Saturday, 21 March 2015

Toxoplasma gondii and schizophrenia (again and again)

The findings reported by Ainsah Omar and colleagues [1] (open-access available here) adding further weight to the notion of a "strong association between the active Tg [Toxoplasma gondii] infection and schizophrenia" are set out for your reading consumption today.

Continuing a research topic that has already enjoyed quite a bit of air time on this blog (see here and see here) whereby the parasite T. gondii known to cause the condition toxoplasmosis might also be implicated in at least some cases of schizophrenia, Omar et al report some pretty stark differences in rates of seropositivity between cases of schizophrenia (n=101) and asymptomatic controls (n=55).

"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 antibodies refers to immune status with regards to a particular agent with the focus on past or recent exposure to said pathogen. In this respect, the results suggest that over half of participants with schizophrenia had met with T. gondii at some point compared with nearly 20% of controls. Insofar as active infection measured by IgM antibodies to T. gondii, the authors reported no significant difference in rates between the groups. DNA, as in measurement for the presence of T. gondii DNA as evidence of infection, also showed some interesting differences between the groups in favour of the schizophrenia group.

"In our study, the OR [odds ratios] of having schizophrenia among those with positive Tg DNA (OR=12.9) was much higher than those with positive Tg IgG antibody (OR=4.8)." This sentence in particular hints at some of the novelty behind the results from Omar et al with their focus on both antibody response to T. gondii infection and their more direct method of looking for T. gondii DNA.

"Although there was significant difference in the seropositivity of Tg IgG and Tg DNA between the 2 groups, however, there was no significant difference between the serointensity of Tg IgG antibody and DNA between schizophrenia patients and controls. These could possibly be due to the effects of antipsychotic medications which caused the reduction in the level of Tg IgG antibody and DNA by inhibiting the replication of Tg." I've talked before on this blog about how a wide variety of the medicines we use in modern times may have so many more 'effects' than those listed on the package insert. Certain antipsychotic drugs are known to possess "anti-toxoplasmic activity" [2] and one might entertain the fact that when used for some with schizophrenia there is the potential for some effect mediated via this pathway. I would like to see a lot more medicines tested for their anti-parasitic effects [3] that's for sure.

Of course one has to be a little cautious not to make too many generalisations from the findings from Omar and other research groups [4] (several other research groups [5]) about the idea that T. gondii might be linked to cases of schizophrenia. But as part of a wider research strategy [6] and accepting the moves towards the possible pluralisation of schizophrenia (see here), I believe there is quite a bit more to see in this area...

Music: The Cure - Pictures Of You.

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[1] Omar A. et al. Seropositivity and Serointensity of Toxoplasma gondii Antibodies and DNA among Patients with Schizophrenia. Korean J Parasitol. 2015 Feb;53(1):29-34.

[2] Fond G. et al. Comparative analysis of anti-toxoplasmic activity of antipsychotic drugs and valproate. Eur Arch Psychiatry Clin Neurosci. 2014 Mar;264(2):179-83.

[3] Fond G. et al. Treatment with anti-toxoplasmic activity (TATA) for toxoplasma positive patients with bipolar disorders or schizophrenia: A cross-sectional study. J Psychiatr Res. 2015 Feb 24. pii: S0022-3956(15)00043-6.

[4] Cevizci S. et al. Seroprevalence of anti-Toxoplasma gondii and anti-Borrelia species antibodies in patients with schizophrenia: a case-control study from western Turkey. World J Biol Psychiatry. 2015 Mar 16:1-7.

[5] Khademvatan S. et al. Toxoplasma gondii Exposure and the Risk of Schizophrenia. Jundishapur J Microbiol. 2014 Nov;7(11):e12776.

[6] Severance EG. et al. Gastroenterology Issues in Schizophrenia: Why the Gut Matters. Current Psychiatry Reports. 2015; 17: 27.

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ResearchBlogging.org Omar A, Bakar OC, Adam NF, Osman H, Osman A, Suleiman AH, Manaf MR, & Selamat MI (2015). Seropositivity and Serointensity of Toxoplasma gondii Antibodies and DNA among Patients with Schizophrenia. The Korean journal of parasitology, 53 (1), 29-34 PMID: 25748706