Insular subdivisions functional connectivity in patients with major depressive disorder: a resting-state functional magnetic resonance imaging study

Abstract

Objective To provide a basic profile of resting-state functional connectivity (FC) in unmedicated patients with major depressive disorder (MDD). Methods Fifty unmedicated patients with MDD and 51 healthy controls underwent the resting-state functional magnetic resonance imaging (rs-fMRI). After preprocessing of rs-fMRI, the seed-based resting-state FC of the insular subdivisions, including the anterior insula, middle insula, and posterior insula, was evaluated. Two-sample t-test and multiple comparison correction of Threshold-Free Cluster Enhancement (TFCE) were used to compare the FC values of each group to locate the regions with significant change, where its correlation to the Hamilton Depression Scale (HAMD24) scores was also explored. Results In comparison to the healthy controls, the MDD patients decreased FC between the left anterior insula and bilateral anterior cingulate cortices (t=-4.83, P<0.05, TFCE correction), and increased FC between the left anterior insula and the left middle frontal gyrus, as well as the bilateral posterior cingulate cortices/precuneus (t=4.08, 4.42; both P<0.05, TFCE correction). There were no significant correlations between the HAMD24 scores and the FC values from the left anterior insula to the bilateral anterior cingulate cortices (r=-0.125, P=0.387), the left middle frontal gyrus (r=0.149, P=0.302), and the bilateral posterior cingulate cortices/precuneus (r=-0.207, P=0.148). Conclusion Patients with depression have abnormal functional connectivity between the left anterior insula and the other two regions, such as the limbic system and the frontal cortex, which may present with an aweakened insula-anterior cingulate gyrus connectivity, and the enhanced insular-frontal, and insula-posterior cingulate/precuneus connectivity. Key words: Depressive disorder; Magnetic resonance imaging; Cerebral cortex