Altered cortical thickness related to clinical severity but not the untreated disease duration in schizophrenia

Although previous studies have reported deficits in the gray matter volume of schizophrenic patients, it remains unclear whether these deficits occur at the onset of the disease, before treatment, and whether they are progressive over the duration of untreated disease. Furthermore, the gray matter volume represents the combinations of cortical thickness and surface area; these features are believed to be influenced by different genetic factors. However, cortical thickness and surface area in antipsychotic-naive first-episode schizophrenic patients have seldom been investigated. Here, the cortical thicknesses and surface areas of 128 antipsychotic-naive first-episode schizophrenic patients were compared with 128 healthy controls. The patients exhibited significantly lower cortical thickness, primarily in the bilateral prefrontal and parietal cortex, and increased thickness in the bilateral anterior temporal lobes, left medial orbitofrontal cortex, and left cuneus. Furthermore, decreased cortical thickness was related to positive schizophrenia symptoms but not to the severity of negative symptoms and the untreated disease duration. No significant difference of surface area was observed between the 2 groups. Thus, without the confounding factors of medication and illness progression, this study provides further evidence to support anatomical deficits in the prefrontal and parietal cortex early in course of the illness. The increased thicknesses of the bilateral anterior temporal lobes may represent a compensatory factor or may be an early-course neuronal pathology caused by preapoptotic osmotic changes or hypertrophy. Furthermore, these anatomical deficits are crucial to the pathogenesis of positive symptoms and relatively stable instead of progressing during the early stages of the disease.