Differential expression of the inflammation marker IL12p40 in the at-risk mental state for psychosis: a predictor of transition to psychotic disorder?

Immune and oxidative stress biomarkers in pediatric psychosis and psychosis-risk: Meta-analyses and systematic review

OBJECTIVE

While genetic and cohort studies suggest immune and reduction/oxidation (redox) alterations occur in psychosis, less is known about potential alterations in children and adolescents.

METHODS

We conducted a systematic review to identify immune and redox biomarker studies in children and adolescents (mean age ≤ 18 years old) across the psychosis spectrum: from psychotic like experiences, which are common in children, to threshold psychotic disorders like schizophrenia. We conducted meta-analyses when at least three studies measured the same biomarker.

RESULTS

The systematic review includes 38 pediatric psychosis studies. The meta-analyses found that youth with threshold psychotic disorders had higher neutrophil/lymphocyte ratio (Hedge's g = 0.40, 95 % CI 0.17 - 0.64), tumor necrosis factor (Hedge's g = 0.38, 95 % CI 0.06 - 0.69), C-reactive protein (Hedge's g = 0.38, 95 % CI 0.05 - 0.70), interleukin-6 (Hedge's g = 0.35; 95 % CI 0.11 - 0.64), and total white blood cell count (Hedge's g = 0.29, 95 % CI 0.12 - 0.46) compared to youth without psychosis. Other immune and oxidative stress meta-analytic findings were very heterogeneous.

CONCLUSION

Results from several studies are consistent with the hypothesis that signals often classified as "proinflammatory" are elevated in threshold pediatric psychotic disorders. Data are less clear for immune markers in subthreshold psychosis and redox markers across the subthreshold and threshold psychosis spectrum. Immune and redox biomarker intervention studies are lacking, and research investigating interventions targeting the immune system in threshold pediatric psychosis is especially warranted.

Baseline benzodiazepine exposure is associated with greater risk of transition in clinical high-risk for psychosis (CHR-P): a meta-analysis

BACKGROUND

Emerging meta-analytical evidence indicates that baseline exposure to antipsychotics and to antidepressants in individuals at clinical high-risk for psychosis (CHR-P) have opposite prognostic effects as regards imminent transition to psychosis, with antipsychotics associated with higher risk and antidepressants associated with a lower risk in comparison to not-exposed individuals. Despite their common use, baseline exposure to benzodiazepines (BDZ) in CHR-P has surprisingly received poor attention as a potential risk modulator for transition to psychosis. The current systematic review and meta-analysis were performed to fix such a knowledge gap.

METHODS

Systematic scrutiny of Medline and Cochrane library, performed up to 31 December 2022, searching for English-language studies on CHR-P reporting numeric data about the sample, the transition outcome at a predefined follow-up time and raw data on BDZ baseline exposure in relation to such outcome.

RESULTS

Of 1893 identified records, five studies were included in the systematic review and meta-analysis. The proportion of participants with exposure to BDZ at baseline ranged from 5.5% (one study) to 46.2%, with an average of 16.8%. At the end of the period of observation, i.e., the follow-up as reported in the study, 28.4% [95% confidence interval (CI) 19.7-39.1%] participants developed psychosis among the BDZ-exposed against 9.3% (7.3 to 11.9%) among the controls. CHR-P participants who were already under BDZ treatment at baseline had more than double chance of transition to psychosis than CHR-P participants who were BDZ-naïve. The risk ratio (RR) was 2.42 (95% CI 1.38-4.23) in the common effects model (z = 3.09; p = 0.002), and 2.40 (1.53 to 3.77) in the random-effects model (z = 5.40; p = 0.006; tau-squared = 0.0). There was no relevant heterogeneity: Cochran's Q = 1.49; df = 4; p = 0.828; I2 = 0.0% (95% CI 0.0-79%). Quality was good in four studies.

CONCLUSIONS

Ongoing BDZ exposure at inception in CHR-P is associated with a higher risk of transition to psychosis at follow up. This meta-analytic association, which echoes a similar effect of baseline antipsychotic exposure, plausibly indicates that the clinicians' prescription of pharmacological intervention captures some form of prognostically-relevant information (e.g. an anxiety permeated mental state requiring BDZ prescription) that are not adequately encompassed by current CHR-P categorical criteria.

Gradual Increase in Inflammation-Linked Glycoproteins and a Proatherogenic Lipoprotein Profile in the Early Stages of Psychosis as Characterized by 1H NMR Blood Analysis

Minimally invasive prognostic markers of inflammation and dyslipidemia in individuals with a risk of psychosis, also called "at-risk mental state" (ARMS), or in the first episode of psychosis (FEP) are of utmost clinical importance to prevent cardiovascular disorders. We analyzed the plasma concentration of inflammation-linked glycoproteins (Glycs) and lipoprotein subclasses by proton nuclear magnetic resonance (¹H NMR) in a single acquisition. Study participants were healthy controls (HCs, N = 67) and patients with ARMS (N = 58), FEP (N = 110), or early psychosis diagnosis with ≥2 episodes (critical period (CP), N = 53). Clinical biomarkers such as high-sensitivity C-reactive protein, interleukin 6, fibrinogen, insulin, and lipoproteins were also measured. Although all participants had normal lipoprotein profiles and no inflammation according to conventional biomarkers, a gradual increase in the Glyc ¹H NMR levels was observed from HCs to CP patients; this increase was statistically significant for GlycA (CP vs HC). In parallel, a progressive and significant proatherogenic ¹H NMR lipoprotein profile was also identified across stages of psychosis (ARMS and CP vs HC). These findings highlight the potential of using ¹H NMR Glyc and lipoprotein profiling to identify blood changes in individuals with ARMS or FEP and pave the way for applications using this technology to monitor metabolic and cardiovascular risks in clinical psychiatry.

