30 Years on: How the Neurodevelopmental Hypothesis of Schizophrenia Morphed Into the Developmental Risk Factor Model of Psychosis

"Schizophrenia, Consciousness, and the Self" Twenty Years Later: Revisiting the Ipseity-Disturbance Model and the Developmental Nature of Self-Disorder in the Schizophrenia Spectrum

Self-disorders (SD) designate a pattern of non-psychotic anomalous self-experiences, which specifically aggregate in clinical and subclinical forms of schizophrenia spectrum disorders (SSD), including familial high-risk configurations. SD have been corroborated as a valuable, quantitatively tractable, trait phenotype for indexing genetic liability to SSD, and, as a risk phenotype, they offer critical insights into the nature of these complex conditions which precede and shape the development of more overt clinical manifestations (including schizotypal features and positive, negative, and disorganized symptoms). In the last three decades, the concept of self-disorders has evolved from early clinical observations to a well-defined research domain, offering a nuanced understanding of schizophrenia spectrum vulnerabilities and holding promise for improving diagnostic accuracy, enhancing prognostic assessments, offering novel targets for intervention, and advancing our understanding of the schizophrenia spectrum.

Longitudinal Development of Neurocognitive Functioning and Gray Matter Volume in Youths With Recurrent Psychosis Spectrum Symptoms

BACKGROUND AND HYPOTHESIS

Neurodevelopmental risk-factor models of psychosis highlight the importance of early developmental deviations in the emergence of psychosis. However, few longitudinal studies map neurodevelopment and neurocognitive trajectories across age in preclinical psychosis. We investigated longitudinal trajectories in neurocognition and brain volume in a community cohort of adolescents with recurrent psychosis spectrum (PS) symptoms, tracking their development into young adulthood compared to their typically developing (TD) peers.

STUDY DESIGN

Utilizing the Philadelphia Neurodevelopmental Cohort, we analyzed data of 231 youths aged 8-30 with at least one follow-up assessment, including 88 with PS.

STUDY RESULTS

Individuals with PS showed similar developmental trajectories but demonstrated significant impairments in executive functioning (t = -2.81, q = 0.010), memory (t = -2.34, q = 0.019), complex cognition (t = -3.72, q = 0.001), social cognition (t = -2.73, q = 0.010), motor (t = -2.50, q = 0.015), and general cognition (t = -3.20, q = 0.004). Lower cortical (t = -2.46, P = .014) and subcortical (t = -2.41, P = .016) gray matter volume in the recurrent PS group compared to the TD group were documented with age-related group differences becoming less pronounced by young adulthood. Further analyses revealed age-by-group interactions (qs < 0.05) observed in a few temporal and frontal regions, with differences between groups at earlier ages.

CONCLUSIONS

These findings suggest that recurrent PS symptoms are linked to early neurocognitive and brain structure deficits, highlighting the need for interventions to reduce psychosis risk and support healthy neurodevelopment.

Causal links between personality disorders and schizophrenia: A Mendelian randomization study

Although observational studies have suggested associations between personality disorders and schizophrenia, the causality of these relationships remains unclear. Determining whether personality disorders causally contribute to schizophrenia could inform early identification and preventive efforts. We performed two-sample Mendelian randomization (MR) analysis using large-scale Genome-wide Association Study data from populations of European ancestry. Because no single nucleotide polymorphism for personality disorders reached the conventional genome-wide significance threshold (P < 5 × 10-8), we sequentially relaxed the criteria (P < 5 × 10-7, P < 5 × 10-6, P < 5 × 10-5) until at least 10 instrumental variables were obtained. Ultimately, 11-95 single nucleotide polymorphism met the relaxed threshold (P < 5 × 10-5), all with F-statistics > 10, thus ensuring robust instrumental variables. The inverse variance weighted method served as our primary MR approach, supplemented by MR-Egger, weighted median, and MR Robust Adjusted Profile Score analyses, to minimize confounding, reverse causation, and weak instrument bias. Inverse variance weighted analysis revealed a significant causal association between genetically predicted personality disorders and schizophrenia (odds ratios = 1.190, 95% confidence intervals: 1.122-1.261, P = 5.51 × 10-9). Additionally, when examining a combined group of specific personality disorders, a similar causal effect was observed (odds ratios = 1.180, 95% confidence intervals: 1.033-1.345, P = .015). The sensitivity analyses showed no evidence of horizontal pleiotropy, thus supporting the robustness of these findings. Our study provides the first genetic evidence that personality disorders may have a causal influence on schizophrenia risk. These results highlight the importance of early screening and targeted interventions in individuals with personality disorders. Future research should expand to more diverse populations, employ dimensional diagnostic frameworks, and investigate the underlying biological and developmental pathways to refine the preventative and therapeutic strategies.

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.

Acute and Long-Term Consequences of Neonatal NMDA Blockade in the Cx3cr1 Knock-Out Mouse

Neuron-microglia communication through the fractalkine pathway is a critical factor mediating microglial proliferation, migration, release of mediators, and clearance of cellular debris, as well as the function of neuronal NMDA receptors. Disruption of the fractalkine-mediated microglia-neuron communication is associated with divergent outcomes, from damaging to protective, in different neurological conditions (including schizophrenia and epilepsy). In the present work we explore the impact of the absence of the fractalkine receptor (CX3CR1) after neonatal blockade of NMDA receptors, which induces acute and long-term alterations in behavior, neuronal integrity and excitability. Wild-type (WT) and Cx3cr1-/- (KO) mice of both sexes randomly received either a low (0.5 mg/kg) or high dose (1 mg/kg) of MK-801 (NMDA receptor antagonist) or saline, for five consecutive days, during early postnatal development. Neuronal apoptosis was assessed at a midpoint of the pharmacological protocol. Survival and growth rates were determined up to adulthood when innate behaviors, unconditioned anxiety, contextual memory and seizure susceptibility were evaluated, as well as hippocampal local field potential and sensory gating. CX3CR1 depletion and neonatal MK-801 treatment had a synergistic acute effect, increasing neuronal apoptosis and overall mortality. Both factors independently induced long-lasting impairments in the wide array of behavioral tasks assessed during adulthood. However, low MK-801 dose treatment greatly augmented the mortality of pentylenetetrazol-induced seizures in WT mice, an effect prevented by CX3CR1 depletion. MK-801 treatment induced a shift in the power spectrum of the hippocampal local field potential towards higher frequencies that was averted in Cx3cr1-/- mice by an opposite shift. Our results reveal that CX3CR1 depletion severely increases the vulnerability to neonatal NMDA antagonism with additional complex interactions regarding cognitive and neurophysiological effects, which should be considered in the context of neuron-microglia miscommunication in many neurological disorders including schizophrenia and epilepsy.

[Illness duration-related developmental trajectory of progressive cerebral gray matter changes in schizophrenia]

In different stages of schizophrenia (SZ), alterations in gray matter volume (GMV) of patients are normally regulated by various pathological mechanisms. Instead of analyzing stage-specific changes, this study employed a multivariate structural covariance model and sliding-window approach to investigate the illness duration-related developmental trajectory of GMV in SZ. The trajectory is defined as a sequence of brain regions activated by illness duration, represented as a sparsely directed matrix. By applying this approach to structural magnetic resonance imaging data from 145 patients with SZ, we observed a continuous developmental trajectory of GMV from cortical to subcortical regions, with an average change occurring every 0.208 years, covering a time window of 20.176 years. The starting points were widely distributed across all networks, except for the ventral attention network. These findings provide insights into the neuropathological mechanism of SZ with a neuroprogressive model and facilitate the development of process for aided diagnosis and intervention with the starting points.

Altered volume of thalamic nuclei and genetic expression in first-episode psychotic patients, and their association with childhood adversity

Childhood maltreatment is a significant risk factor for schizophrenia, and there are correlations between these adversities and thalamic gray matter density. The thalamus, a subcortical structure with various nuclei with specific connections, relays sensory information and participates in higher cognitive processes. Thalamic alterations are evident in psychotic disorders, and early-life adversities may affect its development, potentially contributing to psychosis. However, no evidence exists of volumetric alterations in thalamic nuclei in first-episode psychosis (FEP) patients related to early traumatic events. This study recruited 70 FEP patients and 68 age-matched healthy controls, who underwent 3 T structural MRI and clinical scales, including the Childhood Trauma Questionnaire (CTQ). The thalamus was analyzed for shape and segmented into nuclei to assess volume. Additionally, peripheral blood was analyzed for the expression of VCAN, CSGALNACT1, ST8SIA4, NRGN, SP4, and TOX genes, which are related to neuronal plasticity in the thalamus and psychosis. Results showed volumetric reductions in the whole thalamus and specific nuclei (lateral posterior, lateral geniculate, medial geniculate, ventrolateral, centromedian, anteroventral, mediodorsal, and pulvinar). The thalamus did not show shape alterations. A significant association was observed between physical neglect during childhood and the volume of the left thalamus and its anteroventral nucleus. Reduced expression of ST8SIA4 and SP4 genes was detected in FEP patients compared to healthy controls, with correlations between thalamic nuclei volumes and gene expression differing between groups. In conclusion, this study links thalamic nuclei volume with childhood adversities in FEP and highlights changes in ST8SIA4 and SP4 expression, correlating with thalamic nuclei volumes.

