4. DISCUSSION
In this case-control study, we used serological and molecular techniques
to elucidate a possible connection between T. gondii and
schizophrenia patients compared to healthy people. To the best of our
knowledge, this is the first case-control study conducted in
schizophrenia and healthy individuals with the diagnosis of T.
gondii by serological and also molecular methods. Overall, T.
gondii positivity was found more common in patients with schizophrenia
(53.8%), compared to healthy individuals (27.5%) by ELISA in this
study (p < 0.001).
Conventional diagnostic approaches for T. gondii infection
include microscopical, cultural, serological, and radiological methods.
Because of the fact that natural scantness of conventional diagnostic
techniques, PCR may be adopted to diagnose T. gondiiinfection.13 As far as we know, there is only one
study14 that has limitations such as the lack of a
healthy control group and targeting the SAG1 and B1 regions in the
molecular diagnosis of T. gondii , although it is approximately
similar in general concept to our study. Despite its limitations in this
retrospective study, the authors highlighted that the prominence to use
serological and molecular techniques for correct identification ofT. gondii in schizophrenia patients.14
In recent years there has been a burgeoning concern about the influence
of latent T. gondii infection on mental disorders, especially
schizophrenia. The nature of this connection remains unclear, although
it is conceivable that they manifest causality.15 To
date, numerous studies have been carried out showing the relationship
between T. gondii and schizophrenia.16–19Likewise, these studies and also our study, a meta-analysis reveals a
general significant relation having with T. gondii latent
infection and schizophrenia. Also, this well-designed and highly
scientific paper saying that the latent T. gondii acts an impact
on human behavior as well.20 After two years of this
meta-analysis, a case-control study has been published to determine the
association between schizophrenia and T. gondii conducted with 99
schizophrenia patients and 152 healthy blood donors. Although only
serological methods were used in this study and using only this analysis
has some limitations, the authors reported a positive relationship
between T. gondii and schizophrenia.21
In contrast to various publications that declared a significant
correlation between T. gondii and schizophrenia, some studies
unable to show a significant relationship.22–24Nevertheless, it should not be underestimated that the quality and
quantity of studies showing the percentages of T. gondii , which
has only approximately 30% positivity in a healthy population
worldwide25, was found to be elevated especially in
patients with schizophrenia. In this manner, it is clear that further
research is still warranted.
Suicide is a crucial emerging health problem, commonly seen in people
with mental disorders, and previous suicide attempts or even suicide
ideation are the best indicators of possible suicide
risk.26 In 2019, a meta-analysis with the aim to
determine if T. gondii is linked with suicide attempt was
published.12 In this meta-analysis, 14 studies about
suicide attempts were included and the authors have calculated a
statistically highly significant correlation for T. gondii IgG
antibodies with suicide attempters (OR = 1.39; 95% CI 1.10–1.76, p =
0006). Moreover, the authors reported that latent T. gondiiinfection may play a significant role in the risk of suicide attempts
and potential agents should be evaluated further.12
Besides the contribution of our study with preliminary results ofT. gondii and suicidal attempt history relation in patients with
schizophrenia, there are two major limitations in this study that could
be addressed in future further research. First, we enrolled a relatively
small sample size (in 117 patients with schizophrenia), which would bias
the results of our overall and subdivided schizophrenia group analyses
toward the null hypothesis. Second, we were unable to evaluate the
first-episode psychosis in stages of schizophrenia in the case group. As
previously noticed27, if patients with the
first-episode psychosis of schizophrenia were possible to include in our
study, these outcomes would provide an idea or even insight into howT. gondii behaves during the development of this surreptitious
disease.