Immuno-psychiatry: an agenda for clinical practice and innovative research

Lower risk of hospitalisation for depression following hospitalisation for COVID-19 versus for another reason

INTRODUCTION

Although hospitalisation for COVID-19 is associated with a higher post-discharge risk of mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD), this risk has not been compared to that following hospitalisation for a reason other than COVID-19.

METHODS

Using data from France's National Health Data System (SNDS) database, we compared patients hospitalised for mood disorders in the 12 months following COVID-19/another reason hospitalisation.

RESULTS

96,313 adult individuals were hospitalised for COVID-19, and 2,979,775 were hospitalised for another reason. In the 12 months post-discharge, 110,976 (3.83 %) patients were hospitalised for mood disorders. In unadjusted analyses, patients initially hospitalised for COVID-19 (versus another reason) were more likely to be subsequently hospitalised for a mood disorder (4.27 % versus 3.82 % versus, respectively, p < 0.0001). These patients were also more likely to have a history of mood disorders, especially depressive disorders (6.45 % versus 5.77 %, respectively, p < 0.0001). Women, older age, lower social deprivation, a history of mood disorders, longer initial hospitalisation (COVID-19 or other), and a higher level of clinical care during initial hospitalisation were all significantly associated with the risk of subsequent hospitalisation for MDD and BD. In contrast, after adjusting for all these factors, persons initially hospitalised for COVID-19 were less likely to be subsequently hospitalised for MDD (OR = 0.902 [0.870-0.935]; p < 0.0001). No difference between both groups was observed for BD.

LIMITATIONS

Other reasons were not separately studied.

CONCLUSIONS

After adjusting for confounding factors, initial hospitalisation for COVID-19 versus for another reason was associated with a lower risk of hospitalisation for a mood disorder.

Major depressive disorder as a neuro-immune disorder: Origin, mechanisms, and therapeutic opportunities

Notwithstanding advances in understanding the pathophysiology of major depressive disorder (MDD), no single mechanism can explain all facets of this disorder. An expanding body of evidence indicates a putative role for the inflammatory response. Several meta-analyses showed an increase in systemic peripheral inflammatory markers in individuals with MDD. Numerous conditions and circumstances in the modern world may promote chronic systemic inflammation through mechanisms, including alterations in the gut microbiota. Peripheral cytokines may reach the brain and contribute to neuroinflammation through cellular, humoral, and neural pathways. On the other hand, antidepressant drugs may decrease peripheral levels of inflammatory markers. Anti-inflammatory drugs and nutritional strategies that reduce inflammation also could improve depressive symptoms. The present study provides a critical review of recent advances in the role of inflammation in the pathophysiology of MDD. Furthermore, this review discusses the role of glial cells and the main drivers of changes associated with neuroinflammation. Finally, we highlight possible novel neurotherapeutic targets for MDD that could exert antidepressant effects by modulating inflammation.

Assessing sickness behavior in the French: Validation of the French translation of the sickness questionnaire (SicknessQ) in a non-clinical French population

The Sickness Questionnaire (SicknessQ) is a questionnaire developed to assess symptoms of sickness behavior, including somatic, behavioral, and affective dimensions. To promote cross-cultural assessments of sickness behavior, we aim to expand the use of this questionnaire to other populations and languages. The aim of the present study was to evaluate the French translation of SicknessQ in a French-speaking general population during the COVID-19 pandemic. One hundred and thirty-nine individuals completed the SicknessQ online, along with the construct criteria measures of self-rated health, state anxiety (STAI-S), and depressive symptoms (PHQ-9). The principal component analyses revealed two components: the first component included seven items concerning mood, motivation and experiences of fatigue and pain; the second component included three items concerning somatic sickness symptoms. Higher scores on the total scale and the two component subscales were associated with poorer self-rated health and higher STAI-S and PHQ-9 scores. Since the associations with construct criteria variables were relatively similar between the single- and the two-dimensional solutions, both the total scale and the subscales of the two components of the French SicknessQ can be used in future studies to measure sickness behavior in French-speaking populations.

Immunogenetics of autism spectrum disorder: A systematic literature review

The aetiology of autism spectrum disorder (ASD) is complex and, partly, accounted by genetic factors. Nonetheless, the genetic underpinnings of ASD are poorly defined. The presence of immune dysregulations in autistic individuals, and their families, supports a role of the immune system and its genetic regulators. Albeit immune responses belong either to the innate or adaptive arms, the overall immune system genetics is broad, and encompasses a multitude of functionally heterogenous pathways which may have different influences on ASD. Hence, to gain insights on the immunogenetic underpinnings of ASD, we conducted a systematic literature review of previous immune genetic and transcription studies in ASD. We defined a list of immune genes relevant to ASD and explored their neuro-immune function. Our review confirms the presence of immunogenetic variability in ASD, accounted by inherited variations of innate and adaptive immune system genes and genetic expression changes in the blood and post-mortem brain of autistic individuals. Besides their immune function, the identified genes control neurodevelopment processes (neuronal and synaptic plasticity) and are highly expressed in pre/peri-natal periods. Hence, our synthesis bolsters the hypothesis that perturbation in immune genes may contribute to ASD by derailing the typical trajectory of neurodevelopment. Our review also helped identifying some of the limitations of prior immunogenetic research in ASD. Thus, alongside clarifying the neurodevelopment role of immune genes, we outline key considerations for future work into the aetiology of ASD and possible novel intervention targets.

Psychiatric sequelae after SARS-Cov-2 infection: trajectory, predictors and associations in a longitudinal Australian cohort

A relationship between SARS-CoV-2 infection and psychiatric symptoms has been identified but is still being fully investigated. Neuropsychiatric sequalae have been reported for several infectious agents and are not unexpected for SARS-CoV-2 infection. This study follows for 12 months a sample (N = 144) of people who have had a confirmed infection of SARS-CoV-2. Medical and neuropsychiatric data and biological specimens are collected at 6 study visits. The 34-item SPHERE questionnaire, the Depression in the Medically Ill instrument, the EQ-5D-5L quality of life instrument and the visual analogue scale of fatigue were administered at multiple timepoints and associations with measures of illness and inflammatory biomarkers were investigated using the generalised estimating equation. Associations between inflammatory biomarkers and mental health measures of various effect sizes were identified. A robust inverse association was found between mental health outcomes and long covid status, but not between mental health outcomes and covid illness severity. This study suggests that long covid may be the strongest predictor of neuropsychiatric symptoms amongst people who have been infected with SARS-CoV-2.