Serum immune markers and transition to psychosis in individuals at clinical high risk

Individuals at clinical high risk (CHR) for psychosis have been found to have altered cytokine levels, but whether these changes are related to clinical outcomes remains unclear. We addressed this issue by measuring serum levels of 20 immune markers in 325 participants (n = 269 CHR, n = 56 healthy controls) using multiplex immunoassays, and then followed up the CHR sample to determine their clinical outcomes. Among 269 CHR individuals, 50 (18.6 %) developed psychosis by two years. Univariate and machine learning techniques were used to compare levels of inflammatory markers in CHR subjects and healthy controls, and in CHR subjects who had (CHR-t), or had not (CHR-nt) transitioned to psychosis. An ANCOVA identified significant group differences (CHR-t, CHR-nt and controls) and post-hoc tests indicated that VEGF levels and the IL-10/IL-6 ratio were significantly higher in CHR-t than CHR-nt, after adjusting for multiple comparisons. Using a penalised logistic regression classifier, CHR participants were distinguished from controls with an area-under the curve (AUC) of 0.82, with IL-6 and IL-4 levels the most important discriminating features. Transition to psychosis was predicted with an AUC of 0.57, with higher VEGF level and IL-10/IL-6 ratio the most important discriminating features. These data suggest that alterations in the levels of peripheral immune markers are associated with the subsequent onset of psychosis. The association with increased VEGF levels could reflect altered blood-brain-barrier (BBB) permeability, while the link with an elevated IL-10/IL-6 ratio points to an imbalance between anti- and pro-inflammatory cytokines.

Rethinking Immunity and Cognition in Clinical High Risk for Psychosis

It is well known that schizophrenia is associated with cognitive impairment, reduced cortical grey matter and increased circulating concentrations of inflammatory cytokines. However, the relationship between these findings is not clear. We outline the influential neuroinflammatory hypotheses that raised cytokines provoke a damaging immune response in microglia that results in reduced grey matter and associated cognitive performance. We investigated whether such an interaction might be detectable in the prodromal period as illness emerges from the Clinical High Risk for Psychosis (CHR-P). Meta-analyses suggest that compared with controls, impaired cognition and reduced grey matter are already present by the prodrome and that greater decrements are present in those who later develop symptoms. In contrast, the few cytokine studies report no abnormalities in CHR-P except that interleukin-6 (IL-6) levels were raised versus controls and to a greater extent in the future patients, in one study. We noted that cognitive impairment and less cortical grey matter are more severe in schizophrenia than in affective disorders, but that increased cytokine levels are similarly prevalent across disorders. We found no studies correlating cytokine levels with cognitive impairment in CHR-P but such correlations seem unlikely given the minimal relationship reported in a recent meta-analysis of the many cytokine-cognition studies in established illness. From this and other evidence, we conclude that neuroinflammation is not a core feature of schizophrenia nor a substrate for reduced grey matter volume or cognitive function. We draw attention instead to the emerging evidence that brain-resident immune cells and signalling molecules such as Tregs and IL-6, which are influenced by schizophrenia risk genes, regulate and are necessary for the development and function of neuron-glia interaction. We suggest that cognitive impairment in schizophrenia can be seen as a convergence of genetic and immune-neurodevelopmental dysregulation whereas raised cytokines are a consequence of impaired Tregs control of systemic inflammation.

Machine learning based prediction and the influence of complement - Coagulation pathway proteins on clinical outcome: Results from the NEURAPRO trial

BACKGROUND

Functional outcomes are important measures in the overall clinical course of psychosis and individuals at clinical high-risk (CHR), however, prediction of functional outcome remains difficult based on clinical information alone. In the first part of this study, we evaluated whether a combination of biological and clinical variables could predict future functional outcome in CHR individuals. The complement and coagulation pathways have previously been identified as being of relevance to the pathophysiology of psychosis and have been found to contribute to the prediction of clinical outcome in CHR participants. Hence, in the second part we extended the analysis to evaluate specifically the relationship of complement and coagulation proteins with psychotic symptoms and functional outcome in CHR.

MATERIALS AND METHODS

We carried out plasma proteomics and measured plasma cytokine levels, and erythrocyte membrane fatty acid levels in a sub-sample (n = 158) from the NEURAPRO clinical trial at baseline and 6 months follow up. Functional outcome was measured using Social and Occupational Functional assessment Score (SOFAS) scale. Firstly, we used support vector machine learning techniques to develop predictive models for functional outcome at 12 months. Secondly, we developed linear regression models to understand the association between 6-month follow-up levels of complement and coagulation proteins with 6-month follow-up measures of positive symptoms summary (PSS) scores and functional outcome.

RESULTS AND CONCLUSION

A prediction model based on clinical and biological data including the plasma proteome, erythrocyte fatty acids and cytokines, poorly predicted functional outcome at 12 months follow-up in CHR participants. In linear regression models, four complement and coagulation proteins (coagulation protein X, Complement C1r subcomponent like protein, Complement C4A & Complement C5) indicated a significant association with functional outcome; and two proteins (coagulation factor IX and complement C5) positively associated with the PSS score. Our study does not provide support for the utility of cytokines, proteomic or fatty acid data for prediction of functional outcomes in individuals at high-risk for psychosis. However, the association of complement protein levels with clinical outcome suggests a role for the complement system and the activity of its related pathway in the functional impairment and positive symptom severity of CHR patients.

Understanding the Role of the Gut Microbiome in Brain Development and Its Association With Neurodevelopmental Psychiatric Disorders

The gut microbiome has a tremendous influence on human physiology, including the nervous system. During fetal development, the initial colonization of the microbiome coincides with the development of the nervous system in a timely, coordinated manner. Emerging studies suggest an active involvement of the microbiome and its metabolic by-products in regulating early brain development. However, any disruption during this early developmental process can negatively impact brain functionality, leading to a range of neurodevelopment and neuropsychiatric disorders (NPD). In this review, we summarize recent evidence as to how the gut microbiome can influence the process of early human brain development and its association with major neurodevelopmental psychiatric disorders such as autism spectrum disorders, attention-deficit hyperactivity disorder, and schizophrenia. Further, we discuss how gut microbiome alterations can also play a role in inducing drug resistance in the affected individuals. We propose a model that establishes a direct link of microbiome dysbiosis with the exacerbated inflammatory state, leading to functional brain deficits associated with NPD. Based on the existing research, we discuss a framework whereby early diet intervention can boost mental wellness in the affected subjects and call for further research for a better understanding of mechanisms that govern the gut-brain axis may lead to novel approaches to the study of the pathophysiology and treatment of neuropsychiatric disorders.

