behavior
Seroepidemiology of Toxoplasma gondii infection in psychiatric in-patients in a northern Mexican city
Alvarado-Esquivel, C., Alanis-Quinones, O. P., Arreola-Valenzuela, M. A., Rodriguez-Briones, A., Piedra-Nevarez, L. J., Duran-Morales, E., Estrada-Martinez, S., Martinez-Garcia, S. A., Liesenfeld, O.
BMC Infectious Diseases 2006; 6: 178
Click for abstract
Background: Patients with psychiatric disorders were found to show a high seroprevalence of Toxoplasma gondii infection. There is scarce information about the epidemiology of T. gondii infection in psychiatric patients in Mexico. Therefore, we sought to determine the prevalence of T. gondii infection and associated socio-demographic, clinical and behavioural characteristics in a population of psychiatric patients in Durango City, Mexico. Seroprevalence in patients was compared with that obtained in a control population.
Methods: One hundred and thirty seven inpatients of a public psychiatric hospital and 180 controls were examined for the presence of IgG and IgM antibodies against T. gondii by enzyme-linked immunoassay (Diagnostic Automation Inc., Calabasas, CA, USA). The control population consisted of blood donors of a public blood bank and elderly persons attending a senior center in the same city. Age in controls (42 years +/- 20.2) was comparable with that of the psychiatric patients (43.7 years +/- 13.8) (p = 0.42). Socio-demographic, clinical and behavioral characteristics from the patients were also obtained.
Results: Anti-T. gondii IgG antibodies indicating latent infection with T. gondii was found in 25 (18.2%) of 137 psychiatric inpatients and 16 (8.9%) of 180 controls (p = 0.02). Ten (26.3%) of 38 schizophrenic patients had latent infection and this prevalence was also significantly higher than that observed in controls (p = 0.005). Prevalence of anti-T. gondii IgM antibodies was comparable among patients and controls (4.4% vs 2.2%, respectively, p = 0.22). Multivariate analysis showed that T. gondii infection in inpatients was positively associated with sexual promiscuity (adjusted OR = 15.8; 95% CI: 3.8-64.8), unwashed raw fruit consumption (adjusted OR = 5.19; 95% CI: 2.3-11.3), and a history of surgery (adjusted OR = 6.5; 95% CI: 2.6-16), and negatively associated with lamb meat consumption (adjusted OR = 0.26; 95% CI: 0.10-0.63).
Conclusion: In the present study, psychiatric inpatients in Durango, Mexico, in general and schizophrenia inpatients in particular had a significantly higher prevalence of T. gondii infection than the control group. Results suggest that unwashed raw fruit consumption might be the most important route of T. gondii transmission in our psychiatric inpatients while lamb meat consumption the less important. Additional studies will have to elucidate the causative relation between infection with T. gondii and psychiatric disorders.
Prevalence of Toxoplasma infection in first-episode schizophrenia and comparison between Toxoplasma-seropositive and Toxoplasma-seronegative schizophrenia
Wang, H. L., Wang, G. H., Li, Q. Y., Shu, C., Jiang, M. S., Guo, Y.
Acta Psychiatrica Scandinavica 2006; 114: 40-48.
Click for abstract
Objective: To compare the prevalence of Toxoplasma infection between the first-episode schizophrenia and the controls and to compare the clinical features between the Toxoplasma-seronegative and Toxoplasma-seropositive patients with schizophrenia.
Method: The rate of serum reactivity toToxoplasma in 600 schizophrenia, 600 affective disorders, and 400 controls was investigated. The clinical symptoms of the schizophrenia patients were scored and compared.
Results: The rate of IgG antibody, not IgM in the schizophrenia patients, was higher than the control groups, and the odds ratio of schizophrenia associated with IgG antibody was 2.22-5.12. The affective disorders did not differ in the rate of IgG or IgM antibody from the normal or the physical disease control. The seropositive schizophrenia patients had higher scores on the positive subscale and three components of Positive and Negative Symptoms Scale than the seronegative patients.
Conclusion: This study lent further weight to the hypothesis that exposure to Toxoplasma may be a risk factor for schizophrenia.
Look what the cat dragged in: do parasites contribute to human cultural diversity?
Lafferty, K.D.
