Left Cerebral Cortex Complexity in Patients with Major Depression Disorder: A Small-Sample Pilot Study

To investigate cerebral cortical complexity (CCC) in patients with first-episode, drug-naive major depressive disorder (MDD) with source-based morphometry (SBM) analyses.

We used the SBM parameters gyrification index (GI) and fractal dimension (FD) to evaluate CCC in 14 first-episode, drug-naive patients diagnosed with MDD. The severity of depression symptoms was assessed with the 17-item Hamilton Depression Scale (HAMD-17). GI and FD alterations in the MDD group, relative to healthy controls (HCs), were correlated with depression symptom severity with GI/FD.

Increased GIs in the MDD group, relative to HCs, were found mainly in the left postcentral gyrus, whereas GI reductions were found in the left angular gyrus, left lingual gyrus, left superior temporal gyrus, and left insular cortex. Increased FDs in the MDD group, relative to HCs, were located in the superior frontal gyrus. In contrast, decreased FDs were located in the left superior temporal gyrus and left superior frontal gyrus.

Although the group differences in GI and FD values obtained did not withstand family-wise error (FWE) correction, the results show a consistent trend of alterations in left-hemisphere CCC in first-episode, drug-naive patients diagnosed with MDD. These findings support the hypothesis that there is a pattern of subtle neocortical aberrations in early-stage MDD.