Inflammation Subtypes and Translating Inflammation-Related Genetic Findings in Schizophrenia and Related Psychoses: A Perspective on Pathways for Treatment Stratification and Novel Therapies

Dysregulation of immunological and inflammatory processes is frequently observed in psychotic disorders. Numerous studies have examined the complex components of innate and adaptive immune processes in schizophrenia and related psychoses. Elevated inflammation in these conditions is related to neurobiological phenotypes and associated with both genetics and environmental exposures. Recent studies have utilized multivariate cytokine approaches to identify what appears to be a subset of individuals with elevated inflammation. The degree to which these findings represent a general process of dysregulated inflammation or whether there are more refined subtypes remains unclear. Brain-imaging studies have attempted to establish the link between peripheral inflammation and gray matter disruption, white matter abnormalities, and neuropsychological phenotypes. However, the interplay between peripheral inflammation and neuroinflammation, as well as the consequences of this interplay, in the context of psychosis remains unclear and requires further investigation. This Perspectives article reviews the following elements of immune dysregulation and its clinical and therapeutic implications: (1) evidence supporting inflammation and immune dysregulation in schizophrenia and related psychoses; (2) recent advances in approaches to characterizing subgroups of patients with elevated inflammation; (3) relationships between peripheral inflammation and brain-imaging indicators of neuroinflammation; (4) convergence of large-scale genetic findings and peripheral inflammation findings; and (5) therapeutic implications: anti-inflammation interventions leveraging genetic findings for drug discovery and repurposing. We offer perspectives and examples of how multiomics technologies may be useful for constructing and studying immunogenetic signatures. Advancing research in this area will facilitate biomarker discovery, disease subtyping, and the development of etiological treatments for immune dysregulation in psychosis.

The association of plasma inflammatory markers with omega-3 fatty acids and their mediating role in psychotic symptoms and functioning: An analysis of the NEURAPRO clinical trial

There is increasing evidence that dysregulation of polyunsaturated fatty acids (FAs) mediated membrane function plays a role in the pathophysiology of schizophrenia. Even though preclinical findings have supported the anti-inflammatory properties of omega-3 FAs on brain health, their biological roles as anti-inflammatory agents and their therapeutic role on clinical symptoms of psychosis risk are not well understood. In the current study, we investigated the relationship of erythrocyte omega-3 FAs with plasma immune markers in a clinical high risk for psychosis (CHR) sample. In addition, a mediation analysis was performed to examine whether previously reported associations between omega-3 FAs and clinical outcomes were mediated via plasma immune markers. Clinical outcomes for CHR participants in the NEURAPRO clinical trial were measured using the Brief Psychiatric Rating Scale (BPRS), Schedule for the Scale of Assessment of Negative Symptoms (SANS) and Social and Occupational Functioning Assessment Scale (SOFAS) scales. The erythrocyte omega-3 index [eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)] and plasma concentrations of inflammatory markers were quantified at baseline (n = 268) and 6 month follow-up (n = 146) by gas chromatography and multiplex immunoassay, respectively. In linear regression models, the baseline plasma concentrations of Interleukin (IL)-15, Intercellular adhesion molecule (ICAM)-1 and Vascular cell adhesion molecule (VCAM)-1 were negatively associated with baseline omega-3 index. In addition, 6-month change in IL-12p40 and TNF-α showed a negative association with change in omega-3 index. In longitudinal analyses, the baseline and 6 month change in omega-3 index was negatively associated with VCAM-1 and TNF-α respectively at follow-up. Mediation analyses provided little evidence for mediating effects of plasma immune markers on the relationship between omega-3 FAs and clinical outcomes (psychotic symptoms and functioning) in CHR participants. Our results indicate a predominantly anti-inflammatory relationship of omega-3 FAs on plasma inflammatory status in CHR individuals, but this did not appear to convey clinical benefits at 6 month and 12 month follow-up. Both immune and non-immune biological effects of omega-3 FAs would be resourceful in understanding the clinical benefits of omega-3 FAs in CHR papulation.

Neuroinflammation in schizophrenia: the role of nuclear factor kappa B

Neuroinflammation, particularly in the dorsolateral prefrontal cortex, is well-established in a subset of people with schizophrenia, with significant increases in inflammatory markers including several cytokines. Yet the cause(s) of cortical inflammation in schizophrenia remains unknown. Clues as to potential microenvironmental triggers and/or intracellular deficits in immunoregulation may be gleaned from looking further upstream of effector immune molecules to transcription factors that control inflammatory gene expression. Here, we focus on the 'master immune regulator' nuclear factor kappa B (NF-κB) and review evidence in support of NF-κB dysregulation causing or contributing to neuroinflammation in patients. We discuss the utility of 'immune biotyping' as a tool to analyse immune-related transcripts and proteins in patient tissue, and the insights into cortical NF-κB in schizophrenia revealed by immune biotyping compared to studies treating patients as a single, homogenous group. Though the ubiquitous nature of NF-κB presents several hurdles for drug development, targeting this key immunoregulator with novel or repurposed therapeutics in schizophrenia is a relatively underexplored area that could aid in reducing symptoms of patients with active neuroinflammation.

