Diffusion tensor imaging study of periventricular and cortico-cortical white matter dysconnectivty in never-medicated schizophrenia

Abstract

BACKGROUND: DTI studies of schizophrenia have shown compromised white matter tract integrity but most recruited chronic patients who were already on neuroleptic medication (Kanaan et al 2005). These may represent important confounders. METHODS: Therefore, we recruited 30 never-medicated subjects with first-episode schizophrenia compared to 21 healthy controls, balanced for age, gender, handedness, ethnicity. DTI scans were acquired according to standard protocol using single-shot spin-echo echo-planar imaging with TR=10000 ms, TE=100 ms, acquisition matrix=128 x 128, FOV 28 cm, slice thickness 5 mm, 1.5 mm gap, throughout entire brain. Diffusion-sensitizing gradient encoding was applied in 25 directions, diffusion-weighted factor b=1200 s/mm2. 26 images were obtained at each section, 468 or 494 images in total. Pre-processing was conducted in SPM2 according to Good’s method, including modulation to correct for deformation factors. Voxel-based analysis (VBA) was used to compare fractional anisotropy maps between groups. RESULTS: We found significant decrease in fractional anisotropy in the patients compared to the controls (FDR or false discovery rate pb0.02, corrected) bilaterally in the internal capsules, anterior cinguli, right fronto-occipital fasciculi, genu of the corpus callosum, superior and medial prefrontal cortex. CONCLUSIONS: This is the first study of never-medicated first episode schizophrenia to show striking white periventricular and cortico-cortical white matter dysconnectivity in the brain.