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Toxoplasma gondii & Human Phenotype

Compendium of Known Effects and Ongoing Research

personality changes

Latent Toxoplasmosis and Human

January 29, 2020
Dalimi, A., Abdoli, A.
Iranian Journal of Parasitology 2012, 7: 1 - 17
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Toxoplasmosis is one of the most common parasitic diseases worldwide. Although estimated that one third of the world's population are infected with Toxoplasma gondii, but the most common form of the disease is latent (asymptomatic). On the other hand, recent findings indicated that latent toxoplasmosis is not only unsafe for human, but also may play various roles in the etiology of different mental disorders. This paper reviews new findings about importance of latent toxoplasmosis (except in immunocompromised patients) in alterations of behavioral parameters and also its role in the etiology of schizophrenia and depressive disorders, obsessive compulsive disorder, Alzheimer's diseases and Parkinson's disease, epilepsy, headache and or migraine, mental retardation and intelligence quotients, suicide attempt, risk of traffic accidents, sex ratio and some possible mechanisms of T gondii that could contribute in the etiology of these alterations.

Tagged: alzheimer disease, behavioral parametr, mental disorder, personality changes, Schizophrenia, toxoplasmosis

BehaviorMental health

Toxoplasma gondii exposure and the risk of attention deficit hyperactivity disorder in children and adolescents

February 12, 2018
Khademvatan, S. , Riahi,F., Izadi-Mazidi,M. , Khajeddin, N., Yousefi, E.
Pediatric Infectious Disease Journal 2018; 37: 1097-1100
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Background: Evidence suggests that Toxoplasma gondii, which causes toxoplasmosis, changes the metabolism of neurotransmitters, especially dopamine, resulting in both neurologic and psychiatric disorders. On the other hand, the dysregulation of catecholamines, especially of both norepinephrine and dopamine, has been proposed in the pathophysiology of attention deficit hyperactivity disorder (ADHD). The aim of the present study was to investigate anti-toxoplasma antibodies in children and adolescents with ADHD and compare it with a control group, to determine whether toxoplasmosis is a risk factor for ADHD. Methods: A total of 200 children and adolescents (117 patients with ADHD and 83 individuals without ADHD) participated in the study. Participants were tested for the presence of anti-T. gondii antibodies by enzyme-linked immunosorbent assay. A Parent ADHD Rating Scale and Clinical Global Impression-severity Scale were also completed. Data were analyzed using a (2) test and Fisher exact test. Results: Anti-toxoplasma antibodies were detected in 18.1% of patients with ADHD disorder and 24% of individuals without ADHD. There was no significant difference in seropositivity between the 2 groups (P > 0.05). The number of patients with T. gondii infection in the 3 subgroups was 0, 9 and 12, respectively. The differences in infection rate among subgroups were not statistically significant (P > 0.05). Conclusion: Although not conclusive, the present study does not support the theory that T. gondii is a risk factor for ADHD.

Tagged: attention deficit hyperactivity disorder (ADHD), deficit/hyperactivity, disorder, elisa, infection seroprevalence, Iran, latent toxoplasmosis, mood disorders, personality changes, primary-school children, Schizophrenia, seropositivity, Toxoplasma gondii, women

Mental health

Puppet master: possible influence of the parasite Toxoplasma gondii on managers and employees

October 2, 2017
Houdek, P.
Academy of Management Perspectives 2017; 31: 63-81
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The article reviews recent literature on the effects of host manipulation by the parasite Toxoplasma gondii (prevalent in about a third of the world's population) on perception, cognition, and behavior of humans, and on the changes in their physical appearance and personality characteristics. I argue that the mind-affecting parasite paradigm offers many research opportunities for management sciences, especially for organizational psychology and neuroscience. The article summarizes the parasite's physiological mechanisms of affecting the host; highlights important behavioral effects of the infection in humans; and speculates on the possible impacts on skills and careers of employees and managers, organizational dynamics, intercultural management, and gender work roles. The conclusion shows limitations of the presented speculations and possible directions for future research on Toxoplasma's effect on organizational dynamics.