Immune-inflammatory markers and psychosis risk: A systematic review and meta-analysis

Subclinical inflammation has been associated with psychosis; however, it remains unknown whether this phenomenon appears also in the premorbid phase. Therefore, we performed a systematic review and meta-analysis of studies comparing peripheral blood levels of C-reactive protein (CRP) and cytokines between individuals at risk of psychosis and controls. Moreover, we tested the hypothesis that the levels of these markers may be different in high-risk converters versus non-converters. Two independent reviewers searched electronic databases until Dec 16th, 2020. After reviewing publication records, 16 studies (548 high-risk individuals and 559 controls) were included. Random-effects meta-analyses with Hedges' g as the effect size estimate were performed. Individuals at clinical risk of psychosis had significantly higher levels of interleukin-6 (IL-6) compared to controls (g = 0.33, 95%CI: 0.06-0.60, p = 0.018). Heterogeneity was not significant in this subgroup analysis. Changes in the levels of IL-6 in subjects at familial risk of psychosis were not significant (g = 0.04, 95%CI: -0.24 to 0.31, p = 0.798). The use of antidepressants was associated with significantly higher levels of IL-6 in high-risk individuals (Beta = 1.56, 95%CI: 0.60-2.53, p = 0.001). No significant differences in the levels of immune-inflammatory markers were found between high-risk converters and non-converters. Our findings suggest that individuals at clinical risk of psychosis show subclinical inflammation in terms of elevated IL-6 levels. This phenomenon might be related to the use of antidepressants. The present meta-analysis does not support the usefulness of single immune-inflammatory markers in predicting transition to psychosis.

Complement pathway changes at age 12 are associated with psychotic experiences at age 18 in a longitudinal population-based study: evidence for a role of stress

The complement cascade is a major component of the immune defence against infection, and there is increasing evidence for a role of dysregulated complement in major psychiatric disorders. We undertook a directed proteomic analysis of the complement signalling pathway (n = 29 proteins) using data-independent acquisition. Participants were recruited from the UK avon longitudinal study of parents and children (ALSPAC) cohort who participated in psychiatric assessment interviews at ages 12 and 18. Protein expression levels at age 12 among individuals who reported psychotic experiences (PEs) at age 18 (n = 64) were compared with age-matched controls (n = 67). Six out of the 29 targeted complement proteins or protein subcomponents were significantly upregulated following correction for multiple comparisons (VTN↑, C1RL↑, C8B↑, C8A↑, CFH↑, and C5↑). We then undertook an unbiased plasma proteomic analysis of mice exposed to chronic social stress and observed dysregulation of 11 complement proteins, including three that were altered in the same direction in individuals with PE (C1R↑, CFH↑, and C5↑). Our findings indicate that dysregulation of the complement protein pathway in blood is associated with incidence of psychotic experiences and that these changes may reflect exposure to stress.

Longitudinal Analysis of Mental Disorder Burden Among Elderly Patients With Gastrointestinal Malignancies

BACKGROUND

Patients with cancer are at high risk for having mental disorders, resulting in widespread psychosocial screening efforts. However, there is a need for population-based and longitudinal studies of mental disorders among patients who have gastrointestinal cancer and particular among elderly patients.

PATIENTS AND METHODS

We used the SEER-Medicare database to identify patients aged ≥65 years with colorectal, pancreatic, gastric, hepatic/biliary, esophageal, or anal cancer. Earlier (12 months before or up to 6 months after cancer diagnosis) and subsequent mental disorder diagnoses were identified.

RESULTS

Of 112,283 patients, prevalence of an earlier mental disorder was 21%, 23%, 20%, 20%, 19%, and 26% for colorectal, pancreatic, gastric, hepatic/biliary, esophageal, and anal cancer, respectively. An increased odds of an earlier mental disorder was associated with pancreatic cancer (odds ratio [OR], 1.17; 95% CI, 1.11-1.23), esophageal cancer (OR, 1.10; 95% CI, 1.02-1.18), and anal cancer (OR, 1.17; 95% CI, 1.05-1.30) compared with colorectal cancer and with having regional versus local disease (OR, 1.09; 95% CI, 1.06-1.13). The cumulative incidence of a subsequent mental disorder at 5 years was 19%, 16%, 14%, 13%, 12%, and 10% for patients with anal, colorectal, esophageal, gastric, hepatic/biliary, and pancreatic cancer, respectively. There was an association with having regional disease (hazard ratio [HR], 1.08; 95% CI, 1.04-1.12) or distant disease (HR, 1.36; 95% CI, 1.28-1.45) compared with local disease and the development of a mental disorder. Although the development of a subsequent mental disorder was more common among patients with advanced cancers, there continued to be a significant number of patients with earlier-stage disease at risk.

CONCLUSIONS

This study suggests a larger role for incorporating psychiatric symptom screening and management throughout oncologic care.

Development of Proteomic Prediction Models for Transition to Psychotic Disorder in the Clinical High-Risk State and Psychotic Experiences in Adolescence

IMPORTANCE

Biomarkers that are predictive of outcomes in individuals at risk of psychosis would facilitate individualized prognosis and stratification strategies.

OBJECTIVE

To investigate whether proteomic biomarkers may aid prediction of transition to psychotic disorder in the clinical high-risk (CHR) state and adolescent psychotic experiences (PEs) in the general population.

DESIGN, SETTING, AND PARTICIPANTS

This diagnostic study comprised 2 case-control studies nested within the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions (EU-GEI) and the Avon Longitudinal Study of Parents and Children (ALSPAC). EU-GEI is an international multisite prospective study of participants at CHR referred from local mental health services. ALSPAC is a United Kingdom-based general population birth cohort. Included were EU-GEI participants who met CHR criteria at baseline and ALSPAC participants who did not report PEs at age 12 years. Data were analyzed from September 2018 to April 2020.

MAIN OUTCOMES AND MEASURES

In EU-GEI, transition status was assessed by the Comprehensive Assessment of At-Risk Mental States or contact with clinical services. In ALSPAC, PEs at age 18 years were assessed using the Psychosis-Like Symptoms Interview. Proteomic data were obtained from mass spectrometry of baseline plasma samples in EU-GEI and plasma samples at age 12 years in ALSPAC. Support vector machine learning algorithms were used to develop predictive models.

