Autoimmune diseases and infections as risk factors for schizophrenia

Study of Novel Autoantibodies in Schizophrenia

A recent genome-wide association (GWA) study confirmed 108 genetic loci that were strongly associated with schizophrenia. Fifteen schizophrenia-associated genes were selected for this study based on a number of selection criteria including their high expression in both brain tissues and B-lymphocyte cells. We aimed to investigate whether individuals with schizophrenia showed different levels of plasma IgG antibodies against protein-derived fragments encoded by these 15 genes. A total of 356 plasma samples were used to analyze circulating IgG antibodies against 18 target peptide antigens using an in-house enzyme-linked immunosorbent assay. Of 18 antigens tested, 6 (derived from DPYD, MAD1L1, ZNF804A, DRD2, TRANK1, and MMP16, respectively) showed increased IgG levels and 3 (derived from TSNARE1, TCF4, and VRK2, respectively) showed decreased IgG levels in patients with schizophrenia compared with control subjects. Receiver operating characteristic (ROC) curve analysis revealed that the anti-TRANK1 IgG assay had the area under the ROC curve of 0.68 (95% CI = 0.62-0.73), with the highest sensitivity of 20.7% against specificity of 95.2% among all 18 tests. There was no difference in positivity of anti-double strand DNA IgG between the patient group and the control group and no correlation between total IgG levels and each individual IgG level tested. Although risperidone treatment showed confounding effects on overall IgG levels in the circulation (combined P = .005), anti-TRANK1 IgG levels did not appear to be significantly affected (t = 1.358, P = .176). In conclusion, this study suggests that circulating anti-TRANK1 IgG is likely to serve as a biomarker for identification of a subgroup of schizophrenia.

Inflammation in Schizophrenia: Pathogenetic Aspects and Therapeutic Considerations

This paper discusses the current evidence from animal and human studies for a central role of inflammation in schizophrenia. In animal models, pre- or perinatal elicitation of the immune response may increase immune reactivity throughout life, and similar findings have been described in humans. Levels of pro-inflammatory markers, such as cytokines, have been found to be increased in the blood and cerebrospinal fluid of patients with schizophrenia. Numerous epidemiological and clinical studies have provided evidence that various infectious agents are risk factors for schizophrenia and other psychoses. For example, a large-scale epidemiological study performed in Denmark clearly showed that severe infections and autoimmune disorders are such risk factors. The vulnerability-stress-inflammation model may help to explain the role of inflammation in schizophrenia because stress can increase pro-inflammatory cytokines and may even contribute to a chronic pro-inflammatory state. Schizophrenia is characterized by risk genes that promote inflammation and by environmental stress factors and alterations of the immune system. Typical alterations of dopaminergic, serotonergic, noradrenergic, and glutamatergic neurotransmission described in schizophrenia have also been found in low-level neuroinflammation and consequently may be key factors in the generation of schizophrenia symptoms. Further support for the relevance of a low-level neuroinflammatory process in schizophrenia is provided by the loss of central nervous system volume and microglial activation demonstrated in neuroimaging studies. Last but not least, the benefit of anti-inflammatory medications found in some studies and the intrinsic anti-inflammatory and immunomodulatory effects of antipsychotics provide further support for the role of inflammation in this debilitating disease.

Psychiatric syndromes other than dementia

There is wide variability in how psychiatry guidelines and textbooks address the question of cerebrospinal fluid (CSF) diagnostics in the screening of psychiatric disorders. A United States-based textbook confirms that there is no consensus about which laboratory investigation should be routinely performed in psychiatric patients, but with respect to CSF diagnostics, the differences are even more striking. A survey among European experts showed a wide variety of opinions regarding clinical use and criteria in various countries of Europe and worldwide: some psychiatrists, mostly university hospital-based, recommended performing CSF diagnostics in every patient first experiencing severe mental illness (SMI), but especially in patients from the schizophrenia spectrum, whereas others almost never perform CSF examinations themselves and usually refer patients to neurology departments if necessary. Minor neurologic signs are generally frequent in SMI, mainly in affective and schizophrenic disorders. Even with neurologic signs present, there are no clear guidelines regarding CSF evaluation, leaving doctors with experience-based decision making. However, the field is evolving. A recent review provides helpful yellow and red flags for differential diagnosis of SMI from autoimmune encephalitis; interestingly, minor CSF abnormalities are considered a red flag, suggesting that CSF should be routinely performed in acute psychiatric patients. There are reports of single cases identified as an established neurologic disorder: patients within affective and schizophrenic spectrum disorders systematically underwent CSF examination, and were rediagnosed based on CSF results. This was often to the surprise of the psychiatric doctors. Overall, an increasing number of psychiatrists believe that CSF is too rarely examined in psychiatric patients. This chapter provides an overview of differential diagnostic issues in SMI, particularly for new-onset cases. The general recommendations regarding CSF examination procedures can be found in other chapters of this book. Here we focus on specific aspects of differential diagnosis in SMI. Also, there will be an overview of admittedly limited CSF research efforts in psychiatric disorders, focusing on more recent CSF studies. CSF studies in SMI performed with state-of-the-art methods, for example proteomics or assessments of cytokines, were intriguing but difficult to interpret and required critical considerations regarding respective methodology, an undertaking which is outside the scope of this chapter.

Tumor necrosis factor-alpha -1031T/C polymorphism is associated with cognitive deficits in chronic schizophrenia patients versus healthy controls

Recent compelling research has demonstrated a pathophysiologic role for proinflammatory cytokines of microglial origin in decreasing neurocognitive function. Psychiatric diseases are already known to have reduced cognitive function and are also associated with increased inflammation. To elaborate on these data, our study aims to investigate how a particular polymorphism of the tumor necrosis factor gene, TNF-α -1031T/C, affects neurocognitive performance in patients with schizophrenia. We recruited 905 patients with schizophrenia and 571 healthy control subjects. We employed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to test for neurocognitive function and the positive and negative syndrome scale to evaluate schizophrenia severity. The -1031T/C polymorphism was genotyped in both healthy controls and schizophrenic patients. Our results demonstrate that patients with the C allele (either T/C or C/C) possessed increased immediate memory index, visuospatial/constructional index, and RBANS total scores as compared to patients without it (p < .05). In healthy controls, there was no significant difference across genotypes (p > .05). Our findings demonstrate that the TNF-α -1031T/C polymorphism may not play a role in the susceptibility of schizophrenia itself, but may be involved in the cognitive deficits of schizophrenia. This suggests an important role for cytokine signaling in mediating the severity of cognitive dysfunction in schizophrenia.

Decision-making Capacity for Treatment of Psychotic Patients on Long Acting Injectable Antipsychotic Treatment

OBJECTIVE

Providing informed, consent requires patients' Decision-Making Capacity for treatment. We evaluated the Decision Making Capacity of outpatients diagnosed with schizophrenia and schizoaffective disorder on treatment with Long Acting Injectable Antipsychotic medication.

METHOD

This is a retrospective, cross-sectional, correlational study conducted at two Depot Clinics in Athens, Greece. Participants included 65 outpatients diagnosed with schizophrenia and schizoaffective disorder on treatment with Long Acting Injectable Antipsychotics.

RESULTS

Over half of the participants showed poor understanding of the information given regarding their disease and treatment (Understanding subscale), however >70% seemed to comprehend the relevance of this information to their medical condition (Appreciation subscale). Moreover, half of the participants reported adequate reasoning ability (Reasoning subscale), whilst patients who gained >7% of their body weight scored statistically significantly higher in the subscales of Understanding and Appreciation.

