Serum levels of brain-derived neurotrophic factor and thiobarbituric acid reactive substances in chronically medicated schizophrenic patients: a positive correlation

OBJECTIVE: The neurotrophins, antioxidant enzymes and oxidative markers have reciprocal interactions. This report verified in chronically stable medicated schizophrenic patients whether there are correlations between the serum levels of superoxide dismutase, a key enzyme in the antioxidant defense, thiobarbituric acid reactive substances, a direct index of lipid peroxidation, and brain-derived neurotrophic factor, the most widely distributed neurotrophin. METHOD: Sixty DSM-IV schizophrenic patients were included (43 males, 17 females). Mean age was 34.7 +/- 10.8 years, mean age at first episode was 19.8 +/- 7.9 years, and mean illness duration was 14.9 +/- 8.5 years. Each subject had a blood sample collected for the determination of serum levels of brain-derived neurotrophic factor, thiobarbituric acid reactive substances and superoxide dismutase. RESULTS: Brain-derived neurotrophic factor levels showed a positive correlation with thiobarbituric acid reactive substances levels (r = 0.333, p = 0.009). Brain-derived neurotrophic factor levels were not correlated with superoxide dismutase levels (r = - 0.181, p = 0.166), and superoxide dismutase levels were not correlated with thiobarbituric acid reactive substances levels (r = 0.141, p = 0.284). CONCLUSIONS: The positive correlation between brain-derived neurotrophic factor and thiobarbituric acid reactive substances suggests the need of further investigation on intracellular interactions of neurotrophins, antioxidant enzymes and oxidative markers. In addition, this opens a venue for investigation on treatments for the prevention of neurotoxicity along the course of schizophrenia.