Association between Cortical Gyrification and Major Depression: Clinical Correlates

Major depressive disorder (MDD) is one of the most frequent psychiatric diseases worldwide. Growing evidence suggests that cortical gyrification measures may present an early risk marker for depression. Medial views of cortical surface reconstructions provide the basis for a simple, expert-rated measure of cortical gyrification. In this study, we examined left anterior cingulate cortex (ACC) gyrification as a potential marker of MDD. We selected this region of interest based on the limbic-cortical dysregulation model of depression and prior research results.

In a sample of 386 healthy and depressed young adults (147 with MDD), experts rated ACC gyrification using structural MRI reconstructions. Gyrification patterns were compared on clinical (e.g., MDD status), MRI (e.g., automatically derived region-wise curvature and volumetric variables), and psychological outcomes (e.g., personality questionnaire scores).

One-third of subjects exhibited two anteroposterior gyri in the left hemisphere, whereas the other subjects exhibited one longitudinal gyrus or longitudinal gyrification was interrupted. Subjects with the fewer-gyri left ACC variant more often experienced MDD at some point in their lifetime (p = 0.048). Moreover, among all subjects with MDD, disorder onset happened earlier in subjects with the fewer gyri variant (d = -0.30), hinting at early developmental contributions to the phenotypic marker. In addition, subjects with fewer longitudinal gyri scored higher on neuroticism (η2 = 0.02), but not on extraversion. Automatically derived measures of gyrification and cortical surface area were largely consistent with the differences observed using the expert rater-based gyrification measure.

Future studies should investigate left ACC gyrification and, to what extent, it exists in at-risk subjects, further elucidating it with ACC structural and functional connectivity measures.