The risk of hospitalization for psychotic disorders following hospitalization for COVID-19: a French nationwide longitudinal study

COVID-19, like other infectious diseases, may be a risk factor for psychotic disorders. We aimed to compare the proportions of hospitalizations for psychotic disorders in the 12 months following discharge from hospital for either COVID-19 or for another reason in the adult general population in France during the first wave of the pandemic. We conducted a retrospective longitudinal nationwide study using the national French administrative healthcare database. Psychotic disorders were first studied as a whole, and then chronic and acute disorders separately. The role of several adjustment factors, including sociodemographics, a history of psychotic disorder, the duration of the initial hospitalization, and the level of care received during that hospitalization, were also analyzed. Between 1 January 2020 and 30 June 2020, a total of 14,622 patients were hospitalized for psychotic disorders in the 12 months following discharge from hospital for either COVID-19 or another reason. Initial hospitalization for COVID-19 (vs. another reason) was associated with a lower rate of subsequent hospitalization for psychotic disorders (0.31% vs. 0.51%, odds ratio (OR) = 0.60, 95% confidence interval (CI) [0.53-0.67]). This was true for both chronic and acute disorders, even after adjusting for the various study variables. Importantly, a history of psychotic disorder was a major determinant of hospitalization for psychotic disorders (adjusted OR = 126.56, 95% CI [121.85-131.46]). Our results suggest that, in comparison to individuals initially hospitalized for another reason, individuals initially hospitalized for COVID-19 present a lower risk of hospitalization for first episodes of psychotic symptoms/disorders or for psychotic relapse in the 12 months following discharge. This finding contradicts the hypothesis that there is a higher risk of psychotic disorders after a severe COVID-19.

Genetic polymorphism of IL-17F rs763780 contributes to the susceptibility to bipolar disorder but not to schizophrenia in the Turkish population

This study aims to investigate the genetic polymorphism in the interleukin-17F (IL-17F) (rs763780, 7488 A/G) gene in bipolar disorder (BD) and schizophrenia (SCZ) patients by comparing it with healthy controls considering clinical parameters. A sample of 107 patients with BD, 129 patients with SCZ, and 100 healthy volunteers were included. SCID-I was used to confirm the diagnosis according to DSM-IV-TR criteria. The Young Mania Rating Scale (YMRS) and the Hamilton Depression Rating Scale (HAM-D) were administered to BD patients. The Positive and Negative Symptoms Scale (PANSS) was applied to the patients with SCZ. PCR-RFLP was used to determine IL-17F gene polymorphism. Our results demonstrated that the distributions of the IL-17F genotype and the allele frequencies of BD patients were statistically significantly different from the control group. The AA genotype (OR: 0.283; 95% Cl: 0.140-0.573; p<.001) and A allele (OR: 0.333; 95% Cl: 0.171-0.646; p=.001) frequencies were significantly higher in the control group than in the BD group. The IL-17F genotype and the allele frequency distributions of SCZ patients were not statistically significantly different from the control group. When comparing scale scores due to the IL-17F genotype distributions in patients with BD or SCZ, there was no statistically significant difference between the groups of IL-17F genotypes. In summary, whereas the IL-17F polymorphism may be associated with BD, this polymorphism was not related to SCZ.

Prevalence of Mental, Behavioral, and Developmental Disorders Among Children and Adolescents with Diabetes, United States (2016-2019)

OBJECTIVE

To assess the association of diabetes and mental, behavioral, and developmental disorders in youth, we examined the magnitude of overlap between these disorders in children and adolescents.

STUDY DESIGN

In this cross-sectional study, we calculated prevalence estimates using the 2016-2019 National Survey of Children's Health. Parents reported whether their child was currently diagnosed with diabetes or with any of the following mental, behavioral, or developmental disorders: attention-deficit/hyperactivity disorder, autism spectrum disorder, learning disability, intellectual disability, developmental delay, anxiety, depression, behavioral problems, Tourette syndrome, or speech/language disorder. We present crude prevalence estimates weighted to be representative of the US child population and adjusted prevalence ratios (aPRs) adjusted for age, sex, and race/ethnicity.

RESULTS

Among children and adolescents (aged 2-17 years; n = 121 312), prevalence of mental, behavioral, and developmental disorders varied by diabetes status (diabetes: 39.9% [30.2-50.4]; no diabetes: 20.3% [19.8-20.8]). Compared with children and adolescents without diabetes, those with diabetes had a nearly 2-fold higher prevalence of mental, behavioral, and developmental disorders (aPR: 1.72 [1.31-2.27]); mental, emotional, and behavioral disorders (aPR: 1.90 [1.38-2.61]) and developmental, learning, and language disorders (aPR: 1.89 [1.35-2.66]).

CONCLUSIONS

These results suggest that approximately 2 in 5 children and adolescents with diabetes have a mental, behavioral, or developmental disorder. Understanding potential causal pathways may ultimately lead to future preventative strategies for mental, behavioral, and developmental disorders and diabetes in children and adolescents.

Juvenile Neuropsychiatric Systemic Lupus Erythematosus: Identification of Novel Central Neuroinflammation Biomarkers

INTRODUCTION

Juvenile systemic lupus erythematosus (j-SLE) is a rare chronic autoimmune disease affecting multiple organs. Ranging from minor features, such as headache or mild cognitive impairment, to serious and life-threatening presentations, j-neuropsychiatric SLE (j-NPSLE) is a therapeutic challenge. Thus, the diagnosis of NPSLE remains difficult, especially in pediatrics, with no specific biomarker of the disease yet validated.

OBJECTIVES

To identify central nervous system (CNS) disease biomarkers of j-NPSLE.

METHODS

A 5-year retrospective tertiary reference monocentric j-SLE study. A combination of standardized diagnostic criteria and multidisciplinary pediatric clinical expertise was combined to attribute NP involvement in the context of j-SLE. Neopterin and interferon-alpha (IFN-α) protein levels in cerebrospinal fluid (CSF) were assessed, together with routine biological and radiological investigations.

RESULTS

Among 51 patients with j-SLE included, 39% presented with j-NPSLE. J-NPSLE was diagnosed at onset of j-SLE in 65% of patients. No specific routine biological or radiological marker of j-NPSLE was identified. However, CSF neopterin levels were significantly higher in active j-NPSLE with CNS involvement than in j-SLE alone (p = 0.0008). Neopterin and IFN-α protein levels in CSF were significantly higher at diagnosis of j-NPSLE with CNS involvement than after resolution of NP features (respectively p = 0.0015 and p = 0.0010) upon immunosuppressive treatment in all patients tested (n = 10). Both biomarkers correlated strongly with each other (R_s = 0.832, p < 0.0001, n = 23 paired samples).

