Genetic and biochemical biomarkers related to oxidative stress in patients with schizophrenia
We evaluated the association of glutathione S-transferase polymorphisms (GSTT1 and GSTM1) and oxidative stress biomarkers in patients with schizophrenia. A total of 162 subjects were studied: 53 had schizophrenia (Total Study Group-TSG), and 109 without the disorder (Total Control Group-TCG). To analyze oxidative stress, TSG was distributed into treatment-responsive schizophrenia (N = 26) and treatment-resistant (N = 27) versus control group (N = 36). Peripheral blood collection for analysis of polymorphisms, malondialdehyde (MDA) and trolox equivalent antioxidant capacity (TEAC); a questionnaire or a medical record for clinical profile and lifestyle was also applied. Frequency of genotypes did not differ significantly between the groups. The patients had a significantly reduced frequency of the combination GSTT1-null/GSTM1-present (13 versus 30%) and significantly higher plasma MDA levels, but similar TEAC values. Smoking, diabetes mellitus (DM), systemic arterial hypertension (SAH) and family history (FH) significantly prevailed in patients (TSG) compared to controls (TCG). High sensitivity and specificity values for MDA (area under the curve >0.90) were observed. Reduced frequency of the combination GSTT1-null/GSTM1-present in patients suggests exposure to oxidative stress, represented by increased MDA and mainly aggravated by smoking, SAH, DM and FH. High sensitivity and specificity identifies the potential of MDA as a marker of oxidative stress in schizophrenia.