The schizophrenia and Toxoplasma gondii connection: infectious, immune or both?

Associations between Toxoplasma gondii seropositivity and psychopathological manifestations in schizophrenic patients: A single-center study from Ecuador

BACKGROUND

Schizophrenia, a complex neuropsychiatric disorder, is believed to be influenced by various factors including environmental exposures. A potential environmental factor is the infection by the obligate intracellular parasitic protozoan, Toxoplasma gondii which affects neurotransmitter levels, which could potentially exacerbate, trigger symptoms of schizophrenia or make them worst.

OBJECTIVE

To investigate the association between Toxoplasma gondii seropositivity and psychopathological presentation in persons with schizophrenia in Ecuador.

METHODS

This study was conducted at the Neuroscience Institute of Guayaquil, Ecuador. Among 368 inpatients, 104 were selected based on specific inclusion and exclusion criteria. Descriptive statistics captured patient characteristics and mental health outcomes. Logistic regression models estimated the effect of toxoplasmosis on various mental health outcomes, controlling for demographic and health-related variables.

RESULTS

86.5% of participants were seropositive for toxoplasmosis. Toxoplasma-seropositive schizophrenic patients had a lower risk of depression but a significantly higher risk of disorientation. The most prevalent mental health outcomes were Language Impairments (70.2%) and Bizarre Behavior (76.0%).

CONCLUSION

Our findings suggest that Toxoplasma gondii seropositivity may have specific effects on mental functions in schizophrenic patients, particularly reducing the risk of depression but increasing the risk of disorientation. Further studies are required to clarify these associations and the potential underlying mechanisms.

Association between exposure to toxoplasmosis and major psychiatric disorders: a systematic review

Objective:

To assess the association between exposure to toxoplasmosis and major psychiatric disorders through a systematic review of the literature.

Methods:

The literature review was performed in the MEDLINE, SciELO, and PsycINFO databases. To evaluate the quality of the studies included in the review, the Newcastle-Ottawa Scale was used.

Results:

Thirty-one studies were included, and the majority found an association between exposure to toxoplasmosis and schizophrenia or bipolar disorder (58.3 and 54.5% of the included papers, respectively), but not major depressive disorder. We found no significant difference in mean quality scores between studies that corroborated and contradicted the association hypothesis for either schizophrenia or bipolar disorder. All included papers were considered at least satisfactory according to the Newcastle-Ottawa Scale (total scores ≥ 6 out of 9).

Conclusion:

Although there was no association between exposure to toxoplasmosis and major depressive disorder, the results indicate an association with both bipolar disorder and schizophrenia, despite their heterogeneity. Further studies should be performed with more specific variables so that the nature of these relationships can be elucidated.

Associations of mental disorders and neurotropic parasitic diseases: a meta-analysis in developing and emerging countries

BACKGROUND

Although they are declining worldwide, neurotropic parasitic diseases are still common in developing and emerging countries. The aim of this study was to estimate the pooled prevalence and pooled association measures of comorbidities between mental disorders (anxiety, depression, bipolar disorder, and schizophrenia) and neurotropic parasitic diseases (malaria, cysticercosis, toxoplasmosis, human African trypanosomiasis, Chagas disease, and human toxocariasis) in developing and emerging countries.

METHODS

As the first meta-analysis on this topic, this study was performed in accordance with PRISMA guidelines. The protocol was registered in PROSPERO (N°CRD42017056521). The Medline, Embase, Lilacs, and Institute of Epidemiology and Tropical Neurology databases were used to search for articles without any restriction in language or date. We evaluated the quality of studies independently by two investigators using the Downs and Black assessment grid and pooled estimates using the random-effects method from CMA (Comprehensive Meta Analysis) Version 3.0.

RESULTS

In total, 18 studies published between 1997 and 2016 met our inclusion criteria. We found that the prevalence of anxiety and depression in people suffering from Chagas disease and/or neurocysticercosis was 44.9% (95% CI, 34.4-55.9). In 16 pooled studies that included 1782 people with mental disorders and 1776 controls, toxoplasmosis and/or toxocariasis were associated with increased risk of schizophrenia and/or bipolar disorders (odds ratio = 2.3; 95% CI, 1.7-3.2). Finally, toxocariasis and/or toxoplasmosis were associated with an increased risk of the onset of schizophrenia (odds ratio = 2.4; 95% CI, 1.7-3.4).