CONCLUSION

CSF IFN-α and neopterin constitute promising biomarkers useful in the diagnosis and monitoring of activity in j-NPSLE.

PM2.5 and PM10 air pollution peaks are associated with emergency department visits for psychotic and mood disorders

Particulate matters with a diameter of less than 10 µm (PM10) or less than 2.5 µm (PM2.5) are major air pollutants. Their relationship to psychiatric disorders has not yet been extensively studied. We aimed to explore the relationship between PM10 and PM2.5 air pollution peaks and the daily number of emergency visits for psychotic and mood disorders. Clinical data were collected from the Emergency Department of a Paris suburb (Créteil, France) from 2008 to 2018. Air pollution data were measured by the Paris region air quality network (Airparif) and collected from public databases. Pollution peak periods were defined as days for which the daily mean level of PM was above nationally predefined warning thresholds (20 µg/m3 for PM2.5, and 50 µg/m3 for PM10), and the 6 following days. Multivariable analyses compared the number of daily visits for psychotic and mood (unipolar and bipolar) disorders according to pollution peak, using negative binomial regression. After adjustment on meteorological variables (temperature, humidity, amount of sunshine in minutes), the daily number of emergency visits for psychotic disorders was significantly higher during PM2.5 and PM10 air pollution peak periods; while the number of visits for unipolar depressive disorders was higher only during PM10 peak periods (β = 0.059, p-value = 0.034). There were no significant differences between peak and non-peak periods for bipolar disorders. Differences in the effects of PM air pollution on psychotic and mood disorders should be analyzed in further studies.

Potential Inflammatory Biomarker in Patients with Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder that can diminish the quality of life of both children and adults in academic, occupational, and social contexts. The kynurenine pathway (KP) contains a set of enzymatic reactions involved in tryptophan (TRP) degradation. It is known to be associated with the risk of developing ADHD. This review will address the KP and underlying mechanism of inflammation in ADHD. Potential inflammatory biomarkers reported in the most recent studies are summarized. Although a strong neuroimmunological basis has been established due to the advances of recent neurobiological research, the pathophysiology of ADHD remains unclear.

Development of a suspicion index for secondary schizophrenia using the Delphi method

AIM

The aim of this study was to develop a suspicion index that aids diagnosis of secondary schizophrenia spectrum disorders in regular clinical practice.

METHOD

We used the Delphi method to rate and refine questionnaire items in consecutive rounds. Differences in mean expert responses for schizophrenia spectrum disorders and secondary schizophrenia spectrum disorders populations allowed to define low/middle/high predictive items, which received different weights. Algorithm performance was tested in 198 disease profiles by means of sensitivity and specificity.

RESULTS

Twelve experts completed the Delphi process, and consensus was reached in 19/24 (79.2%) items for schizophrenia spectrum disorders and 17/24 (70.8%) for secondary schizophrenia spectrum disorders. We assigned rounded values to each item category according to their predictive potential. A differential distribution of scores was observed between schizophrenia spectrum disorders and secondary schizophrenia spectrum disorders when applying the suspicion index for validation to 198 disease profiles. Sensitivity and specificity analyses allowed to set a >8/10/16 risk prediction score as a threshold to consider medium/high/very high suspicion of secondary schizophrenia spectrum disorders.

CONCLUSION

Our final outcome was the Secondary Schizophrenia Suspicion Index, the first paper-based and reliable algorithm to discriminate secondary schizophrenia spectrum disorders from schizophrenia spectrum disorders with the potential to help improve the detection of secondary schizophrenia spectrum disorder cases in clinical practice.

Adverse childhood experiences as risk factors for recurrent admissions in young psychiatric inpatients

BACKGROUND

Patients who require psychiatric inpatient treatment early in life are a particularly at-risk population. Factors such as adverse childhood experiences (ACEs) are, however, not well studied in those requiring psychiatric inpatient treatment during both childhood or adolescence and adulthood. Thus, the aim of the current study was to investigate, in young adult inpatients, the risk factors for prior admissions in Child and Adolescent Psychiatry, with a focus on ACEs.

MATERIALS AND METHODS

An explorative population-based systematic chart investigation of psychiatric inpatients aged 18-25 was conducted at the University Hospital Tulln, Austria. Data analysis was done with descriptive methods and Pearson's chi- squared-, Fisher's exact-, Mann-Whitney-U-tests and predictive logistic regression models.

RESULTS

The sample comprised 390 inpatients (51.8% female), with an average age of 20 years at first psychiatric hospital admission. Those with a former child and adolescent psychiatry inpatient treatment (10.3%) were predominantly female (77.5%). Their number of documented ACEs was increased compared to those without former child and adolescent psychiatry admissions (2 vs 1.1), with up to twice as many experiences of family dysfunction, neglect or abuse. Sexual abuse (OR: 3.0), having been an adopted or fostered child (OR: 4.5), and female sex (OR: 3.0) were identified as main risk factors. Furthermore, former child and adolescent psychiatry inpatients suffered from higher rates of psychosomatic or personality disorders, comorbidities and functional impairment, and were readmitted twice as often in young adulthood.

CONCLUSION

Young adult inpatients with reoccurring psychiatric inpatient treatments have increased rates of severe ACEs. Thus, special attention should be given to identifying ACEs, evaluating needs for psychosocial support and therapy, and meeting these needs after discharge.

The future of immunopsychiatry: Three milestones to clinical innovation

Psychoneuroimmunology, the area of research dedicated to understanding the fundamental interactions between the central nervous system and the immune system, has given rise to the development of Immunopsychiatry, a new discipline which harnesses the immune system to produce beneficial outcomes for mental health problems. Immunopsychiatry has the potential to become a clinically relevant specialty area in psychiatric practice, but has not yet been adopted by the wider mental health community. This paper aims to map out the future trajectory of Immunopsychiatry on its road towards science-to-policy knowledge translation and clinical implementation. Three critical milestones which will need to be reached in order for Immunopsychiatry to fulfil its promise for clinical innovation are discussed: a clear definition of patients who fall within the immunopsychiatric continuum; demonstration of well-defined clinical benefit and incorporation in clinical guidelines; and convergence with other paradigms in biological psychiatry.

