Raised cytomegalovirus-antibody level in cerebrospinal fluid of schizophrenic patients

Cytomegalovirus antibodies are associated with mood disorders, suicide, markers of neuroinflammation, and microglia activation in postmortem brain samples

Cytomegalovirus (CMV) is a common, neurotrophic herpesvirus that can be reactivated by inflammation and cause central nervous system disease. We hypothesize that CMV may contribute to the neuroinflammation that underlies some psychiatric disorders by (1) exacerbating inflammation through the induction of anti-viral immune responses, and (2) translating peripheral inflammation into neuroinflammation. We investigated whether the presence of anti-CMV antibodies in blood were associated with mental illness, suicide, neuroinflammation, and microglial density in the dorsolateral prefrontal cortex (DLPFC) in postmortem samples. Data (n = 114 with schizophrenia; n = 78 with bipolar disorder; n = 87 with depression; n = 85 controls) were obtained from the Stanley Medical Research Institute. DLPFC gene expression data from a subset of 82 samples were categorized into "high" (n = 30), and "low" (n = 52) inflammation groups based on a recursive two-step cluster analysis using expression data for four inflammation-related genes. Measurements of the ratio of non-ramified to ramified microglia, a proxy of microglial activation, were available for a subset of 49 samples. All analyses controlled for age, sex, and ethnicity, as well as postmortem interval, and pH for gene expression and microglial outcomes. CMV seropositivity significantly increased the odds of a mood disorder diagnosis (bipolar disorder: OR = 2.45; major depression: OR = 3.70) and among the psychiatric samples, of suicide (OR = 2.09). Samples in the upper tercile of anti-CMV antibody titers were more likely to be members of the "high" inflammation group (OR = 4.41, an effect driven by schizophrenia and bipolar disorder samples). CMV positive samples also showed an increased ratio of non-ramified to ramified microglia in layer I of the DLPFC (Cohen's d = 0.81) as well as a non-significant increase in this ratio for the DLPFC as a whole (d = 0.56). The results raise the possibility that the reactivation of CMV contributes to the neuroinflammation that underlies some cases of psychiatric disorders.

Viral Infections and Schizophrenia: A Comprehensive Review

Schizophrenia is a complex mental disorder with multiple genetic and environmental factors contributing to its pathogenesis. Viral infections have been suggested to be one of the environmental factors associated with the development of this disorder. We comprehensively review all relevant published literature focusing on the relationship between schizophrenia and various viral infections, such as influenza virus, herpes virus 1 and 2 (HSV-1 and HSV-2), cytomegalovirus (CMV), Epstein-Barr virus (EBV), retrovirus, coronavirus, and Borna virus. These viruses may interfere with the normal maturation of the brain directly or through immune-induced mediators, such as cytokines, leading to the onset of schizophrenia. Changes in the expression of critical genes and elevated levels of inflammatory cytokines have been linked to virally-induced infections and relevant immune activities in schizophrenia. Future research is necessary to understand this relationship better and provide insight into the molecular mechanisms underlying the pathophysiology of schizophrenia.

Biomarkers in the cerebrospinal fluid of patients with psychotic disorders compared to healthy controls: a systematic review and meta-analysis

Psychotic disorders are severe mental disorders with poorly understood etiology. Biomarkers in the cerebrospinal fluid (CSF) could provide etiological clues and diagnostic tools for psychosis; however, an unbiased overview of CSF alterations in individuals with psychotic disorders is lacking. The objective of this study was to summarize all quantifiable findings in CSF from individuals with psychotic disorders compared to healthy controls (HC). Studies published before January 25th, 2023 were identified searching PubMed, EMBASE, Cochrane Library, Web of Science, ClinicalTrials.gov, and PsycINFO. Screening, full-text review, data extraction, and risk of bias assessments were performed by two independent reviewers following PRISMA guidelines. Findings in patients and healthy controls were compared and summarized using random-effects analyses and assessment of publication bias, subgroup and sensitivity analyses were performed. 145 studies, covering 197 biomarkers, were included, of which 163 biomarkers have not previously been investigated in meta-analyses. All studies showed some degree of bias. 55 biomarkers measured in CSF were associated with psychosis and of these were 15 biomarkers measured in ≥2 studies. Patients showed increased levels of noradrenaline (standardized mean difference/SMD, 0.53; 95% confidence interval/CI, 0.16 to 0.90) and its metabolite 3-methoxy-4-hydroxyphenylglycol (SMD, 0.30; 95% CI: 0.05 to 0.55), the serotonin metabolite 5-hydroxyindoleacetic acid (SMD, 0.11; 95% CI: 0.01 to 0.21), the pro-inflammatory neurotransmitter kynurenic acid (SMD, 1.58; 95% CI: 0.34 to 2.81), its precursor kynurenine (SMD,0.99; 95% CI: 0.60 to 1.38), the cytokines interleukin-6 (SMD, 0.58; 95% CI: 0.39 to 0.77) and interleukin-8 (SMD, 0.43; 95% CI: 0.24 to 0.62), the endocannabinoid anandamide (SMD, 0.78; 95% CI: 0.53 to 1.02), albumin ratio (SMD, 0.40; 95% CI: 0.08 to 0.72), total protein (SMD, 0.29; 95% CI: 0.16 to 0.43), immunoglobulin ratio (SMD, 0.45; 95% CI: 0.06 to 0.85) and glucose (SMD, 0.48; 95% CI: 0.01 to 0.94). Neurotensin (SMD, -0.67; 95% CI: -0.89 to -0.46) and γ-aminobutyric acid (SMD, -0.29; 95% CI: -0.50 to -0.09) were decreased. Most biomarkers showed no significant differences, including the dopamine metabolites homovanillic acid and 3,4-dihydroxyphenylacetic acid. These findings suggest that dysregulation of the immune and adrenergic system as well as blood-brain barrier dysfunction are implicated in the pathophysiology of psychotic disorders.

Therapeutic Implications of the Microbial Hypothesis of Mental Illness

There is increasingly compelling evidence that microorganisms may play an etiological role in the emergence of mental illness in a subset of the population. Historically, most work has focused on the neurotrophic herpesviruses, herpes simplex virus type 1 (HSV-1), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) as well as the protozoan, Toxoplasma gondii. In this chapter, we provide an umbrella review of this literature and additionally highlight prospective studies that allow more mechanistic conclusions to be drawn. Next, we focus on clinical trials of anti-microbial medications for the treatment of psychiatric disorders. We critically evaluate six trials that tested the impact of anti-herpes medications on inflammatory outcomes in the context of a medical disorder, nine clinical trials utilizing anti-herpetic medications for the treatment of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) or schizophrenia, and four clinical trials utilizing anti-parasitic medications for the treatment of schizophrenia. We then turn our attention to evidence for a gut dysbiosis and altered microbiome in psychiatric disorders, and the potential therapeutic effects of probiotics, including an analysis of more than 10 randomized controlled trials of probiotics in the context of schizophrenia, bipolar disorder (BD), and major depressive disorder (MDD).