CONCLUSION

Our results suggest that there is a proportion of patients with significantly diminished Decision Making Capacity, hence a full assessment is recommended in order to track them down. Further research is needed to better interpret the association between antipsychotic induced weight gain and Decision Making Capacity in patients suffering from schizophrenia or schizoaffective disorder.

A clinical approach to new-onset psychosis associated with immune dysregulation: the concept of autoimmune psychosis

Growing data point to the overlap between psychosis and pathological processes associated with immunological dysregulation as well as inflammation. Notably, the recent discovery of antibodies against synaptic and neuronal cell membrane proteins such as anti-N-methyl-d-aspartate receptor provides more direct evidence of the etiological connection between autoimmunity and subsequent hazard of psychosis. Here, we advocate the use of term “autoimmune psychosis,” as this term suggests that autoimmune disorders can masquerade as drug-resistant primary psychosis, and this subtype of psychosis has anatomical and immunological footprints in the brain, despite the frequent absence of structural abnormalities on conventional brain MRI. Furthermore, this term might serve as a reminder not to overlook appropriate neurological workup such as neuroimaging and EEG testing, as well as CSF analysis, for cases with acute or subacute atypical onset of neuropsychiatric presentations including those dominated by acute psychotic symptoms. We propose etiologically and serologically oriented subclassification as well as multi-modal diagnostic approach to address some of the challenges inherent to early diagnosis of patients presenting with atypical and refractory new-onset psychotic symptoms of autoimmune origin. This is particularly relevant to the diagnosis of seronegative but probable autoimmune psychosis (SPAP) that might masquerade as antipsychotic drug-resistant primary psychotic disorder. This distinction is therapeutically important as autoimmune-related psychotic symptomatology can frequently respond well to timely treatment with proper immune modulatory therapies.

Longitudinal association between mental disorders in childhood and subsequent depression - A nationwide prospective cohort study

BACKGROUND

Depression ranges among the most impairing mental disorders worldwide, and early detection is a global health priority. Little is known about the association between non-affective mental disorders in childhood/adolescence and later depression.

METHODS

Nationwide register-based prospective cohort study, estimating cumulative incidences and incidence rate ratios (IRR) for later depression in individuals with and without non-affective mental disorders in early life.

RESULTS

475,213 females and 484,813 males born 1990-2007 were followed for a mean of 9.14 years (contributing a total of 8778,331 person-years of observation). In the cohort, 7963 (5451 females) were diagnosed with depression. Depression was more common in individuals with prior non-affective mental disorders in adolescence (15.98% in females and 7.02% in males) and in childhood (4.98% in females and 1.6% in males), than in the background population (3.94% and 1.3% in females; 1.37% and 0.47% in males). Eating and anxiety disorders in childhood/adolescence carried the highest absolute risk of depression. The relative risk of depression was particularly high the first year after the first non-affective disorder (IRR = 15.5; 14.07-17.10), but remained highly elevated more than five years after the first non-affective diagnosis (IRR = 2.05; 1.84-2.28), when compared to young people without such disorders.

LIMITATIONS

This study only included diagnoses given at hospital departments, representing the more severe mental disorders.

CONCLUSIONS

Children and adolescents with non-affective mental disorders were at substantially increased absolute and relative risk of developing depression in young adulthood, especially females diagnosed with anxiety- or eating disorders in adolescence. These findings may help identify groups of children and adolescents at very high risk of developing depression.

The blood-brain barrier in psychosis

Blood-brain barrier pathology is recognised as a central factor in the development of many neurological disorders, but much less is known about the role of the blood-brain barrier in psychiatric disorders. We review post-mortem, serum-biomarker, CSF-biomarker, and neuroimaging studies that have examined blood-brain barrier structure and function in schizophrenia and related psychoses. We consider how blood-brain barrier dysfunction could relate to glutamatergic and inflammatory abnormalities, which are increasingly understood to play a part in the pathogenesis of psychosis. Mechanisms by which the blood-brain barrier and its associated solute transporters moderate CNS availability of antipsychotic drugs are summarised. We conclude that the complex nature of blood-brain barrier dysfunction in psychosis might be relevant to many aspects of disrupted neuronal and synaptic function, increased permeability to inflammatory molecules, disrupted glutamate homoeostasis, impaired action of antipsychotics, and development of antipsychotic resistance. Future research should address the longitudinal course of blood-brain barrier alterations in psychosis, to determine whether blood-brain barrier dysfunction is a cause or consequence of the pathology associated with the disorder.

Inflammatory dysregulation of monocytes in pediatric patients with obsessive-compulsive disorder

BACKGROUND

Although the exact etiology of obsessive-compulsive disorder (OCD) is unknown, there is growing evidence of a role for immune dysregulation in the pathophysiology of the disease, especially in the innate immune system including the microglia. To test this hypothesis, we studied inflammatory markers in monocytes from pediatric patients with OCD and from healthy controls.

METHODS

We determined the percentages of total monocytes, CD16+ monocytes, and classical (CD14^highCD16-), intermediate (CD14^highCD16^low), and non-classical (CD14^lowCD16^high) monocyte subsets in 102 patients with early-onset OCD and in 47 healthy controls. Moreover, proinflammatory cytokine production (GM-CSF, IL-1β, IL-6, IL-8, and TNF-α) was measured by multiplex Luminex analysis in isolated monocyte cultures, in basal conditions, after exposure to lipopolysaccharide (LPS) to stimulate immune response or after exposure to LPS and the immunosuppressant dexamethasone.

RESULTS

OCD patients had significantly higher percentages of total monocytes and CD16+ monocytes than healthy controls, mainly due to an increase in the intermediate subset but also in the non-classical monocytes. Monocytes from OCD patients released higher amounts of GM-CSF, IL-1β, IL-6, IL-8, and TNF-α than healthy controls after exposure to LPS. However, there were no significant differences in basal cytokine production or the sensitivity of monocytes to dexamethasone treatment between both groups. Based on monocyte subset distribution and cytokine production after LPS stimulation, patients receiving psychoactive medications seem to have an intermediate inflammatory profile, that is, lower than non-medicated OCD individuals and higher than healthy controls.

CONCLUSIONS

These results strongly support the involvement of an enhanced proinflammatory innate immune response in the etiopathogenesis of early-onset OCD.

Eating Disorders, Autoimmune, and Autoinflammatory Disease

OBJECTIVES

Identifying factors associated with risk for eating disorders is important for clarifying etiology and for enhancing early detection of eating disorders in primary care. We hypothesized that autoimmune and autoinflammatory diseases would be associated with eating disorders in children and adolescents and that family history of these illnesses would be associated with eating disorders in probands.

METHODS

In this large, nationwide, population-based cohort study of all children and adolescents born in Denmark between 1989 and 2006 and managed until 2012, Danish medical registers captured all inpatient and outpatient diagnoses of eating disorders and autoimmune and autoinflammatory diseases. The study population included 930 977 individuals (48.7% girls). Cox proportional hazards regression models and logistic regression were applied to evaluate associations.

RESULTS

We found significantly higher hazards of eating disorders for children and adolescents with autoimmune or autoinflammatory diseases: 36% higher hazard for anorexia nervosa, 73% for bulimia nervosa, and 72% for an eating disorder not otherwise specified. The association was particularly strong in boys. Parental autoimmune or autoinflammatory disease history was associated with significantly increased odds for anorexia nervosa (odds ratio [OR] = 1.13, confidence interval [CI] = 1.01-1.25), bulimia nervosa (OR = 1.29; CI = 1.08-1.55) and for an eating disorder not otherwise specified (OR = 1.27; CI = 1.13-1.44).

CONCLUSIONS

Autoimmune and autoinflammatory diseases are associated with increased risk for eating disorders. Ultimately, understanding the role of immune system disturbance for the etiology and pathogenesis of eating disorders could point toward novel treatment targets.