Natural killer cells in first-episode psychosis: an innate immune signature?

Accumulating evidence majorly implicates immune dysfunction in the etiology of psychotic disorders. In particular, altered numbers and functions of natural killer (NK) cells have been described in psychosis, but interpretation has often been confounded by a number of biases, including treatment. Eighty-one first-episode psychosis (FEP) patients who subsequently received a diagnosis of either schizophrenia (SZ; n = 30) or bipolar disorder (BP; n = 31) over a five-year follow-up period were investigated for their NK cell phenotype and compared to 61 healthy controls (HCs). We found a similar proportion of CD3^-CD56⁺ NK cells in FEP patients and HCs. The frequency of NK cells expressing the late cell activation marker HLA-DR was significantly increased in FEP patients compared to HCs, especially in patients with BP (p < 0.0001) and, to a lesser degree, in patients with SZ (p = 0.0128). Interestingly, the expression of the activating NKG2C receptor, known to be associated with infections, was higher in patients with SZ and BP than in HCs (p < 0.0001) and correlated with HLA-DR expression, altogether defining adaptive NK cells. In terms of NK cell function, we observed a suppressed capacity of SZ-derived NK cells to mount cytotoxic responses in the presence of target cells, while NK cells from patients with BP show an inability to produce IFN-γ, a cytokine pivotal to NK function. This study strongly suggests major dysfunction of NK cells in FEP with functioning impairment correlated with psychotic, manic, and depressive symptoms in subsequently diagnosed patients with SZ and BP.

The diverse and complex modes of action of anti-NMDA receptor autoantibodies

NMDA receptors are ligand-gated ion channels that are found throughout the brain and are required for both brain development and many higher order functions. A variety of human patients with diverse clinical phenotypes have been identified that carry autoantibodies directed against NMDA receptor subunits. Here we focus on two general classes of autoantibodies, anti-GluN1 antibodies associated with anti-NMDA receptor encephalitis and anti-GluN2 antibodies associated with systemic lupus erythematosus (SLE). These two general classes of anti-NMDA receptor autoantibodies display a wide range of pathophysiological mechanisms from altering synaptic composition to gating of NMDARs. While we have made progress in understanding how these autoantibodies work at the molecular and cellular level, many unanswered questions remain including their long-term actions on brain function, the significance of clonal variations, and their effects on different NMDA receptor-expressing cell types in local circuits. This information will be needed to define fully the transition from anti-NMDA receptor autoantibodies to a clinical phenotype.

Identification of inflammatory subgroups of schizophrenia and bipolar disorder patients with HERV-W ENV antigenemia by unsupervised cluster analysis

Human endogenous retroviruses (HERVs) are remnants of infections that took place several million years ago and represent around 8% of the human genome. Despite evidence implicating increased expression of HERV type W envelope (HERV-W ENV) in schizophrenia and bipolar disorder, it remains unknown whether such expression is associated with distinct clinical or biological characteristics and symptoms. Accordingly, we performed unsupervised two-step clustering of a multivariate data set that included HERV-W ENV protein antigenemia, serum cytokine levels, childhood trauma scores, and clinical data of cohorts of patients with schizophrenia (n = 29), bipolar disorder (n = 43) and healthy controls (n = 32). We found that subsets of patients with schizophrenia (~41%) and bipolar disorder (~28%) show positive antigenemia for HERV-W ENV protein, whereas the large majority (96%) of controls was found to be negative for ENV protein. Unsupervised cluster analysis identified the presence of two main clusters of patients, which were best predicted by the presence or absence of HERV-W ENV protein. HERV-W expression was associated with increased serum levels of inflammatory cytokines and higher childhood maltreatment scores. Furthermore, patients with schizophrenia who were positive for HERV-W ENV protein showed more manic symptoms and higher daily chlorpromazine (CPZ) equivalents, whereas HERV-W ENV positive patients with bipolar disorder were found to have an earlier disease onset than those who were negative for HERV-W ENV protein. Taken together, our study suggest that HERV-W ENV protein antigenemia and cytokines can be used to stratify patients with major mood and psychotic disorders into subgroups with differing inflammatory and clinical profiles.

Regulation of membrane NMDA receptors by dynamics and protein interactions

Understanding neurotransmitter system crosstalk in the brain is a major challenge in neurobiology. Several intracellular and genomic cascades have been identified in this crosstalk. However, the discovery that neurotransmitter receptors are highly diffusive in the plasma membrane of neurons, where they form heterocomplexes with other proteins, has profoundly changed our view of neurotransmitter signaling. Here, we review new insights into neurotransmitter crosstalk at the plasma membrane. We focus on the membrane organization and interactome of the ionotropic glutamate N-methyl-D-aspartate receptor (NMDAR) that plays a central role in excitatory synaptic and network physiology and is involved in the etiology of several major neuropsychiatric disorders. The nanoscale organization and dynamics of NMDAR is a key regulatory process for glutamate synapse transmission, plasticity, and crosstalk with other neurotransmitter systems, such as the monoaminergic ones. The plasma membrane appears to be a prime regulatory compartment for spatial and temporal crosstalk between neurotransmitter systems in the healthy and diseased brain. Understanding the molecular mechanisms regulating membrane neurotransmitter receptor crosstalk will likely open research avenues for innovative therapeutical strategies.

Brain-immune crosstalk in the treatment of major depressive disorder

A growing number of studies are pointing out the need for a conceptual shift from a brain-centered to a body-inclusive approach in mental health research. In this perspective, the link between the immune and the nervous system, which are deeply interconnected and continuously interacting, is one of the most important novel theoretical framework to investigate the biological bases of major depressive disorder and, more in general, mental illness. Indeed, depressed patients show high levels of inflammatory markers, administration of pro-inflammatory drugs triggers a depressive symptomatology and antidepressant efficacy is reduced by excessive immune system activation. A number of molecular and cellular mechanisms have been hypothesized to act as a link between the immune and brain function, thus representing potential pharmacologically targetable processes for the development of novel and effective therapeutic strategies. These include the modulation of the kynurenine pathway, the crosstalk between metabolic and inflammatory processes, the imbalance in acquired immune responses, in particular T cell responses, and the interplay between neural plasticity and immune system activation. In the personalized medicine approach, the assessment and regulation of these processes have the potential to lead, respectively, to novel diagnostic approaches for the prediction of treatment outcome according to the patient's immunological profile, and to improved efficacy of antidepressant compounds through immune modulation.

