Antioxidant defense reduced in schizophrenia, bipolar disorder

By Mark Cowen, Senior medwireNews Reporter

Results from a Tunisian study suggest that the antioxidant defense system is altered in patients with schizophrenia and bipolar disorder (BD).

Anwar Mechri (University of Monastir) and team found that schizophrenia and BD patients had lower total glutathione (GSHt) levels and lower levels of reduced glutathione (GSHr) than mentally healthy individuals (controls).

Furthermore, the activity of certain antioxidant enzymes was reduced in patients compared with controls.

"The GSH deficit may be an important indirect biomarker of the oxidative stress in schizophrenia and BD," comment the authors in Progress in Neuro-Psychopharmacology and Biological Psychiatry.

The team studied 46 schizophrenia patients (mean age 33.2 years), 30 BD patients (mean age 31.3 years) and 40 controls (mean age 32.3 years).

Blood samples were collected from all of the participants and assessed for levels of GSHt, GSHr, oxidized glutathione, superoxide dismutase (SOD), glutathione peroxidase, and catalase.

The researchers found that schizophrenia and BD patients had significantly lower mean GSHt levels than controls, at 601.64 and 552.21 versus 826.15 µmol/L, respectively, and lower levels of GSHr, at 579.85 and 526.53 versus 794.91 µmol/L, respectively.

Furthermore, SOD activity levels were significantly lower in schizophrenia patients compared with BD patients and controls, at 1.63 versus 2.17 and 2.35 U/mg Hb, respectively, as were catalase activity levels, at 146.9 versus 216.05 and 285.15 U/mg Hb, respectively. The difference between BD patients and controls regarding catalase levels was also significant.

There were no significant differences among the groups regarding glutathione peroxidase activity levels.

Mechri and team conclude: "The results of the current study show that there is an alteration of the antioxidant defence system in schizophrenia and BD."

They add: "The suggested link that exists between a disturbed antioxidant defence system and the physiopathology of schizophrenia and BD provides a theoretical basis to develop novel therapeutic strategies, such as, the supplementation of glutathione precursor or other antioxidants."

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