Effect of Cytomegalovirus on the Immune System: Implications for Aging and Mental Health

Human cytomegalovirus (HCMV) is a major modulator of the immune system leading to long-term changes in T-lymphocytes, macrophages, and natural killer (NK) cells among others. Perhaps because of this immunomodulatory capacity, HCMV infection has been linked with a host of deleterious effects including accelerated immune aging (premature mortality, increased expression of immunosenescence-linked markers, telomere shortening, speeding-up of epigenetic "clocks"), decreased vaccine immunogenicity, and greater vulnerability to infectious diseases (e.g., tuberculosis) or infectious disease-associated pathology (e.g., HIV). Perhaps not surprisingly given the long co-evolution between HCMV and humans, the virus has also been associated with beneficial effects, such as increased vaccine responsiveness, heterologous protection against infections, and protection against relapse in the context of leukemia. Here, we provide an overview of this literature. Ultimately, we focus on one other deleterious effect of HCMV, namely the emerging literature suggesting that HCMV plays a pathophysiological role in psychiatric illness, particularly depression and schizophrenia. We discuss this literature through the lens of psychological stress and inflammation, two well-established risk factors for psychiatric illness that are also known to predispose to reactivation of HCMV.

Effect of Cytomegalovirus Infection on the Central Nervous System: Implications for Psychiatric Disorders

Cytomegalovirus (CMV) is a common herpesvirus that establishes lifelong latent infections and interacts extensively with the host immune system, potentially contributing to immune activation and inflammation. Given its proclivity for infecting the brain and its reactivation by inflammatory stimuli, CMV is well known for causing central nervous system complications in the immune-naïve (e.g., in utero) and in the immunocompromised (e.g., in neonates, individuals receiving transplants or cancer chemotherapy, or people living with HIV). However, its potentially pathogenic role in diseases that are characterized by more subtle immune dysregulation and inflammation such as psychiatric disorders is still a matter of debate. In this chapter, we briefly summarize the pathogenic role of CMV in immune-naïve and immunocompromised populations and then review the evidence (i.e., epidemiological studies, serological studies, postmortem studies, and recent neuroimaging studies) for a link between CMV infection and psychiatric disorders with a focus on mood disorders and schizophrenia. Finally, we discuss the potential mechanisms through which CMV may cause CNS dysfunction in the context of mental disorders and conclude with a summary of the current state of play as well as potential future research directions in this area.

Neuroinflammation in schizophrenia: the role of nuclear factor kappa B

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

Being Born in Winter-Spring and at Around the Time of an Influenza Pandemic Are Risk Factors for the Development of Schizophrenia: The Apna Study in Navarre, Spain

Background: We analyzed the relationship between the prevalence of schizophrenia and the season of birth and gestation during a period of an influenza pandemic. Methods: Cross-sectional analysis of a prospective population-based cohort of 470,942 adults. We fitted multivariant logistic regression models to determine whether the season of birth and birth in an influenza-pandemic year (1957, 1968, 1977) was associated with schizophrenia. Results: 2077 subjects had been diagnosed with schizophrenia. Logistic regression identified a significantly greater prevalence of schizophrenia in men than in women (OR = 1.516, CI 95% = 1.388–1.665); in those born in the winter or spring than in those born in the summer or autumn (OR = 1.112, CI 95% = 1.020–1.212); and in those born in a period of an influenza pandemic (OR = 1.335, CI 95% = 1.199–1.486). The increase in risk was also significant when each influenza pandemic year was analyzed separately. However, neither month of birth nor season of birth, when each of the four were studied individually, were associated with a statistically significant increase in that risk. Conclusions: The winter–spring period and the influenza pandemics are independent risk factors for developing schizophrenia. This study contradicts many previous studies and thus revitalizes a locked debate in understanding the neurodevelopmental hypothesis of this disorder.

Cerebrospinal fluid markers of inflammation and infections in schizophrenia and affective disorders: a systematic review and meta-analysis

Infections and inflammatory processes have been associated with the development of schizophrenia and affective disorders; however, no study has yet systematically reviewed all available studies on cerebrospinal fluid (CSF) immune alterations. We aimed to systematically review the CSF immunological findings in schizophrenia spectrum and affective disorders. We identified all studies investigating CSF inflammatory markers in persons with schizophrenia or affective disorders published prior to March 23, 2017 searching PubMed, CENTRAL, EMBASE, Psychinfo, and LILACS. Literature search, data extraction and bias assessment were performed by two independent reviewers. Meta-analyses with standardized mean difference (SMD) including 95% confidence intervals (CI) were performed on case-healthy control studies. We identified 112 CSF studies published between 1942-2016, and 32 case-healthy control studies could be included in meta-analyses. Studies varied regarding gender distribution, age, disease duration, treatment, investigated biomarkers, and whether recruitment happened consecutively or based on clinical indication. The CSF/serum albumin ratio was increased in schizophrenia (1 study [54 patients]; SMD = 0.71; 95% CI 0.33-1.09) and affective disorders (4 studies [298 patients]; SMD = 0.41; 95% CI 0.23-0.60, I2 = 0%), compared to healthy controls. Total CSF protein was elevated in both schizophrenia (3 studies [97 patients]; SMD = 0.41; 95% CI 0.15-0.67, I2 = 0%) and affective disorders (2 studies [53 patients]; SMD = 0.80; 95% CI 0.39-1.21, I2 = 0%). The IgG ratio was increased in schizophrenia (1 study [54 patients]; SMD = 0.68; 95% CI 0.30-1.06), whereas the IgG Albumin ratio was decreased (1 study [32 patients]; SMD = -0.62; 95% CI -1.13 to -0.12). Interleukin-6 (IL-6) levels (7 studies [230 patients]; SMD = 0.55; 95% CI 0.35-0.76; I2 = 1%) and IL-8 levels (3 studies [95 patients]; SMD = 0.46; 95% CI 0.17-0.75, I2 = 0%) were increased in schizophrenia but not significantly increased in affective disorders. Most of the remaining inflammatory markers were not significantly different compared to healthy controls in the meta-analyses. However, in the studies which did not include healthy controls, CSF abnormalities were more common, and two studies found CSF dependent re-diagnosis in 3.2-6%. Current findings suggest that schizophrenia and affective disorders may have CSF abnormalities including signs of blood-brain barrier impairment and inflammation. However, the available evidence does not allow any firm conclusion since all studies showed at least some degree of bias and vastly lacked inclusion of confounding factors. Moreover, only few studies investigated the same parameters with healthy controls and high-quality longitudinal CSF studies are lacking, including impact of psychotropic medications, lifestyle factors and potential benefits of anti-inflammatory treatment in subgroups with CSF inflammation.