Early onset obsessive-compulsive disorder: the biological and clinical phenotype

Moving from a behavioral-based to a biological-based classification of mental disorders is a crucial step toward a precision-medicine approach in psychiatry. In the last decade, a big effort has been made in order to stratify genetic, immunological, neurobiological, cognitive, and clinical profiles of patients. Making the case of obsessive-compulsive disorder (OCD), a lot have been made in this direction. Indeed, while the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnosis of OCD aimed to delineate a homogeneous group of patients, it is now clear that OCD is instead an heterogeneous disorders both in terms of neural networks, immunological, genetic, and clinical profiles. In this view, a convergent amount of literature, in the last years, indicated that OCD patients with an early age at onset seem to have a specific clinical and biological profile, suggesting it as a neurodevelopmental disorder. Also, these patients tend to have a worse outcome respect to adult-onset patients and there is growing evidence that early-interventions could potentially improve their prognosis. Therefore, the aim of the present paper is to review the current available genetic, immunological, neurobiological, cognitive, and clinical data in favor of a more biologically precise subtype of OCD: the early-onset subtype. We also briefly resume current available recommendations for the clinical management of this specific population.

Pattern of expression of Toll like receptor (TLR)-3 and -4 genes in drug-naïve and antipsychotic treated patients diagnosed with schizophrenia

Toll like receptors (TLRs), a class of conserved immune molecules are crucially involved in initiating innate immune response to infection. TLR activation and subsequent inflammation are linked to pathogenesis of many brain disorders. Preliminary studies indicate a possible role of TLR-driven immuno-inflammatory responses in schizophrenia. However, gene expression data of TLRs in drug-naïve as well as antipsychotic treated patients diagnosed with schizophrenia are albeit limited. In this study, expression profile of TLR3 and TLR4 genes in peripheral blood mononuclear cells (PBMCs) was compared between drug-naïve patients diagnosed with schizophrenia (N = 31) and healthy controls (N = 30). In addition, the pattern of expression of TLR3 and TLR4 genes were also examined after three months of antipsychotic medication in patients. Compared to healthy controls, gene expression levels of only TLR4 (F = 3.87, p = 0.05, η_p² = 0.06), not TLR3 (F = 0.17, p = 0.71, η_p² = 0.003) was significantly up-regulated in drug-naïve patients. The changes in the levels of gene expression of TLR3 (t = 0.09, p = 0.93, d = 0.02) and TLR4 (t = 0.29, p = 0.77, d = 0.06) before and after antipsychotic medication were not found to be statistically significant. This finding suggests possible contribution of TLR4 in immunopathogenetic pathway of schizophrenia.

Association of high-sensitivity C-reactive protein with susceptibility to Schizophrenia in Tunisian population

The pathogenic mechanisms underlying Schizophrenia (SZ), one of the most frequent mental disorders, are complex and poorly understood. Several evidences suggest that inflammatory processes may underpin some of its neurobiological correlates. The aim of this study was: (i) to analyze the potential association between circulating levels of the C-reactive protein (CRP), a crucial inflammatory marker, and Schizophrenia in Tunisian patients and healthy controls (HC) cohorts; (ii) to investigate the genetic diversity of three CRP variants (rs1417938, rs1130864 and rs1205) and; (iii) to analyze a potential relationship between expression and genetic data and clinical and socio demographical characteristics. CRP polymorphisms were exanimated for 155 patients and 203 HC by taqMan5'-nuclease. High-sensitivity CRP (hs-CRP) serum level was measured in 128 clinically stable out-patient SZ patients and 63 HC subjects via an automated biochemical analyzer. We found that hs-CRP levels were significantly higher in SZ patients as compared to HC. No significant differences were found when the proportions of CRP variants were compared in patients and HC. Further analysis according to clinical and socio demographical characteristics revealed a positive association with age and hypertension. Our data on an original Tunisian sample confirm the previous finding in others population groups.

Perspective: Solving the Heterogeneity Conundrum of TSPO PET Imaging in Psychosis

Positron emission tomography using ligands targeting translocator protein 18 kDa (TSPO PET) is an innovative method to visualize and quantify glial inflammatory responses in the central nervous system in vivo. Compared to some other neuropsychiatric disorders, findings of TSPO PET in schizophrenia and related psychotic disorders have been considerably more heterogeneous. Two conflicting meta-analyses have been published on the topic within the last year: one asserting evidence for decreased TSPO uptake, while the other observed increased TSPO uptake in a selection of studies. In this paper, we review and discuss five hypotheses which may explain the observed variability of TSPO PET findings in psychotic illness, namely that (1) an inflammatory phenotype is only present in a subgroup of psychosis patients; (2) heterogeneity is caused by interference of antipsychotic medication; (3) interference of other clinical confounders in the study populations (such as age, sex, BMI, smoking, and substance use); or (4) methodological variability between studies (such as choice of tracer and kinetic model, genotyping, study power, and diurnal effects); and (5) the glial responses underlying changes in TSPO expression are themselves heterogeneous and dynamic. Finally, we propose four key recommendations for future research proposals to mitigate these different causes of heterogeneity.

Impact of antipsychotic medication on IL-6/STAT3 signaling axis in peripheral blood mononuclear cells of drug-naive schizophrenia patients

AIM

Immunopathogenesis remains a widely appreciated etiopathological model of schizophrenia. Persistent efforts have aimed to identify schizophrenia biomarkers indexing immune system abnormalities and also immuno-dampening effects of antipsychotic medications. Although data arising from published reports are encouraging, such studies are limited to a few immune parameters and not focused on a specific pathway. Th17 cells-mediated immuno-inflammatory responses have emerged as a potential mechanism in various neuropsychiatric conditions, including schizophrenia. The Th17 pathway is distinctly regulated through a coordinated action of multiple cytokines and transcription factors. In this study, we explored whether antipsychotic medication has any effect on the cytokines and transcription factors of the Th17 pathway.

METHODS

A total of 27 drug-naive schizophrenia patients were recruited and followed up for 3 months after initiation of antipsychotic medication. Lymphocyte gene expression levels of two transcription factors (STAT3 and RORC) and one of their upstream regulators, IL6, were quantified before and after treatment. Plasma levels of cytokines, such as interleukin (IL)-1β, IL-6, IL-17A, IL-23, and IL-33, were also analyzed before and after treatment.