RESULTS

The EU-GEI subsample (133 participants at CHR (mean [SD] age, 22.6 [4.5] years; 68 [51.1%] male) comprised 49 (36.8%) who developed psychosis and 84 (63.2%) who did not. A model based on baseline clinical and proteomic data demonstrated excellent performance for prediction of transition outcome (area under the receiver operating characteristic curve [AUC], 0.95; positive predictive value [PPV], 75.0%; and negative predictive value [NPV], 98.6%). Functional analysis of differentially expressed proteins implicated the complement and coagulation cascade. A model based on the 10 most predictive proteins accurately predicted transition status in training (AUC, 0.99; PPV, 76.9%; and NPV, 100%) and test (AUC, 0.92; PPV, 81.8%; and NPV, 96.8%) data. The ALSPAC subsample (121 participants from the general population with plasma samples available at age 12 years (61 [50.4%] male) comprised 55 participants (45.5%) with PEs at age 18 years and 61 (50.4%) without PEs at age 18 years. A model using proteomic data at age 12 years predicted PEs at age 18 years, with an AUC of 0.74 (PPV, 67.8%; and NPV, 75.8%).

CONCLUSIONS AND RELEVANCE

In individuals at risk of psychosis, proteomic biomarkers may contribute to individualized prognosis and stratification strategies. These findings implicate early dysregulation of the complement and coagulation cascade in the development of psychosis outcomes.

Meta-analysis of cytokine and C-reactive protein levels in high-risk psychosis

OBJECTIVE

Schizophrenia is associated with aberrant blood cytokine and C-reactive protein (CRP) levels. However, less is known about alterations in these markers prior to the onset of psychosis. We performed a meta-analysis of blood cytokines and CRP in subjects at high-risk for psychosis.

METHOD

We identified articles by systematic searches of PubMed, PsycINFO, and Web of Science databases, and the reference lists of identified studies. Eight studies met the inclusion criteria, including seven studies of high-risk psychosis versus controls, and four studies of high-risk subjects who converted to a psychotic disorder versus non-converters.

RESULTS

Blood IL-6 levels were significantly higher (SMD = 0.31, 95% CI 0.02-0.59, p = 0.04) and blood IL-1β levels were significantly lower (SMD = -0.66, 95% CI -1.27 to -0.05, p = 0.05) in subjects at high-risk for psychosis versus controls. Between-study heterogeneity was not significant for either IL-1β or IL-6, and there was no evidence of publication bias. There was a non-significant trend for higher blood IL-12 levels in converters versus non-converters (SMD = 0.86, 95% CI -0.06-1.79, p = 0.07).

CONCLUSION

We found limited evidence for blood cytokine and CRP alterations in subjects at high-risk for psychosis. Our findings should be interpreted with caution in light of a small number of studies, cumulative sample size, and heterogeneity of high-risk criteria, but warrant investigation in larger samples. This includes studies of subjects at high-risk of developing psychosis and controls, as well as the potential of inflammation as a predictor of conversion to psychosis. These findings have important potential implications for our understanding of the pathophysiology of schizophrenia.

Immuno-inflammatory changes across phases of early psychosis: The impact of antipsychotic medication and stage of illness

INTRODUCTION

Research examining the role of inflammation in psychosis has produced inconsistent results. Variables that influence inflammation, including antipsychotic medication, are inconsistently controlled across studies and variation of inflammatory analytes across stages of psychosis may also influence findings. The purpose of this study was to assess for evidence of immuno-inflammatory dysregulation across the stages of early psychosis. We examined a immuno-inflammatory analytes in subjects at clinical high risk (CHR) for developing a psychotic disorder, antipsychotic-naïve (-n) and antipsychotic treated (-a) subjects in their first episode of psychosis (FEP), and healthy control (HC) subjects.

METHODS

A total of 11 subjects at CHR, 50 subjects within their FEP (40 FEP-n, 10 FEP-a), and 10 HC subjects were recruited from early psychosis programs in San Diego and Mexico City. Plasma was collected for biomarker assay.

RESULTS

Immuno-inflammatory analytes significantly differed between groups: Interferon-gamma (IFN-γ), Interleukin-10 (IL-10), Eotaxin-1, Interferon Gamma-Induced Protein-10 (IP-10), Monocyte Chemotactic Protein-1 (MCP-1), Macrophage-Derived Chemokine (MDC), Macrophage Inflammatory Protein-1 beta (MIP-1β), Thymus and Activation Regulated Chemokine (TARC), and Brain Derived Neurotropic Factor (BDNF). Post-hoc analyses revealed an overall pattern of higher levels of IL-10, MCP-1, MIP-1β, TARC, and BDNF in CHR as compared to FEP-a, FEP-n, and HC subjects.

CONCLUSIONS

Results reveal a profile of immuno-inflammatory dysregulation in early stages of psychosis prior to psychotic conversion and treatment with antipsychotic medication. The CHR phase of early psychosis may represent a period of increased immuno-inflammatory activation, but due to limited sample size, these results deserve replication in a well characterized early psychosis population.

Progression from being at-risk to psychosis: next steps

Over the past 20 years there has been a great deal of research into those considered to be at risk for developing psychosis. Much has been learned and studies have been encouraging. The aim of this paper is to offer an update of the current status of research on risk for psychosis, and what the next steps might be in examining the progression from CHR to psychosis. Advances have been made in accurate prediction, yet there are some methodological issues in ascertainment, diagnosis, the use of data-driven selection methods and lack of external validation. Although there have been several high-quality treatment trials the heterogeneity of this clinical high-risk population has to be addressed so that their treatment needs can be properly met. Recommendations for the future include more collaborative research programmes, and ensuring they are accessible and harmonized with respect to criteria and outcomes so that the field can continue to move forward with the development of large collaborative consortiums as well as increased funding for multisite projects.

