Association between neurological soft signs and antioxidant enzyme activity in schizophrenic patients

To determine the relationship between alterations in the activity of the enzymes participating in antioxidative defense system and neurological soft signs (NSS) in schizophrenic patients with the first episode psychosis (S_FE, n = 19), patients in relapse (S_R, n = 46), and healthy controls (HC, n = 20). NSS intensity and enzymatic plasma activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) were compared between S_FE, S_R and HC subjects and a follow-up correlation analyses between the enzyme activities and NSS intensity was performed. NSS intensity was increased four times in schizophrenic patients compared with healthy controls. Activities of SOD and CAT were 40% decreased in S_FE and these reductions were ameliorated by antipsychotic treatment. GPX activity was 20% decreased in both patient groups compared with controls. A negative correlation between NSS intensity and GPX activity was specifically found in the S_FE patients. The data in this report argue that a reduction of GPX activity might be one of the causes for the emergence of NSS at the onset of schizophrenia, and provide the evidence that antipsychotic therapy can attenuate activity reductions of SOD and CAT, but not the activity reduction of GPX and the intensity of NSS.