CONCLUSION

Our pooled estimates show that the associations between diseases studied are relatively high in developing and emerging countries. This meta-analysis supports the hypothesis that toxoplasmosis could be the cause of schizophrenia. These findings could prove useful to researchers who want to further explore and understand the associations studied.

A review of toxoplasmosis in humans and animals in Turkey

Infections by the protozoan parasite Toxoplasma gondii are widely prevalent in humans and animals in Turkey but little is known of the burden of their clinical toxoplasmosis. Many early papers on toxoplasmosis in Turkey were published in Turkish and often not available widely. Here, we review prevalence, clinical spectrum, epidemiology and diagnosis of T. gondii in humans and animals in Turkey. This knowledge should be useful to biologists, public health workers, veterinarians and physicians. Although one-third of the human population in Turkey is seropositive, the rate of congenital toxoplasmosis is unknown and no information is available in children 12 years old or younger. One large outbreak of acute toxoplasmosis has been reported in 14–18-year old school children in Turkey. An alarming rate (36%) of T. gondii tissue cysts were reported in tissues of sheep and water buffalo meats destined for human consumption; these reports require verification. Genetically, T. gondii strains from domestic cats and wild birds in Turkey were generally classical type II and III, like those prevalent in Europe. A separate genotype, Type 1 Africa, was isolated from two congenitally infected children and a domestic cat in Turkey.

Sero-prevalence of Toxoplasma gondii and associated risk factors among psychiatric outpatients attending University of Gondar Hospital, Northwest Ethiopia

Background

Toxoplasmosis is caused by an obligatory intracellular coccidian protozoan organism, Toxoplasma gondii. It has a worldwide distribution, affecting one-third of the world population. Psychiatric patients have a higher risk of exposure to Toxoplasma gondii infection due to lack of good personal hygiene. The burden of toxoplasmosis among psychiatric patients in Ethiopia has not been studied extensively. Thus, the study aimed to determine the seroprevalence of Toxoplasma gondii and associated risk factors among psychiatric outpatients at the University of Gondar Comprehensive and Specialized Hospital Psychiatric clinic.

Methods

A cross-sectional study was conducted at the University of Gondar Comprehensive and Specialized Hospital from February to May 2018. Venous blood was collected from 304 study participants (152 psychiatric outpatients and 152 control groups). Anti-toxoplasma antibodies were determined using Onsite Toxo immunoglobulin G (IgG) and immunoglobulin M (IgM) Rapid Test. A Chi-square test was carried out to compare the two groups and a logistic regression analysis was conducted to check the association between variables. P-value less than 0.05 was taken as statistically significant.

Results

The seroprevalence rate of anti-Toxoplasma gondii IgG antibodies was 33.6, and 16.4% in the psychiatric outpatients and the control samples, respectively. Anti-Toxoplasma gondii IgM sero-prevalence was 1.3% in the former patients and 3.9% in the latter group. Owing cat (AOR = 2.862 95% CI = 1.445–5.666 P = 0.003), cleaning cat excreta (AOR = 2.966 95% CI = 1.317–2.652 P = 0.007), and farming (AOR = 2.058 95% CI = 1.018–4.163 P = 0.045) were found to be significantly associated with the sero-prevalence of anti-Toxoplasma gondii IgG antibody.

Conclusions

This study highlighted that, the prevalence of anti-Toxoplasma gondii IgG antibodies was significantly higher in psychiatric outpatients than the control group (p = 0.001). Cat ownership, cleaning of cat excreta, and farming were found to be statistically significantly associated with the seroprevalence of anti-Toxoplasma gondii IgG antibody.

Beyond the association. Toxoplasma gondii in schizophrenia, bipolar disorder, and addiction: systematic review and meta-analysis

OBJECTIVE

To perform a meta-analysis on studies reporting prevalence of Toxoplasma gondii (T. gondii) infection in any psychiatric disorder compared with healthy controls. Our secondary objective was to analyze factors possibly moderating heterogeneity.

METHOD

A systematic search was performed to identify studies into T. gondii infection for all major psychiatric disorders versus healthy controls. Methodological quality, publication bias, and possible moderators were assessed.