The impact of inflammation on neurocognition and risk for psychosis: a critical review

Neurocognitive difficulties are highly prevalent among people with schizophrenia and have been linked to increased inflammation, as well as dysfunction and disability. Poor neurocognitive functioning has also been documented in individuals at clinical high risk for psychosis (CHR) and a burgeoning literature point to alterations in inflammation markers in this population. However, there is limited information regarding the putative link between inflammation and neurocognition in CHR individuals, and the potential role of inflammation in the development of cognitive difficulties and psychosis. As previous reports indicate that early treatment in schizophrenia is associated with better outcomes, there is an urgent need to identify neurobiological mechanisms underlying cognitive deterioration and psychosis in CHR individuals to provide them with care prior to significant cognitive and functional declines. To address this gap in the literature, we review and summarize the relevant literatures on inflammation and neurocognitive dysfunction in schizophrenia and CHR individuals, point to remaining gaps, and suggest directions for future research.

Role of inflammation in the pathogenesis of schizophrenia: A review of the evidence, proposed mechanisms and implications for treatment

AIM

Over the past several decades, there has been a growing research interest in the role of inflammation in the pathogenesis of schizophrenia. This review aims to summarize evidence in support of this relationship, to discuss biological mechanisms that might explain it, and to explore the translational impact by examining evidence from trials of anti-inflammatory and immunomodulatory agents in the treatment of schizophrenia.

METHODS

This narrative review of the literature summarizes evidence from observational studies, clinical trials and meta-analyses to evaluate the role of inflammation in the pathogenesis of schizophrenia and to discuss associated implications for treatment.

RESULTS

Epidemiological evidence and animal models support a hypothesis of maternal immune activation during pregnancy, which increases the risk of schizophrenia in the offspring. Several biomarker studies have found associations between classical pro-inflammatory cytokines and schizophrenia. The precise biological mechanisms by which inflammatory processes might contribute to the pathogenesis of schizophrenia remain unclear, but likely include the actions of microglia and the complement system. Importantly, several trials provide evidence that certain anti-inflammatory and immunomodulatory agents show beneficial effects in the treatment of schizophrenia. Nevertheless, there is a need for further precision-focused basic science and translational research.

CONCLUSIONS

Increasing our understanding of the role of inflammation in schizophrenia will enable novel opportunities for therapeutic and preventative interventions that are informed by the underlying pathogenesis of this complex disorder.

Interventions for prodromal stage of psychosis

BACKGROUND

Psychosis is a serious mental condition characterised by a loss of contact with reality. There may be a prodromal period or stage of psychosis, where early signs of symptoms indicating onset of first episode psychosis (FEP) occur. A number of services, incorporating multimodal treatment approaches (pharmacotherapy, psychotherapy and psychosocial interventions), developed worldwide, now focus on this prodromal period with the aim of preventing psychosis in people at risk of developing FEP.

OBJECTIVES

The primary objective is to assess the safety and efficacy of early interventions for people in the prodromal stage of psychosis. The secondary objective is, if possible, to compare the effectiveness of the various different interventions.

SEARCH METHODS

We searched Cochrane Schizophrenia's study-based Register of studies (including trials registers) on 8 June 2016 and 4 August 2017.

SELECTION CRITERIA

All randomised controlled trials (RCTs) evaluating interventions for participants older than 12 years, who had developed a prodromal stage of psychosis.

DATA COLLECTION AND ANALYSIS

Review authors independently inspected citations, selected studies, extracted data, and assessed study quality.

MAIN RESULTS

We included 20 studies with 2151 participants. The studies analysed 13 different comparisons. Group A comparisons explored the absolute effects of the experimental intervention. Group B were comparisons within which we could not be clear whether differential interactive effects were also ongoing. Group C comparisons explored differential effects between clearly distinct treatments. A key outcome for this review was 'transition to psychosis'. For details of other main outcomes please see 'Summary of findings' tables. In Group A (comparisons of absolute effects) we found no clear difference between amino acids and placebo (risk ratio (RR) 0.48 95% confidence interval (CI) 0.08 to 2.98; 2 RCTs, 52 participants; very low-quality evidence). When omega-3 fatty acids were compared to placebo, fewer participants given the omega-3 (10%) transitioned to psychosis compared to the placebo group (33%) during long-term follow-up of seven years (RR 0.24 95% CI 0.09 to 0.67; 1 RCT, 81 participants; low-quality evidence). In Group B (comparisons where complex interactions are probable) and in the subgroup focusing on antipsychotic drugs added to specific care packages, the amisulpiride + needs-focused intervention (NFI) compared to NFI comparison (no reporting of transition to psychosis; 1 RCT, 102 participants; very low-quality evidence) and the olanzapine + supportive intervention compared to supportive intervention alone comparison (RR 0.58 95% CI 0.28 to 1.18; 1 RCT, 60 participants; very low-quality evidence) showed no clear differences between groups. In the second Group B subgroup (cognitive behavioural therapies (CBT)), when CBT + supportive therapy was compared with supportive therapy alone around 8% of participants allocated to the combination of CBT and supportive therapy group transitioned to psychosis during follow-up by 18 months, compared with double that percentage in the supportive therapy alone group (RR 0.45 95% CI 0.23 to 0.89; 2 RCTs, 252 participants; very low-quality evidence). The CBT + risperidone versus CBT + placebo comparison identified no clear difference between treatments (RR 1.02 95% CI 0.39 to 2.67; 1 RCT, 87 participants; very low-quality evidence) and this also applies to the CBT + needs-based intervention (NBI) + risperidone versus NBI comparison (RR 0.75 95% CI 0.39 to 1.46; 1 RCT, 59 participants; very low-quality evidence). Group C (differential effects) also involved six comparisons. The first compared CBT with supportive therapy. No clear difference was found for the 'transition to psychosis' outcome (RR 0.74 95% CI 0.28 to 1.98; 1 RCT, 72 participants; very low-quality evidence). The second subgroup compared CBT + supportive intervention was compared with a NBI + supportive intervention, again, data were equivocal, few and of very low quality (RR 6.32 95% CI 0.34 to 117.09; 1 RCT, 57 participants). In the CBT + risperidone versus supportive therapy comparison, again there was no clear difference between groups (RR 0.76 95% CI 0.28 to 2.03; 1 RCT, 71 participants; very low-quality evidence). The three other comparisons in Group C demonstrated no clear differences between treatment groups. When cognitive training was compared to active control (tablet games) (no reporting of transition to psychosis; 1 RCT, 62 participants; very low quality data), family treatment compared with enhanced care comparison (RR 0.54 95% CI 0.18 to 1.59; 2 RCTs, 229 participants; very low-quality evidence) and integrated treatment compared to standard treatment comparison (RR 0.57 95% CI 0.28 to 1.15; 1 RCT, 79 participants; very low-quality evidence) no effects of any of these approaches was evident.