Transcriptional Regulators in the Cerebellum in Chronic Schizophrenia: Novel Possible Targets for Pharmacological Interventions

Despite the emerging evidence of the role of transcriptional regulators in schizophrenia as key molecular effectors responsible for the dysregulation of multiple biological processes, limited information is available for brain areas that control higher cognitive functions, such as the cerebellum. To identify transcription factors that could control a wide panel of altered proteins in the cerebellar cortex in schizophrenia, we analyzed a dataset obtained using one-shot liquid chromatography-tandem mass spectrometry on the postmortem human cerebellar cortex in chronic schizophrenia (PXD024937 identifier in the ProteomeXchange repository). Our analysis revealed a panel of 11 enriched transcription factors (SP1, KLF7, SP4, EGR1, HNF4A, CTCF, GABPA, NRF1, NFYA, YY1, and MEF2A) that could be controlling 250 altered proteins. The top three significantly enriched transcription factors were SP1, YY1, and EGR1, and the transcription factors with the largest number of targets were SP1, KLF7, and SP4 which belong to the Krüppel superfamily. An enrichment in vesicle-mediated transport was found for SP1, KLF7, EGR1, HNF4A, CTCF, and MEF2A targets, while pathways related to signaling, inflammation/immune responses, apoptosis, and energy were found for SP1 and KLF7 targets. EGR1 targets were enriched in RNA processing, and GABPA and YY1 targets were mainly involved in organelle organization and assembly. This study provides a reduced panel of transcriptional regulators that could impact multiple pathways through the control of a number of targets in the cerebellum in chronic schizophrenia. These findings suggest that this panel of transcription factors could represent key targets for pharmacological interventions in schizophrenia.

A Genome-Wide Association Study of First-Episode Psychosis: A Genetic Exploration in an Italian Cohort

BACKGROUND

Psychosis, particularly schizophrenia (SZ), is influenced by genetic and environmental factors. The neurodevelopmental hypothesis suggests that genetic factors affect neuronal circuit connectivity during perinatal periods, hence causing the onset of the diseases. In this study, we performed a genome-wide association study (GWAS) in a sample of the first episode of psychosis (FEP).

METHODS

A sample of 147 individuals diagnosed with non-affective psychosis and 102 controls were recruited and assessed. After venous blood and DNA extraction, the samples were genotyped. Genetic data underwent quality controls, genotype imputation, and a case-control genome-wide association study (GWAS). After the GWAS, results were investigated using an in silico functional mapping and annotation approach.

RESULTS

Our GWAS showed the association of 27 variants across 13 chromosomes at genome-wide significance (p < 1 × 10-7) and a total of 1976 candidate variants across 188 genes at suggestive significance (p < 1 × 10-5), mostly mapping in non-coding or intergenic regions. Gene-based tests reported the association of the SUFU (p = 4.8 × 10-7) and NCAN (p = 1.6 × 10-5) genes. Gene-sets enrichment analyses showed associations in the early stages of life, spanning from 12 to 24 post-conception weeks (p < 1.4 × 10-3) and in the late prenatal period (p = 1.4 × 10-3), in favor of the neurodevelopmental hypothesis. Moreover, several matches with the GWAS Catalog reported associations with strictly related traits, such as SZ, as well as with autism spectrum disorder, which shares some genetic overlap, and risk factors, such as neuroticism and alcohol dependence.

CONCLUSIONS

The resulting genetic associations and the consequent functional analysis displayed common genetic liability between the non-affective psychosis, related traits, and risk factors. In sum, our investigation provided novel hints supporting the neurodevelopmental hypothesis in SZ and-in general-in non-affective psychoses.

Neuropsychological profiles in first-episodes psychosis and their relationship with clinical, metacognition and social cognition variables

An increasing interest in the assessment of neuropsychological performance variability in people with first-episode psychosis (FEP) has emerged. However, its association with clinical and functional outcomes requires further study. Furthermore, FEP neuropsychological subgroups have not been characterized by clinical insight or metacognition and social cognition domains. The aim of this exploratory study was to identify specific groups of patients with FEP based on neuropsychological variables and to compare their sociodemographic, clinical, metacognition and social cognition profiles. A sample of 149 FEP was recruited from adult mental health services. Neuropsychological performance was assessed by a neuropsychological battery (WAIS-III; TMT; WSCT; Stroop Test; TAVEC). The assessment also included sociodemographic characteristics, clinical, functional, metacognition and social cognition variables. Two distinct neuropsychological profiles emerged: one neuropsychological impaired cluster (N = 56) and one relatively intact cluster (N = 93). Significant differences were found between both profiles in terms of sociodemographic characteristics (age and level of education) (p = 0.001), clinical symptoms (negative, positive, disorganized, excitement and anxiety) (p = 0.041-0.001), clinical insight (p = 0.038-0.017), global functioning (p = 0.014), as well as in social cognition domains (emotional processing and theory of mind) (p = 0.001; p = 0.002). No significant differences were found in metacognitive variables (cognitive insight and 'jumping to conclusions' bias). Relationship between neurocognitive impairment, social cognition and metacognition deficits are discussed. Early identifying of neuropsychological profiles in FEP, characterized by significant differences in clinical and social cognition variables, could provide insight into the prognosis and guide the implementation of tailored early-intervention.

Immune-developmental processes contribute to schizophrenia risk: insights from a genetic overlap study with height

BACKGROUND

Shorter stature has been phenotypically linked to increased prevalence of schizophrenia (SCZ), but the nature of this association is unknown.

METHODS

Using genome-wide genetic data, we studied the SCZ-height relationship on a genetic level. Applying novel genetic methods and tools, we analyzed gene-sets, tissue-types, cell-types, local genetic correlation, conditional genetic analyses, and fine-mapping of effector-genes to scrutinize the SCZ-height relationship.

RESULTS

We identified 142 genes statistically associated with both SCZ and height and found enrichment in 3 functional gene-sets. Genetic annotations implicated the pituitary and specifically mesenchymal stem cells for height and thyrotropic cells for SCZ. While the global SCZ-height genetic correlation was nonsignificant, 9 genomic regions showed robust local genetic correlations (7 negative, 6 in the MHC-region). The shared genetic signal for SCZ and height within the 6 MHC-regions was partially explained by mutual genetic overlap with white blood cell count, particularly lymphocytes. Fine-mapping prioritized 3 shared effector-genes (GIGYF2, HLA-C, and LIN28B) involved in immune response sensitivity and development of immune and pituitary cell-types.

CONCLUSIONS

Overall, our findings suggest an involvement during height-development of thyrotropic cells and immune response sensitivity contributing towards risk of SCZ.

Lifetime suicidal thoughts, attempts, and lethality of attempts as major outcome domains of psychotic disorders: a 21-year prospective cohort study after a first-episode psychosis

BACKGROUND

Suicidal thoughts and behaviors (STBs) are a major concern in people with psychotic disorders. There is a need to examine their prevalence over long-term follow-up after first-episode psychosis (FEP) and determine their early predictors.

METHODS

Of 510 participants with FEP evaluated on 26 risk factors for later outcomes, 260 were reassessed after 21 years of follow-up for lifetime ratings of most severe suicidal ideation, number of suicide attempts, and lethality of the most severe attempt. Risk factors and STB outcomes were modeled using hierarchical linear regression analysis.

RESULTS

Over the 21-year follow-up period, 62.7% of participants experienced suicidal thoughts, 40.8% attempted suicide, and 18 died of suicide (3.5% case fatality and 20.6% proportionate mortality). Suicidal ideation was independently predicted by parental socioeconomic status, familial load of major depression, neurodevelopmental delay, poor adolescence social networks, and suicidal thoughts/behavior at FEP. The number of suicide attempts was independently predicted by years of follow-up, familial load of major depression, obstetric complications, childhood adversity, and suicidal thoughts/behavior at FEP. Lethality was independently predicted by familial load of major depression, obstetric complications, neurodevelopmental delay, and poor adolescence social networks. The proportion of variance in suicidal ideation, attempts, and lethality explained by the independent predictors was 29.3%, 21.2%, and 18.1%, respectively.

CONCLUSIONS

STBs are highly prevalent in psychotic disorders and leads to substantial morbidity and mortality. They were predicted by a number of early risk factors, whose clinical recognition should contribute to improved prediction and prevention in people with psychotic disorders.