Psychosis: an autoimmune disease?

Psychotic disorders are common and disabling. Overlaps in clinical course in addition to epidemiological and genetic associations raise the possibility that autoimmune mechanisms may underlie some psychoses, potentially offering novel therapeutic approaches. Several immune loci including the major histocompatibility complex and B-cell markers CD19 and CD20 achieve genome-wide significance in schizophrenia. Emerging evidence suggests a potential role via neurodevelopment in addition to classical immune pathways. Additionally, lymphocyte biology is increasingly investigated. Some reports note raised peripheral CD19+ and reduced CD3+ lymphocyte counts, with altered CD4 : CD8 ratios in acute psychosis. Also, post-mortem studies have found CD3+ and CD20+ lymphocyte infiltration in brain regions that are of functional relevance to psychosis. More specifically, the recent paradigm of neuronal surface antibody-mediated (NSAb) central nervous system disease provides an antigen-specific model linking adaptive autoimmunity to psychopathology. NSAbs bind extracellular epitopes of signalling molecules that are classically implicated in psychosis such as NMDA and GABA receptors. This interaction may cause circuit dysfunction leading to psychosis among other neurological features in patients with autoimmune encephalitis. The detection of these cases is crucial as autoimmune encephalitis is ameliorated by commonly available immunotherapies. Meanwhile, the prevalence and relevance of these antibodies in people with isolated psychotic disorders is an area of emerging scientific and clinical interest. Collaborative efforts to achieve larger sample sizes, comparison of assay platforms, and placebo-controlled randomized clinical trials are now needed to establish an autoimmune contribution to psychosis.

Associations between SNPs and immune-related circulating proteins in schizophrenia

Genome-wide association studies (GWAS) and proteomic studies have provided convincing evidence implicating alterations in immune/inflammatory processes in schizophrenia. However, despite the convergence of evidence, direct links between the genetic and proteomic findings are still lacking for schizophrenia. We investigated associations between single nucleotide polymorphisms (SNPs) from the custom-made PsychArray and the expression levels of 190 multiplex immunoassay profiled serum proteins in 149 schizophrenia patients and 198 matched controls. We identified associations between 81 SNPs and 29 proteins, primarily involved in immune/inflammation responses. Significant SNPxDiagnosis interactions were identified for eight serum proteins including Factor-VII[rs555212], Alpha-1-Antitrypsin[rs11846959], Interferon-Gamma Induced Protein 10[rs4256246] and von-Willebrand-Factor[rs12829220] in the control group; Chromogranin-A[rs9658644], Cystatin-C[rs2424577] and Vitamin K-Dependent Protein S[rs6123] in the schizophrenia group; Interleukin-6 receptor[rs7553796] in both the control and schizophrenia groups. These results suggested that the effect of these SNPs on expression of the respective proteins varies with diagnosis. The combination of patient-specific genetic information with blood biomarker data opens a novel approach to investigate disease mechanisms in schizophrenia and other psychiatric disorders. Our findings not only suggest that blood protein expression is influenced by polymorphisms in the corresponding gene, but also that the effect of certain SNPs on expression of proteins can vary with diagnosis.

Remission of Psychosis in Treatment-Resistant Schizophrenia following Bone Marrow Transplantation: A Case Report

The authors present the case of a 24-year-old male with treatment-resistant schizophrenia, with predominant severe delusion and hallucination, who received bone marrow transplantation (BMT) for acute myeloid leukemia. After BMT, he showed a remarkable reduction in psychotic symptoms without administration of neuroleptics. He also showed drastic improvement in social functioning. Follow-up evaluations 2 and 4 years after BMT showed persistent significant improvement of the psychotic state and social functioning. Recent findings show that the major underlying pathogenic mechanism of schizophrenia is immune dysregulation. Thus, conceptually, BMT, a cellular therapy, that facilitates the counteractive processes of balancing inflammation by immune regulation, could produce beneficial clinical effects in patients with treatment-resistant schizophrenia. Further studies are required to define the true benefits of BMT for the possible curative treatment of schizophrenia.

Cross Talk: The Microbiota and Neurodevelopmental Disorders

Humans evolved within a microbial ecosystem resulting in an interlinked physiology. The gut microbiota can signal to the brain via the immune system, the vagus nerve or other host-microbe interactions facilitated by gut hormones, regulation of tryptophan metabolism and microbial metabolites such as short chain fatty acids (SCFA), to influence brain development, function and behavior. Emerging evidence suggests that the gut microbiota may play a role in shaping cognitive networks encompassing emotional and social domains in neurodevelopmental disorders. Drawing upon pre-clinical and clinical evidence, we review the potential role of the gut microbiota in the origins and development of social and emotional domains related to Autism spectrum disorders (ASD) and schizophrenia. Small preliminary clinical studies have demonstrated gut microbiota alterations in both ASD and schizophrenia compared to healthy controls. However, we await the further development of mechanistic insights, together with large scale longitudinal clinical trials, that encompass a systems level dimensional approach, to investigate whether promising pre-clinical and initial clinical findings lead to clinical relevance.

Immunological aspects of the treatment of depression and schizophrenia

Schizophrenia and major depression (MD) have been associated with immune system dysfunction. One example of this is the altered level of cytokines—important inflammatory mediators—in blood, and a proinflammatory immune state has been described in some subgroups of patients. A knock to the immune system in early life might trigger a life-long increased immune reactivity, and infections and autoimmune disorders are now known to be risk factors for development of schizophrenia and MD. Pro- and anti-inflammatory cytokines mediate indoleamine 2,3-dioxygenase activity; this enzyme drives metabolism of tryptophan and kynurenin in the central nervous system and degrades serotonin. Alterations of serotonergic, noradrenergic, and glutamatergic neurotransmission have been associated with low-level neuroinflammation, and anti-inflammatory compounds have a therapeutic benefit in MD and schizophrenia, as shown in meta-analyses. Moreover, antidepressants and antipsychotics have intrinsic immunomodulatory effects. With evidence pointing to the role inflammatory processes play in the pathogenesis of major psychiatric disorders, this review will look at various immunological aspects of treatment of such disorders.

Multiple Sclerosis and Schizophrenia

The psychiatric and neurological aspects of health may present methodological challenges in the diagnosis and treatment of disease. This is especially true for patients whose symptoms indicate the coexistence of multiple sclerosis (MS) and schizophrenia (SCZ). These cases raise critical questions regarding the relationship between the mind and the brain. Studies have noted that patients with MS have an increased risk of developing SCZ or bipolar disorder (BD). It is suggested here that MS and a subgroup of SCZ have similar etiologies. Factors such as gender, ethnicity, geography and season also have an influence on the occurrence of MS and SCZ. This paper aims to examine the differences and similarities between SCZ and MS. For this purpose, scientific papers examining various factors associated with these disorders were reviewed, and similarities and differences in genetic, immunological, seasonal, geographical, and gender-related risk factors and limited similarities in ethnic factors between the two diseases were identified. The findings suggest that subgroups of these two diseases may belong to the same class of disorders.

Schizophrenia among patients with systemic lupus erythematosus: population-based cross-sectional study

AIMS

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease involving multiple organs, including the central nervous system. Evidence of immune dysfunction exists also in schizophrenia, a psychiatric illness involving chronic or recurrent psychosis. The aim of our study was to investigate if there is an epidemiological association between SLE and schizophrenia.

METHOD

A cross-sectional study was conducted comparing patients with SLE with age and gender-matched controls regarding the proportion of patients with comorbid schizophrenia. χ 2- and t-tests were used for univariate analysis, and interaction of schizophrenia with SLE across strata of covariates was checked. A logistic regression model was used for multivariate analysis. The study was performed utilising the medical database of Clalit Health Services in Israel.

