Genetics in schizophrenia: where are we and what next?

Epigenetic profile of the immune system associated with symptom severity and treatment response in schizophrenia

BACKGROUND

Environmental modification of genetic information (epigenetics) is often invoked to explain interindividual differences in the phenotype of schizophrenia. In clinical practice, such variability is most prominent in the symptom profile and the treatment response. Epigenetic regulation of immune function is of particular interest, given the therapeutic relevance of this mechanism in schizophrenia.

METHODS

We analyzed the DNA methylation data of immune-relevant genes in patients with schizophrenia whose disease duration was less than 3 years, with previous lifetime antipsychotic treatment of no more than 2 weeks total.

RESULTS

A total of 441 patients met the inclusion criteria. Core symptoms were consistently associated with 206 methylation positions, many of which had previously been implicated in inflammatory responses. Of these, 24 methylation positions were located either in regulatory regions or near the CpG islands of 20 genes, including the SRC gene, which is a key player in glutamatergic signalling. These symptom-associated immune genes were enriched in neuronal development functions, such as neuronal migration and glutamatergic synapse. Compared with using only clinical information (including scores on the Positive and Negative Syndrome Scale), integrating methylation data into the model significantly improved the predictive ability (as indicated by area under the curve) for response to 8 weeks of antipsychotic treatment.

LIMITATIONS

We focused on a small number of methylation probes (immune-centred search) and lacked nutritional data and direct brain-based measures.

CONCLUSION

Epigenetic modifications of the immune system are associated with symptom severity at onset and subsequent treatment response in schizophrenia.

Characterizing the Shared Genetic Underpinnings of Schizophrenia and Cardiovascular Disease Risk Factors

OBJECTIVE

Schizophrenia is associated with increased risk of cardiovascular disease (CVD), although there is variation in risk among individuals. There are indications of shared genetic etiology between schizophrenia and CVD, but the nature of the overlap remains unclear. The aim of this study was to fill this gap in knowledge.

METHODS

Overlapping genetic architectures between schizophrenia and CVD risk factors were assessed by analyzing recent genome-wide association study (GWAS) results. The bivariate causal mixture model (MiXeR) was applied to estimate the number of shared variants and the conjunctional false discovery rate (conjFDR) approach was used to pinpoint specific shared loci.

RESULTS

Extensive genetic overlap was found between schizophrenia and CVD risk factors, particularly smoking initiation (N=8.6K variants) and body mass index (BMI) (N=8.1K variants). Several specific shared loci were detected between schizophrenia and BMI (N=304), waist-to-hip ratio (N=193), smoking initiation (N=293), systolic (N=294) and diastolic (N=259) blood pressure, type 2 diabetes (N=147), lipids (N=471), and coronary artery disease (N=35). The schizophrenia risk loci shared with smoking initiation had mainly concordant effect directions, and the risk loci shared with BMI had mainly opposite effect directions. The overlapping loci with lipids, blood pressure, waist-to-hip ratio, type 2 diabetes, and coronary artery disease had mixed effect directions. Functional analyses implicated mapped genes that are expressed in brain tissue and immune cells.

CONCLUSIONS

These findings indicate a genetic propensity to smoking and a reduced genetic risk of obesity among individuals with schizophrenia. The bidirectional effects of the shared loci with the other CVD risk factors may imply differences in genetic liability to CVD across schizophrenia subgroups, possibly underlying the variation in CVD comorbidity.

Altered offspring neurodevelopment in an L-NAME-induced preeclampsia rat model

Introduction

To investigate the mechanism underlying the increased risk of subsequent neurodevelopmental disorders in children born to mothers with preeclampsia, we evaluated the neurodevelopment of offspring of a preeclampsia rat model induced by the administration of N-nitro-L-arginine methyl ester (L-NAME) and identified unique protein signatures in the offspring cerebrospinal fluid.

Methods

Pregnant rats received an intraperitoneal injection of L-NAME (250 mg/kg/day) during gestational days 15-20 to establish a preeclampsia model. Behavioral experiments (negative geotaxis, open-field, rotarod treadmill, and active avoidance tests), immunohistochemistry [anti-neuronal nuclei (NeuN) staining in the hippocampal dentate gyrus and cerebral cortex on postnatal day 70], and proteome analysis of the cerebrospinal fluid on postnatal day 5 were performed on male offspring.