Hiding in Plain Sight: A case of post ictal psychosis with suicidal behavior

Postictal psychosis (PIP) is a serious, often unrecognized complication of epilepsy. Early diagnosis and intervention can prevent life-threatening outcomes. We report the case of a 26-year-old woman with childhood-onset frontal lobe epilepsy who attempted suicide, during a postictal psychotic episode, several days after undergoing inpatient video-EEG monitoring. This case presents a real-world scenario with clear guidelines for the on-call neurologist who will need to accurately diagnose and confidently manage PIP with psychotropic medications. Moreover, this case may stimulate discussion about the complex relationship between epilepsy and psychosis.

Blood-Brain Barrier Disruption in Schizophrenia: Insights, Mechanisms, and Future Directions

The blood-brain barrier (BBB) plays a crucial role in maintaining the homeostasis of the central nervous system by regulating solute transport and preventing neurotoxic substances from infiltrating brain tissue. In schizophrenia, emerging evidence identifies BBB dysfunction as a key pathophysiological factor associated with neuroinflammation, tight junction abnormalities, and endothelial dysfunction. Recent advancements in neuroimaging techniques, such as arterial spin labeling (ASL), have provided valuable tools for investigating BBB permeability and its role in disease progression. This review synthesizes findings from postmortem studies, serum and cerebrospinal fluid biomarker analyses, and advanced neuroimaging research to elucidate BBB alterations in schizophrenia. It highlights the mechanistic roles of tight junction protein dysregulation, neurovascular unit dysfunction, and immune responses in disrupting BBB integrity. Furthermore, the review examines the bidirectional effects of antipsychotic medications on BBB, addressing both therapeutic opportunities and potential challenges. By emphasizing the pivotal role of BBB dysfunction in schizophrenia pathogenesis, this review underscores its translational potential. Through the integration of multidisciplinary evidence, it lays the foundation for innovative diagnostic approaches and therapeutic strategies, enhancing our understanding of schizophrenia's complex pathophysiology.

Metoclopramide-induced rapid-onset psychosis in a child with methylphenidate use: a case report

BACKGROUND

Metoclopramide, a dopamine antagonist employed for its antiemetic effects, can precipitate neuropsychiatric adverse effects, including extrapyramidal symptoms and, in a few instances, acute psychosis. Although there have been reports of metoclopramide-induced psychosis in elderly individuals, there is no documentation of such incidents in children as far as we are aware.

CASE PRESENTATION

This case report describes an 11-year-old girl with a history of mild intellectual disability and attention deficit hyperactivity disorder, managed with 10 mg of methylphenidate daily. She presented to the emergency department with acute gastrointestinal symptoms and was administered two tablets of metoclopramide alongside her regular dose of methylphenidate. Subsequently, she developed psychotic symptoms, disorganized behavior, and agitation. An extensive medical evaluation ruled out other organic pathologies, leading to a diagnosis of rapid-onset psychosis induced by metoclopramide. The psychotic episode, which lasted approximately two weeks, resolved with low-dose antipsychotic treatment.

CONCLUSIONS

Children, especially those with neurodevelopmental disorders, are more susceptible to a wide range of side effects. Therefore, this report highlights the necessity for careful pharmacological management. Additionally, this case represents a significant contribution to the scientific literature by being the first to document metoclopramide-induced acute psychosis in children to the best of our knowledge.

A narrative literature review of white matter microstructure in individuals at clinical high risk for psychosis

Schizophrenia is a severe psychiatric disorder characterized by widespread white matter (WM) alterations, manifesting as neurodevelopmental deficits and dysconnectivity abnormalities. Over the past two decades, studies have focused on the clinical high-risk (CHR) stage of psychosis and have yielded fruitful information on WM abnormalities that exist prior to the full onset of psychosis, shedding light on biological mechanisms underlying psychosis development. This review presents a summary of current findings on cross-sectional and longitudinal WM alterations in individuals with CHR and their links to clinical symptoms and neurocognitive dysfunction. Next, we review the utilization of WM characterization in predicting clinical outcomes. Taken together, the literature suggests the clinical significance of WM characteristics and their great potential in predicting the conversion to psychosis, despite some methodological and conceptual challenges that remain to be addressed in future studies. Future CHR research would greatly benefit from utilizing WM to guide pharmacological and non-pharmacological targeted treatments, optimize clinical prediction models, and enable more accurate clinical care.

Childhood Trauma Across the Schizophrenia Spectrum: A Comparison of Schizotypal Personality Disorder and Schizophrenia

BACKGROUND

The etiology of schizophrenia involves both biological and environmental risk factors. Studying childhood trauma in disorders along the schizophrenia spectrum, including schizotypal personality disorder (SPD), can inform early risk and protective factors for psychosis. However, no study has directly compared childhood trauma between SPD and schizophrenia.

STUDY DESIGN

One hundred twenty-four participants (schizophrenia/schizoaffective disorder [SZ] n = 45, SPD n = 32, and healthy controls [HCs] n = 47) matched on age and gender were assessed for different types of childhood abuse and neglect as well as clinical symptoms. Kruskal-Wallis H-tests examined group differences in childhood trauma severity and logistic regression modeled childhood trauma types that were associated with an SZ vs SPD diagnosis.

STUDY RESULTS

SZ and SPD had greater severity than HC on total trauma score and all types of childhood trauma assessed (all P-values < .05). SZ and SPD only differed on childhood sexual abuse, which was greater in SZ (P = .039). Childhood sexual abuse (odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.02-1.27, P = .02) and emotional abuse (OR = 0.82, 95% CI = 0.71-0.95, P = .01) were independent predictors of an SZ vs SPD diagnosis. Sensitivity analysis indicated that a cutoff at mild sexual abuse was significant in predicting SZ vs SPD when compared with none/minimal sexual abuse. In SZ, greater sexual abuse was associated with positive schizotypal traits and in SPD, greater emotional abuse was associated with depressive symptoms.

CONCLUSIONS

Findings suggest that childhood sexual and emotional abuse may be important factors that influence illness trajectory across the severity of disorders on schizophrenia spectrum. These findings have implications for understanding disease mechanisms and early prevention.

Examining the role of common variants in rare neurodevelopmental conditions

Although rare neurodevelopmental conditions have a large Mendelian component1, common genetic variants also contribute to risk2,3. However, little is known about how this polygenic risk is distributed among patients with these conditions and their parents nor its interplay with rare variants. It is also unclear whether polygenic background affects risk directly through alleles transmitted from parents to children, or whether indirect genetic effects mediated through the family environment4 also play a role. Here we addressed these questions using genetic data from 11,573 patients with rare neurodevelopmental conditions, 9,128 of their parents and 26,869 controls. Common variants explained around 10% of variance in risk. Patients with a monogenic diagnosis had significantly less polygenic risk than those without, supporting a liability threshold model5. A polygenic score for neurodevelopmental conditions showed only a direct genetic effect. By contrast, polygenic scores for educational attainment and cognitive performance showed no direct genetic effect, but the non-transmitted alleles in the parents were correlated with the child's risk, potentially due to indirect genetic effects and/or parental assortment for these traits4. Indeed, as expected under parental assortment, we show that common variant predisposition for neurodevelopmental conditions is correlated with the rare variant component of risk. These findings indicate that future studies should investigate the possible role and nature of indirect genetic effects on rare neurodevelopmental conditions, and consider the contribution of common and rare variants simultaneously when studying cognition-related phenotypes.

Schizophrenia spectrum disorders in children and adolescents: Clinical, phenomenological, diagnostic, and prognostic features across subtypes

Schizophrenia spectrum disorders (SSD) typically have a diagnostically recognizable onset in young adulthood, yet it is not unusual that help-seeking due to initial SSD-related clinical manifestations emerge in earlier developmental phases, such as childhood and adolescence. Varieties of SSD manifestations in children and adolescents can be distinguished according to variations in clinical expressivity, severity and timing (i.e. developmental stage). Some individuals may reach the full clinical threshold for a diagnosis of schizophrenia according to the same descriptive diagnostic criteria used for adults, and in this case, it's possible to distinguish a pre-pubertal onset in childhood (aka Very Early Onset Schizophrenia, VEOS) and a post-pubertal onset in adolescence (aka Early Onset Schizophrenia, EOS). Other individuals may not reach such clinically overt diagnostic threshold but nonetheless present Childhood Schizotypal Disorder (CSD) or a Clinical High-Risk for Psychosis (CHRP). While EOS is clinically more similar to the canonical adult-onset presentation, the other 3 subgroups (i.e. VEOS, CSD, CHRP) present more nuances and specific clinical characteristics, which require ad-hoc developmental and phenomenological considerations for appropriate differential diagnosis and prognosis. Therefore, current scoping review intends to saturate such knowledge gap with respect to early SSD-phenotypes.