RESULTS

Treatment with antipsychotic medication for 3 months resulted in significant downregulation of STAT3 gene expression as well as reduction in plasma levels of IL-1β, IL-6, and IL-17A. Significant reduction in total scores for the Scale for Assessment of Positive Symptoms and the Scale for Assessment of Negative Symptoms was also observed in schizophrenia patients after 3 months of antipsychotic treatment.

CONCLUSION

Our findings suggest possible immuno-modulatory effects of antipsychotic medication on the critical regulators, such as IL-6 and STAT3, of the Th17 pathway in schizophrenia patients. The IL-6/STAT3 signaling axis involved in the transcriptional regulation of Th17 cells might appear as an important target of antipsychotic treatment in schizophrenia patients. Alternatively, irrespective of the effect of antipsychotic drugs, the IL-6/STAT3 signaling axis might be crucially involved in ameliorating psychotic symptoms.

Association of Cytomegalovirus and Toxoplasma gondii Antibody Titers With Bipolar Disorder

IMPORTANCE

Infection-associated immune activation and inflammation are increasingly recognized in the pathophysiology of bipolar disorder.

OBJECTIVE

To determine whether antibodies to common infectious agents, including cytomegalovirus (CMV), Toxoplasma gondii, and measles, as well as the inflammatory marker C-reactive protein, in serum samples differ between patients with bipolar disorder and control individuals without bipolar disorder.

DESIGN, SETTING, AND PARTICIPANTS

In this case-control study, antibody titers were measured in serum samples from 1207 patients with bipolar disorder and 745 controls that were obtained from biobanks with participating sites in Rochester and Minneapolis, Minnesota (n = 1537), and Cincinnati, Ohio (n = 415), from January 5, 2009, through May 12, 2014. A subset of case patients and controls from Minnesota were matched by age, sex, and educational level. Bipolar type, age at onset, and history of psychosis were assessed for case patients as well as current drug treatment at the time of blood sample obtainment from the biobank. Data were analyzed from February 5, 2018, to January 4, 2019.

EXPOSURES

The CMV and T gondii antibodies with IgM titers were expressed as z scores and IgG titers dichotomized into seropositive and seronegative based on expected prevalence in the US population and further classified based on the joint CMV-positive/T gondii-negative IgG status, C-reactive protein z score, and drug treatments with antitoxoplasma activity.

MAIN OUTCOMES AND MEASURES

Patients were stratified by bipolar disorder type I or type II, nonearly (>19 years of age) and early (≤19 years of age) onset, and history of psychosis during mania or no psychosis.

RESULTS

Of 1207 patients with bipolar disorder (mean [SD] age, 43.2 [15.1] years; 742 [61.5%] female), the CMV-positive/T gondii-negative IgG status was significantly higher (odds ratio [OR], 1.33; 95% CI, 1.09-1.62; P = .004) compared with that in the 745 controls (mean [SD] age, 44.5 [15.5] years; 444 [59.6%] female). The CMV-positive/T gondii-negative IgG status was associated with bipolar cases type I (OR, 1.41; 95% CI, 1.14-1.75; P = .001), nonearly age at onset (OR, 1.41; 95% CI, 1.16-1.72; P = .001), and history of manic psychosis (OR, 1.46; 95% CI, 1.13-1.88; P = .004). Patients with bipolar disorder who received drug treatment with antitoxoplasma activity (n = 272) had significantly lower T gondii IgM titers (median, 1.59; interquartile range, 1.30-2.07) compared with those (n = 900) who did not receive this treatment (median, 1.69; interquartile range, 1.35-2.25) (P = .03).

CONCLUSIONS AND RELEVANCE

In this sample, increased long-term antibody response to CMV and decreased long-term antibody response to T gondii were associated with bipolar disorder and the subphenotypes of bipolar type I, nonearly disease onset, and manic psychosis. Further work appears to be needed to better understand genetic vs environmental disease risk and infection or immune activation contribution to overall disease pathogenesis with particular reference to disease onset.

The Impact of Immunological Factors on Depression Treatment - Relation Between Antidepressants and Immunomodulation Agents

It is determined that 30% of patients with depression are resistant to antidepressant medication. The increased concentration of inflammation factors, such as C-reactive protein, and pro-inflammatory cytokines, have been detected in serum in these patients. It is necessary to establish new therapeutic possibilities and protocols that are created to overcome the difficulties caused by increased concentration of inflammatory biomarkers in depressive patients. The Selective Serotonin Reuptake Inhibitors (SSRIs) are considered to be the most powerful antidepressants, increasing the level of serotonin in endogenous depression, as well as in that caused by immunological mechanisms. It is believed that agents that influence cytokines, immunological signal pathways and cytokine syntheses, like the inhibitors of cyclooxygenase enzyme and other non-steroidal anti-inflammatory drugs (NSAIDs), are very important in the potential treatment of residual symptoms of depression. Treatment with cytokine antagonists is one of the potential adjuvant therapies, along with antidepressants. Signal pathways blockers, such as the inhibitors of cyclooxygenase and other NSAIDs, are in the phase of research, in terms of their antidepressant effects. Also, it has been shown that the inhibition of indolamin-2,3 deoxygenase (IDO) and kynurenine (KYN) signal pathways in the synthesis of neurotransmitters, by application of IDO antagonists, are leading to suppression of pro-inflammatory cytokine effects. Antidepressants may have anti-inflammatory effects, depending on dose and type, and they achieve this effect through the decrease of pro-inflammatory cytokine production and increase of anti-inflammatory cytokines. Also, antidepressants modulate the humoral and cellular immune system. This work aims to summarise certain neurobiological and neuroimmunological specificities that have been observed in patients with depression, antidepressants and immunomodulation agents. The understanding of complex and heterogenic pathophysiology of depression through the prism of the altered immune system, is of major importance, in terms of better optimisation of pharmacotherapy, and options for a personalised approach in depressive disorder treatment.

[First-episode psychosis as primary manifestation of medical disease: An update]

A huge variety of medical diseases may potentially present with isolated psychotic symptoms, and disease-specific treatment or management is available for a significant part of them. The initial medical work-up of a first-episode psychosis (FEP) is of crucial importance. This literature review aimed to identify medical conditions potentially revealed by FEP, to list the warning signs of secondary psychosis, and to discuss a screening strategy. Underlying organic conditions may be drugs and medications, neurologic diseases, infections, inflammatory and/or autoimmune pathologies, and metabolic disorders whether of hereditary origin. Each patient presenting with a first-episode psychosis should be evaluated with a precise anamnesis, a careful clinical examination, and routine laboratory tests. Brain imaging and tests (depending on the context) should be performed in the presence of atypical clinical features or "red flags", leading to suspect an organic disease.

