Increased oxidative stress in the anterior cingulate cortex of subjects with bipolar disorder and schizophrenia

Background: Recent studies indicate the presence of mitochondrial dysfunction in brains of subjects with bipolar disorder (BD). Because the mitochondrial electron transport chain is a major source for production of reactive oxygen species that cause oxidative stress, we sought to determine in the present study if BD is associated with oxidative stress. Methods: Postmortem anterior cingulate brain sections from subjects with BD, major depressive disorder (MDD), or schizophrenia, and from nonpsychiatric, non-neurologic comparison controls were generously provided by the Stanley Foundation Neuropathology Consortium. Oxidative stress was determined by analyzing 4-hydroxynonenal (4-HNE), a major product of lipid peroxidation. The level of 4-HNE was determined by measuring 4-HNE protein adducts using immunohistochemistry. Results: We found that 4-HNE levels were significantly increased by 59% in BD subjects and by 47% in schizophrenia subjects, but not in MDD subjects, when compared with controls. Levels of 4-HNE were negatively correlated with pH in all 60 subjects. When pH was used as covariate, 4-HNE levels were still significantly increased in BD subjects when compared with controls. Further, 4-HNE levels were significantly correlated with pH values only in BD subjects, but not in MDD, schizophrenia, or control subjects. Conclusions: Oxidative damage in the brain may contribute in part to the pathological process in BD and schizophrenia. This finding also suggests antioxidative stress as a probable alternative approach to the pharmacological treatment of these psychiatric disorders.