RESULTS

The study included 5018 patients with SLE and 25 090 controls. SLE patients had a female predominance, and a higher proportion of smoking compared with age and sex-matched controls. In multivariate analysis, SLE was found to be independently associated with schizophrenia while controlling for age, gender, socioeconomic status (SES) and smoking (OR 1.33, p = 0.042).

CONCLUSIONS

We found a positive association between SLE and schizophrenia across patients of different age, gender and SES. This association can contribute to understanding the pathophysiology of the two disorders and may also have clinical implications for earlier as well as better diagnosis and treatment.

Consensus paper of the WFSBP Task Force on Biological Markers: Criteria for biomarkers and endophenotypes of schizophrenia, part III: Molecular mechanisms

OBJECTIVES

Despite progress in identifying molecular pathophysiological processes in schizophrenia, valid biomarkers are lacking for both the disease and treatment response.

METHODS

This comprehensive review summarises recent efforts to identify molecular mechanisms on the level of protein and gene expression and epigenetics, including DNA methylation, histone modifications and micro RNA expression. Furthermore, it summarises recent findings of alterations in lipid mediators and highlights inflammatory processes. The potential that this research will identify biomarkers of schizophrenia is discussed.

RESULTS

Recent studies have not identified clear biomarkers for schizophrenia. Although several molecular pathways have emerged as potential candidates for future research, a complete understanding of these metabolic pathways is required to reveal better treatment modalities for this disabling condition.

CONCLUSIONS

Large longitudinal cohort studies are essential that pair a thorough phenotypic and clinical evaluation for example with gene expression and proteome analysis in blood at multiple time points. This approach might identify biomarkers that allow patients to be stratified according to treatment response and ideally also allow treatment response to be predicted. Improved knowledge of molecular pathways and epigenetic mechanisms, including their potential association with environmental influences, will facilitate the discovery of biomarkers that could ultimately be effective tools in clinical practice.

Psychoneuroimmunoendocrinology: clinical implications

Psychoneuroimmunoendocrinology, which was first described in 1936, is the study of the interactions between the psyche, neural and endocrine functions and immune responses. The aim of psychoneuroimmunoendocrinology is to apply medical knowledge to the treatment of different allergic, immune, autoimmune, rheumatic, neoplastic, endocrine, cardiovascular and dental pathologies, among other disorders. Epigenetic factors and major stresses from different types of stimuli acting through distinct pathways and neurotransmitters are highly involved in altering the psychoneuroimmunoendocrine axis, resulting in the emergence of disease. The main purpose of this report is to expand the understanding of psychoneuroimmunoendocrinology and to demonstrate the importance of the above-mentioned interactions in the etiology of multiple pathologies. In this review, a search of the medical literature using PubMed (free access search engine for the Medline database of the National Library of Medicine of the United States) over the years 1936 to 2016 was conducted, and descriptive and experimental studies and reviews of the scientific literature were included.

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.

Emergence of new-onset psychotic disorder following recovery from LGI1 antibody-associated limbic encephalitis

Neuronal autoantibodies targeting cell surface antigens have been described in association with autoimmune encephalitides which frequently feature psychosis and other psychiatric disturbances alongside neurological signs and symptoms. Little has been written however about the long-term psychiatric status of individuals following recovery from the acute phase of autoimmune encephalitis, despite case series and anecdotal evidence suggesting this may be a cause of considerable disability. Here, we describe a man aged 58 years with no psychiatric history who developed a severe and acute psychotic disorder following resolution of a protracted course of limbic encephalitis associated with antibodies to leucine-rich glioma inactivated 1 protein. No indications of a gross ongoing inflammatory or encephalopathic process were present at presentation of his psychosis. Possible aetiologies of his acute psychosis are discussed. This case highlights the importance of ongoing psychiatric follow-up of patients following an episode of autoimmune encephalitis.

Ethical Implications of the Mild Encephalitis Hypothesis of Schizophrenia

Schizophrenia is a serious mental disease with a high mortality rate and severe social consequences. Due to insufficient knowledge about its etiopathogenesis, curative treatments are not available. One of the most promising new research concepts is the mild encephalitis hypothesis of schizophrenia, developed mainly by Karl Bechter and Norbert Müller. According to this hypothesis, a significant subgroup of schizophrenia patients suffer from a mild, but chronic, form of encephalitis with markedly different etiologies ranging from viral infections, traumas to autoimmune diseases. This inflammatory process is thought to occur in the beginning or during the course of the disease. In this article, we investigate the consequences of the mild encephalitis hypothesis of schizophrenia for the scientific community, and evaluate these consequences ethically. The mild encephalitis hypothesis implies that schizophrenia would no longer be considered an incurable psychiatric disorder. Instead, it would be considered a chronic, but treatable, neurological disease. This paradigm shift would doubtlessly have significant consequences: (1) major reforms would be necessary in the theoretical conceptualization of schizophrenia, which would challenge the psychiatric diagnostic systems, Diagnostic and Statistical Manual of Mental Disorders version 5 and ICD-10. (2) Psychotic patients should be treated in interdisciplinary teams, optimally in neuropsychiatric units; additionally, specialists for endocrinology, diabetology, and cardiology should be consulted for the frequently occuring somatic comorbidities. (3) Current diagnostic procedures and (4) therapies would have to be modified significantly. (5) There might be repercussions for the pharmaceutical industry as well: first, because old drugs with expired patent protection could partly replace expensive drugs and, second, because there would be a demand for the development of new anti-inflammatory drugs. (6) Legal evaluation of compulsory treatment orders might have to be reconsidered in light of causal therapies; leading to increased legal approval and reduced need for compulsory treatment orders due to better patient compliance. (7) The social inclusion of patients might improve, if treatment became more effective regarding cognitive and social functioning. (8) The stigmatization of patients and their relatives might decrease.

Associations Between Autoimmune Diseases and Attention-Deficit/Hyperactivity Disorder: A Nationwide Study

OBJECTIVE

Recent studies have suggested that autoimmune diseases and immune activation play a part in the pathogenesis of different neurodevelopmental disorders. This study investigated the association between a personal history and a family history of autoimmune disease and the risk of developing attention-deficit/hyperactivity disorder (ADHD).

METHOD

A cohort was formed of all singletons born in Denmark from 1990 to 2007, resulting in a study population of 983,680 individuals followed from 1995 to 2012. Information on autoimmune diseases was obtained from the Danish National Hospital Register. Individuals with ADHD were identified through the Danish National Hospital Register and the Danish Psychiatric Central Register.

RESULTS

In total, 23,645 children were diagnosed with ADHD during the study period. Autoimmune disease in the individual was associated with an increased risk of ADHD by an incidence rate ratio of 1.24 (95% CI 1.10-1.40). The primary analyses associated maternal autoimmune disease with ADHD in the offspring (incidence rate ratio 1.12, 95% CI 1.06-1.19), whereas a paternal history of autoimmune diseases was not significantly associated with ADHD in the offspring. In exploratory analyses, an increased risk of ADHD was observed for children with a family history of thyrotoxicosis, type 1 diabetes, autoimmune hepatitis, psoriasis, and ankylosing spondylitis.

CONCLUSION

A personal history and a maternal history of autoimmune disease were associated with an increased risk of ADHD. The previously reported association between type 1 diabetes and ADHD was confirmed. In addition, specific parental autoimmune diseases were associated with ADHD in offspring.