Behavioural Processes 2005; 68: 279-282
Decreased level of novelty seeking in blood donors infected with Toxoplasma
14 Comments
Skallová, A., Novotná, M., Kolbeková, P., Gasová, Z., Veselý,V., Sechovská, M., Flegr, J.
Neuroendocrinology Letters 2005; 26: 480-486
Skallová, A., Novotná, M., Kolbeková, P., Gasová, Z., Veselý,V., Sechovská, M., Flegr, J.
Neuroendocrinology Letters 2005; 26: 480-486
Click for abstract
OBJECTIVES
:
Toxoplasma gondii
, a parasitic protozoan, infects about 30–60% of
people worldwide.
Toxoplasma
is known to induce behavioral changes and an
increase of dopamine in mice. The presence of anti-
Toxoplasma
antibodies (latent
toxoplasmosis) is also a risk factor for schizophrenia. Latent toxoplasmosis in
men (male soldiers) is associated with lower novelty seeking. As the novelty seek
-
ing is supposed to negatively correlate with level of dopamine, the observed effect
was interpreted as indirect evidence of increased dopamine levels in subjects with
toxoplasmosis. However, it is also possible that the observed effect was caused by
association of both novelty seeking and
Toxoplasma
infection with a third factor,
e.g. size of place of residence.
METHODS
:
Personality profile of 290 blood donors (205 men and 85 women) were
measured by Cloninger’s TCI (Temperament and Character Inventory) and their
blood samples were assayed for the presence of anti-
Toxoplasma
antibodies. Dif
-
ference between
Toxoplasma
-infected and
Toxoplasma
-free subjects was tested
with ANCOVA method with gender, size of place of residence, and age as covari
-
ates.
RESULTS
:
The present analysis revealed that lower novelty seeking was associ
-
ated with latent toxoplasmosis both in men and women. The effect of infection
on novelty seeking remained significant even after adjustment for size of place of
residence (p<0.0).
CONCLUSION
:
Decreased novelty seeking in
Toxoplasma
-infected subjects have
been already confirmed in three independent populations (male soldiers and
male and female blood donors). These findings suggest that the local inflamma
-
tion-induced increase in dopamine in the brain of infected subjects can represent
a missing link between toxoplasmosis and schizophrenia
Parasitic manipulation: where else should we go?
Webster, J. P.
Behavioural Processes 2005; 68: 275-277
Decreased level of psychobiological factor novelty seeking and lower intelligence in men latently infected with the protozoan parasite Toxoplasma gondii. Dopamine, a missing link between schizophrenia and toxoplasmosis?
12 Comments
Flegr, J., Preiss, M., Klose, J., Havlíček, J., Vitáková, M, Kodym, P.
Biological Psychology 2003; 63: 253-268
Flegr, J., Preiss, M., Klose, J., Havlíček, J., Vitáková, M, Kodym, P.
Biological Psychology 2003; 63: 253-268
Click for abstract
Toxoplasma gondii
, a parasitic protozoan, infects about 30
/
60% of people worldwide. The
latent toxoplasmosis, i.e. life-long presence of cysts in the brain and muscular tissues, has no
effect on human health. Howe
v
er, infected subjects score worse in psychomotor performance
tests and ha
v
e different personality profiles than
Toxoplasma
-negati
v
e subjects. The
mechanism of this effect is unknown; howe
v
er, it is supposed that presence of parasites’ cysts
in the brain induces an increase of the concentration of dopamine. Here we search for the
existence of differences in personality profile between
Toxoplasma
-positi
v
e and
Toxoplasma
-
negati
v
e subjects by testing 857 military conscripts using a modern psychobiological
questionnaire, namely with Cloninger’s Temperament and Character In
v
entory (TCI).
ANCOVA showed that
Toxoplasma
-positi
v
e subjects had lower No
v
elty seeking (NS) scores(
P
/
0.035) and lower scores for three of its four subscales, namely Impulsi
v
eness (
P
/
0.049),
Extra
v
agance (
P
/
0.056) and Disorderliness (
P
/
0.006) than the
Toxoplasma
-negati
v
e
subjects. Differences between
Toxoplasma
-negati
v
e and positi
v
e subjects in NS was in
v
ersely
correlated with duration of toxoplasmosis estimated on the basis of concentration anti-
Toxoplasma
antibodies (
P
/
0.031). Unexpectedly, the infected subjects had also lower IQ
(
P
2
/
0.003) and lower probability of achie
v
ing a higher education (
P
2
B
/
0.0000). Decrease of
NS suggests that the increase of dopamine in brain of infected subjects can represent a missing
link between toxoplasmosis and schizophrenia
Antibodies to Toxoplasma gondii in individuals with first-episode schizophrenia
Yolken, R. H., Bachmann, S., Rouslanova, I., Lillehoj, E., Ford, G., Torrey, E. F., Schroeder, J.