Antibodies to the N-methyl-D-aspartate receptor and other synaptic proteins in psychosis

This review concentrates on the evidence for autoantibodies to cell surface synaptic proteins in psychosis and schizophrenia. We and others have recently found antibodies to the N-methyl-D-aspartate receptor in first-episode psychosis. We describe the evidence for pathogenicity and disease-relevance of these antibodies, which builds on the novel field in neuroimmunology of cell surface antibody-associated central nervous system disorders. Relevant autoantibodies in psychosis and schizophrenia are likely to be those directed to cell surface proteins, in which the likelihood of pathogenicity is greater. We discuss the evidence for this from the field of paraneoplastic neurologic syndromes and the discovery of novel cell surface antigen central nervous system autoimmune syndromes.

Cytomegalovirus seropositivity and serointensity are associated with hippocampal volume and verbal memory in schizophrenia and bipolar disorder

INTRODUCTION

Cytomegalovirus (CMV) is a member of the herpesviridae family that has a limbic and temporal gray matter tropism. It is usually latent in humans but has been associated with schizophrenia, bipolar disorder and cognitive deficits in some populations. Hippocampal decreased volume and dysfunction play a critical role in these cognitive deficits. We hypothesized that CMV seropositivity and serointensity would be associated with hippocampal volume and cognitive functioning in patients with schizophrenia or bipolar disorder.

METHODS

102 healthy controls, 118 patients with bipolar disorder and 69 patients with schizophrenia performed the California Verbal Learning Test (CVLT) and had blood samples drawn to assess CMV IgG levels. A subgroup of 52 healthy controls, 31 patients with bipolar disorder and 27 patients with schizophrenia underwent T1 MRI for hippocampal volumetry. We analyzed the association between CMV serointensity and seropositivity with hippocampal volume. We also explored the correlation between CMV serointensity and seropositivity and CVLT scores.

RESULTS

In both patient groups but not in controls, higher CMV serointensity was significantly associated with smaller right hippocampal volume. Further, in the group of patients with schizophrenia but not bipolar disorder, CMV serointensity was negatively correlated with CVLT scores.

CONCLUSION

CMV IgG titers are associated with decreased hippocampal volume and poorer episodic verbal memory in patients with schizophrenia or bipolar disorder. The mechanism of this association warrants further exploration.

Association between antibodies to multiple infectious and food antigens and new onset schizophrenia among US military personnel

INTRODUCTION

Multiple studies have documented immune activation in many individuals with schizophrenia suggesting that antigens capable of generating a prolonged immune response may be important environmental factors in many cases of this disorder. While existing studies have found single-agent associations of antibodies to food and neurotropic infectious agents with schizophrenia, a simultaneous examination of multiple agents may shed light on agent interactions or possible etiopathogenic pathways.

METHODS

We used traditional regression and novel statistical techniques to examine associations of single and combined infectious and food antigens with schizophrenia. We tested 6106 serum samples from 855 cases and 1165 matched controls.

RESULTS

Higher antibody levels to casein were borderline significant in the prediction of schizophrenia (HR=1.08, p=0.06). Study participants with higher cytomegalovirus (CMV) IgG antibody levels had a reduced risk of developing schizophrenia (HR=0.90; p=0.02). While IgG antibodies to gliadin, Toxoplasma gondii, vaccinia, measles, and human herpesvirus-6 (HHV-6) showed no significant independent associations with schizophrenia, the increase in antibody levels to several combinations of agents, to include casein, measles, CMV, T. gondii and vaccinia, was predictive of an 18-34% increase in the risk of developing schizophrenia.

CONCLUSION

Certain patterns of antibodies, involving some agents, were predictive of developing schizophrenia, with the magnitude of association rising when the level of antibodies increased to two or more agents. A heightened antibody response to a combination of several infectious/food antigens might be an indicator of an altered immune response to antigenic stimuli.

Evaluation of HLA polymorphisms in relation to schizophrenia risk and infectious exposure

BACKGROUND

Genome-wide association studies (GWAS) implicate single nucleotide polymorphisms (SNPs) on chromosome 6p21.3-22.1, the human leukocyte antigen (HLA) region, as common risk factors for schizophrenia (SZ). Other studies implicate viral and protozoan exposure. Our study tests chromosome 6p SNPs for effects on SZ risk with and without exposure.

METHOD

GWAS-significant SNPs and ancestry-informative marker SNPs were analyzed among African American patients with SZ (n = 604) and controls (n = 404). Exposure to herpes simplex virus, type 1 (HSV-1), cytomegalovirus (CMV), and Toxoplasma gondii (TOX) was assayed using specific antibody assays.

RESULTS

Five SNPs were nominally associated with SZ, adjusted for population admixture (P < .05, uncorrected for multiple comparisons). These SNPs were next analyzed in relation to infectious exposure. Multivariate analysis indicated significant association between rs3130297 genotype and HSV-1 exposure; the associated allele was different from the SZ risk allele.

CONCLUSIONS

We propose a model for the genesis of SZ incorporating genomic variation in the HLA region and neurotropic viral exposure for testing in additional, independent African American samples.

Cerebrospinal fluid biomarker candidates of schizophrenia: where do we stand?

Here, we review the cerebrospinal fluid (CSF) candidate markers with regard to their clinical relevance as potential surrogates for disease activity, prognosis assessment, and predictors of treatment response. We searched different online databases such as MEDLINE and EMBASE for studies on schizophrenia and CSF. Initial studies on cerebrospinal fluid in patients with schizophrenia revealed increased brain-blood barrier permeability with elevated total protein content, increased CSF-to-serum ratio for albumin, and intrathecal production of immunoglobulins in subgroups of patients. Analyses of metabolites in CSF suggest alterations within glutamatergic neurotransmission as well as monoamine and cannabinoid metabolism. Decreased levels of brain-derived neurotrophic factor and nerve growth factor in CSF of first-episode patients with schizophrenia reported in recent studies point to a dysregulation of neuroprotective and neurodevelopmental processes. Still, these findings must be considered as non-specific. A more profound characterization of the particular psychopathological profiles, the investigation of patients in the prodromal phase or within the first episode of schizophrenia promoting longitudinal investigations, implementation of different approaches of proteomics, and rigorous adherence to standard procedures based on international CSF guidelines are necessary to improve the quality of CSF studies in schizophrenia, paving the way for identification of syndrome-specific biomarker candidates.

