Meta-analysis of cortical thickness abnormalities in medication-free patients with major depressive disorder

Abstract

Alterations in cortical thickness have been identified in major depressive disorder (MDD), but findings have been variable and inconsistent. To date, no reliable tools have been available for the meta-analysis of surface-based morphometric (SBM) studies to effectively characterize what has been learned in previous studies, and drug treatments may have differentially impacted findings. We conducted a comprehensive meta-analysis of magnetic resonance imaging (MRI) studies that explored cortical thickness in medication-free patients with MDD, using a newly developed meta-analytic mask compatible with seed-based d mapping (SDM) meta-analytic software. We performed the meta-regression to explore the effects of demographics and clinical characteristics on variation in cortical thickness in MDD. Fifteen studies describing 529 patients and 586 healthy controls (HCs) were included. Medication-free patients with MDD, relative to HCs, showed a complex pattern of increased cortical thickness in some areas (posterior cingulate cortex, ventromedial prefrontal cortex, and anterior cingulate cortex) and decreased cortical thickness in others (gyrus rectus, orbital segment of the superior frontal gyrus, and middle temporal gyrus). Most findings in the whole sample analysis were confirmed in a meta-analysis of studies recruiting medication-naive patients. Using the new mask specifically developed for SBM studies, this SDM meta-analysis provides evidence for regional cortical thickness alterations in MDD, mainly involving increased cortical thickness in the default mode network and decreased cortical thickness in the orbitofrontal and temporal cortex.

Fig. 1

The demonstration of the newly created mask and the mask of gray matter previously available in SDM software. The demonstration of the newly created mask special for meta-analyzing the surface-based morphometric studies in the present study (a) and the existing mask of gray matter for meta-analyzing voxel-based structural studies in SDM software (b)

Fig. 2

Flowchart of literature search and selection criteria. Search terms were (depression OR depressive disorder OR unipolar depression) AND (cortical thickness OR thickness)

Fig. 3

Cortical thickness alterations in medication-free patients with major depressive disorder compared with healthy controls. Regions of increased (warm color) and decreased (cool color) cortical thickness in medication-free patients with MDD than HCs in the pooled meta-analysis. ACC, anterior cingulate cortex; GR, gyrus rectus; L, left; oSFG, orbital segment of the superior frontal gyrus; PCC, posterior cingulate cortex; vmPFC, ventromedial prefrontal cortex; MTG; middle temporal gyrus; R, right

Fig. 4

The results of meta-regression analysis. The percentage of female patients with the major depressive disorder was negatively correlated with cortical thickness in the left gyrus rectus in the meta-regression. The effect sizes to create this plot were extracted from the peak of the maximum slope difference and each study is represented as a dot. The regression line (meta-regression signed differential mapping slope) is shown