Results

Offspring of the preeclampsia dam exhibited increased growth restriction at birth (52.5%), but showed postnatal catch-up growth on postnatal day 14. Several behavioral abnormalities including motor development and vestibular function (negative geotaxis test: p < 0.01) in the neonatal period; motor coordination and learning skills (rotarod treadmill test: p = 0.01); and memory skills (active avoidance test: p < 0.01) in the juvenile period were observed. NeuN-positive cells in preeclampsia rats were significantly reduced in both the hippocampal dentate gyrus and cerebral cortex (p < 0.01, p < 0.01, respectively). Among the 1270 proteins in the cerebrospinal fluid identified using liquid chromatography-tandem mass spectrometry, 32 were differentially expressed. Principal component analysis showed that most cerebrospinal fluid samples achieved clear separation between preeclampsia and control rats. Pathway analysis revealed that differentially expressed proteins were associated with endoplasmic reticulum translocation, Rab proteins, and ribosomal proteins, which are involved in various nervous system disorders including autism spectrum disorders, schizophrenia, and Alzheimer's disease.

Conclusion

The offspring of the L-NAME-induced preeclampsia model rats exhibited key features of neurodevelopmental abnormalities on behavioral and pathological examinations similar to humans. We found altered cerebrospinal fluid protein profiling in this preeclampsia rat, and the unique protein signatures related to endoplasmic reticulum translocation, Rab proteins, and ribosomal proteins may be associated with subsequent adverse neurodevelopment in the offspring.

The financial situation before and after first-time psychiatric in-patient diagnosis of schizophrenia spectrum, bipolar, and major depressive disorder

Schizophrenia spectrum, bipolar, and major depressive disorders are severe mental illnesses (SMIs) that not only entail great suffering for those affected but also major societal costs. In this study, I use administrative register data to provide a detailed picture of the financial situation of people with SMI in Sweden during a period of ±10 years around first-time psychiatric in-patient diagnosis of schizophrenia spectrum, bipolar, and major depressive disorders. Receiving a diagnosis was associated with a considerable drop in earnings, which was largely compensated for by social transfers: mainly sickness and disability insurance. However, there were also large and increasing pre-diagnosis earnings gaps, relative to matched comparison groups, especially among those with schizophrenia spectrum disorders. These gaps were to a lesser extent compensated for by social transfers. Consequently, there were permanent and increasing - due to lost earnings growth - income differentials. Hence, findings in previous studies are confirmed: even in an advanced welfare state, people with SMI - especially those with schizophrenia - have an extremely weak position on the labour market and an equally difficult financial situation.

Schizophrenia: One Name, Many Different Manifestations

Schizophrenia is a disabling condition impacting approximately 1% of the worldwide population. Symptoms include positive symptoms (eg, hallucinations, delusions), negative symptoms (eg, avolition, anhedonia), and cognitive impairment. There are likely many different environmental and pathophysiologic etiologies involving distinct neurotransmitters and neurocircuits. Pharmacologic treatment at present consists of dopamine receptor antagonists, which are reasonably effective at treating positive symptoms, but less effective at treating cognitive and negative symptoms. Nondopaminergic medications targeting alternative receptors are under investigation. Supportive psychosocial treatments can work in tandem with antipsychotic medications and optimize patient care.

Neuroimaging in schizophrenia: A review article

In this review article we have consolidated the imaging literature of patients with schizophrenia across the full spectrum of modalities in radiology including computed tomography (CT), morphologic magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), and magnetoencephalography (MEG). We look at the impact of various subtypes of schizophrenia on imaging findings and the changes that occur with medical and transcranial magnetic stimulation (TMS) therapy. Our goal was a comprehensive multimodality summary of the findings of state-of-the-art imaging in untreated and treated patients with schizophrenia. Clinical imaging in schizophrenia is used to exclude structural lesions which may produce symptoms that may mimic those of patients with schizophrenia. Nonetheless one finds global volume loss in the brains of patients with schizophrenia with associated increased cerebrospinal fluid (CSF) volume and decreased gray matter volume. These features may be influenced by the duration of disease and or medication use. For functional studies, be they fluorodeoxyglucose positron emission tomography (FDG PET), rs-fMRI, task-based fMRI, diffusion tensor imaging (DTI) or MEG there generally is hypoactivation and disconnection between brain regions. However, these findings may vary depending upon the negative or positive symptomatology manifested in the patients. MR spectroscopy generally shows low N-acetylaspartate from neuronal loss and low glutamine (a neuroexcitatory marker) but glutathione may be elevated, particularly in non-treatment responders. The literature in schizophrenia is difficult to evaluate because age, gender, symptomatology, comorbidities, therapy use, disease duration, substance abuse, and coexisting other psychiatric disorders have not been adequately controlled for, even in large studies and meta-analyses.