An Association Between Functional Polymorphisms of the Interleukin 1 Gene Complex and Schizophrenia Using Transmission Disequilibrium Test

IL1 gene complex has been implicated in the etiology of schizophrenia. To assess whether IL1 gene complex is associated with susceptibility to schizophrenia in Polish population we conducted family-based study. Functional polymorphisms from IL1A (rs1800587, rs17561, rs11677416), IL1B (rs1143634, rs1143643, rs16944, rs4848306, rs1143623, rs1143633, rs1143627) and IL1RN (rs419598, rs315952, rs9005, rs4251961) genes were genotyped in 143 trio with schizophrenia. Statistical analysis was performed using transmission disequilibrium test. We have found a trend toward an association of rs1143627, rs16944, rs1143623 in IL1B gene with the risk of schizophrenia. Our results show a protective effect of allele T of rs4251961 in IL1RN against schizophrenia. We also performed haplotype analysis of IL1 gene complex and found a trend toward an association with schizophrenia of GAGG haplotype (rs1143627, rs16944, rs1143623, rs4848306) in IL1B gene, haplotypes: TG (rs315952, rs9005) and TT (rs4251961, rs419598) in IL1RN. Haplotype CT (rs4251961, rs419598) in IL1RN was found to be associated with schizophrenia. After correction for multiple testing associations did not reach significance level. Our results might support theory that polymorphisms of interleukin 1 complex genes (rs1143627, rs16944, rs1143623, rs4848306 in IL1B gene and rs4251961, rs419598, rs315952, rs9005 in IL1RN gene) are involved in the pathogenesis of schizophrenia, however, none of the results reach significance level after correction for multiple testing.

IL1R2, CCR2, and CXCR4 May Form Heteroreceptor Complexes with NMDAR and D2R: Relevance for Schizophrenia

The mild neuroinflammation hypothesis of schizophrenia was introduced by Bechter in 2001. It has been hypothesized that a hypofunction of glutamatergic signaling via N-methyl-D-aspartate receptors (NMDARs) and hyperactivation of dopamine D2 receptors play a role in schizophrenia. The triplet puzzle theory states that sets of triplet amino acid homologies guide two different receptors toward each other and contributes to the formation of a receptor heteromer. It is, therefore, proposed that putative NMDAR-C-C chemokine receptor type 2 (CCR2), NMDAR-C-X-C chemokine receptor type 4 (CXCR4), and NMDAR- interleukin 1 receptor type II (IL1R2) heteromers can be formed in the neuronal networks in mild neuroinflammation due to demonstration of Gly-Leu-Leu (GLL), Val-Ser-Thr (VST), and/or Ser-Val-Ser (SVS) amino acid homologies between these receptor protomers. This molecular process may underlie the ability to produce symptoms of schizophrenia in mild neuroinflammation. In this state, volume transmission (VT) is increased involving increased extracellular vesicle-mediated VT from microglia and astroglia. These vesicles may contain CCR2, CXCR4, and/or IL1R2 as well as their ligands and upon internalization by endocytic pathways into neurons can form heteroreceptor complexes with NMDAR in the plasma membrane with pathological allosteric receptor-receptor interactions involving increased internalization and reduced NMDAR signaling. The triplet puzzle theory also suggests the formation of putative D2R-CCR2, D2R-CXCR4, and D2R-IL1R2 heteromers in mild neuroinflammation in view of their demonstrated sets of Leu-Tyr-Ser (LYS), Leu-Pro-Phe (LPF), and/or Ser-Leu-Ala (SLA) triplet homologies. These D2R heteroreceptor complexes may also contribute to schizophrenia-like symptoms in mild neuroinflammation by enhancing D2R protomer function.

Influence of Polygenic Risk Scores on the Association Between Infections and Schizophrenia

BACKGROUND

Several studies have suggested an important role of infections in the etiology of schizophrenia; however, shared genetic liability toward infections and schizophrenia could influence the association. We therefore investigated the possible effect of polygenic risk scores (PRSs) for schizophrenia on the association between infections and the risk of schizophrenia.

METHODS

We conducted a nested case-control study on a Danish population-based sample born after 1981 comprising of 1692 cases diagnosed with schizophrenia between 1994 and 2008 and 1724 matched controls. All individuals were linked utilizing nationwide population-based registers with virtually complete registration of all hospital contacts for infections. PRSs were calculated using discovery effect size estimates weights from an independent meta-analysis (34,600 cases and 45,968 control individuals).

RESULTS

A prior hospital contact with infection had occurred in 41% of the individuals with schizophrenia and increased the incidence rate ratio (IRR) of schizophrenia by 1.43 (95% confidence interval [CI] = 1.22-1.67). Adding PRS, which was robustly associated with schizophrenia (by an IRR of 1.46 [95% CI = 1.34-1.60] per standard deviation of the score), did not alter the association with infections and the increased risk of schizophrenia remained (IRR = 1.41; 95% CI = 1.20-1.66). Furthermore, there were no interactions between PRS and infections on the risk of developing schizophrenia (p = .554). Neither did PRS affect the risk of acquiring infections among patients with schizophrenia (odds ratio = 1.00; 95% CI = 0.89-1.12) nor among controls (odds ratio = 1.09; 95% CI: 0.96-1.24).

CONCLUSIONS

PRS and a history of infections have independent effects on the risk for schizophrenia, and the common genetic risk measured by PRS did not account for the association with infection in this sample.

A study of type-1 diabetes associated autoantibodies in schizophrenia

Epidemiological studies revealed an association between type-1 diabetes (T1D) and schizophrenia but the findings reported to date have been controversial. To clarify the inconsistency across studies, T1D-associated autoantibodies were examined in plasma samples collected from 272 patients with schizophrenia and 276 control subjects. An in-house enzyme-linked immunosorbent assay (ELISA) was developed using three linear peptide antigens, one of which was derived from glutamic acid decarboxylase (GAD) and two were derived from insulinoma-associated antigen 2 (IA2). Mann-Whitney U test showed a significant decrease in the levels of plasma IgG against the IA2b antigen in schizophrenia patients as compared to control subjects (Z=-3.54, p=0.0007), while no significant difference was found between these two groups either in anti-IA2a IgG levels (Z=-1.62, p=0.105) or in anti-GAD IgG levels (Z=-1.63, p=0.104). Linear regression analysis indicated no association of antipsychotic medication with the levels of plasma IgG against IA2a, IA2b or GAD, while the levels of plasma IgG for these 3 peptide antigens were significantly correlated with each other. Binary logistic regression showed that neither the DQ2.5 variant nor the DQ8 variant was associated with circulating levels of 3 T1D-associated autoantibodies in both the patient group and the control group. The coefficient of variation was 10.7% for anti-IA2a IgG assay, 10.1% for anti-IA2b IgG assay and 10.7% for anti-GAD IgG assay. The present work suggests that T1D-associated antibodies are unlikely to confer risk of schizophrenia and that the in-house ELISA developed with linear peptide antigens is highly reproducible.

Hospital admission for infection during early childhood influences developmental vulnerabilities at age 5 years

AIM

Childhood infectious diseases can be associated with later physical and psychological ill health, and the effects of this association may be evident during early childhood development. This study aimed to examine the effects of hospitalisation for early life infection on early childhood development.

METHODS

Hospital admission data for infection were obtained from the New South Wales Ministry of Health Admitted Patient Data Collection for 87 026 children, for whom the Australian Early Development Census (AEDC) was completed in their first year of formal schooling (age approximately 5 years). The AEDC provides estimates of each child's level of functioning on five domains of development spanning social and emotional skills, communication skills, numeracy and literacy and physical health. Multinomial logistic regressions were used to determine the relationship between exposure to hospital admissions for infectious disease prior to age 4 years and vulnerability on the AEDC. Models were adjusted for the effects of potential confounding factors related to the perinatal period, exposure to maltreatment and family characteristics.