Obstetric complications and psychopathology in schizophrenia: A systematic review and meta-analysis

Schizophrenia (SZ) is a severe mental health condition involving gene-environment interactions, with obstetric complications (OCs) conferring an elevated risk for the disease. Current research suggests that OCs may exacerbate SZ symptoms. This study conducted a systematic review and meta-analysis to comprehensively evaluate differences in psychopathology between individuals with and without exposure to OCs in relation to SZ and related disorders. We systematically searched PubMed, PsycINFO, and SCOPUS to identify eligible studies. A total of 4091 records were retrieved through systematic and citation searches. 14 studies were included in the review, and 12 met the criteria for meta-analysis, involving 2992 patients. The analysis revealed that SZ patients who had been exposed to OCs exhibited significantly higher levels of positive symptoms (SMD=0.10, 95 %CI=0.01,0.20; p=0.03), general psychopathology (SMD=0.37, 95 %CI=0.22,0.52; p<0.001), total clinical symptomatology (SMD=0.44, 95 %CI=0.24,0.64; p<0.001) and depressive symptoms (SMD=0.47, 95 %CI=0.09,0.84; p=0.01). No significant differences were found in negative symptomatology and functioning. Our results suggest that OCs are not only associated with an increased risk of developing psychosis but with more severe symptomatology.

Perinatal risk factors and subclinical hypomania: A prospective community study

BACKGROUND

Perinatal risk factors are implicated in the development of psychopathology, but their role in bipolar disorder (BD) and hypomania is unclear. Using data from a prospective community cohort, this is the first study to investigate the association between a range of perinatal risk factors, hypomanic symptoms, and 'high-risk' for BD in the general population.

METHODS

Parent report of perinatal events were available for 26,040 eighteen-month-olds from the Twins Early Development Study. Subsequent self-report hypomania was measured at ages 16 (Hypomania Checklist-16; N = 2943) and 26 (Mood Disorders Questionnaire; N = 7748). Participants were categorised as 'high-risk' for BD using established classifications. Linear and logistic regressions were conducted within a generalised estimating equations framework to account for relatedness in the sample.

RESULTS

Prenatal alcohol exposure (β = 0.08, SE = 0.04, p = .0002) and number of alcohol units consumed (β = 0.09, SE = 0.02, p < .0001) were associated with hypomanic symptoms at age 16, and number of alcohol units (OR = 1.13, 95 % CI:1.06-1.21, p = .0003) and maternal stress (OR = 1.68, 95 % CI:1.21-2.34, p = .002) were associated with 'high-risk' for BD age 16. Prenatal tobacco exposure (β = 0.10, SE = 0.04, p < .0001) and number of cigarettes smoked (β = 0.10, SE = 0.01, p < .0001) were associated with hypomanic symptoms and 'high-risk' for BD at age 26, although these result were attenuated controlling for parental psychiatric history.

LIMITATIONS

Familial confounding could not be fully adjusted for. Rater reports include some biases.

CONCLUSIONS

These findings show perinatal risk factors to be associated with subclinical hypomania and 'high-risk' for BD. Future work should explore the mechanisms underlying these longitudinal associations, which could shed light on prevention and intervention efforts.

Impact of early risk factors on schizophrenia risk and age of diagnosis: A Danish population-based register study

BACKGROUND

While several risk factors for schizophrenia have been identified, their individual impacts are rather small. The relative independent and cumulative impacts of multiple risk factors on disease risk and age of onset warrant further investigation.

STUDY DESIGN

We conducted a register-based case-control study including all individuals receiving a schizophrenia spectrum disorder in Denmark from 1973 to 2018 (N = 29,142), and a healthy control sample matched 5:1 on age, sex, and parental socioeconomic status (N = 136,387). Register data included parental history of psychiatric illness, birth weight, gestational age, season of birth, population density of birthplace, immigration, paternal age, and Apgar scores. Data were analysed using logistic regression and machine learning.

RESULTS

Parental history of psychiatric illness (OR = 2.32 [95%CI 2.21-2.43]), high paternal age (OR = 1.30 [1.16-1.45]), and low birth weight (OR = 1.28 [1.16-1.41]) increased the odds of belonging to the patient group. In contrast, being a second-generation immigrant (OR = 0.65 [0.61-0.69]) and high population density of the birthplace (OR = 0.92 [0.89-0.96]) decreased the odds. The findings were supported by a decision tree analysis where parental history, paternal age, and birth weight contributed most to diagnostic classification (ACCtest = 0.69, AUCtest = 0.59, p < 0.001). Twenty percent of patients were child-onset cases. Here, female sex (OR = 1.82 [1.69-1.97]) and parental psychiatric illness (OR = 1.62 [1.49-1.77]) increased the odds of receiving the diagnosis <18 years.

CONCLUSION

Multiple early factors contribute independently to a higher psychosis risk, suggesting cumulative effects leading to symptom onset. Routine assessments of the most influential risk factors could be incorporated into clinical practise. Being female increased the risk of diagnosis during childhood, suggesting sex differences in the developmental trajectories of the disorder.

GABAergic neuron dysregulation in a human neurodevelopmental model for major psychiatric disorders

"GABA dysfunction" is a major hypothesis for the biological basis of schizophrenia with indirect supporting evidence from human post-mortem brain and genetic studies. Patient-derived induced pluripotent stem cells (iPSCs) have emerged as a valuable platform for modeling psychiatric disorders, and previous modeling has revealed glutamatergic synapse deficits. Whether GABAergic synapse properties are affected in patient-derived human neurons and how this impacts neuronal network activity remain poorly understood. Here we optimized a protocol to differentiate iPSCs into highly enriched ganglionic eminence-like neural progenitors and GABAergic neurons. Using a collection of iPSCs derived from patients of psychiatric disorders carrying a Disrupted-in-Schizophrenia 1 ( DISC1 ) mutation and their unaffected family member, together with respective isogenic lines, we identified mutation-dependent deficits in GABAergic synapse formation and function, a phenotype similar to that of mutant glutamatergic neurons. However, mutant glutamatergic and GABAergic neurons contribute differentially to neuronal network excitability and synchrony deficits. Finally, we showed that GABAergic synaptic transmission is also defective in neurons derived from several idiopathic schizophrenia patient iPSCs. Transcriptome analysis further showed some shared gene expression dysregulation, which is more prominent in DISC1 mutant neurons. Together, our study supports a functional GABAergic synaptic deficit in major psychiatric disorders.

Loss of normal facial asymmetry in schizophrenia and bipolar disorder: Implications for development of brain asymmetry in psychotic illness

Development of the craniofacies occurs in embryological intimacy with development of the brain and both show normal left-right asymmetries. While facial dysmorphology occurs to excess in psychotic illness, facial asymmetry has yet to be investigated as a putative index of brain asymmetry. Ninety-three subjects (49 controls, 22 schizophrenia, 22 bipolar disorder) received 3D laser surface imaging of the face. On geometric morphometric analysis with (x, y, z) visualisations of statistical models for facial asymmetries, in controls the upper face and periorbital region, which share embryological intimacy with the forebrain, showed marked asymmetries. Their geometry included: along the x-axis, rightward asymmetry in its dorsal-medial aspects and leftward asymmetry in its ventral-lateral aspects; along the z-axis, anterior protrusion in its right ventral-lateral aspect. In both schizophrenia and bipolar disorder these normal facial asymmetries were diminished, with residual retention of asymmetries in bipolar disorder. This geometry of normal facial asymmetries shows commonalities with that of normal frontal lobe asymmetries. These findings indicate a trans-diagnostic process that involves loss of facial asymmetries in both schizophrenia and bipolar disorder. Embryologically, they implicate loss of face-brain asymmetries across gestational weeks 7-14 in processes that involve genes previously associated with risk for schizophrenia.

'Whole-Body' Perspectives of Schizophrenia and Related Psychotic Illness: miRNA-143 as an Exemplary Molecule Implicated across Multi-System Dysfunctions

A wide array of biological abnormalities in psychotic illness appear to reflect non-cerebral involvement. This review first outlines the evidence for such a whole-body concept of schizophrenia pathobiology, focusing particularly on cardiovascular disease, metabolic syndrome and diabetes, immunity and inflammation, cancer, and the gut-brain axis. It then considers the roles of miRNAs in general and of miRNA-143 in particular as they relate to the epidemiology, pathobiology, and treatment of schizophrenia. This is followed by notable evidence that miRNA-143 is also implicated in each of these domains of cardiovascular disease, metabolic syndrome and diabetes, immunity and inflammation, cancer, and the gut-brain axis. Thus, miRNA-143 is an exemplar of what may be a class of molecules that play a role across the multiple domains of bodily dysfunction that appear to characterize a whole-body perspective of illness in schizophrenia. Importantly, the existence of such an exemplary molecule across these multiple domains implies a coordinated rather than stochastic basis. One candidate process would be a pleiotropic effect of genetic risk for schizophrenia across the whole body.

