Schizophrenia is a disabling psychiatric disorder characterized by positive symptoms, such as hallucinations and delusions, negative symptoms, such as decreased expression ability, and cognitive defects, such as impaired executive function and memory ability. Excessive oxidative stress and dysregulated antioxidant defense system have been proposed to be important risk factors for schizophrenia. The activities of superoxide dismutase (SOD), an important antioxidant enzyme, were found to be abnormal in patients with schizophrenia.

Previous studies have shown sex differences in disease risk, course and outcome of schizophrenia. Moreover, some animal studies have reported sex differences in oxidative stress markers. However, no studies have explored the sex difference in the association between SOD activity and clinical symptoms in patients with schizophrenia.

Recently, Dr. WANG Dongmei and her colleagues, under the guidance of Prof. ZHANG Xiangyang, from the Institute of Psychology of the Chinese Academy of Sciences, explored the sex differences in clinical characteristics and SOD activity as well as their relationship in never-treated first-episode (NTFE) patients with schizophrenia in the Han Chinese population.

165 NTFE patients with schizophrenia and 133 healthy controls were recruited. Further, the researchers examined their total SOD and manganese SOD (MnSOD) activities, and evaluated the psychopathological symptoms by a five-factor model of the Positive and Negative Syndrome Scale (PANSS).

"Depressive factor was positively correlated with MnSOD and total SOD activity in male patients, while PANSS positive symptom was independently correlated with MnSOD activity in female patients," said Dr. WANG. 

"There were sex differences in the association between SOD activity and clinical phenotype in NTFE patients with schizophrenia, sex is one of the important factors in evaluating the relationship between antioxidant activity and clinical psychopathological symptoms in patients with schizophrenia," she said.

This work was published online in The World Journal of Biological Psychiatry on August 27th, 2020 entitled "Sex differences in the association between symptoms and superoxide dismutase in patients with never-treated first-episode schizophrenia".

It was funded by the National Key Research and Development Program of China, related CAS Program, the National Natural Science Foundation of China and the CAS Key Lab of Mental Health.