RESULTS

Single and multiple hospitalisation(s) for infections were consistently associated with increased likelihood of being developmentally vulnerable on all AEDC domains, with odds ratios ranging from 1.02 to 1.28, after adjustment for confounding factors.

CONCLUSIONS

This study demonstrates a pervasive effect of early life infections that require hospital admission on multiple aspects of early child development, even after adjustment for potential confounding factors. Relatively, severe infection during early childhood constitutes a risk factor for developmental vulnerability by the time of entry to school.

Implications for reactive oxygen species in schizophrenia pathogenesis

Oxidative stress is a well-recognized participant in the pathophysiology of multiple brain disorders, particularly neurodegenerative conditions such as Alzheimer's and Parkinson's diseases. While not a dementia, a wide body of evidence has also been accumulating for aberrant reactive oxygen species and inflammation in schizophrenia. Here we highlight roles for oxidative stress as a common mechanism by which varied genetic and epidemiologic risk factors impact upon neurodevelopmental processes that underlie the schizophrenia syndrome. While there is longstanding evidence that schizophrenia may not have a single causative lesion, a common pathway involving oxidative stress opens the possibility for intervention at susceptible phases.

Family-based association study of interleukin 10 (IL10) and interleukin 10 receptor alpha (IL10RA) functional polymorphisms in schizophrenia in Polish population

Schizophrenia is a heterogeneous disorder and its etiology remains incompletely elucidated. Among possible causes, immunological factors have been implicated in its pathogenesis and course. Interleukin-10 (IL10) and it's receptor IL10RA may play an important role for immunological aspects in etiologies of major psychiatric disorders including schizophrenia. The aim of this study was to perform a transmission disequilibrium test (TDT) on a group of 146 schizophrenia trios from the Polish population. Functional polymorphisms from IL10 (rs1800872, rs1800871, rs1800896, rs1800890, and rs6676671) and IL10RA (rs3135932 and rs2229113) genes were analyzed. A lack of association with schizophrenia was detected for IL10 and IL10RA single polymorphisms and haplotypes.

Schizophrenia

Schizophrenia is a complex, heterogeneous behavioural and cognitive syndrome that seems to originate from disruption of brain development caused by genetic or environmental factors, or both. Dysfunction of dopaminergic neurotransmission contributes to the genesis of psychotic symptoms, but evidence also points to a widespread and variable involvement of other brain areas and circuits. Disturbances of synaptic function might underlie abnormalities of neuronal connectivity that possibly involves interneurons, but the precise nature, location, and timing of these events are uncertain. At present, treatment mainly consists of antipsychotic drugs combined with psychological therapies, social support, and rehabilitation, but a pressing need for more effective treatments and delivery of services exists. Advances in genomics, epidemiology, and neuroscience have led to great progress in understanding the disorder, and the opportunities for further scientific breakthrough are numerous--but so are the challenges.

Lack of genetic association of the TGM2 gene with schizophrenia in a Chinese population

The gene coding for transglutaminase 2 (TGM2) has been reported to be associated with schizophrenia in a White population. The present study was then designed to replicate this initial finding in a Chinese population. A total of 428 individuals with schizophrenia and 555 control participants were recruited for genetic analysis. Four single nucleotide polymorphisms present in the TGM2 gene were selected for genotyping, including rs2076380, rs7270785, rs4811528, and rs6023526, by PCR-based restriction fragment length polymorphism analysis. None of these four single nucleotide polymorphisms genotyped showed an association with schizophrenia, although these 428 cases and 555 controls had 97% power to detect a disease association in small effect size (odds ratio=1.5). The present results did not support the TGM2 association with schizophrenia. It is thus possible that the TGM2 finding may have resulted from a random error of sampling.

Comprehensive analysis of schizophrenia-associated loci highlights ion channel pathways and biologically plausible candidate causal genes

Over 100 associated genetic loci have been robustly associated with schizophrenia. Gene prioritization and pathway analysis have focused on a priori hypotheses and thus may have been unduly influenced by prior assumptions and missed important causal genes and pathways. Using a data-driven approach, we show that genes in associated loci: (1) are highly expressed in cortical brain areas; (2) are enriched for ion channel pathways (false discovery rates <0.05); and (3) contain 62 genes that are functionally related to each other and hence represent promising candidates for experimental follow up. We validate the relevance of the prioritized genes by showing that they are enriched for rare disruptive variants and de novo variants from schizophrenia sequencing studies (odds ratio 1.67, P = 0.039), and are enriched for genes encoding members of mouse and human postsynaptic density proteomes (odds ratio 4.56, P = 5.00 × 10(-4); odds ratio 2.60, P = 0.049).The authors wish it to be known that, in their opinion, the first 2 authors should be regarded as joint First Author.

Meta-analysis of Positive and Negative Symptoms Reveals Schizophrenia Modifier Genes

BACKGROUND

Evidence suggests that genetic factors may influence both schizophrenia (Scz) and its clinical presentation. In recent years, genome-wide association studies (GWAS) have demonstrated considerable success in identifying risk loci. Detection of "modifier loci" has the potential to further elucidate underlying disease processes.

METHODS

We performed GWAS of empirically derived positive and negative symptom scales in Irish cases from multiply affected pedigrees and a larger, independent case-control sample, subsequently combining these into a large Irish meta-analysis. In addition to single-SNP associations, we considered gene-based and pathway analyses to better capture convergent genetic effects, and to facilitate biological interpretation of these findings. Replication and testing of aggregate genetic effects was conducted using an independent European-American sample.

RESULTS

Though no single marker met the genome-wide significance threshold, genes and ontologies/pathways were significantly associated with negative and positive symptoms; notably, NKAIN2 and NRG1, respectively. We observed limited overlap in ontologies/pathways associated with different symptom profiles, with immune-related categories over-represented for negative symptoms, and addiction-related categories for positive symptoms. Replication analyses suggested that genes associated with clinical presentation are generalizable to non-Irish samples.

CONCLUSIONS

These findings strongly support the hypothesis that modifier loci contribute to the etiology of distinct Scz symptom profiles. The finding that previously implicated "risk loci" actually influence particular symptom dimensions has the potential to better delineate the roles of these genes in Scz etiology. Furthermore, the over-representation of distinct gene ontologies/pathways across symptom profiles suggests that the clinical heterogeneity of Scz is due in part to complex and diverse genetic factors.

Activated Phosphorylated STAT1 Levels as a Biologically Relevant Immune Signal in Schizophrenia

OBJECTIVE

Activation of STAT1 is directly downstream of the cytokine receptors that signal from specific proinflammatory cytokines known to be dysregulated in schizophrenia (SZ), such as IFNγ, IL6, IL2 and IL10, as well as hypoxia, viral/bacterial infections and peptide growth factors. If the increased cytokine protein levels repeatedly observed in SZ have biological consequences, then the measurement of pSTAT1 is a logical step forward.

METHODS

Peripheral blood mononuclear cells (PBMCs) from controls (n = 13) and subjects with SZ (n = 22) were extracted using the Ficoll method. Participants with SZ were diagnosed using the SCID, clinical symptomatology was measured using the Positive and Negative Syndrome Scale (PANSS), and cognitive functioning was measured using the MATRICS Consensus Cognitive Battery. Levels of activated STAT1 (Y701), i.e. phosphorylated STAT1 (pSTAT1), were measured by a commercially available ELISA in nuclear extracts from PBMCs.