AUTHORS' CONCLUSIONS

There has been considerable research effort in this area and several interventions have been trialled. The evidence available suggests that omega-3 fatty acids may prevent transition to psychosis but this evidence is low quality and more research is needed to confirm this finding. Other comparisons did not show any clear differences in effect for preventing transition to psychosis but again, the quality of this evidence is very low or low and not strong enough to make firm conclusions.

Association of baseline inflammatory markers and the development of negative symptoms in individuals at clinical high risk for psychosis

Negative symptoms are common in individuals at clinical high-risk (CHR) for psychosis and are associated with worse functional outcomes. Inflammation may be one mechanism underlying negative symptoms. Inflammatory markers are altered in individuals at CHR and are associated with negative symptoms in patients with schizophrenia. We thus hypothesized that baseline inflammatory markers would predict the development of negative symptoms in individuals at CHR for psychosis. Thirty seven individuals from the North American Prodromal Longitudinal Study who met CHR criteria were included in the study. Inflammatory cytokines, including interferon (IFN)-λ, Interleukin (IL)-1β, IL-1 receptor antagonist (IL-1RA), IL-4, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF) were measured at baseline. Negative symptoms as measured by the Scale of Prodromal Symptoms, were measured at baseline and six and twelve months. Associations between inflammatory markers and the trajectory of negative symptoms (slope) over the first year of follow-up, were assessed using linear regression models controlling for age, sex, race and depressive symptom severity (as assessed by the Calgary Depression Scale for Schizophrenia). Baseline TNF (beta = 0.361, p = 0.007) and IL-6 (beta = -0.306, p = 0.026) predicted negative symptoms slopes, along with depressive symptom severity at baseline (beta = -0.596, p = 0.000). These findings demonstrate that inflammatory cytokines may underlie the development of negative symptoms in some individuals at CHR for psychosis. TNF predicted the development of negative symptoms independent of baseline depression. Given the heterogeneity of the CHR population, the comorbidity of negative symptoms and depression in this population, and the particular challenges in treating negative symptoms, immune markers could represent potential biomarkers that underlie the development of negative symptoms, representing a potential treatment target.

Inflammatory biomarkers in individuals at clinical high risk for psychosis (CHR-P): State or trait?

BACKGROUND

Studies linking neuro-inflammation to psychotic episodes has been rapidly expanding. Assessments of changes in inflammatory biomarkers in prodromal patients who subsequently convert to psychosis may help in predicting those likely to transition to psychosis.

METHODS

We reviewed the literature for original studies that measured inflammatory biomarkers in individuals at clinical high risk for psychosis (CHR-P), and compared pro-inflammatory biomarker data between converters and non-converters to psychosis as well as in healthy controls.

RESULTS

Our search yielded 15 studies. Our findings suggest a possible role of plasma levels of Interleukins-1β, 7, 8, matrix metalloproteinase (MMP)-8, cortisol, albumin and salivary cortisol, measured at baseline, as predictors of psychotic transition. Both baseline C-reactive protein (CRP) and Interleukin-6 levels were not shown to discriminate between converters and non-converters to psychosis. The dearth of longitudinal biomarker measures, before and after treating the psychotic episodes, was a limitation for assessing inflammatory biomarkers as trait vs state marker properties of biomarkers.

DISCUSSION

Gaps of data in published studies prevent confirming whether inflammatory biomarkers are state or trait indicators of transition to psychosis in the CHR-P populations. Future investigations should be designed to longitudinally measure inflammatory biomarkers in order to navigate the extensive heterogeneity of the schizophrenia syndrome and its prodrome.

A systematic review of metabolite biomarkers of schizophrenia

Current diagnosis of schizophrenia relies exclusively on the potentially subjective interpretation of clinical symptoms and social functioning as more objective biological measurement and medical diagnostic tests are not presently available. The use of metabolomics in the discovery of disease biomarkers has grown in recent years. Metabolomic methods could aid in the discovery of diagnostic biomarkers of schizophrenia. This systematic review focuses on biofluid metabolites associated with schizophrenia. A systematic search of Web of Science and Ovid Medline databases was conducted and 63 studies investigating metabolite biomarkers of schizophrenia were included. A review of these studies revealed several potential metabolite signatures of schizophrenia including reduced levels of essential polyunsaturated fatty acids (EPUFAs), vitamin E and creatinine; and elevated levels of lipid peroxidation metabolites and glutamate. Further research is needed to validate these biomarkers and would benefit from large cohort studies and more homogeneous and well-defined subject groups.

Effects of omega-3 PUFA on immune markers in adolescent individuals at ultra-high risk for psychosis - Results of the randomized controlled Vienna omega-3 study

Alterations of immune function have been reported in ultra-high risk (UHR) for psychosis patients causing expectations in terms of predictive meaningfulness and benefits of anti-inflammatory agents. According to a RCT in UHR-patients supplementation of omega-3 polyunsaturated fatty acids (PUFA) was effective in reducing transition to psychosis risk and to improve symptomatology. Based on preclinical findings, we now investigated state marker properties of and the influence of PUFA on immune markers in a RCT (clinical trials.gov Identifier: NCT00396643). In a longitudinal design we measured plasma levels of the pro-inflammatory interleukin 6 (IL-6), the soluble alpha (Tac) subunit of the interleukin 2 receptor (sIL-2r), and the circulating soluble form of the intercellular adhesion molecule one (sICAM-1), in 79 help-seeking UHR individuals (13-25years of age). Using linear mixed model (LMM) analysis, we investigated the effects of 12weeks supplementation of either 1.2g/d PUFA (n=38) or Placebo (n=41). At baseline, inflammatory markers were not altered in patients who later suffered transition to psychosis within one year (n=12; 11 PUFA-group, 1 PL-group). IL-6 was weakly inverse associated with omega-6 PUFA, and highly increased in nicotine users. In univariate tests of the LMM omega-3 PUFA caused a significant increase of sICAM-1 (p=0.022). PUFA did not significantly influence IL-6 or sIL-2r. The enhancement of sICAM-1 in the PUFA condition is suggestive for supportive effects on vascular immune response and immediate Th1 helper cell mediated immune answer, which was found disturbed in manifest schizophrenia, e.g. by facilitating the leukocyte adhesion and migration across the endothelium.

