Diffusion Tensor Imaging Findings in First-Episode and Chronic Schizophrenia Patients

Objective: Comparisons of diffusion tensor imaging (DTI) data between first-episode and chronic schizophrenia patients assessed in different studies have led to the suggestion that the decreased fractional anisotropy observed in chronic schizophrenia patients is less pronounced in first-episode patients. However, such comparisons of imaging data generated across studies are susceptible to numerous confounders, which may limit the interpretation of any differences. In order to address these issues and determine whether the DTI abnormalities of chronic schizophrenia are present at illness onset, the authors conducted a DTI investigation of the largest cohort of first-episode schizophrenia patients yet reported in conjunction with a group of chronic schizophrenia patients and healthy subjects for comparison. Method: Fractional anisotropy data generated by diffusion tensor imaging with a 3-T Siemens Allegra head-dedicated MRI system were compared between 40 first-episode schizophrenia patients and 39 age- and gender-matched healthy comparison subjects and between 40 chronic schizophrenia patients and 40 age- and gender-matched healthy comparison subjects. The following regions of interest were assessed: forceps minor (bilaterally), forceps major (bilaterally), inferior longitudinal fasciculus (bilaterally), and the genu and splenium of the corpus callosum. Results: In most regions, chronic schizophrenia patients showed significant or trend-level lower fractional anisotropy than healthy comparison subjects, whereas the first-episode schizophrenia patients showed only trend-level lower fractional anisotropy in the inferior longitudinal fasciculus. Conclusions: The cross-sectional data reported here suggest less widespread changes in white matter at illness onset in schizophrenia which progress in more chronic states. More definitive conclusions will require follow-up imaging of first-episode schizophrenia patients.