Genetic Diversity in Schizophrenia: Developmental Implications of Ultra-Rare, Protein-Truncating Mutations

The genetic basis of schizophrenia (SZ) remains elusive despite its characterization as a highly heritable disorder. This incomplete understanding has led to stagnation in therapeutics and treatment, leaving many suffering with insufficient relief from symptoms. However, recent large-cohort genome- and exome-wide association studies have provided insights into the underlying genetic machinery. The scale of these studies allows for the identification of ultra-rare mutations that confer substantial disease risk, guiding clinicians and researchers toward general classes of genes that are central to SZ etiology. One such large-scale collaboration effort by the Schizophrenia Exome Sequencing Meta-Analysis consortium identified ten, high-risk, ultra-rare, protein-truncating variants, providing the clearest picture to date of the dysfunctional gene products that substantially increase risk for SZ. While genetic studies of SZ provide valuable information regarding "what" genes are linked with the disorder, it is an open question as to "when" during brain development these genetic mutations impose deleterious effects. To shed light on this unresolved aspect of SZ etiology, we queried the BrainSpan developmental mRNA expression database for these ten high-risk genes and discovered three general expression trajectories throughout pre- and postnatal brain development. The elusiveness of SZ etiology, we infer, is not only borne out of the genetic heterogeneity across clinical cases, but also in our incomplete understanding of how genetic mutations perturb neurodevelopment during multiple critical periods. We contextualize this notion within the National Institute of Mental Health's Research Domain Criteria framework and emphasize the utility of considering both genetic variables and developmental context in future studies.

Predictive factors and symptom severity spectrum in adult schizophrenia: Potential insights for improved management and adequate care

Schizophrenia is one of the most disabling psychiatric disorders characterized by positive (hallucinations, delusions, formal thinking disorder) and negative symptoms (anhedonia, lack of speech and motivation). The present study aimed to identify the predictive factors of schizophrenia in adults, and potential differences in the environment of origin, sex, levels of occupational stress, intellectual level, marital status and age of onset of the disease depending on the severity of symptoms using analysis of data collected from 120 patients with a diagnosis of schizophrenia. The study was conducted at the 'Prof. Dr. Alexandru Obregia' Clinical Psychiatric Hospital in Bucharest and included adult patients hospitalized between March 2018 and January 2021 diagnosed with schizophrenia and evaluated by general clinical examination, psychiatric, neurological and psychological evaluation. Results revealed that robust predictors of mild and moderate symptoms were affective symptoms, heredo-collateral history of schizophrenia, late onset, the presence of positive and negative symptoms, substance abuse, stress and marital status, unmarried, lower IQ and mental deficiency. For moderate-severe and severe symptoms, predictors were affective symptoms, heredo-collateral history of schizophrenia and affective disorders, substance abuse, stress, borderline IQ and mild mental deficiency. The present results can be used for further development of psychopharmacological management of schizophrenia.

Structural and functional abnormalities across clinical stages of psychosis: A multimodal neuroimaging investigation

BACKGROUND

Structural and functional neurobiological abnormalities have been observed in schizophrenia. Previous studies have concentrated on specific illness stages, obscuring relationships between functional/structural changes and disorder progression. The present study aimed to quantify structural and functional abnormalities across different clinical stages using functional near-infrared spectroscopy (fNIRS) and structural magnetic resonance imaging (sMRI).

METHODS

Fifty-four participants with first-episode schizophrenia (FES), 120 with clinically high risk of psychosis (CHR), and 111 healthy controls (HCs) underwent functional near-infrared spectroscopy (fNIRS) to measure oxyhemoglobin (Oxy-Hb) during the verbal fluency task. Among them, 28FES, 64CHR and 55HC also finished sMRI. Oxy-Hb and gray matter volume (GMV) were compared among the three groups while controlling for covariates, including age, sex, years of education, and task performance. Mediation analysis was utilized to determine the mediating effect of GMV on Oxy-Hb and cognition.

RESULTS

Compared with the HC group, CHR and FES groups showed significantly reduced brain activity. However, there were no significant differences between the FES and CHR. Pronounced GMV increase in the right frontal pole area (F = 4.234, p = 0.016) was identified in the CHR and FES groups. Mediation analysis showed a significant mediation effect of the right frontal pole GMV between Channel 31 Oxy-Hb and processing speed (z = 2.105, p = 0.035) and attention/vigilance (z = 1.992, p = 0.046).

CONCLUSIONS

Brain activation and anatomical deficits were observed in different brain regions, suggesting that anatomical and functional abnormalities are dissociated in the early stages of psychosis. The relationship between neural activity and anatomy may reflect a specific pathophysiology related to cognitive deterioration in schizophrenia.

The association of adverse childhood experiences with long-term outcomes of psychosis: a 21-year prospective cohort study after a first episode of psychosis

BACKGROUND

Evidence suggests a possible relationship between exposure to childhood adversity (CA) and functional impairment in psychosis. However, the impact of CA on long-term outcomes of psychotic disorders remains poorly understood.

METHODS

Two hundred and forty-three patients were assessed at their first episode of psychosis for CA and re-assessed after a mean of 21 years of follow-up for several outcome domains, including symptoms, functioning, quality of life, cognitive performance, neurological dysfunction, and comorbidity. The unique predictive ability of CA exposure for outcomes was examined using linear regression analysis controlling for relevant confounders, including socioeconomic status, family risk of schizophrenia, and obstetric complications.

RESULTS

There were 54% of the patients with a documented history of CA at mild or higher levels. CA experiences were more prevalent and severe in schizophrenia than in other psychotic disorders (p < 0.001). Large to very large effect sizes were observed for CA predicting most role functioning variables and negative symptoms (ΔR2 between 0.105 and 0.181). Moderate effect sizes were observed for positive symptoms, personal functioning, impaired social cognition, impaired immediate verbal learning, poor global cognition, internalized stigma, poor personal recovery, and drug abuse severity (ΔR2 between 0.040 and 0.066). A dose-response relationship was observed between levels of CA and severity of outcome domains.

CONCLUSION

Our results suggest a strong and widespread link between early adversity exposure and outcomes of psychotic disorders. Awareness of the serious long-term consequences of CA should encourage better identification of those at risk and the development of effective interventions.

Advances in the study of phencyclidine-induced schizophrenia-like animal models and the underlying neural mechanisms

Schizophrenia (SZ) is a chronic, severe mental disorder with heterogeneous clinical manifestations and unknown etiology. Research on SZ has long been limited by the low reliability of and ambiguous pathogenesis in schizophrenia animal models. Phencyclidine (PCP), a noncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist, rapidly induces both positive and negative symptoms of SZ as well as stable SZ-related cognitive impairment in rodents. However, the neural mechanism underlying PCP-induced SZ-like symptoms is not fully understood. Nondopaminergic pathophysiology, particularly excessive glutamate release induced by NMDAR hypofunction in the prefrontal cortex (PFC), may play a key role in the development of PCP-induced SZ-like symptoms. In this review, we summarize studies on the behavioral and metabolic effects of PCP and the cellular and circuitary targets of PCP in the PFC and hippocampus (HIP). PCP is thought to target the ventral HIP-PFC pathway more strongly than the PFC-VTA pathway and thalamocortical pathway. Systemic PCP administration might preferentially inhibit gamma-aminobutyric acid (GABA) neurons in the vHIP and in turn lead to hippocampal pyramidal cell disinhibition. Excitatory inputs from the HIP may trigger sustained, excessive and pathological PFC pyramidal neuron activation to mediate various SZ-like symptoms. In addition, astrocyte and microglial activation and oxidative stress in the cerebral cortex or hippocampus have been observed in PCP-induced models of SZ. These findings perfect the hypoglutamatergic hypothesis of schizophrenia. However, whether these effects direct the consequences of PCP administration and how about the relationships between these changes induced by PCP remain further elucidation through rigorous, causal and direct experimental evidence.

Transcriptomic analysis of the human habenula in schizophrenia

Pathophysiology of many neuropsychiatric disorders, including schizophrenia (SCZD), is linked to habenula (Hb) function. While pharmacotherapies and deep brain stimulation targeting the Hb are emerging as promising therapeutic treatments, little is known about the cell type-specific transcriptomic organization of the human Hb or how it is altered in SCZD. Here we define the molecular neuroanatomy of the human Hb and identify transcriptomic changes in individuals with SCZD compared to neurotypical controls. Utilizing Hb-enriched postmortem human brain tissue, we performed single nucleus RNA-sequencing (snRNA-seq; n=7 neurotypical donors) and identified 17 molecularly defined Hb cell types across 16,437 nuclei, including 3 medial and 7 lateral Hb populations, several of which were conserved between rodents and humans. Single molecule fluorescent in situ hybridization (smFISH; n=3 neurotypical donors) validated snRNA-seq Hb cell types and mapped their spatial locations. Bulk RNA-sequencing and cell type deconvolution in Hb-enriched tissue from 35 individuals with SCZD and 33 neurotypical controls yielded 45 SCZD-associated differentially expressed genes (DEGs, FDR < 0.05), with 32 (71%) unique to Hb-enriched tissue. eQTL analysis identified 717 independent SNP-gene pairs (FDR < 0.05), where either the SNP is a SCZD risk variant (16 pairs) or the gene is a SCZD DEG (7 pairs). eQTL and SCZD risk colocalization analysis identified 16 colocalized genes. These results identify topographically organized cell types with distinct molecular signatures in the human Hb and demonstrate unique genetic changes associated with SCZD, thereby providing novel molecular insights into the role of Hb in neuropsychiatric disorders.

