Regional gray matter changes in major depressive disorder: an optimized voxel-based morphometry study

Introduction Voxel based morphometry (VBM) is a neuroimaging analysis technique that allows investigation of focal differences in brain anatomy, using the statistical approach of so-called statistical parametric mapping [1,2]. Major depressive disorder (MDD) is a common and serious psychiatric illness. In past study, the authors have done many researches to reveal the change in grey matter [3-7]. However, the neurobiology of MDD is largely unknown. The purpose of the present study was to identify brain regions with gray matter volume and density changes with relative large MDD subjects and controls using optimized voxel-based morphometry. Material and Method Fifty one patients experiencing MDD (mean age = 34.6 ± 12.7, twenty five males and twenty eight females) according to the diagnostic criterion of DSM-IV, who had a score of 18 or greater on the 17-item Hamilton Depression Rating Scale (HAMD), and fifty two age and sex matched normal controls (mean age = 37.2 ± 16.1, twenty three males and twenty eight females) were recruited. MR scanning was carried out on a 3.0 TMR scanner (EXCITE, GE Signa, Milwaukee, USA). High resolution 3-dimensional T1-weighted (T1W) images were acquired employing a spoiled gradient recalled (SPGR) sequence with TR/TE = 8.5/3.4 ms, FA = 120, 156 axial slices with thickness = 1 mm, axial FOV 24 × 24 cm and data matrix = 256 × 256. Optimized voxel-based morphometry [2] was conducted using Statistical Parametric Mapping–2 (SPM2) (Welcome Department of Imaging Neuroscience, London [http://www.fil.ion.ucl.ac.uk/spm]). The voxel-based morphometry–2 toolbox, which implements the optimized voxel-based morphometry approach [2], was used for data preprocessing. Voxel-by-voxel-based comparisons of gray matter density and volume were performed between groups using two-sample t tests. The correlation between the regional gray matter changes and clinical symptom severity was examined. A corrected p value of less than 0.001 was deemed to be significant. Results Patients with MDD exhibited higher grey matter volume than normal controls in multiple brain regions including bilateral thalamus, left and right superior parietal lobule, right frontal lobe (Table 1, Figure 1 A, B and C). MDD patients also showed higher grey matter density than normal controls in bilateral thalamus (cluster level p < 0.001, corrected) (Table 1, Figure 1 D). No significant correlation between regional gray matter changes and HAMD scores was found after controlling for age, years of education and duration of illness.