The relationship between cognitive impairment and superoxide dismutase activity in untreated first-episode patients with schizophrenia

Abstract

Objectives: Cognitive decline is an essential characteristic of schizophrenia and may be due to the disturbance between reactive oxygen species generation and antioxidant capacity. The study aimed to explore the association between cognitive deficits and antioxidant defence parameters in untreated first-episode patients with schizophrenia.

Methods: We determined important antioxidant enzymes, total superoxide dismutase (SOD) and manganese SOD (MnSOD), and their relationship with cognitive impairment in 168 untreated patients with first-episode schizophrenia and 168 age- and sex-matched healthy controls. The evaluation of psychopathological symptoms of all patients was based on the Positive and Negative Syndrome Scale (PANSS). We measured cognitive function by the Repeated Battery for the Assessment of Neuropsychological Status (RBANS) and activities of total SOD and MnSOD in all participants.

Results: The results showed that untreated patients with first-episode schizophrenia had deficient cognitive functioning in four RBANS indices and total scores, except for the visuospatial/constructional index, as well as higher plasma total SOD activity compared with the control subjects. In addition, significant negative correlations were identified between MnSOD activity and attention index or RBANS total score in patients.

Conclusions: Our results suggest that oxidative stress may be partly responsible for cognitive dysfunction in the early course of schizophrenia.

Keywords:

• Schizophrenia
• cognition
• superoxide dismutase
• first-episode
• oxidative stress

Acknowledgments

We sincerely thank the subjects whose participation made this study possible.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author.

Additional information

Funding

This work was supported by the National Key Research and Development Program of China under Grant [2017YFC1310405]; CAS Pioneer Hundred Talents Program; the National Natural Science Foundation of China under Grant [81371477]; and the CAS Key Lab of Mental Health.