Clinical Infectious Diseases 2001; 32: 842-844
Click for abstract
We employed enzyme immunoassay (EIA) and Western blotting techniques to measure the level of antibodies to Toxoplasma gondii proteins in serum samples from 38 individuals undergoing their first episode of schizophrenia and from a group of matched control subjects. We found that the individuals with first-episode schizophrenia had significantly increased levels of IgG, IgM, and IgA class antibodies to Toxoplasma proteins, as compared with the control subjects.
Correlation of duration of latent Toxoplasma gondii infection with personality changes in women
Click for abstract
Many parasites induce characteristic changes in behavior of their hosts. In humans latent
toxoplasmosis is associated with changes in personality profiles. It has been already shown
that a decrease in superego strength is correlated with duration of toxoplasmosis in men.
Here we studied changes in personality profiles with Cattell’s 16 PF questionnaire in
Toxoplasma
-infected women. The changes were measured as differences in personality
factors between
Toxoplasma
-infected subjects and uninfected controls of the same age. The
low-rate changes were studied in 230 women diagnosed with acute toxoplasmosis during past
14 years. The results showed the correlation between duration of toxoplasmosis and level of
factors G (high superego strength) and Q3 (high strength of self sentiment). The high-rate
changes were estimated by measuring the correlation between level of
Toxoplasma
-antibody
titers (which rapidly decline after the end of acute phase of toxoplasmosis) and personality
factors in an experimental set of 55 young mothers with latent toxoplasmosis. Again, certain
factors, namely A (affectothymia), F (surgence), G (high superego strength), H (parmia), and
L (protension), correlated with the length of the infection. We suggest that the parasite
induced the changes in the personality profiles of the women because of our observation of
an increasingly different personality profile over time between women with latent infection
and controls. The same evidence questions the view that women with a particular personality profile are more prone to acquisition
Differences in personality profiles of Toxoplasma gondii infected and uninfected biologist
Click for abstract
Parasitic protozoan Toxoplasma gondii induces specific changes the behavior of its intermediate hosts. Human latent toxoplasmosis (presence of anti-Toxoplasma immunity in subjects without any clinical symptoms of acute toxoplasmosis) is known to be associated with specific changes of personality profiles of infected subjects. I the present work we studied the toxoplasmosis-associated differences in personality profiles (monitored by Cattell's 16PF questionnaire) in a population of 443 university students and teachers of biology. Our results show that the factors A, G, L, N and Q3 were shifted in the opposite direction in men and women; the factor O was shifted in the same direction, however, the intensity of the shift in women was relatively low. The men with latent toxoplasmosis had lower factor G (had higher tendency to disregard rules) p=0.049, higher factor L (were more suspecting, jealous, dogmatic) p=0.015, and higher factor O (were more apprehensive, self-reproaching, insecure) p=0.046. The Toxoplasma-infected women had higher factor A (warm-hearted, outgoing, easygoing) p=0.001. Several personality factors were shifted (both in men and women) from extreme values toward the middle of the psychological scales. Therefore, the Toxoplasma-infected subjects expressed less extreme personality attitudes in factors F, M, Q1 and Q4.
Toxoplasmosis, behaviour and personality
Holliman, R. E.
Journal of Infection 1997; 35: 105-110
Click for abstract
The clinical sequelae of acute and congenital toxoplasmosis are well established, but that of chronic toxoplasma infection remains uncertain. In rodents, chronic toxoplasma infection is associated with altered behaviour leading to an enhanced risk of feline predation and a putative selective advantage to the parasite. It is proposed that neurotropic cysts of toxoplasma exert an effect on animal behaviour, either directly or via the release of metabolic products. Long-standing toxoplasma infection in humans has been linked to cerebral tumour formation and personality shift. In view of the vast population with chronic toxoplasma infection, further studies of the clinical sequelae of this condition are required.