Abstract
Objectives: Increasing evidence demonstrates that infections and activated immune system may play a role in the pathogenesis of schizophrenia. In this study, we aimed to investigate the possible relationship between anti-streptolysin O (ASO) antibodies titer and schizophrenia.
Methods: This study included 33 patients with first episode psychosis, 42 patients with chronic schizophrenia, and 41 randomly selected age- and gender-matched healthy volunteers. The severity of schizophrenia symptoms in the patients were evaluated using the Positive and Negative Syndrome Scale (PANSS). The enzyme-linked immunosorbent assay (ELISA) method was used to measure ASO titer.
Results: Three groups had similar demographic characteristics. The mean ASO titer was 200.23±173.14 IU/ml in patients with first episode psychosis, 151.66±128.74 IU/ml in patients with chronic schizophrenia and 108.56±93.67 IU/ml in healthy controls. According to pairwise comparison; ASO titer of the first episode psychosis and chronic schizophrenia groups were significantly higher than the healthy controls (F=14.367, p=0.015). There was a statistically significant positive correlation between total PANSS score and ASO titer (the total PANSS score increases with ASO titer) (r=0.193, p=0.037).
Conclusion: To our knowledge, this study is the first study in the literature investigating ASO titer in patients with first episode psychosis and chronic schizophrenia. The findings of our study suggest that there is a relationship between psychosis severity and ASO titer in both patients with first episode psychosis and chronic schizophrenia. Based on these results, streptococcal infectionsmay be related to some central nervous system pathologies such as schizophrenia.

Key words: First episode psychosis, chronic schizophrenia, anti-streptolysin O (ASO) antibodies.