One Sentence Summary

Transcriptomic analysis of the human habenula and identification of molecular changes associated with schizophrenia risk and illness state.

Exploring the complex relationship between caffeine consumption and schizophrenia: A review of epidemiological and clinical studies

This review delves into the intricate interplay between caffeine consumption and schizophrenia, examining evidence from epidemiological and clinical studies. While epidemiological research offers conflicting findings regarding the association between coffee intake and schizophrenia risk, clinical studies reveal diverse impacts of caffeine on symptomatology and cognition in individuals with schizophrenia. Some epidemiological studies suggest a potential protective effect of coffee consumption against schizophrenia, whereas others fail to establish a significant correlation. Clinical investigations highlight the complexity of caffeine's influence, with varied effects on symptom severity and cognitive function observed among schizophrenia patients. Notably, caffeine may exacerbate positive symptoms while alleviating negative symptoms and cognitive deficits in this population. However, limitations such as small sample sizes and reliance on self-reported data hinder the generalizability of these findings. Furthermore, genetic factors, prenatal exposure, and substance abuse contribute to the complexity of the relationship between caffeine and schizophrenia. Studies indicate that individuals with a genetic predisposition to schizophrenia may be more vulnerable to the effects of caffeine, while prenatal exposure to caffeine may elevate the risk of schizophrenia in offspring. Additionally, substance abuse, including high caffeine and nicotine consumption, is prevalent among individuals with schizophrenia, exacerbating symptom severity. Future research directions include addressing methodological limitations, such as small sample sizes and reliance on self-reported data, and exploring the effects of caffeine on schizophrenia using larger, more diverse cohorts and controlled methodologies. A deeper understanding of caffeine's impact on schizophrenia is crucial for informing clinical practice and developing personalized interventions for patients. Ultimately, this review underscores the need for further investigation into the complex relationship between caffeine consumption and schizophrenia to improve patient outcomes and inform evidence-based interventions.

Ferret as a model system for studying the anatomy and function of the prefrontal cortex: A systematic review

There is a lack of consensus on anatomical nomenclature, standards of documentation, and functional equivalence of the frontal cortex between species. There remains a major gap between human prefrontal function and interpretation of findings in the mouse brain that appears to lack several key prefrontal areas involved in cognition and psychiatric illnesses. The ferret is an emerging model organism that has gained traction as an intermediate model species for the study of top-down cognitive control and other higher-order brain functions. However, this research has yet to benefit from synthesis. Here, we provide a summary of all published research pertaining to the frontal and/or prefrontal cortex of the ferret across research scales. The targeted location within the ferret brain is summarized visually for each experiment, and the anatomical terminology used at time of publishing is compared to what would be the appropriate term to use presently. By doing so, we hope to improve clarity in the interpretation of both previous and future publications on the comparative study of frontal cortex.

Difficulties during delivery, brain ventricle enlargement and cognitive impairment in first episode psychosis

BACKGROUND

Patients with a first episode of psychosis (FEP) display clinical, cognitive, and structural brain abnormalities at illness onset. Ventricular enlargement has been identified in schizophrenia since the initial development of neuroimaging techniques. Obstetric abnormalities have been associated with an increased risk of developing psychosis but also with cognitive impairment and brain structure abnormalities. Difficulties during delivery are associated with a higher risk of birth asphyxia leading to brain structural abnormalities, such as ventriculomegaly, which has been related to cognitive disturbances.

METHODS

We examined differences in ventricular size between 142 FEP patients and 123 healthy control participants using magnetic resonance imaging. Obstetric complications were evaluated using the Lewis-Murray scale. We examined the impact of obstetric difficulties during delivery on ventricle size as well as the possible relationship between ventricle size and cognitive impairment in both groups.

RESULTS

FEP patients displayed significantly larger third ventricle size compared with healthy controls. Third ventricle enlargement was associated with diagnosis (higher volume in patients), with difficulties during delivery (higher volume in subjects with difficulties), and was highest in patients with difficulties during delivery. Verbal memory was significantly associated with third ventricle to brain ratio.

CONCLUSIONS

Our results suggest that difficulties during delivery might be significant contributors to the ventricular enlargement historically described in schizophrenia. Thus, obstetric complications may contribute to the development of psychosis through changes in brain architecture.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Anthropometry in antipsychotic-naïve first-episode psychosis patients: An exploratory approach to the role of environmental early life events in two independent samples

BACKGROUND

Patients with schizophrenia exhibit a reduced life expectancy mainly due to medical-related pathologies which might have been initiated due to stressful events during fetal development. Indeed, intra-uterus growth patterns predict anthropometric measures in adulthood, describing risk factors for schizophrenia and metabolic disorders. We aim to evaluate anthropometric values in two cohorts of antipsychotic-naïve first-episode episode psychosis (FEP) and correlated them with surrogate markers of the fetal environment such as birth weight (BW) and season of birth.

METHODS

BW, season of birth, and anthropometric values from 2 cohorts of FEP patients (Barcelona and Santander) were evaluated. In cohort B, 91 patients, and 110 controls while in cohort S, 644 and 235 were included respectively.

RESULTS

Patients were shorter, slimmer, and with lower BMI compared with controls. In both cohorts, patients, and female patients born in winter displayed the shortest height. Regarding BW, height was significantly associated with the interaction of diagnosis and BW in the whole sample and the male subsample.

CONCLUSIONS

Our results confirm reduced anthropometric features in FEP at onset while suggesting the influence of winter birth and BW, highlighting the role of early life events in the later outcome of FEP with sex differences.

Differential Effects of Neonatal Ventral Hippocampus Lesion on Behavior and Corticolimbic Plasticity in Wistar-Kyoto and Spontaneously Hypertensive Rats

Dysfunction of the corticolimbic system, particularly at the dendritic spine level, is a recognized core mechanism in neurodevelopmental disorders such as schizophrenia. Neonatal ventral hippocampus lesion (NVHL) in Sprague-Dawley rats induces both a schizophrenia-related behavioral phenotype and dendritic spine pathology (reduced total number and mature spines) in corticolimbic areas, which is mitigated by antipsychotics. However, there is limited information on the impact of rat strain on NVHL outcomes and antipsychotic effects. We compared the behavioral performance in the open field, novel object recognition (NORT), and social interaction tests, as well as structural neuroplasticity with the Golgi-Cox stain in Wistar-Kyoto (WKY) and spontaneously hypertensive (SH) male rats with and without NVHL. Additionally, we explored the effect of the atypical antipsychotic risperidone (RISP). WKY rats with NVHL displayed motor hyperactivity without impairments in memory and social behavior, accompanied by dendritic spine pathology in the neurons of the prefrontal cortex (PFC) layer 3 and basolateral amygdala. RISP treatment reduced motor activity and had subtle and selective effects on the neuroplasticity alterations. In SH rats, NVHL increased the time spent in the border area during the open field test, impaired the short-term performance in NORT, and reduced social interaction time, deficits that were corrected after RISP administration. The NVHL caused dendritic spine pathology in the PFC layers 3 and 5 of SH rats, which RISP treatment ameliorated. Our results support the utility of the NVHL model for exploring neuroplasticity mechanisms in schizophrenia and understanding pharmacotherapy.

Atypical semantic cognition in schizotypal personality disorder and borderline personality disorder

Increased schizotypal traits have previously been associated with atypical semantic cognition in community samples. However, no study has yet examined whether adults diagnosed with schizotypal personality disorder (SPD) display atypical semantic fluency and memory. We hypothesized that 24 adults diagnosed with SPD would name more idiosyncratic words on the semantic fluency task and show decreased semantic recall for animal and fruit category words compared with 29 participants with borderline personality disorder (BPD) and a community sample of 96 age-matched controls. We examined whether atypical semantic cognition was specifically associated with disorganized and eccentric speech and thinking, or more broadly with pathological personality traits and personality functioning. Our main hypothesis was confirmed, as the SPD participants named more idiosyncratic words and recalled fewer semantically related words compared with controls. Surprisingly, participants with BPD likewise named more atypical words compared with controls. More idiosyncratic semantic fluency was associated with more eccentric speech and thinking. Increased idiosyncratic semantic fluency and reduced semantic recall were both coupled to increased detachment and lowered personality functioning, while reduced semantic recall further was related to increased interpersonal problems. Our findings suggest that persons with SPD, and to a lesser degree BPD, show atypical semantic cognition, which is associated with eccentric speech and thinking, and more broadly with impaired personality function, social withdrawal, and emotional flatness. The idiosyncratic semantic cognition may worsen difficulties with social reciprocity seen in SPD and BPD.