Microvascular anomaly conditions in psychiatric disease. Schizophrenia - angiogenesis connection

Schizophrenia (SZ) is a severe mental disorder with unknown etiology and elusive neuropathological and neurobiological features have been a focus of many theoretical hypotheses and empirical studies. Current genetic and neurobiology information relevant to SZ implicates neuronal developmental and synaptic plasticity abnormalities, and neurotransmitter, microglial and oligodendrocytes dysfunction. Several recent theories have highlighted the neurovascular unit as a potential contributor to the pathophysiology of SZ. We explored the biological plausibility of a link between SZ and the neurovascular system by examining insights gained from genetic, neuroimaging and postmortem studies, which include gene expression and neuropathology analyses. We also reviewed information from animal models of cerebral angiogenesis in order to understand better the complex interplay between angiogenic and neurotrophic factors in development, vascular endothelium/blood brain barrier remodeling and maintenance, all of which contribute to sustaining adequate regional blood flow and safeguarding normal brain function. Microvascular and hemodynamic alterations in SZ highlight the importance of further research and reveal the neurovascular unit as a potential therapeutic target in SZ.

Microvascular anomaly conditions in psychiatric disease. Schizophrenia - angiogenesis connection

Schizophrenia (SZ) is a severe mental disorder with unknown etiology and elusive neuropathological and neurobiological features have been a focus of many theoretical hypotheses and empirical studies. Current genetic and neurobiology information relevant to SZ implicates neuronal developmental and synaptic plasticity abnormalities, and neurotransmitter, microglial and oligodendrocytes dysfunction. Several recent theories have highlighted the neurovascular unit as a potential contributor to the pathophysiology of SZ. We explored the biological plausibility of a link between SZ and the neurovascular system by examining insights gained from genetic, neuroimaging and postmortem studies, which include gene expression and neuropathology analyses. We also reviewed information from animal models of cerebral angiogenesis in order to understand better the complex interplay between angiogenic and neurotrophic factors in development, vascular endothelium/blood brain barrier remodeling and maintenance, all of which contribute to sustaining adequate regional blood flow and safeguarding normal brain function. Microvascular and hemodynamic alterations in SZ highlight the importance of further research and reveal the neurovascular unit as a potential therapeutic target in SZ.

Understanding complex transcriptome dynamics in schizophrenia and other neurological diseases using RNA sequencing

How the human brain develops and adapts with its trillions of functionally integrated synapses remains one of the greatest mysteries of life. With tremendous advances in neuroscience, genetics, and molecular biology, we are beginning to appreciate the scope of this complexity and define some of the parameters of the systems that make it possible. These same tools are also leading to advances in our understanding of the pathophysiology of neurocognitive and neuropsychiatric disorders. Like the substrate for these problems, the etiology is usually complex-involving an array of genetic and environmental influences. To resolve these influences and derive better interventions, we need to reveal every aspect of this complexity and model their interactions and define the systems and their regulatory structure. This is particularly important at the tissue-specific molecular interface between the underlying genetic and environmental influence defined by the transcriptome. Recent advances in transcriptome analysis facilitated by RNA sequencing (RNA-Seq) can provide unprecedented insight into the functional genomics of neurological disorders. In this review, we outline the advantages of this approach and highlight some early application of this technology in the investigation of the neuropathology of schizophrenia. Recent progress of RNA-Seq studies in schizophrenia has shown that there is extraordinary transcriptome dynamics with significant levels of alternative splicing. These studies only scratch the surface of this complexity and therefore future studies with greater depth and samples size will be vital to fully explore transcriptional diversity and its underlying influences in schizophrenia and provide the basis for new biomarkers and improved treatments.

A comparative study of disease genes and drug targets in the human protein interactome

BACKGROUND

Disease genes cause or contribute genetically to the development of the most complex diseases. Drugs are the major approaches to treat the complex disease through interacting with their targets. Thus, drug targets are critical for treatment efficacy. However, the interrelationship between the disease genes and drug targets is not clear.

RESULTS

In this study, we comprehensively compared the network properties of disease genes and drug targets for five major disease categories (cancer, cardiovascular disease, immune system disease, metabolic disease, and nervous system disease). We first collected disease genes from genome-wide association studies (GWAS) for five disease categories and collected their corresponding drugs based on drugs' Anatomical Therapeutic Chemical (ATC) classification. Then, we obtained the drug targets for these five different disease categories. We found that, though the intersections between disease genes and drug targets were small, disease genes were significantly enriched in targets compared to their enrichment in human protein-coding genes. We further compared network properties of the proteins encoded by disease genes and drug targets in human protein-protein interaction networks (interactome). The results showed that the drug targets tended to have higher degree, higher betweenness, and lower clustering coefficient in cancer Furthermore, we observed a clear fraction increase of disease proteins or drug targets in the near neighborhood compared with the randomized genes.

