[O-1-102] Relationship between cortical thickness and serum cortisol levels in major depressive disorder
Background and Objective: In major depressive disorder (MDD) patients, a higher daytime cortisol levels due to a hyperactive hypothalamic-pituitary-adrenal axis have been reported. Our aim was to evaluate the relationship between the cortical thinning and serum cortisol levels during the first depressive episode in drug-naive MDD patients using an automated surface-based morphometry (SBM) method.Materials and Methods: MR imaging data were obtained at a 3T scanner with 3D fast-spoiled gradient recalled acquisition with steady state (3D-FSPGR). Thirty drug-naive patients with MDD and 41 age- and gender-matched healthy subjects (controls) were enrolled. We then used the SBM method (Freesurfer) to generate cortical thickness maps and measured the cortical thickness in each subject. Morning blood samples were drawn from all participants for cortisol measurements. Results: The serum cortisol levels were significantly higher in the MDD patients than in the controls. The MDD patients manifested significant thinning of the left lateral orbitofrontal cortex compared with the controls. There was a significant negative linear correlation between the thickness of the left lateral orbitofrontal cortex and the serum cortisol level in the MDD patients. Conclusion: In the early stage of MDD, the thickness of the lateral orbitofrontal cortex was significantly reduced, and also showed a significant inverse correlation with the serum cortisol level. Since the lateral orbitofrontal cortex contains a high concentration of glucocorticoid receptor, glucocorticoid receptor-mediated neurotoxicity might occur under the high cortisol levels in MDD.