RESULTS

A total of 2866 citations were retrieved and 50 studies finally included. Significant odds ratios (ORs) with IgG antibodies were found in schizophrenia (OR 1.81, P < 0.00001), bipolar disorder (OR 1.52, P = 0.02), obsessive-compulsive disorder (OR 3.4, P < 0.001), and addiction (OR 1.91, P < 0.00001), but not for major depression (OR 1.21, P = 0.28). Exploration of the association between T. gondii and schizophrenia yielded a significant effect of seropositivity before onset and serointensity, but not IgM antibodies or gender. The amplitude of the OR was influenced by region and general seroprevalence. Moderators together accounted for 56% of the observed variance in study effects. After controlling for publication bias, the adjusted OR (1.43) in schizophrenia remained significant.

CONCLUSION

These findings suggest that T. gondii infection is associated with several psychiatric disorders and that in schizophrenia reactivation of latent T. gondii infection may occur.

Meta-Analysis of Anti-Toxoplasma gondii IgM Antibodies in Acute Psychosis

INTRODUCTION

A number of different infections are associated with acute psychosis. However, relationships between infections and acute psychosis in patients with schizophrenia have not been extensively explored. Exposure to Toxoplasma gondii is a replicated risk factor for schizophrenia. Previous studies have focused on T. gondii IgG antibodies, which are a marker of lifetime exposure, whereas IgM antibodies are a marker of acute/recent exposure, persistent infection, or reinfection. We performed a meta-analysis of T. gondii IgM antibodies and acute psychosis, to further investigate whether infections may be associated with relapse in schizophrenia.

METHODS

We identified articles by systematic searches of PubMed, PsycINFO, and ISI databases. We included studies, in English, of serum T. gondii IgM antibodies in patients with acute psychosis and controls.

RESULTS

Sixteen independent samples (2353 patients and 1707 controls) met inclusion criteria. Data were pooled using a random effects model. There was a significant increase in risk of positive T. gondii IgM antibodies in acute psychosis compared with controls (7.6% vs 5.7%, OR = 1.68, 95% CI = 1.23-2.27, P = .001). The association was stronger for patients with chronic schizophrenia (8.7% vs 4.6%, OR = 2.54, 95% CI = 1.63-3.96, P < .001) than first-episode psychosis. In meta-regression analyses, age, sex, and publication year were unrelated to the association; however, there was a significant association with geographic region.

DISCUSSION

An increased seroprevalence of T. gondii IgM in patients with acute psychosis complements and extends previous findings, suggesting that infections may be relevant to the etiopathophysiology of relapse in some patients with schizophrenia.

Seroprevalence of anti-Toxoplasma gondii and anti-Borrelia species antibodies in patients with schizophrenia: a case-control study from western Turkey

OBJECTIVES

We examined IgG antibody seroprevalence and risk factors for anti-Toxoplasma gondii and anti-Borrelia sp. in schizophrenic patients.

METHODS

This case-control study included 30 schizophrenic patients and 60 healthy individuals. Serological analyses were identified by using ELISA technique.

RESULTS

In the case group the Toxoplasma seropositivity was 33.3% and Borrelia seropositivity was 13.3%, while in the control group the Toxoplasma positivity was 21.7% and Borrelia seropositivity was 15.0%. There was no significant difference with regard to seroprevalence between the groups (P = 0.232; P = 0.832, respectively). There was statistically significant difference between case and control groups related to hand and kitchen utensil hygiene after dealing with raw meat (P = 0.001).

CONCLUSIONS

Our data showed the rate of Toxoplasma antibodies was higher in the case group, while the rate of Borrelia antibodies was higher in the control group. In both groups the high rates of seropositivity for Toxoplasma gondii and Borrelia sp. is thought to be due to neglect of personal hygiene. The present study also is the first to examine the association between Borrelia sp. and schizophrenia. Further studies are needed to determine whether there is an association between Borrelia sp. and schizophrenia or not.

Seropositivity and serointensity of Toxoplasma gondii antibodies and DNA among patients with schizophrenia

The aim of this cross sectional case control study was to examine the serofrequency and serointensity of Toxoplasma gondii (Tg) IgG, IgM, and DNA among patients with schizophrenia. A total of 101 patients with schizophrenia and 55 healthy controls from Sungai Buloh Hospital, Selangor, Malaysia and University Malaya Medical Center (UMMC) were included in this study. The diagnosis of schizophrenia was made based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). The presence of Tg infection was examined using both indirect (ELISA) and direct (quantitative real-time PCR) detection methods by measuring Tg IgG and IgM and DNA, respectively. The serofrequency of Tg IgG antibodies (51.5%, 52/101) and DNA (32.67%, 33/101) among patients with schizophrenia was significantly higher than IgG (18.2%, 10/55) and DNA (3.64%, 2/55) of the controls (IgG, P=0.000, OD=4.8, CI=2.2-10.5; DNA, P=0.000, OD=12.9, CI=2.17-10.51). However, the Tg IgM antibody between patients with schizophrenia and controls was not significant (P>0.005). There was no significant difference (P>0.005) in both serointensity of Tg IgG and DNA between patients with schizophrenia and controls. These findings have further demonstrated the strong association between the active Tg infection and schizophrenia.

