Redox-oxidative stress and micronutrients interplay in the clinical phenotype of schizophrenia in Nigerian subjects

Abstract

Aim: Redox-oxidative dysregulation is implicated in the aetiology of several diseases, including schizophrenia, with a possible influence on clinical symptoms. This study investigated the influence of redox, lipid peroxidation, and micronutrient antioxidants on the expression of clinical phenotypes of schizophrenia. Methods: A total of 220 consenting drug-naïve volunteers, including 120 participants with schizophrenia and 100 apparently healthy controls, were recruited. Schizophrenia symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS). Lipid peroxidation (malondialdehyde; MDA) was quantified using the thiobarbituric acid reactive substances (TBARS) spectrophotometric method; glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) were assessed using established enzymatic activity assays; total antioxidant capacity (TAC) was determined by the phosphomolybdenum colorimetric method; vitamins C and E were measured using spectrophotometric biochemical assays; and zinc (Zn) and selenium (Se) concentrations were quantified using atomic absorption spectrophotometry (AAS). Results: Enzymatic antioxidants, SOD (19.58 ± 0.80; 10.12 ± 0.45 U/L) and CAT (41.73 ± 1.81; 21.33 ± 0.98 U/L), increased in schizophrenia compared with controls (p < 0.05), but decreased non-enzymatic antioxidants; GSH (14.5 ± 0.28; 15.9 ± 1.59 µmol/L, p < 0.05). Furthermore, serum levels of zinc (1.8 ± 0.01; 2.7 ± 0.02 mg/L), selenium (0.08 ± 0.01; 0.10 ± 0.01 mg/L), and vitamin C (12.98 ± 0.49; 15.08 ± 0.37 mg/L) were lowered in schizophrenia compared with controls (p < 0.05). GSH had a negative correlation with positive symptoms (r = –0.285, p = 0.013) while SOD (r = 0.281, p = 0.001) and CAT (r = 0.179, p = 0.034) correlated positively with MDA (p < 0.05). In contrast, GSH (r = –0.247, p = 0.003) and TAC (r = –0.221, p = 0.009) correlated negatively with MDA (p < 0.05). Conclusions: Drug-naïve Nigerian individuals with schizophrenia appear to exhibit a pattern of redox imbalance, including increased lipid peroxidation, altered antioxidant enzyme activity, and reduced non-enzymatic antioxidants, with lower GSH levels modestly associated with greater positive symptom severity.