Toxoplasma gondii infection affects cognitive function - corrigendum

Abstract

253In the recent issue of Folia Parasitologica (59: 93-98), Guenter et al. (2012) published results of a study showing that the effect of latent toxoplasmosis on cognitive function of 70 subjects cannot be proved to exist using a panel of five neuropsychological tests (Guenter et al. 2012). It must be mentioned that the data (mostly ordinal variables without normal distribution) were analysed either with parametric tests (GLM) or with more proper nonparametric tests, but without controlling for age and sex of subjects. It is known for a long time that shifts in personality profile and behaviour associated with latent toxoplasmosis differ very often in their direction between men and women Hrdý 1994, Flegr et al. 1996;Lindová et al. 2006Lindová et al. , 2010. This raises the question whether cognitive functions reveal a similar phenomenon.Therefore, we re-analysed the data on 56 women and 14 men separately. To control for the effect of age, which is known to influence the performance of subjects and also the probability of being Toxoplasma-infected, we analyzed the data with partial Kendall regression, the nonparametric technique that controls for one confounding variable (Kaňková et al. 2011). The results showed that, generally, women scored worse in tests except Digit span-backward test (significantly worse only in the verbal fluency test, p = 0.015), whereas males scored better in all tests except in percentage of correct answers in N-back test (significantly better in digit span-forward, p = 0.008 and in Stroop test I, p = 0.017).Published results of a simple reaction time test show that psychomotor performance of both men and women is lower in subjects with latent toxoplasmosis (Flegr et al. 2008). However, most of personality factors and in some population also intelligence are shifted in an opposite direction in Toxoplasma-infected men and women

Toxoplasma gondii seropositivity and serointensity and cognitive function in adults

“…In that study, Toxoplasma gondii seropositivity was associated with better action control, which the authors speculated might have been due to changes in dopamine transmission related to Toxoplasma gondii seropositivity [31]. Finally, one other study found some evidence of better performance in participants positive for Toxoplasma gondii on some but not all cognitive tests administered [32]. While unexpected, our finding of an association between Toxoplasma gondii serointensity and better reaction time comes from a sample size of 6,752, a large sample that minimizes the chance for error due to small sample.…”

Hepatitis C virus antibody titers associated with cognitive dysfunction in an asymptomatic community-based sample

“…Previous studies reports have been contradictory results, with some investigators reporting impaired function (Gajewski, Falkenstein, Hengstler, & Golka, 2014) , while others did not detect statistically significant effects (Guenter et al, 2012) & Kruszonet al 2014) , (J. Flegr et al, 2012) (Pearce, Kruszon-Moran, & Jones, 2014).…”

“…Others have suggested that the associations are stronger in men, possibly due to hormonal effects (J. Flegr et al, 2012) (J. Flegr et al, 2012; J.…”

Association between Toxoplasma gondii seropositivity and memory function in nondemented older adults

“…However, even though many studies suggest seropositivity for latent toxoplasmosis is associated with worse outcome, whether it be cognitive or psychiatric, other studies suggest that seropositivity may not be purely detrimental. For example, Flegr et al (2012) analyzed males and females separately and found that while seropositive females did more poorly on one of several cognitive measures compared to seronegative females, seropositive males did equally well on most cognitive measures and actually did better than seronegative males on two of the cognitive measures. Similarly, Stock et al (2014) found that seropositivity for T. gondii was associated with better performance on a measure of action control.…”