RESEARCH ARTICLE a i

Full list of author information is available at the end of the articleBackground Schizophrenia is a chronic psychiatric disorder and its etiology is not precisely known. A biomarker obtainable from peripheral tissues of schizophrenia patients would help to confirm the diagnosis and monitor its treatment. Mitochondrial function and cerebral energy metabolism abnormalities have been identified in patients with schi-zophrenia [1-4]. Impaired mitochondrial function ne-gatively affects neuronal plasticity, and causes cognitive deficits and behavioral abnormalities that can be observed during the clinical course of schizophrenia [5]. Some studies that examined brain tissue in schizo-phrenia patients reported an increase in activation of the mitochondrial complex, as compared to controls [6,7], whereas others reported a decrease [8,9]. Location and function of the brain tissue examined were important in the formation of these results. Changes in mitochondrial complex activation in brain tissues occur based on positive or negative symptoms of schizophrenia. For example, acti-vation of mitochondrial complex I subunits in prefrontal * Correspondence