Infectious agents associated with schizophrenia: a meta-analysis

Schizophrenia is a highly disabling and limiting disorder for patients and the possibility that infections by some microorganisms may be associated to its development may allow prevention and recovery. In the current study we have done a meta-analysis of studies that have assessed the possible association between detection of different infectious agents and schizophrenia. We report results that support the idea that there is a statistically significant association between schizophrenia and infection by Human Herpesvirus 2 (OR=1.34; CI 95%: 1.09-1.70; p=0.05), Borna Disease Virus (OR=2.03; CI 95%: 1.35-3.06; p<0.01), Human Endogenous Retrovirus W (OR=19.31; CI 95%: 6.74-55.29; p<0.001), Chlamydophila pneumoniae (OR=6.34; CI 95%: 2.83-14.19; p<0.001), Chlamydophila psittaci (OR=29.05; CI 95%: 8.91-94.70; p<0.001) and Toxoplasma gondii (OR=2.70; CI 95%: 1.34-4.42; p=0.005). The implications of these findings are discussed and further research options are also explicated.

Effect of cytomegalovirus infection on temporal lobe development in utero: quantitative MRI studies

Several environmental factors, including viral infections during fetal development, are known to increase the risk of schizophrenia. Cytomegalovirus (CMV) is the main cause of viral congenital infection. Since changes in temporal lobe structures are a consistent finding in imaging studies of adult schizophrenics, we investigated possible derangement in temporal lobe development in CMV infected fetuses. Abdominal MRI (1.5 T) was performed using a single-shot fast spin echo T2-weighted sequence. MRI volumetry was employed to measure brain and temporal lobe size in 27 CMV infected fetuses and 52 gestational age matched controls in utero. The ratio of temporal lobe to whole brain was computed for each fetus and group comparisons were performed using Student's t-test or ANOVA. Temporal lobe volumes, normalized to whole brain and co-varied with gestational age; were significantly smaller in fetuses infected with CMV compared to uninfected fetuses. (Infected group mean ± SEM: 0.086 ± 0.006, controls: 0.113 ± 0.003, p<0.0001). Infection during the 1st and 2nd trimester had a more pronounced effect than infection during the 3rd trimester. Infected fetuses with no MRI findings had significantly lower temporal lobe/whole brain ratios than controls (0.092 ± 0.008, p<0.01, N=11) and the lowest ratios were observed in fetuses with overt findings such as cysts or gray matter heterotopy (0.067 ± 0.015). These results demonstrate the ability of quantitative fetal brain MRI to detect previously unreported, specific deficits in brain development in CMV infected fetuses, which, in conjunction with other genetic and environmental factors, may contribute to the risk of developing schizophrenia later in life.

The human endogenous retrovirus link between genes and environment in multiple sclerosis and in multifactorial diseases associating neuroinflammation

Endogenous retroviruses represent about 8% of the human genome and belong to the superfamily of transposable and retrotransposable genetic elements. Altogether, these mobile genetic elements and their numerous inactivated "junk" sequences represent nearly one half of the human DNA. Nonetheless, a significant part of this "non-conventional" genome has retained potential activity. Epigenetic control is notably involved in silencing most of these genetic elements but certain environmental factors such as viruses are known to dysregulate their expression in susceptible cells. More particularly, embryonal cells with limited gene methylation are most susceptible to uncontrolled activation of these mobile genetic elements by, e.g., viral infections. In particular, certain viruses transactivate promoters from endogenous retroviral family type W (HERV-W). HERV-W RNA was first isolated in circulating viral particles (Multiple Sclerosis-associated RetroViral element, MSRV) that have been associated with the evolution and prognosis of multiple sclerosis. HERV-W elements encode a powerful immunopathogenic envelope protein (ENV) that activates a pro-inflammatory and autoimmune cascade through interaction with Toll-like receptor 4 on immune cells. This ENV protein has repeatedly been detected in MS brain lesions and may be involved in other diseases. Epigenetic factors controlling HERV-W ENV protein expression then reveal critical. This review addresses the gene-environment epigenetic interface of such HERV-W elements and its potential involvement in disease.

Role of Borna disease virus in neuropsychiatric illnesses: are we inching closer?

The biological cause of psychiatric illnesses continues to be under intense scrutiny. Among the various neurotropic viruses, Borna disease virus (BDV) is another virus that preferentially targets the neurons of the limbic system and has been shown to be associated with behavioural abnormalities. Presence of various BDV markers, including viral RNA, in patients with affective and mood disorders have triggered ongoing debate worldwide regarding its aetiopathogenic relationship. This article analyses its current state of knowledge and recent advances in diagnosis in order to prove or refute the association of BDV in causation of human neuropsychiatric disorders. This emerging viral causative association of behavioural disorders, which seems to be inching closer, has implication not only for a paradigm shift in the treatment and management of neuropsychiatric illnesses but also has an important impact on the public health systems.

Results from a hypothesis generating case-control study: herpes family viruses and schizophrenia among military personnel

BACKGROUND

Herpes family viruses can cause central nervous system inflammatory changes that can present with symptoms indistinguishable from schizophrenia and therefore are of interest in schizophrenia research. Most existing studies of herpes viruses have used small populations and postdiagnosis specimens. As part of a larger research program, we conducted a hypothesis-generating case-control study of selected herpes virus antibodies among individuals discharged from the US military with schizophrenia and pre- and postdiagnosis sera.

METHODS

Cases (n = 180) were servicemembers hospitalized and discharged from military service with schizophrenia. Controls, 3:1 matched on several factors, were members not discharged. The military routinely collects and stores members' serum specimens. We used microplate enzyme immunoassay to measure immunoglobulin G (IgG) antibody levels to 6 herpes viruses in pre- and postdiagnosis specimens. Conditional logistic regression was used, and the measure of association was the hazard ratio (HR).

RESULTS

Overall, we found a significant association between human herpes virus type 6 and schizophrenia, with an HR of 1.17 (95% confidence interval [CI] = 1.04, 1.32). Women and blacks had significant negative associations with herpes simplex virus type 2 and cytomegalovirus; among blacks, there was a significant positive association with herpes simplex virus type 1. Among men, there was a HHV-6 temporal effect with an HR of 1.41 (95% CI = 1.02, 1.96) for sera drawn 6-12 months before diagnosis.

DISCUSSION

Findings from previous studies of herpes family viruses and schizophrenia have been inconsistent. Our study is based on a larger population than most previous studies and used serum specimens collected before onset of illness. This study adds to the body of knowledge and provides testable hypotheses for follow-on studies.