RESULTS

There was a significant bimodal distribution in the sample, with an SZ subgroup expressing significantly greater levels of activated pSTAT1 than the remainder of the participants. In this subgroup, levels of pSTAT1 were significantly higher than in the control group, as well as significantly higher than in the remainder of the SZ subjects. Furthermore, this subsample of patients manifested significantly poorer cognitive performance on several measures of the MATRICS.

DISCUSSION

pSTAT1 levels may provide a measure of the biological relevance of widely reported elevations in levels of cytokines in SZ over the past several decades. Activation of kinase cascades can be used to partition or disassemble the composite immune signal in patients living with SZ.

Reinforcement Learning Performance and Risk for Psychosis in Youth

Early identification efforts for psychosis have thus far yielded many more individuals "at risk" than actually develop psychotic illness. Here, we test whether measures of reinforcement learning (RL), known to be impaired in chronic schizophrenia, are related to the severity of clinical risk symptoms. Because of the reliance of RL on dopamine-rich frontostriatal systems and evidence of dopamine system dysfunction in the psychosis prodrome, RL measures are of specific interest in this clinical population. The current study examines relationships between psychosis risk symptoms and RL task performance in a sample of adolescents and young adults (n = 70) receiving mental health services. We observed significant correlations between multiple measures of RL performance and measures of both positive and negative symptoms. These results suggest that RL measures may provide a psychosis risk signal in treatment-seeking youth. Further research is necessary to understand the potential predictive role of RL measures for conversion to psychosis.

Association study of functional polymorphisms in interleukins and interleukin receptors genes: IL1A, IL1B, IL1RN, IL6, IL6R, IL10, IL10RA and TGFB1 in schizophrenia in Polish population

Schizophrenia has been associated with a large range of autoimmune diseases, with a history of any autoimmune disease being associated with a 45% increase in risk for the illness. The inflammatory system may trigger or modulate the course of schizophrenia through complex mechanisms influencing neurodevelopment, neuroplasticity and neurotransmission. In particular, increases or imbalance in cytokine before birth or during the early stages of life may affect neurodevelopment and produce vulnerability to the disease. A total of 27 polymorphisms of IL1N gene: rs1800587, rs17561; IL1B gene: rs1143634, rs1143643, rs16944, rs4848306, rs1143623, rs1143633, rs1143627; IL1RN gene: rs419598, rs315952, rs9005, rs4251961; IL6 gene: rs1800795, rs1800797; IL6R gene: rs4537545, rs4845617, rs2228145, IL10 gene: rs1800896, rs1800871, rs1800872, rs1800890, rs6676671; IL10RA gene: rs2229113, rs3135932; TGF1B gene: rs1800469, rs1800470; each selected on the basis of molecular evidence for functionality, were investigated in this study. Analysis was performed on a group of 621 patients with diagnosis of schizophrenia and 531 healthy controls in Polish population. An association of rs4848306 in IL1B gene, rs4251961 in IL1RN gene, rs2228145 and rs4537545 in IL6R with schizophrenia have been observed. rs6676671 in IL10 was associated with early age of onset. Strong linkage disequilibrium was observed between analyzed polymorphisms in each gene, except of IL10RA. We observed that haplotypes composed of rs4537545 and rs2228145 in IL6R gene were associated with schizophrenia. Analyses with family history of schizophrenia, other psychiatric disorders and alcohol abuse/dependence did not show any positive findings. Further studies on larger groups along with correlation with circulating protein levels are needed.

The role of inflammation in schizophrenia

High levels of pro-inflammatory substances such as cytokines have been described in the blood and cerebrospinal fluid of schizophrenia patients. Animal models of schizophrenia show that under certain conditions an immune disturbance during early life, such as an infection-triggered immune activation, might trigger lifelong increased immune reactivity. A large epidemiological study clearly demonstrated that severe infections and autoimmune disorders are risk factors for schizophrenia. Genetic studies have shown a strong signal for schizophrenia on chromosome 6p22.1, in a region related to the human leucocyte antigen (HLA) system and other immune functions. Another line of evidence demonstrates that chronic (dis)stress is associated with immune activation. The vulnerability-stress-inflammation model of schizophrenia includes the contribution of stress on the basis of increased genetic vulnerability for the pathogenesis of schizophrenia, because stress may increase pro-inflammatory cytokines and even contribute to a lasting pro-inflammatory state. Immune alterations influence the dopaminergic, serotonergic, noradrenergic, and glutamatergic neurotransmission. The activated immune system in turn activates the enzyme indoleamine 2,3-dioxygenase (IDO) of the tryptophan/kynurenine metabolism which influences the serotonergic and glutamatergic neurotransmission via neuroactive metabolites such as kynurenic acid. The described loss of central nervous system volume and the activation of microglia, both of which have been clearly demonstrated in neuroimaging studies of schizophrenia patients, match the assumption of a (low level) inflammatory neurotoxic process. Further support for the inflammatory hypothesis comes from the therapeutic benefit of anti-inflammatory medication. Metaanalyses have shown an advantageous effect of cyclo-oxygenase-2 inhibitors in early stages of schizophrenia. Moreover, intrinsic anti-inflammatory, and immunomodulatory effects of antipsychotic drugs are known since a long time. Anti-inflammatory effects of antipsychotics, therapeutic effects of anti-inflammtory compounds, genetic, biochemical, and immunological findings point to a major role of inflammation in schizophrenia.

High levels of vitamin D in relation to reduced risk of schizophrenia with elevated C-reactive protein

There is growing evidence on the novel role of vitamin D in reducing inflammation. This study aimed to examine the hypothesis that vitamin D is inversely associated with C-reactive protein (CRP) in patients with schizophrenia, and high levels of vitamin D may be linked to reduced risk of schizophrenia with elevated CRP. Ninety-three patients with schizophrenia and 93 family-matched controls were recruited in this cross-sectional study. Plasma concentrations of CRP and 25-hydroxyvitamin D [25(OH)D] were measured using commercial kits. Information about demographic characteristics and clinic data were obtained by interviews or medical records. Mean levels of CRP and 25(OH)D were 43.3% higher and 26.7% lower for patients compared to controls, respectively. 25(OH)D were inversely associated with CRP in the patients, but not in the controls. The proportions of patients significantly increased with increasing quartiles of CRP, while significantly decreased with increasing quartiles of 25(OH)D. Among individuals with high CRP, participants with high 25(OH)D have significantly lower proportion (adjusted OR =0.217, 95% CI 0.063, 0.751) of schizophrenia compared to those with low 25(OH)D. The evidence suggested that high levels of vitamin D may be linked to reduced risk of schizophrenia with elevated CRP.

Maternal history of autoimmune disease and later development of tourette syndrome in offspring

OBJECTIVE

In a nationwide prospective cohort study, we examined the possible association between maternal autoimmune disease (AD) and later diagnosis of Tourette syndrome (TS) in offspring.

METHOD

Data from national Danish health registers identified a cohort consisting of all children born in Denmark between 1990 and 2007 (n = 1,116,255), followed prospectively from birth until 2011, date of TS diagnosis, death, or emigration/disappearance, whichever came first. The incidence rate ratio (IRR) of TS, dependent on whether or not the mother had a prior diagnosis of AD, was estimated by Poisson regression with 95% CIs and adjusted for age, calendar time, place of birth, maternal and paternal age, parental psychiatric diagnoses other than TS, and parental TS.

RESULTS

The cohort contributed a total of 13,000,162 person years and 2,442 participants with a diagnosis of TS (414 females and 2,028 males). Prior maternal AD was found in 110 of the 2,442 children with TS, corresponding to an increased risk of TS, with an adjusted IRR of 1.22 (95% CI = 1.01-1.48). Maternal history of a prior AD increased the risk of TS in males, with an adjusted IRR of 1.29 (95% CI = 1.05-1.58), but not in females, with an adjusted IRR of 0.89 (95% CI = 0.52-1.52).

