Age-related changes of superoxide dismutase activity in patients with schizophrenia

Abstract

© 2017, Institut za Vojnomedicinske Naucne Informacije/Documentaciju. All rights reserved. Background/Aim. Superoxide dismutase (SOD) is the critical enzyme in the detoxification of superoxide radicals because those are the first species produced in the majority of biological free radical producing reactions. Inconsistent data are present about SOD activity in patients with schizophrenia. Numerous studies show that SOD is elevated in chronic schizophrenic patients. However, decreased SOD activity is found in neuroleptic naive, first episode schizophrenic patients, in chronic-medicated patients and in chronic-unmedicated patients. The aim of this study was to examine the influence of age, gender, age at disease onset, the duration of the disease, the number of episodes, heredity, psychopathologic symptoms and drug treatment on erythrocyte SOD activity in patients with schizophrenia. Methods. This study included 68 consecutive patients with schizophrenia (29 males and 39 females) ranging in age from 18 to 61 years, divided into two age groups (< 34 years and > 34 years). SOD activity was measured in erythrocyte hemolyzates by commercially available Ransod test. Results. In the group of patients younger than 34 years SOD levels were significantly higher (1,381 ± 273 U/gHb, p = 0.038) compared to the levels in the older patients (1,231 ± 206 U/gHb). Gender and heredity did not induce any significant difference in SOD activity between the groups. A significant difference in enzyme activity was found between the younger and older patient groups having the onset of the disease after 24 years of age (1,408 ± 217 U/gHb vs 1,252 ± 213 U/gHb, p = 0.031, respectively). The patients in the younger group with more than one psychotic episodes had significantly higher SOD activity (1,492 ± 298 U/gHb; p = 0.009) than those with only one episode (1,256 ± 177 U/gHb), as well as than the older patients with more than one episode (1,253 ± 231 U/gHb; p = 0.014). Although the duration of the disease did not induce any significant difference in enzyme activity between the younger and older patient groups, a significant negative correlation was obtained between SOD activity and the duration of the disease (r = -0.511, p < 0.01). No significant differences were found in SOD activity between the groups with the different positive and negative syndrome scale (PANSS) scores. First generation antipsychotics were associated with elevated enzyme activity in both groups. Simultaneous treatment of patients with first generation antipsychotics and second generation antipsychotics induced a significant decrease in SOD activity in the younger patient group. Conclusion. Our results show that erythrocyte SOD activity is increased in the early phase of schizophrenia, depending on age at the onset of the disease, the number of psychotic episodes, the duration of the disease and medical treatment.