Different presence of Chlamydia pneumoniae, herpes simplex virus type 1, human herpes virus 6, and Toxoplasma gondii in schizophrenia: meta-analysis and analytical study

In the present study we have performed both a meta-analysis and an analytical study exploring the presence of Chlamydia pneumoniae, herpes simplex virus type 1, human herpes virus 6, and Toxoplasma gondii antibodies in a sample of 143 schizophrenic patients and 143 control subjects. The meta-analysis was performed on papers published up to April 2014. The presence of serum immunoglobulin G and immunoglobulin A was performed by enzyme-linked immunosorbent assay test. The detection of microbial DNA in total peripheral blood was performed by nested polymerase chain reaction. The meta-analysis showed that: 1) C. pneumoniae DNA in blood and brain are more common in schizophrenic patients; 2) there is association with parasitism by T. gondii, despite the existence of publication bias; and 3) herpes viruses were not more common in schizophrenic patients. In our sample only anti-Toxoplasma immunoglobulin G was more prevalent and may be a risk factor related to schizophrenia, with potential value for prevention.

Toxoplasma gondii and other risk factors for schizophrenia: an update

The failure to find genes of major effect in schizophrenia has refocused attention on nongenetic, including infectious factors. In a previous study, antibodies to Toxoplasma gondii were found to be elevated in 23 studies of schizophrenia (OR 2.73; 95% CI 2.10-3.60). The current study replicates this finding with 15 additional studies (OR 2.71; 95% CI 1.93-3.80) and compares this with other identified schizophrenia risk factors. The highest risk factors are having an affected mother (relative risks [RR] 9.31; 95% CI 7.24-11.96), father (RR 7.20; 95% CI 5.10-10.16), or sibling (RR 6.99; 95% CI 5.38-9.08) or being the offspring of immigrants from selected countries (RR 4.5; 95% CI 1.5-13.1). Intermediate risk factors, in addition to infection with T. gondii, include being an immigrant from and to selected countries (RR 2.7; 95% CI 2.3-3.2), being born in (RR 2.24; 95% CI 1.92-2.61) or raised in (RR 2.75; 95% CI 2.31-3.28) an urban area, cannabis use (OR 2.10-2.93; 95% CI 1.08-6.13), having minor physical anomalies (OR 2.23; 95% CI 1.42-3.58), or having a father 55 or older (OR 2.21-5.92; 95% CI 1.46-17.02). Low-risk factors include a history of traumatic brain injury (OR 1.65; 95% CI 1.17-2.32), sex abuse in childhood (OR 1.46; 95% CI 0.84-2.52), obstetrical complications (OR 1.29-1.38; 95% CI 1.00-1.84), having a father 45 or older (OR 1.21-1.66; 95% CI 1.09-2.01), specific genetic polymorphisms (OR 1.09-1.24; 95% CI 1.06-1.45), birth seasonality (OR 1.07-1.95; 95% CI 1.05-2.91), maternal exposure to influenza (RR 1.05; 95% CI 0.98-1.12), or prenatal stress (RR 0.98-1.00; 95% CI 0.85-1.16).

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.

Toxoplasma gondii infection and schizophrenia: a case control study in a low Toxoplasma seroprevalence Mexican population

