The aim of the study would be to determine the effects of adjuvant aspirin therapy on soft neurological signs, PANSS and the cytokine profile. The investigators expect the reduction of PANSS scores in both groups of patients (aspirin group and placebo group). If there is no significant changes of SNS between groups, the results would support SNS as trait characteristics of schizophrenia. In the case of significant changes of cytokine profile/ratios in experimental group, the results would go in favour of the cytokine hypothesis.