CONCLUSIONS

The study presents the first comprehensive comparison of the disease genes and drug targets in the context of interactome. The results provide some foundational network characteristics for further designing computational strategies to predict novel drug targets and drug repurposing.

Theory of Mind in Bipolar Disorder, with Comparison to the Impairments Observed in Schizophrenia

Our ability to make sense of information on the potential intentions and dispositions of others is of paramount importance for understanding their communicative intent, and for judging what an appropriate reaction might be. Thus, anything that impinges on this ability has the potential to cause significant social impairment, and compromise an individual's level of functioning. Both bipolar disorder and schizophrenia are known to feature theory of mind impairment. We conducted a theoretical review to determine the extent and types of theory of mind impairment in bipolar disorder, and evaluate their relationship to medication and symptoms. We also considered possible mediatory mechanisms, and set out to discover what else could be learnt about the impairment in bipolar disorder by comparison to the profile of impairment in schizophrenia. The literature established that in bipolar disorder (i) some form of theory of mind impairment has been observed in all mood states, including euthymia, (ii) the form of theory of mind assessed and task used to make the assessment influence the impairment observed, and (iii) there might be some relationship to cognitive impairment, although a relationship to standard clinical variables was harder to establish. What also became clear in the literature on bipolar disorder itself was the possible relationship of theory of mind impairment to history of psychotic symptoms. Direct comparative studies, including patients with schizophrenia, were thus examined, and provided several important directions for future research on the bases of impairment in bipolar disorder. Particularly prominent was the issue of whether theory of mind impairment could be considered a candidate endophenotype for the psychoses, although current evidence suggests that this may be premature. The differences in impairment across schizophrenia and bipolar disorder may, however, have genuine differential effects on social functioning and the likely success of remediation.

The insertion/deletion polymorphism in the angiotensin-converting enzyme and susceptibility to schizophrenia or Parkinson's disease: A meta-analysis

INTRODUCTION

The purpose of this study was to examine whether the insertion (I) and deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) confers susceptibility to schizophrenia and Parkinson's disease (PD).

MATERIALS AND METHODS

A meta-analysis was performed of the associations between the ACE I/D polymorphism and schizophrenia and PD.

RESULTS

Thirteen studies with 2024 cases and 2230 controls comprising eight studies on schizophrenia and five on PD were included in the meta-analysis. The meta-analysis revealed no association between the ACE D allele and schizophrenia (OR = 0.990, 95% CI = 0.889-1.102, p = 0.856) or PD (OR = 1.067, 95% CI = 0.907-1.255, p = 0.433). Stratification by ethnicity indicated no association between the ACE D allele and schizophrenia in European, Asian, or Turkish ethnic groups (OR = 0.896, 95% CI = 0.566-1.419, p = 0.640; OR = 1.057, 95% CI = 0.903-1.238, p = 0.492; OR = 1.111, 95% CI = 0.889-1.389, p = 0.354, respectively). Ethnicity-specific meta-analysis was not conducted for PD because only one ethnic PD study was available.

CONCLUSIONS

This meta-analysis found no association between the ACE I/D polymorphism and schizophrenia or PD.

Individualizing clozapine and risperidone treatment for schizophrenia patients

Schizophrenia is a severe disorder that significantly affects the quality of life and total functioning of patients and their caregivers. Clozapine is the first atypical antipsychotic with fewer adverse effects and established efficacy. As a rule of thumb, risperidone is one of the most reliable and effective antipsychotics for newly diagnosed and chronic schizophrenics. Pharmacogenetic studies have identified genomic variants of candidate genes that seem to be important in the way a patient responds to treatment. The recent progress made in pharmacogenomics will improve the quality of treatment, since drug doses will be tailored to the special needs of each patient. In this article, we review the available literature attempting to delineate the role of genomic variations in clozapine and risperidone response in schizophrenic patients of various ethnicities. We conclude that pharmacogenomics for these two drugs is still not ready for implementation in the clinic.

Pathway analysis of a genome-wide association study in schizophrenia

OBJECTIVE

The aim of this study was to identify the candidate single nucleotide polymorphisms (SNPs) and candidate mechanisms that contribute to schizophrenia susceptibility and to generate a SNP to gene to pathway hypothesis using an analytical pathway-based approach.

METHODS

We used schizophrenia GWAS data of the genotypes of 660,259 SNPs in 1378 controls and 1351 cases of European descent after quality control filtering. ICSNPathway (Identify candidate Causal SNPs and Pathways) analysis was applied to the schizophrenia GWAS dataset. The first stage involved the pre-selection of candidate SNPs by linkage disequilibrium analysis and the functional SNP annotation of the most significant SNPs found. The second stage involved the annotation of biological mechanisms for the pre-selected candidate SNPs using improved-gene set enrichment analysis.

