• major depressive disorder;
  • longitudinal study;
  • hippocampus;
  • magnetic resonance imaging

Ahdidan J, Hviid LB, Chakravarty MM, Ravnkilde B, Rosenberg R, Rodell A, Stødkilde-Jørgensen H, Videbech P. Longitudinal MR study of brain structure and hippocampus volume in major depressive disorder.

Objective:  To determine whether long-term course of treated major depression has an effect on the structure of the brain and the hippocampal volume.

Method:  An 11-year follow-up procedure was used with data collection at baseline and again at follow-up. Tensor-based morphometry (TBM) and automatic hippocampal volume measure was performed on different datasets. The baseline dataset consisted of T1-weighted magnetic resonance images (MRIs) of 24 in-patients suffering from major depression and 33 healthy controls. The second dataset consisted of T1-weighted MRIs of 31 remitted depressive patients and 36 healthy controls. The longitudinal dataset consisted of 19 patients and 19 matched healthy controls present at both the first and the second dataset. Brain segmentation and hippocampal segmentation were fully automated and were based on a spatial normalization to the International Consortium of Brain Mapping (ICBM) non-linear model.

Results:  Depressed patients were found to have smaller temporal lobes bilaterally, medulla and right hippocampus at baseline. However, these changes were not found at follow-up 11 years later. Moreover, these changes did not significantly correlate with the illness outcome.

Conclusion:  Brain structure changes seem to be state dependent in major depression, only occurring in acute episode of major depression and normalizing after remission.