Global, pathway and gene coverage of three Illumina arrays with respect to inflammatory and immune-related pathways

Genome-wide association studies have led in the past to the discovery of susceptibility genes for many diseases including cancer and inflammatory conditions. However, a number of these studies did not realise their full potential. A first critical step in developing such large-scale studies is the choice of genotyping array with respect to the study goal. Coverage is the central criterion for array evaluation. We distinguish between estimates of global coverage across the genome, coverage for each chromosome, coverage for selected pathways and the coverage for genes of interest. Here, we focus on inflammatory and immunological pathways and genes relevant for haematopoietic stem cell transplantation. We compared three arrays: the Infinium Global Screening Array-24 v1.0, the Infinium OncoArray-500 K BeadChip and the Infinium PsychArray-24 v1.2 BeadChip. We employed the European population from the 1000 Genomes Project as reference genome. Global coverage was found to range between 12.2 and 14.2% whereas coverage for a selected pathway ranged from 6.2 to 13.2% and gene coverage ranged from 0 to 54.1%. The Global Screening Array outperformed both other arrays in terms of global coverage, for most chromosomes, most considered pathways and most genes. When selecting suitable arrays for a new study, the coverage of pathways or genes of interest should be considered in addition to global coverage. Local coverage should be regarded when discussing association findings inconsistent across studies and can be useful in data analysis and decision making for additional genotyping.

Protocol and Rationale: A 24-week Double-blind, Randomized, Placebo Controlled Trial of the Efficacy of Adjunctive Garcinia mangostanaLinn. (Mangosteen) Pericarp for Schizophrenia

Objective

Garcinia mangostana Linn., commonly known as mangosteen, is a tropical fruit with a thick pericarp rind containing bioactive compounds that may be beneficial as an adjunctive treatment for schizophrenia. The biological underpinnings of schizophrenia are believed to involve altered neurotransmission, inflammation, redox systems, mitochondrial dysfunction, and neurogenesis. Mangosteen pericarp contains xanthones which may target these biological pathways and improve symptoms; this is supported by preclinical evidence. Here we outline the protocol for a double-blind randomized placebo-controlled trial evaluating the efficacy of adjunctive mangosteen pericarp (1,000 mg/day), compared to placebo, in the treatment of schizophrenia.

Methods

We aim to recruit 150 participants across two sites (Geelong and Brisbane). Participants diagnosed with schizophrenia or schizoaffective disorder will be randomized to receive 24 weeks of either adjunctive 1,000 mg/day of mangosteen pericarp or matched placebo, in addition to their usual treatment. The primary outcome measure is mean change in the Positive and Negative Symptom Scale (total score) over the 24 weeks. Secondary outcomes include positive and negative symptoms, general psychopathology, clinical global severity and improvement, depressive symptoms, life satisfaction, functioning, participants reported overall improvement, substance use, cognition, safety and biological data. A 4-week post treatment interview at week 28 will explore post-discontinuations effects.

Results

Ethical and governance approvals were gained and the trial commenced.

Conclusion

A positive finding in this study has the potential to provide a new adjunctive treatment option for people with schizophrenia and schizoaffective disorder. It may also lead to a greater understanding of the pathophysiology of the disorder.

Dysregulation of the gut-brain axis in schizophrenia and bipolar disorder: probiotic supplementation as a supportive treatment in psychiatric disorders

PURPOSE OF REVIEW

Schizophrenia (SCZ) and bipolar disorder are severe mental disorders, both placing a significant burden on individuals' wellbeing and global health generally. The complex interaction of multiple mechanisms, underlying these disorders, still needs further elucidation. Increased activation of components of the immune system may be involved, including alterations in intestinal permeability and gut microbiome. Probiotics, defined as living microorganisms conferring health benefits to the host when administered in adequate amounts, seem to have supportive therapeutic effect in psychiatric disorders. The authors in this review provide an overview of this emerging research field and summarize both the publicated microbiome studies in SCZ and bipolar disorder and the current clinical research using probiotic supplementation in patients diagnosed with these disorders.

RECENT FINDINGS

The current data indicate that there are differences in the microbiome in SCZ and bipolar disorder patients as compared with healthy controls. Part of these differences may be induced by medication use, others by smoking and other lifestyle factors. Correlations between microbiome quantification and symptom severity have been observed in cross-sectional studies, but unfortunately, no replicated findings so far. Probiotic supplementation was shown not only to alleviate gastrointestinal complaints but also reduce symptom severity, rehospitalization rates and cognitive improvement. Replication of improvement of cognition is needed.

SUMMARY

Differences in microbiome have been shown in both SCZ and bipolar disorder in comparison to healthy controls. Evidence that probiotics can improve psychiatric functioning is still very limited.

A multisystem composite biomarker as a preliminary diagnostic test in bipolar disorder

OBJECTIVE

Diagnosis and management of bipolar disorder (BD) are limited by the absence of available laboratory tests. We aimed to combine data from different molecular levels and tissues into a composite diagnostic and state biomarker.

METHODS

Expression levels of 19 candidate genes in peripheral blood, plasma levels of BDNF, NT-3, IL-6 and IL-18, leukocyte counts, and urinary markers of oxidative damage to DNA and RNA were measured in 37 adult rapid-cycling patients with BD in different affective states during a 6- to 12-month period and in 40 age- and gender-matched healthy individuals in a longitudinal, repeated measures design comprising a total of 211 samples. A composite biomarker was constructed using data-driven variable selection.

RESULTS

The composite biomarker discriminated between patients with BD and healthy control individuals with an area under the receiver operating characteristic curve (AUC) of 0.83 and a sensitivity of 73% and specificity of 71% corresponding with a moderately accurate test. Discrimination between manic and depressive states had a moderate accuracy, with an AUC of 0.82 and a sensitivity of 92% and a specificity of 40%.

CONCLUSION

Combining individual biomarkers across tissues and molecular systems could be a promising avenue for research in biomarker models in BD.

