Background: Toxoplasma gondii is an intracellular parasite that in most individuals can persist in multiple tissues where the latent stage of the parasite is mainly found in the central nervous system. Schizophrenia is a serious neuropsychiatric disease of uncertain etiology, and recent studies have focused on T. gondii as a possible causal factor in schizophrenia. Soluble intercellular adhesion molecule 1 (sICAM-1), which represents a circulating form of ICAM-1, has been implicated in the development of many diseases.
Aim: The present study aimed to investigate the frequency of T. gondii infection among schizophrenia patients and to determine the usefulness of sICAM-1 as an indicator of Toxoplasma role in the etiopathogenesis of schizophrenia.
Methods: Sixty patients with schizophrenia, 30 with depressive disorder, and 20 healthy volunteers were subjected to determination of anti–T. gondii immunoglobulin G (IgG) antibody seropositivity and sICAM-1 serum level using commercially available enzyme-linked immunosorbent assay kits.
Results: The results showed that the seropositivity rate of anti–T. gondii IgG antibodies among schizophrenia patients (56.7%) was higher than among patients with depressive disorder (40%); despite this, the difference was not statistically significant. It was significantly higher in schizophrenia patients than in the healthy volunteers group (30%). Regarding the serum level of sICAM-1, it was significantly higher in the anti–T. gondii IgG–seropositive schizophrenia subgroup compared with those of the seropositive healthy volunteers and seropositive depressive disorder subgroups. Moreover, there was a significantly higher level of sICAM-1 in the seropositive schizophrenia subgroup compared with that of the seronegative schizophrenia subgroup. Concerning the seropositive depressive disorder subgroup, there was a significantly higher level of sICAM-1 compared with that of the seronegative depressive disorder subgroup.
Conclusions: These statistically significant results support the association between T. gondii infection and schizophrenia and suggest the usefulness of sICAM-1 as an indicator for the possible role of Toxoplasma among other factors in the etiopathogenesis of schizophrenia.