RESULTS

ICSNPathway analysis identified fifteen candidate SNPs, ten candidate pathways, and nine hypothetical biological mechanisms. The most strongly associated potential pathways were as follows. First, rs1644731 and rs1644730 to RDH8 to estrogen biosynthetic process (p<0.001, FDR<0.001). The genes involved in this pathway are RDH8 and HSD3B1 (p<0.05). All-trans-retinol dehydrogenase (RDH8) is a visual cycle enzyme that reduces all-trans-retinal to all-trans-retinol in the presence of NADPH. The chemical reactions and pathways involved result in the formation of estrogens, which are C18 steroid hormones that can stimulate the development of female sexual characteristics. Second, rs1146031 to ACVR1 to mesoderm formation and activin binding (p<0.001, FDR=0.032, 0.034). Two of 15 candidate genes are known genes associated with schizophrenia: KCNQ2 and APOL2. One of the 10 candidate pathways, estrogen biosynthetic process, is known to be associated with schizophrenia (p<0.001, FDR<0.001). However, 13 of candidate genes (RDH8, ACVR1, PSMD9, KCNAB1, SLC17A3, ARCN1, COG7, STAB2, LRPAP1, STAB1, CXCL16, COL4A4, EXOSC3) and 9 of candidate pathways were novel.

CONCLUSION

By applying ICSNPathway analysis to schizophrenia GWAS data, we identified candidate SNPs, genes like KCNQ2 and APOL2 and pathways involving the estrogen biosynthetic process may contribute to schizophrenia susceptibility. Further analyses are needed to validate the results of this analysis.

Influence of ANKK1 and DRD2 polymorphisms in response to haloperidol

The present study explores whether ankyrin repeat and kinase domain containing 1 (ANKK1) and dopamine receptor D2 (DRD2) variants could predict efficacy and tolerability of haloperidol in the treatment of psychotic patients. We also attempted to replicate findings in a group of schizophrenic patients from the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) study. Eighty-eight acutely psychotic patients were genotyped for 9 ANKK1 and 27 DRD2 SNPs. Treatment efficacy and tolerability were assessed using the Positive and Negative Symptoms Scale and the Udvalg for Kliniske Undersogelser side effects rating scales, respectively. Multivariate analyses were employed to test possible influences of single-nucleotide polymorphisms on clinical and safety variables. Analysis of haplotypes was also performed. Outcomes in the replication sample were response versus nonresponse and the presence versus absence of motor side effects at 1 month of treatment. rs2242592 within ANKK1 gene and rs1124493 within DRD2 gene were associated with clinical improvement (p = 0.008 and p = 0.001, respectively). Results were confirmed in the allelic analysis. Three haplotype blocks, one among ANKK1 and two among DRD2 gene were associated with better clinical improvement. Our results were not replicated in the CATIE sample, although rs11604671, which is in strong linkage disequilibrium with rs2242592, was associated with response in the replication sample. Our findings support a possible role of ANKK1 and DRD2 variability on haloperidol efficacy. However, due to the discrepancies between the results in the two samples, our results need further validation.

Explorando o componente inflamatório da esquizofrenia

A esquizofrenia é uma doença heterogênea caracterizada por um conjunto de manifestações clínicas. Um grande número de estudos ao longo dos últimos 20 anos apontou para anormalidades no sistema imune em pacientes que sofrem dessa condição. Em adição, tem sido mostrado que a psicose e a disfunção cognitiva associadas com a esquizofrenia estão ligadas a doenças autoimunes. Aqui, revisamos a evidência que sugere que um status pró-inflamatório do sistema imune induz sintomas psicopatológicos e pode estar envolvido na fisiopatologia dessa principal doença mental. Também propomos que futuros estudos pré-clínicos e clínicos deveriam levar em conta tais causas predefinidas e o status do componente inflamatório. Estratificação de pacientes e estratégias de medicina personalizadas baseadas no direcionamento ao componente inflamatório da doença poderiam ajudar na redução de sintomas e da progressão da doença. Por fim, isso poderia levar a novos conceitos na identificação de alvos moleculares em esquizofrenia e estratégias de descoberta de drogas.

Latent toxoplasmosis reduces gray matter density in schizophrenia but not in controls: voxel-based-morphometry (VBM) study

OBJECTIVES

To address the role of latent T. gondii infection in schizophrenia we studied the influence of latent toxoplasmosis on brain morphology.

METHODS

An optimized voxel-based morphometry of magnetic resonance imaging was analyzed by analysis of variance with diagnosis and seropositivity as factors in 44 schizophrenic patients (12 T. gondii positive) and 56 controls (13 T. gondii positive).