Cytomegalovirus and schizophrenia

Several lines of evidence suggest that cytomegalovirus (CMV) may play an aetiological role in schizophrenia. Epidemiologically, both have a worldwide distribution and an increased prevalence in lower socioeconomic groups. Studies have reported that some patients experiencing initial episodes of schizophrenia have increased levels of IgG antibodies against CMV, but not other herpes viruses, in their sera and CSF. Treatment with antipsychotic medications may result in a decrease in CMV antibodies, while treatment with anti-herpes virus and anti-inflammatory medications may reduce symptoms in some individuals with schizophrenia. There is also some overlap in the genes that are thought to operate in CMV infections and schizophrenia. The strongest argument against the role of CMV in schizophrenia is the absence of the traditional CMV neuropathological changes in the brains of individuals with schizophrenia; however, neuropathological studies of CMV have mostly been conducted in immune-compromised individuals. Further studies on CMV and schizophrenia are needed and may lead to improved treatments for schizophrenia.

Schizophrenia, autoimmunity and immune system dysregulation: A comprehensive model updated and revisited

Recent investigation suggests a strong relationship between immunological effects and the pathophysiology of schizophrenia. Two prevalent approaches exist to this association. First, is more empirical a-priori research investigating immunological changes prevalent in schizophrenia and the second approach is more hypothesis-driven with analysis of immunological changes in schizophrenia based on known irregularities of the illness. The former approach is based upon three predominant lines of investigation including observations of a diffuse non-specific overactivation of the immunological response system, of a T-helper cell type 1 immune activation and of a T-helper cell type 2 immune activation in subgroups of schizophrenia patients. These last two theories suggest that a subgroup of patients with schizophrenia may demonstrate features of an autoimmune process, a theory supported by a growing database of investigation. The latter approach notes that many observations of immune dysregulation in schizophrenia overlap with central etiopathophysiological mechanisms as well as with clinical manifestations of the illness. Immunotherapy offers the opportunity to modify or re-balance the immune system and may become useful in management of the illness. Given that autoimmune mechanisms could interrupt neurotransmission, any process interfering with this disruption including therapeutic antibodies to involved cytokines, or with various other natural autoantibodies or immune system regulators, may become useful in the augmentative management of the illness.

Immunological aetiology of major psychiatric disorders: evidence and therapeutic implications

Historically, immunological research in psychiatry was based on empirical findings and early epidemiological studies indicating a possible relationship between psychiatric symptoms and acute infectious diseases. However, aetiopathological explanations for psychiatric disorders are no longer closely related to acute infection. Nevertheless, immune hypotheses have been discussed in schizophrenia, affective disorders and infantile autism in the last decades. Although the variability between the results of the epidemiological studies conducted to date is strikingly high, there is still some evidence that the immune system might play a role in the aetiopathogenesis of these three psychiatric diseases, at least in subgroups of patients. In anxiety disorders immunological research is still very much in its infancy, and the few and inconsistent data of immune changes in these patients are believed to reflect the influence of short- or long-term stress exposure. Nevertheless, there are also some hints raising the possibility that autoimmune mechanisms could interrupt neurotransmission, which would be of significance in certain patients with anxiety and panic disorders. Drug and alcohol (ethanol) dependence are not believed to be primarily influenced by an immunological aetiology. On the other hand, immune reactions due to different drugs of abuse and alcohol may directly or indirectly influence the course of concomitant somatic diseases. In different organic brain disorders the underlying somatic disease is defined as a primary immune or autoimmune disorder, for instance HIV infection or systemic lupus erythematosus (SLE). For other neurodegenerative disorders, such as Alzheimer's disease, immunoaetiopathological mechanisms are supported by experimental and clinical studies. Treatment strategies based on immune mechanisms have been investigated in patients with schizophrenia and affective disorders. Furthermore, some antipsychotics and most antidepressants are known to have direct or indirect effects on the immune system. Different immunotherapies have been used in autism, including transfer factor, pentoxifylline, intravenous immunoglobulins and corticosteroids. Immunosuppressive and/or immunomodulating agents are well established methods for treating the neuropsychiatric sequelae of immune or autoimmune disorders, for example AIDS and SLE. Therapeutic approaches in Alzheimer's disease also apply immunological methods such as strategies of active/passive immunisation and NSAIDs. Considering the comprehensive interactive network between mind and body, future research should focus on approaches linking targets of the different involved systems.

Probable neuroimmunological link between Toxoplasma and cytomegalovirus infections and personality changes in the human host

Background

Recently, a negative association between Toxoplasma-infection and novelty seeking was reported. The authors suggested that changes of personality trait were caused by manipulation activity of the parasite, aimed at increasing the probability of transmission of the parasite from an intermediate to a definitive host. They also suggested that low novelty seeking indicated an increased level of the neurotransmitter dopamine in the brain of infected subjects, a phenomenon already observed in experimentally infected rodents. However, the changes in personality can also be just a byproduct of any neurotropic infection. Moreover, the association between a personality trait and the toxoplasmosis can even be caused by an independent correlation of both the probability of Toxoplasma-infection and the personality trait with the third factor, namely with the size of living place of a subject. To test these two alternative hypotheses, we studied the influence of another neurotropic pathogen, the cytomegalovirus, on the personality of infected subjects, and reanalyzed the original data after the effect of the potential confounder, the size of living place, was controlled.

Methods

In the case-control study, 533 conscripts were tested for toxoplasmosis and presence of anti-cytomegalovirus antibodies and their novelty seeking was examined with Cloninger's TCI questionnaire. Possible association between the two infections and TCI dimensions was analyzed.

Results

The decrease of novelty seeking is associated also with cytomegalovirus infection. After the size of living place was controlled, the effect of toxoplasmosis on novelty seeking increased. Significant difference in novelty seeking was observed only in the largest city, Prague.

Conclusion

Toxoplasma and cytomegalovirus probably induce a decrease of novelty seeking. As the cytomegalovirus spreads in population by direct contact (not by predation as with Toxoplasma), the observed changes are the byproduct of brain infections rather than the result of manipulation activity of a parasite. Four independent lines of indirect evidence, namely direct measurement of neurotransmitter concentration in mice, the nature of behavioral changes in rodents, the nature of personality changes in humans, and the observed association between schizophrenia and toxoplasmosis, suggest that the changes of dopamine concentration in brain could play a role in behavioral changes of infected hosts.

