Structural brain abnormalities common to posttraumatic stress disorder and depression

Background: Posttraumatic stress disorder (PTSD) and major depression are reliably associated with reductions in brain volume in markedly similar areas. To our knowledge, no volumetric studies have directly contrasted these conditions. We investigated which, if any, grey matter reductions would be uniquely associated with each disorder. We also investigated more subtle independent effects: specifically, correlations between brain volume and self-report measures of psychopathology. Methods: We obtained structural magnetic resonance imaging scans from participants with PTSD, major depression and healthy controls exposed to trauma. Participants completed standardized self-report measures of anxiety and depression. We used voxel-based morphometry, applying the DARTEL algorithm within SPM5 to identify associated volumetric changes. Results: We enrolled 24 patients with PTSD, 29 with major depression and 29 controls in our study. The clinical groups had regions of markedly smaller volume compared with the control group, particularly in prefrontal areas, but did not differ from each other. Greater self-reported anxiety was inversely related to volume in several areas, particularly the inferior temporal cortex, among patients with PTSD, but was associated with some volume increases in patients with major depression. Greater self-reported depression showed similar but weaker effects, being inversely related to brain volume in patients with PTSD but positively related to volume in the cuneus and precuneus of those with major depression. Limitations: To maintain the representativeness of the sample, patients with PTSD were not excluded if they had typical comorbid conditions, such as depression. Patients were not all medication-free, but we controlled for group differences in antidepressant use in the analyses. Conclusion: We identified commonalities in areas of brain volume in patients with PTSD and those with major depression, suggesting that existing findings concerning reductions in prefrontal areas in particular may not be specific to PTSD but rather related to features of the disorder that are shared with other conditions, such as depression. More subtle differences between patients with PTSD and those with major depression were represented by distinct structural correlates of self-reported anxiety and depression.