Cognition and Educational Achievement in the Toronto Adolescent and Youth Cohort Study: Rationale, Methods, and Early Data

BACKGROUND

Both cognition and educational achievement in youths are linked to psychosis risk. One major aim of the Toronto Adolescent and Youth (TAY) Cohort Study is to characterize how cognitive and educational achievement trajectories inform the course of psychosis spectrum symptoms (PSSs), functioning, and suicidality. Here, we describe the protocol for the cognitive and educational data and early baseline data.

METHODS

The cognitive assessment design is consistent with youth population cohort studies, including the NIH Toolbox, Rey Auditory Verbal Learning Test, Wechsler Matrix Reasoning Task, and Little Man Task. Participants complete an educational achievement questionnaire, and report cards are requested. Completion rates, descriptive data, and differences across PSS status are reported for the first participants (N = 417) ages 11 to 24 years, who were recruited between May 4, 2021, and February 2, 2023.

RESULTS

Nearly 84% of the sample completed cognitive testing, and 88.2% completed the educational questionnaire, whereas report cards were collected for only 40.3%. Modifications to workflows were implemented to improve data collection. Participants who met criteria for PSSs demonstrated lower performance than those who did not on numerous key cognitive indices (p < .05) and also had more academic/educational problems.

CONCLUSIONS

Following youths longitudinally enabled trajectory mapping and prediction based on cognitive and educational performance in relation to PSSs in treatment-seeking youths. Youths with PSSs had lower cognitive performance and worse educational outcomes than youths without PSSs. Results show the feasibility of collecting data on cognitive and educational outcomes in a cohort of youths seeking treatment related to mental illness and substance use.

Prodromal symptoms and the duration of untreated psychosis in first episode of psychosis patients: what differences are there between early vs. adult onset and between schizophrenia vs. bipolar disorder?

To assess the role of age (early onset psychosis-EOP < 18 years vs. adult onset psychosis-AOP) and diagnosis (schizophrenia spectrum disorders-SSD vs. bipolar disorders-BD) on the duration of untreated psychosis (DUP) and prodromal symptoms in a sample of patients with a first episode of psychosis. 331 patients with a first episode of psychosis (7-35 years old) were recruited and 174 (52.6%) diagnosed with SSD or BD at one-year follow-up through a multicenter longitudinal study. The Symptom Onset in Schizophrenia (SOS) inventory, the Positive and Negative Syndrome Scale and the structured clinical interviews for DSM-IV diagnoses were administered. Generalized linear models compared the main effects and group interaction. 273 AOP (25.2 ± 5.1 years; 66.5% male) and 58 EOP patients (15.5 ± 1.8 years; 70.7% male) were included. EOP patients had significantly more prodromal symptoms with a higher frequency of trouble with thinking, avolition and hallucinations than AOP patients, and significantly different median DUP (91 [33-177] vs. 58 [21-140] days; Z = - 2.006, p = 0.045). This was also significantly longer in SSD vs. BD patients (90 [31-155] vs. 30 [7-66] days; Z = - 2.916, p = 0.004) who, moreover had different profiles of prodromal symptoms. When assessing the interaction between age at onset (EOP/AOP) and type of diagnosis (SSD/BD), avolition was significantly higher (Wald statistic = 3.945; p = 0.047), in AOP patients with SSD compared to AOP BD patients (p = 0.004). Awareness of differences in length of DUP and prodromal symptoms in EOP vs. AOP and SSD vs. BD patients could help improve the early detection of psychosis among minors.

Cerebrospinal fluid proteomic signatures are associated with symptom severity of first-episode psychosis

Apart from their diagnostic, monitoring, or prognostic utility in clinical settings, molecular biomarkers may be instrumental in understanding the pathophysiology of psychiatric disorders, including schizophrenia. Using untargeted metabolomics, we recently identified eight cerebrospinal fluid (CSF) metabolites unique to first-episode psychosis (FEP) subjects compared to healthy controls (HC). In this study, we sought to investigate the CSF proteomic signatures associated with FEP. We employed 16-plex tandem mass tag (TMT) mass spectrometry (MS) to examine the relative protein abundance in CSF samples of 15 individuals diagnosed with FEP and 15 age-and-sex-matched healthy controls (HC). Multiple linear regression model (MLRM) identified 16 differentially abundant CSF proteins between FEP and HC at p < 0.01. Among them, the two most significant CSF proteins were collagen alpha-2 (IV) chain (COL4A2: standard mean difference [SMD] = -1.12, p = 1.64 × 10-4) and neuron-derived neurotrophic factor (NDNF: SMD = -1.03, p = 4.52 × 10-4) both of which were down-regulated in FEP subjects compared to HC. We also identified several potential CSF proteins associated with the pathophysiology and the symptom profile and severity in FEP subjects, including COL4A2, NDNF, hornerin (HRNR), contactin-6 (CNTN6), voltage-dependent calcium channel subunit alpha-2/delta-3 (CACNA2D3), tropomyosin alpha-3 chain (TPM3 and TPM4). Moreover, several protein signatures were associated with cognitive performance. Although the results need replication, our exploratory study suggests that CSF protein signatures can be used to increase the understanding of the pathophysiology of psychosis.

Assessing the association between global structural brain age and polygenic risk for schizophrenia in early adulthood: A recall-by-genotype study

Neuroimaging studies consistently show advanced brain age in schizophrenia, suggesting that brain structure is often 'older' than expected at a given chronological age. Whether advanced brain age is linked to genetic liability for schizophrenia remains unclear. In this pre-registered secondary data analysis, we utilised a recall-by-genotype approach applied to a population-based subsample from the Avon Longitudinal Study of Parents and Children to assess brain age differences between young adults aged 21-24 years with relatively high (n = 96) and low (n = 93) polygenic risk for schizophrenia (SCZ-PRS). A global index of brain age (or brain-predicted age) was estimated using a publicly available machine learning model previously trained on a combination of region-wise gray-matter measures, including cortical thickness, surface area and subcortical volumes derived from T1-weighted magnetic resonance imaging (MRI) scans. We found no difference in mean brain-PAD (the difference between brain-predicted age and chronological age) between the high- and low-SCZ-PRS groups, controlling for the effects of sex and age at time of scanning (b = -.21; 95% CI -2.00, 1.58; p = .82; Cohen's d = -.034; partial R2 = .00029). These findings do not support an association between SCZ-PRS and brain-PAD based on global age-related structural brain patterns, suggesting that brain age may not be a vulnerability marker of common genetic risk for SCZ. Future studies with larger samples and multimodal brain age measures could further investigate global or localised effects of SCZ-PRS.

Structural and biochemical alterations in dendritic spines as key mechanisms for severe mental illnesses

Severe mental illnesses (SMI) collectively affect approximately 20% of the global population, as estimated by the World Health Organization (WHO). Despite having diverse etiologies, clinical symptoms, and pharmacotherapies, these diseases share a common pathophysiological characteristic: the misconnection of brain areas involved in reality perception, executive control, and cognition, including the corticolimbic system. Dendritic spines play a crucial role in excitatory neurotransmission within the central nervous system. These small structures exhibit remarkable plasticity, regulated by factors such as neurotransmitter tone, neurotrophic factors, and innate immunity-related molecules, and other mechanisms - all of which are associated with the pathophysiology of SMI. However, studying dendritic spine mechanisms in both healthy and pathological conditions in patients is fraught with technical limitations. This is where animal models related to these diseases become indispensable. They have played a pivotal role in elucidating the significance of dendritic spines in SMI. In this review, the information regarding the potential role of dendritic spines in SMI was summarized, drawing from clinical and animal model reports. Also, the implications of targeting dendritic spine-related molecules for SMI treatment were explored. Specifically, our focus is on major depressive disorder and the neurodevelopmental disorders schizophrenia and autism spectrum disorder. Abundant clinical and basic research has studied the functional and structural plasticity of dendritic spines in these diseases, along with potential pharmacological targets that modulate the dynamics of these structures. These targets may be associated with the clinical efficacy of the pharmacotherapy.

Interactive neuroinflammation pathways and transcriptomics-based identification of drugs and chemical compounds for schizophrenia

OBJECTIVES

Schizophrenia is a psychiatric disorder affecting 1% of the population. Accumulating evidence indicates that neuroinflammation is involved in the pathology of these disorders by altering neurodevelopmental processes and specifically affecting glutamatergic signalling and astrocytic functioning. The aim of this study was to curate interactive biological pathways involved in schizophrenia for the identification of novel pharmacological targets implementing pathway, gene ontology, and network analysis.

METHODS

Neuroinflammatory pathways were created using PathVisio and published in WikiPathways. A transcriptomics dataset, originally created by Narla et al. was selected for data visualisation and analysis. Transcriptomics data was visualised within pathways and networks, extended with transcription factors, pathways, and drugs. Network hubs were determined based on degrees of connectivity.

