Clinical symptoms and cognitive impairment associated with male schizophrenia relate to plasma manganese superoxide dismutase activity: a case-control study

Several lines of evidence suggest that excessive reactive oxygen species-induced oxidative damage may underlie cognitive impairment in psychiatric disorders. A growing body of evidence show that oxidative damage may relate to the range of cognitive deficits associated with schizophrenia. In this study we examine one of the primary antioxidant defense enzymes manganese superoxide dismutase (MnSOD), and whether it relates to cognitive deficits in schizophrenia. We recruited 185 chronic male schizophrenia patients and 132 male controls and compared results from the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and plasma MnSOD activity between groups. Symptom severity in patients with schizophrenia was assessed with the Positive and Negative Syndrome Scale (PANSS). Our results showed that MnSOD activities were significantly lower in patients than controls (p<0.05). Cognitive scores on the RBANS and nearly all of its five subscales (all p<0.001) except for the Visuospatial/Constructional index were significantly lower in schizophrenia patients than normal controls. MnSOD was negatively correlated with the general psychopathology subscale of PANSS, PANSS total score, positive symptoms and RBANS total score in patients with schizophrenia. Our findings add to growing evidence that oxidative stress may be involved in the psychopathology of male schizophrenia, and its associated cognitive impairment.