There are conflicting reports concerning the association of Toxoplasma gondii infection and schizophrenia in humans. Therefore, we determined such association in a Mexican population of Mestizo ethnicity. Through a case-control study design, 50 schizophrenic patients and 150 control subjects matched by gender, age, residence place, and ethnicity were examined with enzyme-linked immunoassays for the presence and levels of T. gondii IgG antibodies and for the presence of T. gondii IgM antibodies. Schizophrenic patients attended a public psychiatric hospital in Durango City, Mexico, and the control group consisted of individuals of the general population of the same city. Socio-demographic, clinical and behavioral characteristics from the study subjects were also obtained. Both the seroprevalence and the level of T.gondii IgG antibodies were higher in schizophrenic patients (10/50; 20%) than in control subjects (8/150; 5.3%) (OR=4.44; 95% CI: 1.49-13.37; P=0.003). The IgG T. gondii levels higher than 150 IU/ml were more frequently observed in patients than in controls (10% versus 2%, respectively; P=0.02). One (50%) of the two patients with recently diagnosed schizophrenia and none of the controls had T. gondii IgM antibodies (P=0.01). T. gondii seropositivity was significantly higher in patients with a history of cleaning cat excrement (P=0.005), and suffering from simple schizophrenia (ICD-10 classification: F20.6) (P=0.03) than patients without these characteristics. Toxoplasma seroprevalence was also significantly higher in patients with simple schizophrenia (F20.6) than in those with paranoid schizophrenia (F20.0) (P=0.02). This study provides elements to clarify the controversial information on the association of T. gondii infection and schizophrenia.

Toxoplasma gondii infection in first-episode and inpatient individuals with schizophrenia

BACKGROUND

A high seroprevalence of Toxoplasma gondii infection has been detected in psychiatric patients, particularly in schizophrenia cases.

METHODS

In the present study 98 patients suffering from schizophrenia (58 inpatients and 40 first-episode patients) and 96 control patients (50 healthy volunteers and 46 with a depressive disorder) were examined for the presence of both IgG and IgM antibodies against T. gondii by enzyme-linked immunosorbent assay (ELISA). We applied the Bradford Hill criteria to identify the weight of causal inference.

RESULTS

The positivity rate of anti-T. gondii IgG antibodies among individuals with schizophrenia (57.1%) was significantly higher than in healthy controls (29.2%). There were no associations between immune status ratio (ISR) values and the risk of schizophrenia. The weight of evidence approach using the Bradford Hill criteria revealed a 92% probability of a causal association.

CONCLUSION

Our results show that exposure to T. gondii may lead to schizophrenia.

Toxoplasmosis as a cause for behaviour disorders--overview of evidence and mechanisms

BACKGROUND

There is growing interest in the role of microbial agents in the causation of psychiatric disorders. The neurotropic protozoan parasite Toxoplasma gondii is one of the main candidates and has been associated with various psychiatric conditions, including schizophrenia.

METHODS

A narrative review of the literature from the main medical databases (Medline, PubMed, PsycINFO), Google Scholar and Google using combinations of applicable terms.

RESULTS

T. gondii affects the brain in both the acute and the latent stages of infection causing apparent brain pathologies in infected rodents and both immuno-compromised and immuno-competent humans. In immuno-competent individuals, behavioural disorders are primarily related to the latent stages of the illness. Behavioural/mental disorders that include schizophrenia, mood disorders, personality changes and cognitive impairments may be related to infection with T. gondii. Evidence for a behavioural effect of T. gondii comes from observational reports in animal models and controlled behavioural analysis in humans. Indirect clues of infection also come from raised seroprevalence or serotitres of antitoxoplasma antibodies among those with mental disorders. The pathophysiologic mechanism through which T. gondii may exert its effect is not clear, but direct impact on the brain and changes in neuroimmunomodulation, neurotransmission and some gene-environment interactions are postulated.

CONCLUSION

There is evidence supporting a potential role of T. gondii infection in the onset of some behavioural disorders. Confirmation of such a role would prove a significant breakthrough in the search for the aetiology, treatment and prevention of behavioural disorders, such as schizophrenia. However, the associations remain preliminary.

The role of latent toxoplasmosis in the aetiopathogenesis of schizophrenia--the risk factor or an indication of a contact with cat?