Tagged: cognitive function, dynamic capabilities, facial structure predicts, gender differences, general mental-ability, job-performance, latent toxoplasmosis, personality changes, positive organizational-behavior, risk factors

BehaviorPersonality

Reciprocal moderation by Toxoplasma gondii seropositivity and blood phenylalanine – tyrosine ratio of their associations with trait aggression

October 6, 2016
Mathai, A. J., Lowry, C. A., Cook, T. B., Brenner, L. A., Brundin, L., Groer, M. W., Peng, X. Q., Giegling, I., Hartmann, A. M., Konte, B., Friedl, M. Fuchs, D. Rujescu, D. Postolache, T. T.
Pteridines 2016; 27: 77-85.
Click for abstract
We previously reported that trait aggression, proposed as an endophenotype for suicidal behavior, is positively associated with Toxoplasma gondii (T. gondii) seropositivity in females, but not in males. Additionally, older males seropositive for T. gondii had lower scores on measures of trait aggression, including self-aggression. Trait aggression may be influenced by dopaminergic signaling, which is known to be moderated by gender and age, and potentially enhanced in T. gondii positives through the intrinsic production of dopamine by the microorganism. Therefore, we investigated associations between trait aggression and interactions between T. gondii enzyme-linked immunoabsorbant assay (ELISA) IgG titer-determined seropositivity and high-performance liquid chromatography-(HPLC-) measured blood levels of dopamine precursors phenylalanine (Phe), tyrosine (Tyr), and their ratio in a sample of 1000 psychiatrically healthy participants. Aggressive traits were assessed using the questionnaire for measuring factors of aggression (FAF), the German version of the Buss-Durkee hostility questionnaire. We found that 1) the decrease in trait aggression scores in T. gondii-positive older males was only present in individuals with a low Phe:Tyr ratio, and 2) that there was a positive correlation between Phe: Tyr ratio and total aggression and selected subscales of aggression in T. gondii-positive males, but not in T. gondii-negative males. These findings point toward a gender-specific reciprocal moderation by Phe: Tyr ratio and T. gondii seropositivity of their associations with aggression scores, and lead to experimental interventions geared to manipulating levels of dopamine precursors in selected T. gondii positive individuals with increased propensity for aggression.

Tagged: aggressive personality traits, amino-acids, bipolar disorder, cytokine alterations, depressive symptoms, Dopamine, electroconvulsive-therapy, personality changes, phenylalanine, release, self-directed violence, seropositivity, serum, suicidal-behavior, Toxoplasma gondii, tyrosine

BehaviorPersonality

Toxoplasma gondii immunoglobulin G antibodies and nonfatal suicidal self-directed violence

October 11, 2012
Zhang, Y. F., Traskman-Bendz, L., Janelidze, S., Langenberg, P., Saleh, A., Constantine, N., Okusaga, O., Bay-Richter, C., Brundin, L., Postolache, T. T.
Journal of Clinical Psychiatry 2012; 73: 1069-1076
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Objective: The primary aim was to relate Toxoplasma gondii seropositivity and serointensity to scores on the self-rated Suicide Assessment Scale (SUAS-S). Another aim was to reevaluate the previously reported positive association between T gondii serointensity and a history of nonfatal suicidal self-directed violence. Method: This cross-sectional, observational study compared T gondii serointensity and seropositivity in plasma from 54 adult suicide attempters (inpatients at Lund University Hospital, Lund, Sweden) and 30 adult control subjects (randomly selected from the municipal population register in Lund, Sweden) recruited between 2006 and 2010.The potential of patients and controls for self-directed violence was evaluated with the SUAS-S. Psychiatric diagnoses were made according to DSM-IV criteria. Plasma samples were tested for immunoglobulin G antibodies to T gondii, cytomegalovirus, and herpes simplex virus type 1. Data were analyzed using multivariable logistic regression to investigate the association between T gondii serointensity or seropositivity and a history of nonfatal suicidal self-directed violence; multivariable linear regression was used to explore the relationship between T gondii serointensify or seropositivity and the SUAS-S. Both regression models included sex, age, and body mass index as covariates. Results: Seropositivity of T gondii (adjusted odds ratio [OR]=7.12; 95% CI, 1.66-30.6; P=.008) and serointensity of T gondii (adjusted OR=2.01; 95% CI, 1.09-3.71; P=.03) were positively associated with a history of nonfatal suicidal self-directed violence. Seropositivity of T gondii was associated with higher SUAS-S scores, a relationship significant for the whole sample (P=.026), but not for suicide attempters only. No significant associations with other pathogens were identified. Conclusions: These results are consistent with previous reports on the association between T gondii infection and nonfatal suicidal self-directed violence. Confirming these results in future large longitudinal studies and including suicide as an outcome may lead to novel individualized approaches in suicide prevention. J Clin Psychiatry 2012;73 (8):1069-1076 (c) Copyright 2012 Physicians Postgraduate Press, Inc.

