Differential impacts of endogenous antioxidants on clinical symptoms and cognitive function in acute and chronic schizophrenia patients.

Abstract

Impaired antioxidant defense is implicated in the pathophysiology of schizophrenia; and superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) are three first-line endogenous antioxidants. Various cognitive functions decline differently during schizophrenia course. The characteristic roles of the three antioxidants in clinical and cognitive profiles in acute and chronic phases of schizophrenia require study. We recruited 311 patients with schizophrenia, including 92 acutely exacerbated patients who had been off antipsychotics for at least 2 weeks and 219 chronic patients who had been stable on medication for at least 2 months. Blood SOD, CAT, and GSH, clinical symptoms, and nine cognitive tests were measured. Blood CAT levels were higher in the acute patients than in the chronic patients, while SOD and GSH levels were similar between them. Higher CAT levels were correlated with less positive symptoms, better working memory and problem solving in the acute phase, and less negative symptoms, less general psychopathology, better global assessment of function (GAF), and better cognitive function (in speed of processing, attention, problem solving) in the chronic period. Higher SOD levels were correlated with better GAF in the acute phase, and better speed of processing, working memory, and verbal learning and memory in the chronic period. GSH influenced neither clinical nor cognitive manifestations. This study showed that blood CAT affected different clinical and cognitive domains between acute and chronic stages of schizophrenia, SOD influenced cognitive functions in chronic state, but GSH impacted none. Further studies are needed to explore the underlying mechanisms.