Association of antioxidant deficiency and the level of products of protein and lipid peroxidation in patients with the first episode of schizophrenia

Schizophrenia is considered a multifactorial disease, where one of the pathogenetic links is oxidative stress; however, the results of studies are often contradictory, largely due to significant heterogeneity among study methods. The present study was undertaken to compare the levels of oxidative stress markers in the peripheral blood of patients with a first episode of schizophrenia (FES) and in healthy volunteers (HV). The study included 50 patients with FES and 37 HV. Blood samples were collected for spectrophotometric assessment of reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), aldehyde-2,4-dinitrophenylhydrazone (ADNPH), and ketone-2,4-dinitrophenylhydrazone (KDNPH) in blood plasma. Results showed that in patients with FES compared with HV, a significant decrease in CAT activity and an increase in oxidative modification of proteins (OMP) were found. In both groups, a significant increase in the level of MDA with age was revealed. In patients, the GSH plasma level was inversely proportional to the ADNPH level, and SOD activity was directly proportional to the KDNPH level. In volunteers there was no such correlation; however, there was a direct correlation between CAT activity and the levels of OMP and MDA. In both groups, a moderate direct correlation between peroxidation products was observed. The results confirm that a redox imbalance (a deficiency of antioxidants, in particular CAT, and excess OMP) may be a pathogenetic link in schizophrenia, which is manifested already at an early stage of the disease.