engleski

Voxel-based Morphometry in Chronic Schizophrenia

Introduction: Schizophrenia (SCH) is a serious mental disorder without a clear etiology. Numerous molecular mechanisms are being examined in relation to the etiology of SCH. Some hypotheses reason that abnormalities in membrane phospholipids and cytokines affect oxidative and antioxidative processes in SCH, as changes in membrane phospholipids are associated with the intensity of symptoms and with specific clinical manifestations in SCH. Another hypothesis suggests that a decrease in the rate of cerebral protein synthesis is at the root of SCH (cerebral prothesis rate [CPSR] hypothesis). The CPSR hypothesis explains 96.7a of the major findings in SCH, reveals links between previously unrelated findings, and is able to integrate several important hypotheses. Central to the CPSR hypothesis is the assumption of a deficient protein synthesis rate, especially in the cortical and lymbic systems. Analyses of existing theories of schizophrenia showed discrepancies between well-proved facts and hypotheses (dopamine, neural development, synaptic plasticity, glutamate and viruses as etiologic entities) in the development of schizophrenia. The neurotoxic hypothesis of schizophrenia is based on the idea that psychosis is biologically toxic. The number of psychotic episodes in patients with chronic schizophrenia varies ; some patients have one or few psychotic episodes, while others have many. If we consider a psychotic episode a neurotoxic insult we should find severe brain abnormalities in patients with multiple episodes of schizophrenia. Voxel-based morphometry helps us detect brain regions that are affected by neurotoxic processes. Objectives: To investigate differences in gray matter volume (GMV) between patients with chronic schizophrenia and different numbers of psychotic episodes as well as non-schizophrenic controls (NC), using voxel-based morphometry (VBM). Patients and Methods: Patients were diagnosed according to DSM- IV-TR. The control group (NC) consisted of healthy individuals. All participants were from the same Croatian region. The study included 76 schizophrenic patients with disease duration longer than 8 years, grouped according the number of psychotic episodes (31 patients with up to 3 episodes and 45 patients with at least 4 episodes) and 63 NC. Voxel-based morphometry (VBM) is an adaption of the statistical parametric mapping technique that allows investigation of quantitative brain structural changes. VBM involves a voxel-wise comparison of the local concentration of gray matter between two groups of subjects. Voxel-wise parametric statistical tests which compare the smoothed gray-matter images from the two groups are performed. Results: Patients with up to 3 psychotic episodes, when compared to NC, had reduced GMV in the inferior frontal gyrus and prefrontal gyrus. Patients with at least 4 episodes, when compared to NC, revealed GMV reduction in cingulate bilaterally, middle frontal gyrus bilaterally, right medial frontal gyrus, left parahippocampal gyrus, left superior temporal gyrus, insula bilaterally, frontal sub-gyral gray matter, right posterior cingulate gray matter and right culmen. Conclusion: GMV reduction in schizophrenia varies depending on the number of psychotic episodes. The involvement of many more brain regions in patients with multiple episodes than in patients with less episodes indicates the existence of a neurotoxic effect induced by the psychotic state.

Schizophrenia ; Neuroimaging ; Neuroanatomy

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