Functional Connectivity of the Anterior Cingulate Cortex and the Right Anterior Insula Differentiates between Major Depressive Disorder, Bipolar Disorder and Healthy Controls

Abstract

Background: This study aimed to explore possible differences of the whole-brain functional connectivity of the anterior cingulate cortex (ACC) and anterior insula (AI), in a sample of depressed patients with major depressive disorder (MDD), bipolar disorder (BD) and healthy controls (HC). Methods: A hundred and three subjects (nMDD = 35, nBD = 25, and nHC = 43) between the ages of eighteen and sixty-five years old underwent functional magnetic resonance imaging. The CONN Toolbox was used to process and analyze the functional connectivity of the ACC and AI. Results: The comparison between the patients (MDD/BD) and HC yielded increased resting-state functional connectivity (rsFC) between the ACC and the motor and somatosensory cortices (SSC), superior parietal lobule (SPL), precuneus, and lateral occipital cortex, which was driven by the BD group. In addition, hyperconnectivity between the right AI and the motor and SSC was found in BD, as compared to HC. In MDD, as compared to HC, hyperconnectivity between ACC and SPL and the lateral occipital cortex was found, with no statistical rsFC differences for the AI seed. Compared to BD, the MDD group showed ACC–cerebellum hyperconnectivity and a trend for increased rsFC between the right AI and the bilateral superior frontal cortex. Conclusions: Considering the observed hyperconnectivity between the ACC/somatosensory cortex in the patient group, we suggest depression may be related to an impairment of the sensory-discriminative function of the SSC, which results in the phenomenological signature of mental pain in both MDD and BD. These findings suggest that future research should investigate this particular network with respect to motor functions and executive control, as a potential differential diagnostic biomarker for MDD and BD.

Degeneracy and disordered brain networks in psychiatric patients using multivariate structural covariance analyzes

“…The postcentral gyrus, on the other hand, has been linked with the sensory-discriminative component of pain. In a previous study our research group found increased resting-state functional connectivity between the ACC and the postcentral gyrus in patients with depression in the context of both MDD and BD as opposed to healthy controls and we hypothesized that this finding may be interpreted as an impairment reflecting the signature of mental pain in depression ( 63 ). Moreover, a reduction of the gray-matter volume of the subgenual ACC was demonstrated in MDD but not in BD and healthy individuals which further supports the significance of this region for the etiopathophysiology of MDD ( 64 ).…”

The Cerebellum’s Role in Affective Disorders: The Onset of Its Social Dimension

“…When the connections between the insula, cerebral cortex and Cbm are altered, emotions have a lesser positive impact on mood that tends, therefore, to subside [76]. Along with the insula, an additional brain area fundamental to the affective sphere is represented by the anterior cingulate cortex [94]. In this regard, it has been observed that patients with MDD exhibit a volumetric reduction of the grey matter at the level of this area, unlike those diagnosed with BD in which this decrease is evidenced in the Hip and Amg [94].…”

“…Along with the insula, an additional brain area fundamental to the affective sphere is represented by the anterior cingulate cortex [94]. In this regard, it has been observed that patients with MDD exhibit a volumetric reduction of the grey matter at the level of this area, unlike those diagnosed with BD in which this decrease is evidenced in the Hip and Amg [94]. At the cerebellar level, the anterior cingulate cortex establishes relationships with both Crus I and Crus II, and in case of BD, these connections show reduced functional connectivity by confirming, once again, that the role of the Cbm cannot be limited to motor functions [94].…”

Integrated analysis of transcriptional changes in major depressive disorder: Insights from blood and anterior cingulate cortex

“…Many neuroimaging studies observed the abnormal functional connectivity in ACC of MDD patients [ 8 , 9 ]. For example, a study from Bulgaria found the hyperconnectivity was existed between ACC and superior parietal lobule, lateral occipital cortex in MDD patients [ 10 ]. Another study found MDD patients emerged hyper-responses to loss outcomes in the ventral ACC [ 11 ].…”