RESULTS

Grey matter (GM) volume was reduced in schizophrenia patients compared with controls in the cortical regions, hippocampus and in the caudate. In the schizophrenia sample we found a significant reduction of GM volume in T. gondii positive comparing with T. gondii-negative patients bilaterally in the caudate, median cingulate, thalamus and occipital cortex and in the left cerebellar hemispheres. T. gondii-positive and -negative controls did not differ in any cluster. Among participants seropositive to T. gondii the reduction of GM in the schizophrenia subjects was located in the same regions when comparing the entire sample (11,660 over-threshold voxels (P ≤ 0.05, FWR corrected). The differences between T. gondii-negative patients and controls consisted only of 289 voxels in temporal regions.

CONCLUSIONS

Our study is the first to document that latent toxoplasmosis reduces GM in schizophrenia but not in controls.

NMDA receptor and schizophrenia: a brief history

Although glutamate was first hypothesized to be involved in the pathophysiology of schizophrenia in the 1980s, it was the demonstration that N-methyl-D-aspartate (NMDA) receptor antagonists, the dissociative anesthetics, could replicate the full range of psychotic, negative, cognitive, and physiologic features of schizophrenia in normal subjects that placed the "NMDA receptor hypofunction hypothesis" on firm footing. Additional support came from the demonstration that a variety of agents that enhanced NMDA receptor function at the glycine modulatory site significantly reduced negative symptoms and variably improved cognition in patients with schizophrenia receiving antipsychotic drugs. Finally, persistent blockade of NMDA receptors recreates in experimental animals the critical pathologic features of schizophrenia including downregulation of parvalbumin-positive cortical GABAergic neurons, pyramidal neuron dendritic dysgenesis, and reduced spine density.

Antibodies to retroviruses in recent onset psychosis and multi-episode schizophrenia

BACKGROUND

Immunological abnormalities involving the upregulation of endogenous retroviruses have been associated with schizophrenia in small studies.

METHODS

Blood samples from 666 individuals (163 with recent onset psychosis, 268 with multi-episode schizophrenia, and 235 controls) were assayed for IgG antibodies to murine leukemia virus (MuLV), Mason-Pfizer monkey virus (MPMV), and feline immunodeficiency virus (FIV) by enzyme immunoassay utilizing whole virus and viral components. Antibody levels in the psychiatric groups were compared to controls by multivariate linear regression. Odds ratios associated with increased antibody levels were calculated based on values ≥ 75th percentile of the controls. Samples were also tested for antibodies to viral proteins by Western blotting and for DNA from infectious retroviruses by real time PCR. Homology between the target virus and the prototype human genome was determined using sequence analysis methods.

RESULTS

Compared with controls, individuals with recent onset of psychosis had increased levels of antibodies to MPMV and MuLV (both p<.001 adjusted for covariates), and increased antibody levels for defined portions of the MPMV and MuLV gag, pol and env proteins. The specificity of these antibodies was confirmed by Western blotting. Individuals with multi-episode schizophrenia did not show elevated antibody levels to any of the retroviruses measured. Infectious retroviruses were not detected in the blood of any participants. Homology analyses indicated that there are multiple regions of the human genome homologous with MPMV and MuLV proteins, the highest being with the MuLV gag protein.

CONCLUSIONS

Antibodies to retroviral proteins are elevated in individuals with recent onset psychosis but not in individuals with multi-episode schizophrenia. The immunopathological consequences of this antibody response should be the subject of additional studies.

Abnormal activity of the MAPK- and cAMP-associated signaling pathways in frontal cortical areas in postmortem brain in schizophrenia

Recent evidence suggests that schizophrenia may result from alterations of integration of signaling mediated by multiple neurotransmitter systems. Abnormalities of associated intracellular signaling pathways may contribute to the pathophysiology of schizophrenia. Proteins and phospho-proteins comprising mitogen activated protein kinase (MAPK) and 3'-5'-cyclic adenosine monophosphate (cAMP)-associated signaling pathways may be abnormally expressed in the anterior cingulate (ACC) and dorsolateral prefrontal cortex (DLPFC) in schizophrenia. Using western blot analysis we examined proteins of the MAPK- and cAMP-associated pathways in these two brain regions. Postmortem samples were used from a well-characterized collection of elderly patients with schizophrenia (ACC=36, DLPFC=35) and a comparison (ACC=33, DLPFC=31) group. Near-infrared intensity of IR-dye labeled secondary antisera bound to targeted proteins of the MAPK- and cAMP-associated signaling pathways was measured using LiCor Odyssey imaging system. We found decreased expression of Rap2, JNK1, JNK2, PSD-95, and decreased phosphorylation of JNK1/2 at T183/Y185 and PSD-95 at S295 in the ACC in schizophrenia. In the DLPFC, we found increased expression of Rack1, Fyn, Cdk5, and increased phosphorylation of PSD-95 at S295 and NR2B at Y1336. MAPK- and cAMP-associated molecules constitute ubiquitous intracellular signaling pathways that integrate extracellular stimuli, modify receptor expression and function, and regulate cell survival and neuroplasticity. These data suggest abnormal activity of the MAPK- and cAMP-associated pathways in frontal cortical areas in schizophrenia. These alterations may underlie the hypothesized hypoglutamatergic function in this illness. Together with previous findings, these data suggest that abnormalities of intracellular signaling pathways may contribute to the pathophysiology of schizophrenia.

