Cortical abnormalities and association with symptom dimensions across the depressive spectrum

Background: Few studies have investigated the relationship between structural brain abnormalities and dimensions of depressive symptomatology.

Methods: In the current study, we examined the relationship between cortical structural abnormalities and specific behavioral dimensions relevant to depression in a sample of unmedicated patients with major depressive disorder (MDD, n=57) and demographically similar healthy control volunteers (HC, n=29). All subjects underwent diagnostic assessment with the SCID, MRI at 3T, and dimensional assessments using the visual analog scales (VAS). Cortical regions were extracted for each subject, and group comparisons of cortical volume (CV), surface area (SA), and cortical thickness (CT) were performed controlling for multiple comparisons using a bootstrapping technique. Regions demonstrating group differences were analyzed for correlation with specific dimensions assessments.

Results: As compared with HC, MDD subjects exhibited reduced CV within the left supramarginal gyrus, right ventrolateral prefrontal cortex (VLPFC), entorhinal cortex, parahippocampal gyrus, fusiform gyrus and pericalcarine; reduced SA in the right VLPFC, cuneus, and left temporal pole; and reduced CT in the right rostral anterior cingulate cortex (rACC) (all p's<0.05, corrected). The largest effect occurred within the right VLPFC for CV and SA (MDD<HC; effect sizes: 0.60). CV in the right VLPFC inversely correlated with sadness, fatigue and worry; CT in the right rACC inversely correlated with irritability and fatigue.

Limitations: Future studies will be required to further map the anatomical changes in depression to behavioral dimensions.

Conclusions: Our results indicate that specific cortical abnormalities are associated with specific behavioral components linked to depression.