Identification of a plasma signature of psychotic disorder in children and adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort

The identification of an early biomarker of psychotic disorder is important as early treatment is associated with improved patient outcome. Metabolomic and lipidomic approaches in combination with multivariate statistical analysis were applied to identify plasma alterations in children (age 11) (38 cases vs 67 controls) and adolescents (age 18) (36 cases vs 117 controls) preceeding or coincident with the development of psychotic disorder (PD) at age 18 in the Avon Longitudinal Study of Parents and Children (ALSPAC). Overall, 179 lipids were identified at age 11, with 32 found to be significantly altered between the control and PD groups. Following correction for multiple comparisons, 8 of these lipids remained significant (lysophosphatidlycholines (LPCs) LPC(18:1), LPC(18:2), LPC(20:3); phosphatidlycholines (PCs) PC(32:2; PC(34:2), PC(36:4), PC(0-34-3) and sphingomyelin (SM) SM(d18:1/24:0)), all of which were elevated in the PD group. At age 18, 23 lipids were significantly different between the control and PD groups, although none remained significant following correction for multiple comparisons. In conclusion, the findings indicate that the lipidome is altered in the blood during childhood, long before the development of psychotic disorder. LPCs in particular are elevated in those who develop PD, indicating inflammatory abnormalities and altered phospholipid metabolism. These findings were not found at age 18, suggesting there may be ongoing alterations in the pathophysiological processes from prodrome to onset of PD.

Microbiome, inflammation, epigenetic alterations, and mental diseases

Major mental diseases such as autism, bipolar disorder, schizophrenia, and major depressive disorder are debilitating illnesses with complex etiologies. Recent findings show that the onset and development of these illnesses cannot be well described by the one-gene; one-disease approach. Instead, their clinical presentation is thought to result from the regulative interplay of a large number of genes. Even though the involvement of many genes are likely, up regulating and activation or down regulation and silencing of these genes by the environmental factors play a crucial role in contributing to their pathogenesis. Much of this interplay may be moderated by epigenetic changes. Similar to genetic mutations, epigenetic modifications such as DNA methylation, histone modifications, and RNA interference can influence gene expression and therefore may cause behavioral and neuronal changes observed in mental disorders. Environmental factors such as diet, gut microbiota, and infections have significant role in these epigenetic modifications. Studies show that bioactive nutrients and gut microbiota can alter either DNA methylation and histone signatures through a variety of mechanisms. Indeed, microbes within the human gut may play a significant role in the regulation of various elements of "gut-brain axis," via their influence on inflammatory cytokines and production of antimicrobial peptides that affect the epigenome through their involvement in generating short chain fatty acids, vitamin synthesis, and nutrient absorption. In addition, they may participate in-gut production of many common neurotransmitters. In this review we will consider the potential interactions of diet, gastrointestinal microbiome, inflammation, and epigenetic alterations in psychiatric disorders.

Prediction of conversion to psychosis in individuals with an at-risk mental state: a brief update on recent developments

PURPOSE OF REVIEW

So far, only little more than one-third of individuals classified as being at-risk for psychosis have been shown to actually convert to frank psychosis during follow-up. There have therefore been enormous efforts to improve the accuracy of predicting this transition. We reviewed the most recent studies in the field with the aim to clarify whether accuracy of prediction has been improved by the different research endeavors and what could be done to further improve it, and/or what alternative goals research should pursue.

RECENT FINDINGS

A total of 56 studies published between May 2015 and December 2016 were included, of which eight were meta-analyses. New meta-analytical evidence confirms that established instruments for checking clinical risk criteria have an excellent clinical utility in individuals referred to high-risk services. Within a such identified group of ultra-high-risk (UHR) individuals, especially Brief Limited Intermittent Psychotic Symptoms and Attenuated Psychotic Symptoms seem to predict transition. Further assessments should be performed within the UHR individuals, as risk of transition seems particularly high in those with an even higher severity of certain symptoms such as suspiciousness or anhedonia, in those with lower global or social functioning, poor neurocognitive performance or cannabis abuse. Also, electroencephalography, neuroimaging and blood biomarkers might contribute to improving individual prediction. The most promising approach certainly is a staged multidomain assessment. Risk calculators to integrate all data for an individualized prediction are being developed.

SUMMARY

Prediction of psychosis is already possible with an excellent prognostic performance based on clinical assessments. Recent studies show that this accuracy can be further improved by using multidomain approaches and modern statistics for individualized prediction. The challenge now is the translation into the clinic with a broad clinical implementation.

Inflammation, Stress Response, and Redox Dysregulation Biomarkers: Clinical Outcomes and Pharmacological Implications for Psychosis

In recent years, several studies claiming the finding of a specific biomarker for the identification of the "high-risk state" to develop psychosis, first psychotic episode, as well as the prediction of the individual response to antipsychotics have been published. Together with genetic reports, numerous publications in this field have been focused on inflammation and stress response blood biomarkers, as well as on indicators of redox dysregulation. In this review, we focus on human studies found in PubMed from January 1^st 2010 to January 31^st 2017, describing the clinical use of these biomarkers to detect the "premorbid" psychotic state and early phases of the disease. Their pharmacological implications in predicting and monitoring the individual response to antipsychotic medication is also discussed.