Insula and amygdala resting‐state functional connectivity differentiate bipolar from unipolar depression

Abstract

Objective Distinguishing depressive episodes due to bipolar disorder (BD) or major depressive disorder (MDD) solely on clinical grounds is challenging. We aimed at comparing resting-state functional connectivity (rsFC) of regions subserving emotional regulation in similarly depressed BD and MDD. Method We enrolled 76 inpatients (BD, n=36; MDD, n=40), and healthy controls (HC, n=40). A seed-based approach was used to identify regions showing different rsFC with the insula and the amygdala. Insular and amygdalar parcellations were then performed along with diagnostic accuracy of the main findings. Results Lower rsFC between the left insula and the left mid-dorsolateral prefrontal cortex and between bilateral insula and right frontopolar prefrontal cortex (FPPFC) were observed in BD compared to MDD and HC. These results were driven by the dorsal anterior and posterior insula (PI). Lower rsFC between the right amygdala and the left anterior hippocampus was observed in MDD compared to BD and HC. These results were driven by the centromedial and laterobasal amygdala. Left PI/right FPPC rsFC showed 78% accuracy differentiating BD and MDD. Conclusion Amygdalar and insular rsFC distinguished between depressed BD and MDD. The observed differences suggest the possibility of differential pathophysiological mechanisms of emotional dysfunction in bipolar and unipolar depression.

The metabolic basis of psychosis in bipolar disorder: A positron emission tomography study

“…Additionally, we found that both disorders shared common FDG uptake alterations in insula compared to HC, which is in line with previous evidence reporting insula as a key region associated with BD and mood disorders in general . This structure seems to be responsible for the detection of emotional salience and the integration of sensory, emotional and cognitive information and it is a critical node within the salience network, along with amygdala and anterior cingulate cortex .…”

Aberrant brain network topology in fronto‐limbic circuitry differentiates euthymic bipolar disorder from recurrent major depressive disorder

“…These findings indicate that the aforementioned nodes are more integrated into the brain network of BD patients than in networks of individuals not suffering from BD, possibly leading to a disturbed perception of emotions in BD. Changes in the limbic system supporting our results were both found in resting‐state paradigms (Ambrosi et al, ; Anand et al, ; Lois, Linke, & Wessa, ; Wang, Wang, Jia, Zhong, Zhong et al, ) as well as in task‐based paradigms (Gruber et al, ; Strakowski, Adler, Holland, Mills, & DelBello, ; Thermenos et al, ; Townsend & Altshuler, ). In most studies, irregularities were registered in the frontal lobes along with temporal and subcortical regions such as hippocampus and basal ganglia.…”

“…These findings indicate that the aforementioned nodes are more integrated into the brain network of BD patients than in networks of individuals not suffering from BD, possibly leading to a disturbed perception of emotions in BD. Changes in the limbic system supporting our results were both found in resting-state paradigms(Ambrosi et al, 2017;Anand et al, 2009;Lois, Linke, & Wessa, 2014; as well as in task-based paradigms…”

Classifying suicidal behavior with resting‐state functional connectivity and structural neuroimaging

“…Psychiatric inpatients ( N = 423) were recruited from the Menninger Clinic in Houston, Texas as a part of the McNair Initiative for Neuroscience Discovery—Menninger/Baylor (MIND‐MB) research study . Inpatients were eligible if mentally stable enough to participate, had no contraindications for magnetic resonance imaging (MRI), and gave signed, informed consent (procedures were approved by the Institutional Review Board).…”