Schizophrenia and other mental disorders require long-term adoptive immunotherapy

Many different microbial factors seem to contribute to the pathogenesis of schizophrenic and other psychiatric disorders. Activation of all T lymphocytes reactivates those downregulated by low-grade chronic infections and restores equilibrium in immune cell subpopulations. Different immune cell subpopulations express different neurotrophin receptors and produce different cytokines, particularly brain-derived neurotrophin (BDNF) and neurotrophin 3 (NT3) [M. Besser, R. Wank, J. Immunol. 162 (1998) 6303-6306] that appear to play a key role in schizophrenic and bipolar disorders [E. Jonsson, S. Brene, X.R. Zhang, et al., Acta Psychiatr. Scand. 95 (1997) 414-419; R.S. Duman, Arch. Gen. Psychiatry 54 (1997) 597-606; J.A. Siuciak, D.R. Lewis, S.J. Wiegand, R.M. Lindsay, Pharmacol. Biochem. Be 56 (1997) 131-137]. The hypothesis that adoptive immunotherapy is effective in psychiatric disorders will be supported by three case reports, in a patient with bipolar disorder, a patient with schizophrenia, and a patient with autism.

Review of immunological and immunopathological findings in schizophrenia

The involvement of immunological and immunopathological mechanisms in the etiopathogenesis of schizophrenia has been a matter of research, with recently increasing effort. This article reviews the findings focusing on postmortem neuropathology, the blood-brain barrier, antibodies, acute phase proteins, immunocompetent cells, and activation markers of immunocompetent cells. Evidence for the two primarily postulated hypotheses (the infectious hypothesis and the autoimmune hypothesis) is critically discussed. On the basis of the findings, perspectives for future research are outlined aiming at a precise and consequent strategy to elucidate a potential involvement of immune mechanisms in the etiopathogenesis of schizophrenia.

Detection and sequence analysis of borna disease virus p24 RNA from peripheral blood mononuclear cells of patients with mood disorders or schizophrenia and of blood donors

Borna disease virus (BDV) p24 RNA was detected in the peripheral blood mononuclear cells (PBMCs) of psychiatric patients and blood donors by nested reverse transcriptase PCR (RT-PCR). The prevalences of BDV p24 RNA in patients with mood disorders (4%) and schizophrenia (4%) were not significantly different from that in blood donors (2%). This finding was inconsistent with previous reports that showed either a high prevalence or absence of BDV p24 RNA in patients with psychiatric disorders. The differences in BDV p24 RNA prevalence in these studies may be due to differences in the criteria for positivity, the number of PBMCs used for RNA extraction, or the amount of RNA tested for nested RT-PCR or to laboratory contamination. Sequence analysis of BDV p24 RNA from the PBMCs of patients and blood donors showed a high nucleotide sequence conservation but definite nucleotide mutations compared with horse BDV p24 RNA sequences. In comparison with human BDV p24 RNA sequences previously reported from Japan and Germany, there were several positions with silent nucleotide mutations among these clones.

Polymerase chain reaction (PCR) search for viral nucleic acid sequences in schizophrenia

BACKGROUND

Previous studies looking for evidence of viral infection in schizophrenics have yielded conflicting results. We searched for viral nucleic acids to test the hypothesis of the viral aetiology of schizophrenia.

METHOD

We used the polymerase chain reaction (PCR) to search for cytomegalovirus (CMV), human immunodeficiency virus (HIV), influenza A, Borna disease virus (BDV), and bovine viral diarrhoea virus (BVDV) in: hippocampus from three schizophrenic and three non-schizophrenic subjects; cerebrospinal fluid (CSF) from 48 schizophrenic patients; CSF and peripheral blood mononuclear cells (PBMC) from nine sets of identical twins discordant for schizophrenia; and SK-N-SHEP cells co-cultured with schizophrenic and non-schizophrenic brain homogenates. All patients met DSM-III-R criteria.

RESULTS

Virus-specific nucleic acids were not found in any of the samples tested.

CONCLUSIONS

The absence of viral nucleic acids in the samples tested suggest that, in these patients, schizophrenia is not associated with a persistent or latent infection due to these viruses.

Viruses, schizophrenia, and bipolar disorder

The hypothesis that viruses or other infectious agents may cause schizophrenia or bipolar disorder dates to the 19th century but has recently been revived. It could explain many clinical, genetic, and epidemiologic aspects of these diseases, including the winter-spring birth seasonality, regional differences, urban birth, household crowding, having an older sibling, and prenatal exposure to influenza as risk factors. It could also explain observed immunological changes such as abnormalities of lymphocytes, proteins, autoantibodies, and cytokines. However, direct studies of viral infections in individuals with these psychiatric diseases have been predominantly negative. Most studies have examined antibodies in blood or cerebrospinal fluid, and relatively few studies have been done on viral antigens, genomes, cytopathic effect on cell culture, and animal transmission experiments. Viral research on schizophrenia and bipolar disorder is thus comparable to viral research on multiple sclerosis and Parkinson's disease: an attractive hypothesis with scattered interesting findings but no clear proof. The application of molecular biological techniques may allow the identification of novel infectious agents and the associations of these novel agents with serious mental diseases.

Viral antibodies in recent onset, nonorganic psychoses: correspondence with symptomatic severity

A parallel of generalized viral infection with psychiatric symptoms has been reported in nonorganic psychotic disorders. The patients concerned had been ill for long periods and some of them had been readmitted. In order to determine the presence of viral infection at the very onset of the psychosis, antibodies in blood and cerebrospinal fluid (CSF) to six viruses [cytomegalovirus (CMV), herpes simplex (HSV) Type 1, mumps, measles, varicella zoster virus (VZV), and Japanese encephalitis virus (JEV)] were assayed in 35 psychotic patients [14 schizophrenics; 13 manic patients; and 8 patients with psychosis not otherwise specified (NOS)] within 1 month of onset of illness. Ten (28.6%) patients had a diagnostic (fourfold) change in the antibody titer in the paired serum and/or CSF samples (drawn at 2-week intervals) and another 10 had high titers (above 2 SDs from the mean in 35 control subjects). The striking temporal correlation with the initial severity and resolution of psychopathology by 2 weeks on the Brief Psychiatric Rating Scale (BPRS) suggests a causally significant, currently active viral infection in these 20 cases.

Viruses and schizophrenia

A viral hypothesis for the pathogenesis of schizophrenia has been under serious consideration for more than 70 years. To date, attempts have failed to identify a specific virus which contributes to the aetiology of the disorder. There has, however, been a recent resurgence of interest in a possible relationship between viral illness and schizophrenia. This renewed attention is the result of epidemiological evidence suggesting an excess of winter births in patients with schizophrenia, indications of foetal insults in persons who develop schizophrenia and an association between foetal exposure to the influenza virus and the subsequent development of schizophrenia. Advances in our understanding of the pathophysiology of viral diseases and the development of sophisticated techniques to study them have resulted in more complex viral hypotheses of schizophrenic aetiology, such as viral disruption of normal neurodevelopment, viral induced autoimmunity and retroviral integration. These hypotheses are now beginning to be tested experimentally.