Genetic variations in the ADAMTS12 gene are associated with schizophrenia in Puerto Rican patients of Spanish descent

ADAMTS12 belongs to the family of metalloproteinases that mediate a communication between specific cell types and play a key role in the regulation of normal tissue development, remodeling, and degradation. Members of this family have been implicated in neurodegenerative and neuroinflammatory, as well as in muscular-skeletal, cardiovascular, respiratory and renal diseases, and cancer. Several metalloproteinases have been associated with schizophrenia. In our previous study of the pedigree from a genetic isolate of Spanish origin in Puerto Rico, we identified a schizophrenia susceptibility locus on chromosome 5p13 containing ADAMTS12. This gene, therefore, is not only a functional but also a positional candidate gene for susceptibility to the disorder. In order to examine possible involvement of ADAMTS12 in schizophrenia, we performed mutation analysis of the coding, 5'- and 3'-untranslated, and putative promoter regions of the gene in affected members of the pedigree and identified 18 sequence variants segregated with schizophrenia. We then tested these variants in 135 unrelated Puerto Rican schizophrenia patients of Spanish origin and 203 controls and identified the intronic variant rs256792 (P = 0.0035; OR = 1.59; 95% CI = 1.16-2.17) and the two-SNP haplotype rs256603-rs256792 (P = 0.0023; OR = 1.62; 95% CI = 1.19-2.21) associated with the disorder. The association remained significant after correction for multiple testing. Our data support the hypothesis that genetic variations in ADAMTS12 influence the risk of schizophrenia.

Diethylstilbestrol and risk of psychiatric disorders: a critical review and new insights

OBJECTIVES

We explored whether in utero DES exposure has produced consistent findings with regard to an increased risk of psychiatric disorders.

METHODS

We reviewed systematically the epidemiological studies investigating a possible association between prenatal DES exposure and risk of psychiatric disorders.

RESULTS

We identified 10 relevant studies reporting the psychiatric outcome of offspring with a history of in utero DES exposure compared to a control group. We classified them into four categories: (1) a mail survey in a sample from a randomized double-blind controlled trial of prophylactic DES for first pregnancy in the early 1950s reported that depression and anxiety were twice as frequent in the exposed group compared to the placebo group; (2) five small clinical samples with inconclusive results; (3) two large cohorts of DES-exposed participants: the first study reported a higher lifetime history of weight loss related to anorexia nervosa whereas the second did not found any significant difference; (4) two subsamples from general population cohorts: the first study did not found any significant difference whereas the second reported that exposed women showed a higher rate of incident depression than non-exposed women.

CONCLUSIONS

The role of prenatal exposure to DES as an environmental risk factor for psychiatric disorders requires more evidence before any conclusions can be drawn. If confirmed, several explanations could be proposed: gene × environment interaction and epigenetic mechanisms, although phenocopy and gene-environment aggregation are plausible.

[Schizophrenia, genetics and cognition]

Schizophrenia is a complex and heritable disorder. Nevertheless, molecular genetics of schizophrenia remains inconclusive. By developing the concept of endophenotype for the disorder, it is easier to define an association between a phenotype and genetic variants or physiopathological processes. Cognitive disorders could be useful endophenotypes for schizophrenia. For example, the val(158)/met COMT polymorphism has been associated with executive function or working memory. Therefore, several cognitive dysfunctions were proposed as endophenotypes and were investigated in the context of different genetic polymorphisms. Genome-wide association studies and epistatic studies demonstrated the complexity of the mechanisms underlying cognitive disturbance. However, meta-analysis remains inconclusive. Altogether, the study of endophenotypes is an attractive approach to solve the complex mechanisms causing schizophrenia vulnerability. Nevertheless, several limitations exist and include the lack of reproducibility, the discordant results between healthy subjects and patients, the exclusion of the many rare variants.

Additive effects of elevated C-reactive protein and exposure to Herpes Simplex Virus type 1 on cognitive impairment in individuals with schizophrenia

OBJECTIVES

We investigated the effect of elevated levels of C-reactive protein (CRP) and exposure to Herpes simplex virus type 1 (HSV-1) on the severity of cognitive impairment in individuals with schizophrenia.