Tagged: assessment scale, Cerebral toxoplasmosis, cerebrospinal fluid, depression scale, interferon-gamma, latent toxoplasmosis, personality changes, quinolinic acid, traffic accidents, united-states

BehaviorMental health

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

October 19, 2010
Fekadu A, Shibre T, Cleare AJ.
Folia Parasitologica 2010; 57: 105-113
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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.

Tagged: 1st-episode schizophrenia, agents, antibodies, behavioural disorder, decreased level, gondii infection, individuals, mental-health surveys, mood, mood disorders, novelty seeking, personality changes, review, risk, Schizophrenia, Toxoplasma gondii, toxoplasmosis

Mental healthReviews

Epidemiological evidences from China assume that psychiatric-related diseases may be associated with Toxoplasma gondii infection

January 4, 2007
Zhu, S., Guo, M. F., Feng, Q. C., Fan, J. M.,
Neuroendocrinology Letters, 2007, 28: 115-120
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In recent years, the effect of Toxoplasma gondii infection on psychiatric-related aspects has been increasingly recognized. T gondii has a high affinity for brain tissue where tachyzoites may form tissue cysts and persist life long. In recent years, 15 serological surveys about T gondii infection and psychiatric diseases have been carried out in different areas in China. Studies showed that the prevalence of antibodies against T gondii in psychotic patients was much higher than in normal persons; statistically differences were significant. Studies also reported that raising cats or enjoying the habit of eating raw or under cooked meet were potential risk factors for the infection of T gondii. The epidemiological and serological evidence support the hypothesis that some psychiatric diseases such as schizophrenia or mental retardation might be linked to T gondii infection.

Tagged: 1st-episode schizophrenia, antibodies, behavior, cats, host, novelty seeking, parasites, personality changes, psychiatric-related disease, rattus-norvegicus, toxoplasmosis

Mental health

Can the common brain parasite, Toxoplasma gondii, influence human culture?

October 30, 2006
Lafferty, K.D.
Proceedings of the Royal Society B-Biological Sciences 2006; 273: 2749-2755.
Click for abstract
The latent prevalence of a long-lived and common brain parasite, Toxoplasma gondii, explains a statistically significant portion of the variance in aggregate neuroticisin among populations, as well as in the 'neurotic' cultural dimensions of sex roles and uncertainty avoidance. Spurious or non-causal correlations between aggregate personality and aspects of climate and culture that influence T gondii transmission could also drive these patterns. A link between culture and T gondii hypothetically results from a behavioural manipulation that the parasite uses to increase its transmission to the next host in the life cycle: a cat. While latent toxoplasmosis is usually benign, the parasite's subtle effect on individual personality appears to alter the aggregate personality at the population level. Drivers of the geographical variation in the prevalence of this parasite include the effects of climate on the persistence of infectious stages in soil, the cultural practices of food preparation and cats as pets. Some variation in culture, therefore, may ultimately be related to how climate affects the distribution of T gondii, though the results only explain a fraction of the variation in two of the four cultural dimensions, suggesting that if T gondii does influence human culture, it is only one among many factors.

Tagged: antibodies, decreased level, Dopamine, infection, masculinity, nations, neuroticism, novelty seeking, personality, personality changes, population, pregnant women, prevalence, risk factors, uncertainty avoidance

BehaviorPersonality

Topics

  • Behavior 105
  • Cognitive functions 64
  • Mental health 439
  • Morphology 6
  • Motor functions 10
  • Personality 36
  • Physical health 134
  • Reproduction 36
  • Reviews 40
  • Sensory functions 3
  • Uncategorized 2

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Recent articles

  • Mortality Patterns of Toxoplasmosis and Its Comorbidities in Tanzania: A 10-Year Retrospective Hospital-Based Survey February 6, 2020
  • The role of latent toxoplasmosis in the aetiopathogenesis of schizophrenia–the risk factor or an indication of a contact with cat? February 6, 2020
  • The Association between Toxoplasma gondii Infection and Risk of Parkinson’s Disease: A Systematic Review and Meta-Analysis February 6, 2020

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