Receptor-initiated activation of cells and their oncogenes by herpes-family viruses

The interaction of human cytomegalovirus (HCMV) with the cell membrane has been shown to initiate a cascade of physiologic and biochemical responses that result in the transcriptional activation of specific cellular proto-oncogenes. The cell-activation responses initiated by the virus membrane interaction appear to be important for efficient HCMV replication, as pharmacologic inhibition of cell activation responses significantly reduces the expression of immediate early viral genes and the production of infectious progeny virus. Cellular receptor proteins for other viruses have been shown to be molecules with physiologic activities. Binding of virus to these receptors may trigger the cell to initiate changes that are important for efficient viral replication. These viruses may also trigger inappropriate physiologic responses in the absence of viral replication, thereby causing more covert manifestations of viral pathology.

Haloperidol and lithium carbonate treatment did not influence serum immunoglobulin levels in schizophrenic and affective patients

Serum immunoglobulin levels were studied in 153 psychiatric patients (87 schizophrenic, 48 bipolar and 18 unipolar patients), and 35 healthy controls. Psychotropic treatments (haloperidol in the schizophrenic patients and lithium in the bipolar affective patients) did not alter serum immunoglobulin levels. Decreased mean IgM serum level was detected in the major affective patients (unipolar and bipolar) compared with normal controls. Nonspecific environmental, infectious, autoimmune and emotional factors that can play a role in the alterations obtained in psychiatric patients are discussed.

The functional psychoses--are oncogenes involved in their pathogenesis? Some speculations

Oncogenes are genes whose expression has been associated with malignant transformation of cells in tissue culture and with neoplastic changein vivo(Bishop, 1987). Much of the current understanding of their nature and action has stemmed from work, over the past 20 years, on tumour viruses (Temin, 1971; Rapp, 1983). One group of tumour viruses, the retroviruses, are unique in possessing an enzyme, reverse transcriptase, which transcribes to the cell DNA a copy of the viral RNA genome (Marks, 1987). After the discovery of viral oncogenes, such DNA copies were used as probes in hybridisation studies (Stehelinet al, 1976; Frankel & Fischinger, 1976). These probes, capable of annealing to complementary DNA sequences, revealed the existence of the latter in normal, unaffected cells (Willecke & Schäfer, 1984). These sequences, called cellular or proto-oncogenes, exist in a wide range of eukaryotic organisms, from yeast to man.

Antiphospholipid, antinuclear, Epstein-Barr and cytomegalovirus antibodies, and soluble interleukin-2 receptors in depressive patients

To determine whether depression might be associated with serologic indices of autoimmune processes or active virus infections, we measured the following parameters in healthy controls, minor, simple major and melancholic patients: antiphospholipid (anticardiolipin, antiphosphatidylserine), antinuclear, and Epstein-Barr (EBV) and cytomegalovirus (CMV) antibodies. In addition, the soluble interleukin-2 receptor (sIL-2R) circulating levels in serum were measured and used as a marker of T cell activation. The anticardiolipin antibody titers were higher in melancholics than in healthy controls and minor depressives. Antinuclear antibodies were present significantly more frequently in depressed patients than in normal volunteers. The anticardiolipin and antinuclear antibody titers were significantly and positively intercorrelated. Depression is characterized by increased serum circulating levels of sIL-2Rs compared to the healthy state. Antinuclear-positive subjects exhibited significantly higher sIL-2Rs than those without detectable antinuclear titers. There was a positive correlation between anticardiolipin activity and sIL-2Rs. We found no evidence that depression is linked to EBV or CMV infection.

The relationship of negative schizophrenia to parkinsonism

The positive-negative distinction of schizophrenia has emerged as a valid means of clarifying its heterogeneity. Despite evidence that the two symptom classes may reflect different dimensions of the disease, there is presently no integrated model for understanding of the pathophysiology of these symptoms and their co-occurrence in schizophrenia. We propose that negative phenomena of schizophrenia may be a variant of Parkinsonism. This view is supported by the overlap with Parkinsonism in terms of clinical features, neurochemistry, pharmacology, as well as neuroradiological and neuropathological aspects. As such, negative symptoms may be a manifestation of disease of the basal ganglia and constitute the core pathology in schizophrenia. Positive symptoms, conversely, may reflect an "accessory" process related to a compensatory increase in striatal and limbic dopamine activity following an injury to the dopaminergic system. In the present communication we present a series of studies that support the association of negative schizophrenia and Parkinsonism. Based on this evidence, we suggest that schizophrenic patients with prominent negative symptoms might be managed like patients with Parkinson's disease, namely, with dopaminergic drugs and MAO-B inhibitors. Finally, the association of negative schizophrenia with Parkinsonism raises the possibility that adrenal medullary tissue transplantation, which may benefit a selected group of Parkinsonian patients, may be a future promising therapy for refractory negative schizophrenia.

Serum interferon in first psychotic attack

A group of 34 physically healthy young patients, aged 18-27 years at their first psychotic attack, before neuroleptic treatment and admission, were tested simultaneously with 24 age- and sex-matched controls for levels of serum interferon. No statistically significant differences were found between patients and controls. Therefore, no correlation between acute viral infection and schizophrenia was demonstrated.

Serum IgG antibody to herpes viruses in schizophrenia

Immunoglobulin measurements have provided indirect evidence to suggest that viruses may play an etiologic role in schizophrenia. The authors review the conflicting studies and report their own measurements of serum antibody absorbance to five viral antigens using an ELISA technique in 38 schizophrenic patients and 22 matched controls. For herpes simplex virus, 12 subjects (32%) had antibody levels more than 2 SD above the control mean.

An integrated neuropathophysiological model of schizophrenia

Schizophrenia is a disease of consciousness. The different neuroscientific disciplines have reported correlations with dysfunction and pathology at various levels in the hierarchy of biological explanation. A holistic model of schizophrenia is presented, developed from the premise that the neurophysiological correlate of consciousness is the cortical electrical interference pattern produced by the superimposition of the sensory event related potential on the basal alpha rhythm. The role of the Isodendritic Core of the Brain is discussed and the genesis of schizophrenic symptoms is related to post mortem histopathological findings that can be attributed to viral induced fibrillary gliosis.