Immunological Aspects of Depressive Disorder – The Review

Depression represents a mood disorder and is considered to be one of the most common mental disorders in general. World Health Organization estimates that depression will be the leading cause of disability-adjusted life years, until 2030. Depression is a complex heterogeneous disorder where immune system and its regulation play an important role. Innate and adaptive immunity mecha nisms are included, along with processes of immune activation and suppression. The expression of humoral factors of innate immunity, especially pro-inflammatory cytokines, is increased, whereas the intensity of cellular immune mechanisms, primarily T cells and NK cells, are impaired. The influence of pro-inflammatory cytokines on depression is reflected in their effect on certain enzymes and ensuing reduction of neurotransmitters serotonin and dopamine. They also affect the neuroendocrine function in central nervous system, resulting in increase of cortisol levels and inactivation of glucocorticoid receptors in the periphery, which leads to neurodegeneration and decrease in neurotransmitter production. Certain cytokines affect neuroplasticity through the decreasing of concentration of neurotrophic brain factor and induction of brain cell apoptosis. The results are often contradictory talking about mechanisms of adaptive immunity. On one hand, an increased activity of Tlymphocytes is observed, while on the other, there are evidence of spontaneous apoptosis and impaired function of these cells in depression. In addition, neuroprotective role of autoreactive and regulatory T cells in prevention of depression has also been demonstrated. The aim of this paper is to analyze the current knowledge on the role of immune mechanisms in the pathogenesis of depression.

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.

Individualized Immunological Data for Precise Classification of OCD Patients

Obsessive⁻compulsive disorder (OCD) affects about 2% of the general population, for which several etiological factors were identified. Important among these is immunological dysfunction. This review aims to show how immunology can inform specific etiological factors, and how distinguishing between these etiologies is important from a personalized treatment perspective. We found discrepancies concerning cytokines, raising the hypothesis of specific immunological etiological factors. Antibody studies support the existence of a potential autoimmune etiological factor. Infections may also provoke OCD symptoms, and therefore, could be considered as specific etiological factors with specific immunological impairments. Finally, we underline the importance of distinguishing between different etiological factors since some specific treatments already exist in the context of immunological factors for the improvement of classic treatments.

Toxoplasma gondii: Biological Parameters of the Connection to Schizophrenia

It is increasingly evident that the brain is not truly an immune privileged site and that cells of the central nervous system are sensitive to the inflammation generated when the brain is fighting off infection. Among the many microorganisms that have access to the brain, the apicomplexan protozoan Toxoplasma gondii has been one of the most studied. This parasite has been associated with many neuropsychiatric disorders including schizophrenia. This article provides a comprehensive review of the status of Toxoplasma research in schizophrenia. Areas of interest include (1) the limitations and improvements of immune-based assays to detect these infections in humans, (2) recent discoveries concerning the schizophrenia-Toxoplasma association, (3) findings of Toxoplasma neuropathology in animal models related to schizophrenia pathogenesis, (4) interactions of Toxoplasma with the host genome, (5) gastrointestinal effects of Toxoplasma infections, and (6) therapeutic intervention of Toxoplasma infections.

Pathogenicity of Antibodies against NMDA Receptor: Molecular Insights into Autoimmune Psychosis

Recent years have seen a flourishing literature on detection of circulating autoantibodies against neurotransmitter receptors in patients with neuropsychiatric disorders. These studies have generated hope for a better understanding of the underlying molecular dysfunctions and for appropriate therapeutic strategies. However, the detection of these autoantibodies in healthy subjects, and the lack of mechanistic insights have fostered debate about the pathogenic role of such autoantibodies. Here, we specifically discuss the biological evidence linking autoantibodies directed against the glutamatergic N-methyl-d-aspartate (NMDA) receptor (NMDAR-Abs) and psychosis, emphasising recent single-molecule imaging investigations that unveiled the impaired surface trafficking of NMDAR in the presence of NMDAR-Abs from psychotic patients. Although still in its infancy, the hypothesis that NMDAR-Abs from patients with psychosis play a pathogenic role is thus gaining support, opening avenues of fundamental and translational investigations.

Atomic psychiatry? An essay

OBJECTIVE

This article aims to address the need to rethink the classification of mental illness and to draw attention to the current use of quantum biology and its likely future use in understanding the nature of mental illness.

CONCLUSION

It is desirable to separate out neuroscience and clinical research and to become better acquainted with the concepts of quantum mechanical/quantum biological theory and its contribution to medicine.

The association between immune markers and recent suicide attempts in patients with serious mental illness: A pilot study

Previous studies have identified elevations in markers of gastrointestinal inflammation in schizophrenia and mood disorders but studies have not measured the association between these markers and recent suicide attempts. We assessed 210 patients receiving treatment for schizophrenia, bipolar disorder, or major depression. We employed the Columbia Suicide Severity Rating Scale to identify recent and lifetime suicide attempts (actual, aborted, and interrupted). Psychiatric participants and a control group of 72 individuals without a psychiatric disorder had a blood sample drawn from which were measured specific markers of gastrointestinal inflammation and also C-Reactive protein (CRP). A total of 20 (10%) of psychiatric participants had a suicide attempt in the previous one month and 95 (45%) an attempt during their lifetime but not in the previous one month. The recent attempters had significantly elevated levels of antibodies to yeast mannan from Saccharomyces cerevisiae (ASCA), the food antigen gliadin, and bacterial lipopolysaccharide (LPS) compared with the non-psychiatric group when adjusting for demographic and clinical variables. These markers were not elevated in individuals with a past, but not recent, suicide attempt history. Our study indicates that there is evidence of gastrointestinal inflammation in some individuals who have had a recent suicide attempt.

The microbiome, immunity, and schizophrenia and bipolar disorder

Schizophrenia and bipolar disorder are serious neuropsychiatric disorders of uncertain etiology. Recent studies indicate that immune activation may contribute to the etiopathogenesis of these disorders. Numerous studies in animal models indicate that the mucosal microbiome may influence cognition and behavior by altering the functioning of the immune system. It is thus likely that the microbiome plays a role in human psychiatric disorders. The study of immune alterations and the microbiome in schizophrenia and bipolar disorder is in its infancy. Two recent investigations of the oro-pharyngeal microbiota in schizophrenia found differences between cases and controls. Other studies have found increased gastrointestinal inflammation in schizophrenia and bipolar disorder based on measures of microbial translocation. Several studies have also found an association between the receipt of antibiotics and an increased incidence of psychiatric disorders, perhaps due to alterations in the microbiome. Studies to characterize the intestinal microbiome of individuals with these disorders are in progress. The ultimate test of the role of the microbiome and immune-mediated pathology in schizophrenia and bipolar disorder will come from clinical trials of therapeutic agents which alter gut microbiota or gastrointestinal inflammation. The successful development of such modalities would represent a novel strategy to prevent and treat serious psychiatric disorders.