Oxidative stress linked to NSS severity in schizophrenia

By Mark Cowen

The severity of neurologic soft signs (NSS) negatively correlates with antioxidant superoxide dismutase activity in patients with schizophrenia, research shows.

"These results may support the potential role of oxidative stress in the determinism of NSS in schizophrenia," write Anwar Mechri (Teaching Hospital of Monastir, Tunisia) and colleagues in Progress in Neuro-Psychopharmacology and Biological Psychiatry.

The team investigated the relationship between antioxidant enzyme activity and NSS in 60 stable patients with schizophrenia and in 30 age- and gender-matched mentally healthy controls.

The mean age of the schizophrenia patients was 32 years and most had received treatment with first-generation antipsychotics, the researchers note.

All of the participants were assessed for NSS using a standardized scale composed of 23 items rated from 0 to 3 and regrouped into five subscales: motor coordination, motor integration, sensory integration, quality of lateralization, and involuntary movements.

Blood samples collected from the participants were analysed for superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) antioxidant activity using spectrophotometry.

The team found that the mean total NSS score was significantly higher in schizophrenia patients than controls, at 19.5 versus 4.2, as were all NSS subscale scores.

Schizophrenia patients also showed reduced SOD, GSH-Px, and CAT antioxidant activity in red blood cells compared with controls, at 1.7 versus 2.4 IU/mg hemoglobin (Hb), 28.3 versus 37.9 IU/g Hb, and 164.0 versus 209.7 IU/g Hb, respectively.

In the schizophrenia patients, there was a negative correlation between SOD activity and NSS total scores, as well as between SOD activity and NSS subscale scores for motor coordination and motor integration.

Mechri and team conclude: "The association between low SOD activity, as a marker of oxidative stress, and NSS, especially motor signs, in schizophrenic patients suggests a common pathological process of these abnormalities."

They add that "although these findings need to be replicated, they may have important implications for studies of oxidative stress and neurodevelopment in schizophrenia."

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