CONCLUSION

Maternal AD was associated with a 29% increased incidence rate of TS in male offspring. This finding supports the hypothesis that neuroimmunological disorders may act as a component in the etiology of a subset of TS.

The Association between Infections and General Cognitive Ability in Young Men - A Nationwide Study

Background

Infections and activated immune responses can affect the brain through several pathways that might also affect cognition. However, no large-scale study has previously investigated the effect of infections on the general cognitive ability in the general population.

Methods

Danish nationwide registers were linked to establish a cohort of all 161,696 male conscripts during the years 2006–2012 who were tested for cognitive ability, which was based on logical, verbal, numerical and spatial reasoning at a mean age of 19.4 years. Test scores were converted to a mean of 100.00 and with a standard deviation (SD) of 15. Data were analyzed as a cohort study with severe infections requiring hospitalization as exposure using linear regression.

Results

Adjusted effect sizes were calculated with non-exposure to severe infections as reference, ranging from 0.12 SD to 0.63 SD on general cognitive ability. A prior infection was associated with significantly lower cognitive ability by a mean of 1.76 (95%CI: -1.92 to -1.61; corresponding to 0.12 SD). The cognitive ability was affected the most by the temporal proximity of the last infection (P<0.001) and by the severity of infection measured by days of admission (P<0.001). The number of infections were associated with decreased cognitive ability in a dose-response relationship, and highest mean differences were found for ≥10 hospital contacts for infections (Mean: -5.54; 95%CI: -7.20 to -3.89; corresponding to 0.37 SD), and for ≥5 different types of infections (Mean: -9.44; 95%CI: -13.2 to -5.69; corresponding to 0.63 SD). Hospital contacts with infections had occurred in 35% of the individuals prior to conscription.

Conclusions

Independent of a wide range of possible confounders, significant associations between infections and cognitive ability were observed. Infections or related immune responses might directly affect the cognitive ability; however, associated heritable and environmental factors might also account for the lowered cognitive ability.

Soluble urokinase-type plasminogen activator receptor levels in patients with schizophrenia

BACKGROUND

The etiology of schizophrenia remains largely unknown but alterations in the immune system may be involved. In addition to the psychiatric symptoms, schizophrenia is also associated with up to 20 years reduction in life span. Soluble urokinase-type plasminogen activator receptor (suPAR) is a protein that can be measured in blood samples and reflects the levels of inflammatory activity. It has been associated with mortality and the development of type 2 diabetes and cardiovascular disease.

METHODS

suPAR levels in patients with schizophrenia were compared to healthy controls from the Danish Blood Donor Study. SuPAR levels were dichotomized at >4.0 ng/ml, which is considered the threshold for low grade inflammation. A multiple logistic regression model was used and adjusted for age, sex, and current smoking.

RESULTS

In total we included 1009 subjects, 105 cases with schizophrenia (10.4%) and 904 controls (89.6%). The mean suPAR values were 4.01 ng/ml (SD = 1.43) for the cases vs 1.91 ng/ml (SD = 1.35) for the controls (P < .001). Multiple logistic regression with odds ratio (OR) for suPAR levels >4.0 ng/ml yielded: schizophrenia, OR: 46.15 95% CI 22.69-93.87, P < .001; age, OR: 1.02 95% CI 0.99-1.02, P = .15; male sex, OR: 0.70 95% CI 0.35-1.36, P = .29; and current smoking, OR: 3.51 95% CI 1.78-6.94, P < .001.

CONCLUSIONS

Patients with schizophrenia had significantly higher suPAR levels than healthy controls. Further studies are warranted to clarify if elevated suPAR levels are involved in the pathophysiology of schizophrenia and/or the increased mortality found in patients with schizophrenia.

Improvement in psychotic symptoms after a gluten-free diet in a boy with complex autoimmune illness

At age 8, “Chris,” a Caucasian boy, experienced intermittent auditory and visual hallucinations, but without bizarre behaviors or much deterioration in functioning. At age 15, he developed a depressed mood, started talking to himself, and became socially withdrawn, and his academic performance declined. He was hospitalized and diagnosed as having major depressive disorder with psychotic features. MRI and EEG showed no abnormalities. Treatment with escitalopram (10 mg/day) and aripiprazole (5 mg/day) had little effect. Several weeks after discharge, he was admitted for a second time with the same diagnosis; a third admission, again with the same diagnosis, occurred several months after that. At age 16, Chris developed visual and auditory hallucinations with homicidal ideations. He cut himself superficially following the command of voice hallucinations, and he was hospitalized again, with the diagnosis changed to schizophrenia, paranoid type. During this inpatient stay, he was treated with venlafaxine (150 mg/day) and risperidone (1.5 mg/day). During the same admission, a blood test showed the presence of antinuclear antibodies (ANAs), but the patient had no symptoms of any autoimmune disease. In the meantime, he was also receiving clindamycin/benzoyl peroxide and adapaline gels and minocycline for acne and fluticasone nasal spray and albuterol for asthma. An allergy to gluten was demonstrated by an assay (Accessa Labs) that showed only IgE antigluten antibodies. Chris’sparents reported that he developed anallergy to peanuts and soy at about the same time. Gluten was removed from his diet at the suggestion of the mother, a licensed dietitian. After the dietary change, the intensity of Chris’s auditory hallucinations declined dramatically and the violent element diminished, and he was discharged after 9 weeks. During the next 2 years, Chris remained on a gluten-free diet, which he and his family associated with the disappearance of his psychotic symptoms. Sensitivity to gluten was demonstrated by an assay (Metametrix Clinical Laboratory) of a stool sample that yielded a value of 10.6 mg/dL of IgA antigliadin antibodies, in the top quintile of the reference range. The dosage of risperidone was tapered to 0.5 mg/day, and no auditory or visual hallucinations occurred, although when the dosage was lowered to 0.25 mg/day, Chris reported feeling anxious, and the dosage was returned to 0.5 mg/day for a time. Eventually the risperidone was discontinued completely. Chris was able to return to school, where his academic performance was normal and he joined several athletic teams. At age 16, after his hospital stay, Chris lost his hearing suddenly and was fitted with a hearing aid. His ANA level was high, and the diagnosis of autoimmune inner ear disease was made. He was treated with prednisone and then methotrexate over a 2-month period. Despite his hearing loss, he has maintained a high level of functioning, including learning to read lips, and he has continued to play competitive sports. Both of Chris’s parents have a history of seasonal affective disorder, and two grandparents had experienced bouts of depression. The father had hypothyroidism, and the father’s aunt had Crohn’s disease. The mother’s brother had hearing loss with ANAs, and the mother’s cousin had systemic lupus erythematosus. The parents were 32 years old when Chris was born, and the pregnancy and birth were unremarkable, with no complications. He is the second son. Starting in infancy, he had recurrent bouts of otitis media, which were treated with tympanoplasty and continued until age 12. At 3 months, he was diagnosed with eosinophilic gastritis.

Schizophrenia and the gut-brain axis

Several risk factors for the development of schizophrenia can be linked through a common pathway in the intestinal tract. It is now increasingly recognized that bidirectional communication exists between the brain and the gut that uses neural, hormonal, and immunological routes. An increased incidence of gastrointestinal (GI) barrier dysfunction, food antigen sensitivity, inflammation, and the metabolic syndrome is seen in schizophrenia. These findings may be influenced by the composition of the gut microbiota. A significant subgroup of patients may benefit from the initiation of a gluten and casein-free diet. Antimicrobials and probiotics have therapeutic potential for reducing the metabolic dysfunction and immune dysregulation seen in patients with schizophrenia.