It has been demonstrated in a number of studies that the prevalence of schizophrenia is significantly higher in toxoplasmosis positive subjects than in those with T.gondii negative status. However, the clinical significance of this finding remains poorly understood. We have designed our study to identify clinical phenomena that are more frequent in toxoplasmosis-associated (T.gondii seropositive) schizophrenia compared to toxoplasma-seronegative schizophrenia. A retrospective database analysis of serum samples from 105 inpatients with schizophrenia (ICD-10 diagnosis F20; 55 male patients; mean age of 27.4 ± 6.4 years) was carried out. The clinical examination involved a structured interview including ICD-10 and E. Bleuler’s criteria for schizophrenia, as well as the Positive and Negative Syndrome Scale for schizophrenia (PANSS). Serum antibodies (IgG) to T.gondii were identified using ELISA. As a result, the proportion of seropositive patients  in the sample was identified as 16.2%. Comparison of toxoplasma-seropositive and seronegative schizophrenia patients revealed no statistically significant differences for the mean total PANSS score, mean PANSS-P, PANSS-N or PANSS-G scores. For the majority of PANSS items, differences were also statistically insignificant, except for G5 and G6 — “mannerism and posturing” and “depression”, respectively. Seropositive patients had a higher score for these items than seronegative patients: 3.5 versus 2.1 points (U=389.5; ?=0.001). Depression, on the contrary, was less pronounced in seropositive than seronegative patients: 1.4 versus 2.4 points (U=509.5; ?=0.023). In addition, in seropositive patients, the frequency of symptoms such as mutism according to ICD-10 criteria for schizophrenia, and the whole group of catatonic symptoms according to the E. Bleuler’s criteria for schizophrenia were significantly higher: 23.5% versus 3.4%, ?2=9.27 (?=0.013) and 52.9% versus 28.4%, ?2=3.916 (p = 0.048) respectively. Thus, the association between a positive toxoplasmosis status in patients with schizophrenia and catatonic symptoms has been revealed. 

Dmitry V. Romanov has completed his PHD at the age of 28 years and his professor theses at the age of 34 years from Mental Health Research Center, Moscow, Russia. He is the professor of the Department of Psychiatry and Psychosomatic Disorders, Sechenov University, Moscow Russia. He’s articles (Scopus = 50, WOS =49, Google Scholar=94, eLIBRARY.RU=148) have been cited 1025 times in the last 5 years. In Scopus and WOS, H-index is 10. In Google Scholar, H-index is 13. eLIBRARY.RU H-index is 14.