Abstract
BackgroundThe key pathophysiological mechanism of executive dysfunction in patients with bipolar disorder type I (BD-I) is still unclear. Previous studies have demonstrated that it may be related to the disbalance of the sensory motor network (SMN).ObjectiveThis study was designed to explore the aberrant functional connectivity (FC) of SMN in BD-I patients and its potential associations with executive dysfunction.MethodsEighteen BD-I patients and 20 healthy controls (HCs) underwent resting-state fMRI scans. The intranetwork and internetwork functional connectivities of SMN were extracted by independent component analysis (ICA). Clinical symptoms were assessed by the Bech–Rafaelsen Mania Rating Scale (BRMS) and Positive and Negative Syndrome Scale (PANSS). Executive function was measured by digit span tasks and a verbal fluency test. Finally, linear regression and correlation analyses were applied to measure the potential associations between clinical symptoms, intranetwork and internetwork functional connectivities, and executive function performance.Results(1) Patients with BD-I showed increased connectivity in the right paracentral lobule and the right postcentral gyrus within the SMN, and the increased connectivity value was positively correlated with the BRMS score (P < 0.05) but negatively correlated with digit span forward scores (P < 0.05). (2) Compared with HC, the connectivity value increased between the SMN and dorsal attention network (DAN) (P < 0.01) and between the default mode network (DMN) and DAN (P < 0.05) but decreased between the DAN and auditory network (AN) (P < 0.05) and between the SMN and DMN (P < 0.01) in patients with BD-I. (3) Digit span forward scores and education of all participants were negatively correlated with FC between SMN and DAN. Age of all subjects was positively correlated with FC between SMN and DMN.ConclusionOur findings suggest that the sensorimotor network of BD-I has abnormal functional connections within and between networks, and the abnormal FC value correlated with clinical symptoms and executive function, which provide new information for exploring the neural physiopathology of executive dysfunction in BD-I patients.
Highlights
Bipolar disorder (BD) is a type of mood disorder characterized by the core feature of recurrence of mania (BD type I, BDI) or hypomania (BD type II, BD-II) and depressive episodes with high disability and high burden (Hahn et al, 2014)
Peters et al (2020) probed the network of major depressive disorder and BD, and the results showed that memory impairment displays a central role in the cognitive impairment of patients with unipolar depression, whereas executive dysfunction appears to be more central in bipolar depression
The other seven components were separately identified as the default mode network (DMN), right frontoparietal network (rFPN), dorsal attention network (DAN), auditory network (AN), and visual network (VN)
Summary
Bipolar disorder (BD) is a type of mood disorder characterized by the core feature of recurrence of mania (BD type I, BDI) or hypomania (BD type II, BD-II) and depressive episodes with high disability and high burden (Hahn et al, 2014). Most of the findings show that BD, especially bipolar disorder type I (BD-I), is associated with deficits in cognitive functions, in executive function, which correlated with the ability to integrate various skills to prepare for and execute complex behaviors (Ozonoff et al, 2004; Elshahawi et al, 2011; Liu et al, 2011; Peters et al, 2014; Drakopoulos et al, 2020). Peters et al (2020) probed the network of major depressive disorder and BD, and the results showed that memory impairment displays a central role in the cognitive impairment of patients with unipolar depression, whereas executive dysfunction appears to be more central in bipolar depression. The key pathophysiological mechanism of executive dysfunction in patients with bipolar disorder type I (BD-I) is still unclear. Previous studies have demonstrated that it may be related to the disbalance of the sensory motor network (SMN)
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