ and 44 non-psychiatric comparison subjects using Illumina Infinium MethylationEPIC BeadChip microarrays, and extracted cell-type-specific methylation signals by applying tensor composition analysis. We identified SZ-associated differential methylation at 242 sites, and 44 regions containing two or more sites (FDR cutoff of q = 0.1) and determined a subset of these were cell-type specific. We found mitotic arrest deficient 1-like 1 (MAD1L1), a gene within an established GWAS risk locus, harbored robust SZ-associated differential methylation. We investigated the potential role of MAD1L1 DNAm in conferring SZ risk by assessing for colocalization among quantitative trait loci for methylation and gene transcripts (mQTLs and tQTLs) in brain tissue and GWAS signal at the locus using multiple-trait-colocalization analysis. We found that mQTLs and tQTLs colocalized with the GWAS signal (posterior probability >0.8). Our findings suggest that alterations in MAD1L1 methylation and transcription may mediate risk for SZ at the MAD1L1-containing locus. Future studies to identify how SZ-associated differential methylation affects MAD1L1 biological function are indicated.

Persistent Childhood and Adolescent Anxiety and Risk for Psychosis: A Longitudinal Birth Cohort Study

BACKGROUND

Persistent anxiety in childhood and adolescence could represent a novel treatment target for psychosis, potentially targeting activation of stress pathways and secondary nonresolving inflammatory response. Here, we examined the association between persistent anxiety through childhood and adolescence with individuals with psychotic experiences (PEs) or who met criteria for psychotic disorder (PD) at age 24 years. We also investigated whether C-reactive protein mediated any association.

METHODS

Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) were available in 8242 children at age 8 years, 7658 at age 10 years, 6906 at age 13 years, and 3889 at age 24 years. The Development and Well-Being Assessment was administered to capture child and adolescent anxiety. We created a composite score of generalized anxiety at ages 8, 10, and 13. PEs and PD were assessed at age 24, derived from the Psychosis-like Symptoms Interview. The mean of C-reactive protein at ages 9 and 15 years was used as a mediator.

RESULTS

Individuals with persistent high levels of anxiety were more likely to develop PEs (odds ratio 2.02, 95% CI 1.26-3.23, p = .003) and PD at age 24 (odds ratio 4.23, 95% CI 2.27-7.88, p < .001). The mean of C-reactive protein at ages 9 and 15 mediated the associations of persistent anxiety with PEs (bias-corrected estimate -0.001, p = .013) and PD (bias-corrected estimate 0.001, p = .003).

CONCLUSIONS

Persistent high levels of anxiety through childhood and adolescence could be a risk factor for psychosis. Persistent anxiety is potentially related to subsequent psychosis via activation of stress hormones and nonresolving inflammation. These results contribute to the potential for preventive interventions in psychosis, with the novel target of early anxiety.

First-Episode Psychosis Patients Who Deteriorated in the Premorbid Period Do Not Have Higher Polygenic Risk Scores Than Others: A Cluster Analysis of EU-GEI Data

Cluster studies identified a subgroup of patients with psychosis whose premorbid adjustment deteriorates before the onset, which may reflect variation in genetic influence. However, other studies reported a complex relationship between distinctive patterns of cannabis use and cognitive and premorbid impairment that is worthy of consideration. We examined whether: (1) premorbid social functioning (PSF) and premorbid academic functioning (PAF) in childhood and adolescence and current intellectual quotient (IQ) define different clusters in 802 first-episode of psychosis (FEP) patients; resulting clusters vary in (2) polygenic risk scores (PRSs) for schizophrenia (SCZ_PRS), bipolar disorder (BD_PRS), major depression (MD_PRS), and IQ (IQ_PRS), and (3) patterns of cannabis use, compared to 1,263 population-based controls. Four transdiagnostic clusters emerged (BIC = 2268.5): (1) high-cognitive-functioning (n = 205), with the highest IQ (Mean = 106.1, 95% CI: 104.3, 107.9) and PAF, but low PSF. (2) Low-cognitive-functioning (n = 223), with the lowest IQ (Mean = 73.9, 95% CI: 72.2, 75.7) and PAF, but normal PSF. (3) Intermediate (n = 224) (Mean_IQ = 80.8, 95% CI: 79.1, 82.5) with low-improving PAF and PSF. 4) Deteriorating (n = 150) (Mean_IQ = 80.6, 95% CI: 78.5, 82.7), with normal-deteriorating PAF and PSF. The PRSs explained 7.9% of between-group membership. FEP had higher SCZ_PRS than controls [F(4,1319) = 20.4, P < .001]. Among the clusters, the deteriorating group had lower SCZ_PRS and was likelier to have used high-potency cannabis daily. Patients with FEP clustered according to their premorbid and cognitive abilities. Pronounced premorbid deterioration was not typical of most FEP, including those more strongly predisposed to schizophrenia, but appeared in a cluster with a history of high-potency cannabis use.

Impaired migration of autologous induced neural stem cells from patients with schizophrenia and implications for genetic risk for psychosis

Stem cell technologies have presented explicit evidence of the neurodevelopmental hypothesis of schizophrenia. However, few studies investigated relevance of the schizophrenia genetic liability and the use of genetic reprogramming on pluripotent stem cells to the impaired neurodevelopment shown by stem cells. Therefore, this study sought to investigate the cellular phenotypes of induced neural stem cells (iNSCs) derived without genetic modification from patients with schizophrenia and from genetic high risk (GHR) individuals. Three patients with a diagnosis of schizophrenia, 3 GHR individuals who had two or more relatives with schizophrenia, and 3 healthy volunteers participated. iNSCs were derived using a small molecule-based lineage switch method, and their gene expression levels and migration capabilities were examined. Demographic characteristics were not different among the groups (age, χ² = 5.637, P = .060; education, χ² = 2.111, P = .348). All participants stayed well during the follow-up except one GHR individual who developed psychosis 1.5 years later. Migration capacity was impaired in iNSCs from patients with schizophrenia (SZ-iNSCs) compared to iNSCs from GHR individuals or controls (P < .001). iNSCs from a GHR individual who later developed schizophrenia showed migratory impairment that was similar to SZ-iNSCs. Gene expression levels of Sox2 in SZ-iNSCs were significantly lower than those in controls (P = .028). Defective migration in genetically unmodified SZ-iNSCs is the first direct demonstration of neurodevelopmental abnormalities in schizophrenia. Additionally, alterations in gene expression in SZ-iNSCs suggest mechanisms by which genetic liability leads to aberrant neurodevelopment.