RETRACTED ARTICLE: Differences in cognitive functions between cytomegalovirus-infected and cytomegalovirus-free university students: a case control study

Abstract

Cytomegalovirus (CMV) is the herpetic virus, which infects 45–100% people worldwide. Many reports suggest that CMV could impair cognitive functions of infected subjects. Here we searched for indices of effects of CMV on infected subjects’ intelligence and knowledge. The Intelligence Structure Test I-S-T 2000 R was used to compare IQ of 148 CMV-infected and 135 CMV-free university students. Infected students expressed higher intelligence. Paradoxically, their IQ decreased with decreasing concentration of anti-CMV antibodies, which can be used, statistically, as a proxy of the time passed from the moment of infection in young subjects when the age of subjects is statistically controlled. The paradox of seemingly higher intelligence of CMV infected subjects could be explained by the presence of the subpopulation of about 5–10% CMV-positive individuals in the population of “CMV-negative students”. These false negative subjects had probably not only the oldest infections and therefore the lowest concentration of anamnestic antibodies, but also the lowest intelligence among the infected students. Prevalence of CMV infection in all countries is very high, approaching sometimes 90%. Therefore, the total impact of CMV on human intelligence may be large.

New approach and new permutation tests with R programs for analyses of false negatives-contaminated data in medicine and biology

“…Based on the theoretical grounding described above and our experience with the research of two unrelated species of parasites, Toxoplasma gondii (Flegr et al, 2005(Flegr et al, , 2000 and human cytomegalovirus (Chvatalova et al, 2018), we strongly recommend the usage of permutation tests for contaminated data at https://github.com/ costlysignalling/Permutation_test_for_contaminated_data whenever any properties of parasite-infected and parasite-free individuals are compared.…”

“…A Monte Carlo simulation was performed with R 3.3.3. We generated a population of 150 parasite-free and 150 infected subjects (mean intelligence was 101.5 in the parasite-free group and 98.5 in the infected groupthe between-group difference was 3, the population mean intelligence was 100) (Flegr et al, 2013(Flegr et al, , 2003Chvatalova et al, 2018). Subjects were normally distributed around group means with equal standard deviations (SD).…”

“…This is also true for parasites that stay dormant in infected cells until the end of the life of infected hosts. Any subsample of seronegative subjects could, therefore, be contaminated with an unknown proportion of misdiagnosed parasite-positive individuals who became infected a long time ago (Flegr and Havlícěk, 1999;Flegr et al, 2005;Griffiths et al, 1978;Chvatalova et al, 2018;Lee et al, 2008;Waner et al, 1973). This subpopulation of infected but seronegative subjects could be the most influenced by the infection (Fig.…”

Cognitive Effects ofToxoplasmaand CMV Infections: A Cross-Sectional Study of 557 Young Adults Considering Modulation by Sex and Rh Factor

“…The effects of CMV infection on intelligence and cognitive performance, particularly in young and middle-aged individuals, have not been extensively studied. An earlier study [60], which stemmed from the first author's diploma thesis [61], reported negative impacts of CMV infection on the IQ of university students. However, this study was retracted due to an error in the permutation tests, specifically the mislabeling of infected and uninfected individuals' codes [62].…”