We assessed IgG antibody to Toxoplasma gondii in 300 inpatients with schizophrenia (SG), 150 outpatients with anxiety and depressive disorders (PCG), and 150 healthy blood donors (HCG). Seropositivity rates were 60.7% for SG, 36.7% for PCG, and 45.3% for HCG (p<0.001). The seropositivity rate for anti-Toxoplasma IgG antibodies in SG was significantly higher that in PCG (chi2 = 23.11, OR = 2.66, p = 0.001) and HCG (chi2 = 9.52, OR = 1.86, p = 0.002). Among SG, 85% of those who reported close cat contact had IgG antibodies to T. gondii. Close cat contacts were reported by 59% of SG, 6% of PCG, and 9% of HCG (p<0.001). There was a nonsignificant positive association between toxoplasmosis and schizophrenia for people with a contact with a cat (OR = 2.221, p = 0.127, CI95 = 0.796-6.192), and significant negative association between toxoplasmosis and schizophrenia for people without contact with a cat (OR = 0.532, p = 0.009, CI95 = 0.332-0.854). Close cat contact (OR = 2.679, p<0.001), 51-65-year age group (OR = 1.703, p<0.001) and education [illiterate+primary (OR = 6.146, p<0.001) and high school (OR = 1.974, p = 0.023)] were detected as independent risk factors in multivariate logistic regression. The effect of toxoplasmosis on risk of schizophrenia disappeared in the complex model analyzed with multivariate logistic regression. In conclusion, our data suggest that the toxoplasmosis has no direct effect on the risk of schizophrenia in Turkey but is just an indication of previous contacts with a cat.

The probable relation between Toxoplasma gondii and Parkinson's disease

Parkinson's disease (PD), a chronic progressive neurodegenerative disorder, has a mainly unknown multifactorial etiology. Neuroinflammatory mechanisms might contribute to the cascade of events leading to neuronal degeneration. Toxoplasmosis can be associated with various neuropsychiatric disorders. The most commonly affected central nervous system (CNS) region in toxoplasmosis is the cerebral hemisphere, followed by the basal ganglia, cerebellum and brain stem. Therefore, in this study, we aimed to investigate the possible association between Toxoplasma infection and PD by evaluating the serum anti-Toxoplasma gondii IgG antibodies. There were no difference between the socioeconomic status of the patients and control subjects and magnetic resonance images of the patients were normal. Serum anti-T. gondii IgG levels were measured using ELISA. There was no statistically significant differences among the patients and control subjects with respect to age (66.01+/-12.14 years, 62.42+/-5.93 years, p=0.089; respectively) and gender. The sero-positivity rate for anti-T. gondii IgG antibodies in PD patients and control groups were 42.3 and 22.5%, respectively, and they were statistically significant (p=0.006). These results suggest that Toxoplasma infection may be involved in the pathogenetic mechanisms of PD. If confirmed, this hypothesis would represent a valuable advancement in care of patients with Parkinson's disease.

Toxoplasma and schizophrenia

Research on infectious agents as a possible cause of schizophrenia has become prominent in the past decade. Toxoplasma gondii has emerged as a prime candidate for a variety of reasons; (i) many studies have reported that individuals with schizophrenia, compared to controls, have a higher prevalence of antibodies to T. gondii, (ii) some individuals with adult toxoplasmosis develop psychotic symptoms similar to those of schizophrenia, (iii) epidemiologically, there are many similarities between toxoplasmosis and schizophrenia, (iv) antipsychotic drugs known to be effective in schizophrenia also inhibit some parasites, including T. gondii, (v) Toxoplasma has been shown to induce elevated levels of dopamine in experimentally infected animals (elevated dopamine is commonly seen in individuals with schizophrenia) and (vi) studies have shown that individuals with schizophrenia, compared to controls, have had greater exposure to cats in childhood. A number of questions remain concerning a role for Toxoplasma in the aetiology of schizophrenia, including the roles of strain variation, the timing and source of infection, and the role of host genes in determining disease susceptibility. The establishment of a firm association between Toxoplasma and the aetiology of schizophrenia and related disorders would represent a major breakthrough in the understanding of these disorders and would lead to novel methods for their treatment and prevention.

A possible relationship between Toxoplasma gondii and schizophrenia: A seroprevalence study

Objective. Schizophrenia is a pervasive neuropsychiatric disease of uncertain etiology. We aimed to investigate a possible association between Toxoplasma gondii infection and schizophrenia in this study. Method. We selected individuals with schizophrenia (n=88) and tested them with commercially available enzyme-linked immunosorbent assay (ELISA) for anti-Toxoplasma IgG and IgM antibodies and compared these seropositivity rate to those of controls without psychiatric disease (n=88). Results. The rate of IgG antibody in the schizophrenia patients (47.7%) was higher than the control groups (20.4%) (P<0.001). We did not find any anti-Toxoplasma IgM seropositivity in both schizophrenia patients and control group. In schizophrenic patients with and without anti-Toxoplasma IgG groups statistical analysis did not reveal any correlation between demographic variables and Toxoplasma infection. Conclusion. Our findings supported previous studies indicate that T.gondii may play a role in etiopathogenesis in some cases of schizophrenia.