Viruses, immunity and mental disorder

Are viruses the cause of mental illness, or does stress or mental disorder produce impaired immunity, with increased susceptibility to infection? These two separate but not unrelated questions have been debated periodically and there has been much renewed interest recently, with increased sophistication in immunology and widespread topical concern about immunodeficiency. The neuropsychiatry of the acquired immunodeficiency syndrome (AIDS) (Snider et al, 1983; Carne & Adler, 1986; Wortis, 1986; Burton, 1987; Fenton, 1987) and the validity of a ‘post-viral fatigue syndrome’ as a clinical entity (Behan, 1983; Southern & Oldstone, 1986; Dawson, 1987; David et al, 1988) are not discussed here, but have been dealt with in the editorials and reviews cited.

Current perspectives on immunology and psychiatry

We selectively review recent research findings in the field of psychoimmunology which test the hypotheses that immunological dysfunction may be aetiologically related to mental illnesses such as schizophrenia, and that certain morbid affective states such as depression and other forms of psychosocial distress may be the cause of immunosuppression and through this mechanism affect the outcome of illnesses such as cancer. Our examination of research implicating immunological or infective mechanisms in the aetiology of schizophrenia indicates that most studies have been unable to control for major methodological difficulties but the compatibility of these theories with the dopamine hypothesis suggests that further research attention is warranted. More clearly, there is growing evidence demonstrating a link between depression, other states of psychological distress and immunosuppression, but the clinical significance of these findings remains uncertain. The complex relationship between stress and the outcome of illnesses such as cancer is discussed and the possible implications of these findings for clinical psychiatry are suggested.

Human cytomegalovirus DNA in the temporal cortex of a schizophrenic patient

Using highly sensitive nucleic acids hybridization techniques, which allow the detection of 0.1-0.5 single copy gene equivalents per cell, DNA from the temporal cortex of seven definite schizophrenics, five persons with schizophrenia-like psychoses, three patients with Huntington's chorea and nine mentally normal individuals were probed with human cytomegalovirus (HCMV) DNA. A clear hybridization signal was obtained with DNA from the temporal lobe of a young schizophrenic patient, whereas DNA from the temporal cortex of controls did not hybridize to the HCMV probe. This finding is in agreement with the cytomegalovirus hypothesis of schizophrenia and hints at the possibility that viral infection of the temporal cortex may in some sporadic cases be a contributing factor to the development of schizophrenic psychoses. There is no indication, however, that infection of the central nervous system with HCMV is an aetiological factor in the great majority of schizophrenic disorders. Clearly further studies, preferably in situ hybridizations of whole brains, are needed to prove or disprove the cytomegalovirus hypothesis of schizophrenia.

Schizophrenic births and viral diseases in two states

In order to investigate a possible relationship between schizophrenic births and viral diseases, the birth month and year of all state hospital admissions for schizophrenia in Connecticut and Massachusetts from 1973-1974 were compared with the occurrence of reportable viral diseases for 1920-1955. Data was statistically examined by time series using spectral analysis. Statistically significant coherences were found between schizophrenic births and measles (both states), varicella-zoster (Connecticut) and polio (Connecticut). Influenza just missed statistical significance. No temporal relationship between schizophrenic births and rubella or mumps was found. The results are compared with similar studies in Minnesota and Finland. Definitive explanations for the observed relationships are precluded by the emerging complexity of virus-CNS interactions. A triggering of immune dysfunction by the infectious agents is proposed as the most reasonable explanation.

Stress, immunity and illness--a review

Psychological factors have long been thought to play a contributing role in either the predisposition, onset or course of various physical illnesses. Recently, rapid advances in immunology have created interest in the interaction between psychosocial factors, behaviour and the immune system. This paper reviews some of the models proposed to explain the relationship between psychological variables and physical illness and presents evidence for a contribution of psychological factors to certain illnesses in which abnormalities in immunologic state are thought to be important. From a somewhat different perspective, animal studies have demonstrated complex effects of stress, on disease susceptibility. Recent human studies have demonstrated consistent immunologic changes in people undergoing acute naturally occurring psychological stress such as bereavement or an important examination. In humans, the effects of chronic stress may be different from acute stress, corresponding to the findings in animals. Abnormalities in immunologic functioning and physical illness are reviewed for different psychiatric disorders--depression, anorexia nervosa and schizophrenia; depression is the only disorder which consistently demonstrated immunologic changes. Possible mechanisms for the stress/immune-change relationship are suggested.

Search for viral nucleic acid sequences in the post mortem brains of patients with schizophrenia and individuals who have committed suicide

Molecular hybridisation has been used to screen several areas of post mortem brain from 20 patients with schizophrenia, 23 individuals who were suspected of having committed suicide and 21 control cases, for viral nucleic acids. Cloned probes were able to detect picogram levels of viral DNA and to quantify herpes simplex type 1 DNA from encephalitic brain, but no sequences hybridising to cytomegalovirus, varicella zoster virus, herpes simplex type I or JC or BK papovaviruses were detected in any of the experimental samples. These findings are discussed with reference to the viral hypothesis of the aetiology of psychiatric disease.

Immunoglobulin and C3 abnormalities in acute psychiatric disorders

In a prospective study of 54 patients with acute psychiatric disorders, elevated absolute concentrations of immunoglobulin G (IgG), IgM and complement factor C3 were found in the cerebrospinal fluid (CSF) in seven (P less than 0.001), eight (P less than 0.01) and in four patients, respectively, and in serum in seven, 19 and 17 patients (P less than 0.001 in all), respectively, quantified by automated immunoprecipitin nephelometry in unconcentrated CSF and serum and compared with neurological controls with peripheral neurological symptoms. Elevation of the IgG-index was observed in seven patients (P less than 0.001) and CSF/S albumin ratio in four patients (P less than 0.05). The presence of oligoclonal IgG bands was found in 22 patients (P less than 0.001). The results suggest that viral infections, inflammatory and autoimmune processes may have significance in the etiopathogenesis of acute psychiatric disorders.

Serum and cerebrospinal fluid antibodies to cytomegalovirus in schizophrenia

Antibodies to cytomegalovirus (CMV) were determined in the serum and cerebrospinal fluid (CSF) by complement-fixing (CF), enzyme immunoassay (EIA), and enhanced virus neutralization test (EVNT), in acute unmedicated schizophrenic patients and neurological controls. An elevated level of CF antibody was observed in three serum specimens from the schizophrenic patients and in one control specimen. No CF antibody was present in the CSF samples of the two patient groups tested. By EIA none of the serum or CSF specimens was positive for IgM antibody to CMV. By EVNT, 17% of the schizophrenic patients exhibited a CSF/serum ratio greater than 2 SD, whereas the corresponding figure for the control group was 4% (P greater than 0.05). The role of CMV in the etiopathogenesis of schizophrenia is discussed in the light of the present and previous negative findings.