METHODS

We measured the levels of CRP and of antibodies to HSV-1 in serum samples from 588 individuals with schizophrenia by enzyme immunoassay tests. Cognitive functioning was measured with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and psychiatric symptoms with the Positive and Negative Syndrome Scale (PANSS). The effects of HSV1 and CRP on cognitive functioning were analyzed with linear and logistic regression analyses adjusting for demographic and clinical variables.

RESULTS

The individuals with elevated CRP levels and HSV-1 seropositivity had lower RBANS cognitive scores. The strongest effect was found in individuals who had both serological evidence of HSV-1 exposure and elevated levels of CRP. These individuals had odds of 2.35 to have an RBANS Total score<=60 as compared to individuals who were HSV-1 seronegative and who did not have elevated levels of CRP (p=.002). The risks of decreased cognitive functioning associated with HSV-1 exposure and elevated levels of CRP were independent and additive. There was no effect of HSV-1 exposure and CRP levels on the severity of symptoms as measured by the PANSS (all p>.5).

CONCLUSIONS

Elevated levels of CRP and exposure to HSV-1 are associated with the severity of cognitive impairment in schizophrenia. These findings indicate that infection and inflammation may play a major role in the cognitive deficits associated with schizophrenia.

Association study of myelin transcription factor 1-like polymorphisms with schizophrenia in Han Chinese population

Schizophrenia (SZ) is characterized by a variety of complex positive, negative and cognitive symptoms that are differentially expressed in individual patients. Variability in symptom presentation indicates that multiple genes, many involved in neurodevelopment, contribute to the etiology of SZ. The myelin transcription factor 1-like (MYT1L) gene encodes the MYT1L protein that participates in several neurodevelopment pathways. The copy number variant of MYT1L gene is associated with SZ, and single-nucleotide polymorphisms (SNPs) of MYT1L contribute to major depressive disorder. To explore the association of MYT1L polymorphisms with SZ, we examined six SNPs of MYT1L in a Han Chinese population consisting of 528 paranoid schizophrenic patients and 528 healthy subjects. Our results showed that rs17039584 was significantly associated with SZ (A>G), even after Bonferroni correction. When subjects were divided by gender, the rs10190125 allele and genotype remained significantly associated with SZ in female patients. Moreover, we found that rs6742365 was associated with a family history of SZ in females. Other SNPs did not achieve statistical significance for SZ but were associated with individual phenotypes, as measured by the Positive and Negative Syndrome Scale (PANSS) inventory. Our findings suggest that MYT1L may represent a susceptibility gene for SZ in the Han Chinese population and show that a specific SNP may increase susceptibility in females.

Is schizophrenia developmental adaptation to environmental menaces?

Schizophrenia is a devastating mental disorder, with its symptoms typically emerging during late adolescence to young adulthood. In contrast, accumulating evidence suggests that schizophrenia is a developmental disorder in which brain abnormalities may occur even before birth. This has brought the major challenge to explain such discrepancy of brain deficits occurring during prenatal period and emergence of symptoms during adulthood. A number of ideas have been proposed to explain delayed emergence of symptoms at adulthood in relation to maturational processes of various brain systems during adolescence. However, these still lack clear relationship to prenatal deficits. Thus, a key to better understand the pathology of schizophrenia is to unveil a theory or model that can explain the relationship between prenatal deficits and post-pubertal onset of symptoms. Here we propose a novel hypothesis, along with discussion of several lines of evidences supporting it, that schizophrenia may not be a disorder in a strict sense, but rather be understood as the biological state occurring as consequence of adaptation to severe environmental conditions during the prenatal periods, which explains the relationship between prenatal developmental deficits and the postnatal maturational process for onset of symptoms.

Dissecting the Syndrome of Schizophrenia: Progress toward Clinically Useful Biomarkers

The search for clinically useful biomarkers has been one of the holy grails of schizophrenia research. This paper will outline the evolving notion of biomarkers and then outline outcomes from a variety of biomarkers discovery strategies. In particular, the impact of high-throughput screening technologies on biomarker discovery will be highlighted and how new or improved technologies may allow the discovery of either diagnostic biomarkers for schizophrenia or biomarkers that will be useful in determining appropriate treatments for people with the disorder. History tells those involved in biomarker research that the discovery and validation of useful biomarkers is a long process and current progress must always be viewed in that light. However, the approval of the first biomarker screen with some value in predicting responsiveness to antipsychotic drugs suggests that biomarkers can be identified and that these biomarkers that will be useful in diagnosing and treating people with schizophrenia.