RESULTS

Glutamatergic, immune, and astrocytic signalling as well as extracellular matrix reorganisation were altered in schizophrenia while we did not find an effect on the complement system. Pharmacological agents that target the glutamate receptor subunits, inflammatory mediators, and metabolic enzymes were identified.

CONCLUSIONS

New neuroinflammatory pathways incorporating the extracellular matrix, glutamatergic neurons, and astrocytes in the aetiology of schizophrenia were established. Transcriptomics based network analysis provided novel targets, including extra-synaptic glutamate receptors, glutamate transporters and extracellular matrix molecules that can be evaluated for therapeutic strategies.

Transdiagnostic subgroups of cognitive impairment in early affective and psychotic illness

Cognitively impaired and spared patient subgroups were identified in psychosis and depression, and in clinical high-risk for psychosis (CHR). Studies suggest differences in underlying brain structural and functional characteristics. It is unclear whether cognitive subgroups are transdiagnostic phenomena in early stages of psychotic and affective disorder which can be validated on the neural level. Patients with recent-onset psychosis (ROP; N = 140; female = 54), recent-onset depression (ROD; N = 130; female = 73), CHR (N = 128; female = 61) and healthy controls (HC; N = 270; female = 165) were recruited through the multi-site study PRONIA. The transdiagnostic sample and individual study groups were clustered into subgroups based on their performance in eight cognitive domains and characterized by gray matter volume (sMRI) and resting-state functional connectivity (rsFC) using support vector machine (SVM) classification. We identified an impaired subgroup (NROP = 79, NROD = 30, NCHR = 37) showing cognitive impairment in executive functioning, working memory, processing speed and verbal learning (all p < 0.001). A spared subgroup (NROP = 61, NROD = 100, NCHR = 91) performed comparable to HC. Single-disease subgroups indicated that cognitive impairment is stronger pronounced in impaired ROP compared to impaired ROD and CHR. Subgroups in ROP and ROD showed specific symptom- and functioning-patterns. rsFC showed superior accuracy compared to sMRI in differentiating transdiagnostic subgroups from HC (BACimpaired = 58.5%; BACspared = 61.7%, both: p < 0.01). Cognitive findings were validated in the PRONIA replication sample (N = 409). Individual cognitive subgroups in ROP, ROD and CHR are more informative than transdiagnostic subgroups as they map onto individual cognitive impairment and specific functioning- and symptom-patterns which show limited overlap in sMRI and rsFC. CLINICAL TRIAL REGISTRY NAME: German Clinical Trials Register (DRKS). Clinical trial registry URL: https://www.drks.de/drks_web/ . Clinical trial registry number: DRKS00005042.

Schizophrenia endothelial cells exhibit higher permeability and altered angiogenesis patterns in patient-derived organoids

Schizophrenia (SCZ) is a complex neurodevelopmental disorder characterized by the manifestation of psychiatric symptoms in early adulthood. While many research avenues into the origins of SCZ during brain development have been explored, the contribution of endothelial/vascular dysfunction to the disease remains largely elusive. To model the neuropathology of SCZ during early critical periods of brain development, we utilized patient-derived induced pluripotent stem cells (iPSCs) to generate 3D cerebral organoids and define cell-specific signatures of disease. Single-cell RNA sequencing revealed that while SCZ organoids were similar in their macromolecular diversity to organoids generated from healthy controls (CTRL), SCZ organoids exhibited a higher percentage of endothelial cells when normalized to total cell numbers. Additionally, when compared to CTRL, differential gene expression analysis revealed a significant enrichment in genes that function in vessel formation, vascular regulation, and inflammatory response in SCZ endothelial cells. In line with these findings, data from 23 donors demonstrated that PECAM1+ microvascular vessel-like structures were increased in length and number in SCZ organoids in comparison to CTRL organoids. Furthermore, we report that patient-derived endothelial cells displayed higher paracellular permeability, implicating elevated vascular activity. Collectively, our data identified altered gene expression patterns, vessel-like structural changes, and enhanced permeability of endothelial cells in patient-derived models of SCZ. Hence, brain microvascular cells could play a role in the etiology of SCZ by modulating the permeability of the developing blood brain barrier (BBB).

Schizophrenia in the genetic era: a review from development history, clinical features and genomic research approaches to insights of susceptibility genes

Schizophrenia is a devastating neuropsychiatric disorder affecting 1% of the world population and ranks as one of the disorders providing the most severe burden for society. Schizophrenia etiology remains obscure involving multi-risk factors, such as genetic, environmental, nutritional, and developmental factors. Complex interactions of genetic and environmental factors have been implicated in the etiology of schizophrenia. This review provides an overview of the historical origins, pathophysiological mechanisms, diagnosis, clinical symptoms and corresponding treatment of schizophrenia. In addition, as schizophrenia is a polygenic, genetic disorder caused by the combined action of multiple micro-effective genes, we further detail several approaches, such as candidate gene association study (CGAS) and genome-wide association study (GWAS), which are commonly used in schizophrenia genomics studies. A number of GWASs about schizophrenia have been performed with the hope to identify novel, consistent and influential risk genetic factors. Finally, some schizophrenia susceptibility genes have been identified and reported in recent years and their biological functions are also listed. This review may serve as a summary of past research on schizophrenia genomics and susceptibility genes (NRG1, DISC1, RELN, BDNF, MSI2), which may point the way to future schizophrenia genetics research. In addition, depending on the above discovery of susceptibility genes and their exact function, the development and application of antipsychotic drugs will be promoted in the future.

Cognitive predictors of transition and remission of psychosis risk syndrome in a child and adolescent sample: longitudinal findings from the CAPRIS study

Cognitive impairments are proposed as predictors in the differentiation between subjects with psychosis risk syndrome (PRS) who will develop a psychotic disorder (PRS-P) and those who will not (PRS-NP). More in-depth study of the PRS-NP group could contribute to defining the role of cognitive alterations in psychosis. This study aims to analyze cognition of children and adolescents with PRS in terms of their clinical outcome at 18-month follow-up (psychosis, remission, and non-remission) and of determinate predictors of transition to psychosis and remission of PRS. The method is two-site, naturalistic, longitudinal study design, with 98 help-seeking adolescents with PRS and 64 healthy controls (HC). PRS-P (n = 24) and PRS-NP (n = 74) participants were clinically and cognitively assessed at baseline, and when full-blown psychotic disorder had developed or at 18-month follow-up. PRS-P subjects showed lower scores at baseline in processing speed, visuospatial memory, attention, and executive function (cognitive flexibility/processing speed) compared to HC. PRS-NP subjects showed lower baseline scores in verbal working memory and verbal fluency compared to HC. This deficit is also observed in the PRS group of participants still presenting attenuated psychotic symptoms at 18-month follow-up, while PRS subjects in remission showed a similar cognitive profile to HC subjects. Baseline score on processing speed, measured with a coding task, appeared to be a predictive variable for the development of a psychotic disorder. Performance in verbal working memory was predictive of remission in the PRS-NP. Post hoc comparisons indicate the need for careful interpretation of cognitive markers as predictors of psychosis. Cognitive impairments are present in both PRS-P and PRS-NP. Those individuals who recover from PRS show baseline cognitive performance comparable to the HC group. Together with sociodemographic variables, this observation could help in the differentiation of a variety of PRS trajectories in children and adolescents.

Pediatric traumatic brain injury as a risk factor for psychosis and psychotic symptoms: a systematic review and meta-analysis

BACKGROUND

Psychosis is one of the most disabling psychiatric disorders. Pediatric traumatic brain injury (pTBI) has been cited as a developmental risk factor for psychosis, however this association has never been assessed meta-analytically.

METHODS

A systematic review and meta-analysis of the association between pTBI and subsequent psychotic disorders/symptoms was performed. The study was pre-registered (CRD42022360772) adopting a random-effects model to estimate meta-analytic odds ratio (OR) and 95% confidence interval (CI) using the Paule-Mandel estimator. Subgroup (study location, study design, psychotic disorder v. subthreshold symptoms, assessment type, and adult v. adolescent onset) and meta-regression (quality of evidence) analyses were also performed. The robustness of findings was assessed through sensitivity analyses. The meta-analysis is available online as a computational notebook with an open dataset.

RESULTS

We identified 10 relevant studies and eight were included in the meta-analysis. Based on a pooled sample size of 479686, the pooled OR for the association between pTBI and psychosis outcomes was 1.80 (95% CI 1.11-2.95). There were no subgroup effects and no outliers. Both psychotic disorder and subthreshold symptoms were associated with pTBI. The overall association remained robust after removal of low-quality studies, however the OR reduced to 1.43 (95% CI 1.04-1.98). A leave-one-out sensitivity analysis showed the association was robust to removal of all but one study which changed the estimate to marginally non-significant.

CONCLUSIONS

We report cautious meta-analytic evidence for a positive association between pTBI and future psychosis. New evidence will be key in determining long-term reliability of this finding.