Aberrant resting-state functional network centrality and cognitive impairment in unmedicated, euthymic bipolar patients.

Background: Cognitive impairment is prevalent in bipolar disorder (BD), and has negative impacts on functional impairments and quality of life, despite euthymic states in most individuals. The underlying neurobiological basis of cognitive impairment in BD is still unclear.

Methods: To further explore potential connectivity abnormalities and their associations with cognitive impairment, we conducted a degree centrality (DC) analysis and DC (seed)-based functional connectivity (FC) approach in unmedicated, euthymic individuals with BD. Our study included 34 euthymic BD patients and 35 healthy controls (HC) matched for age, gender, and education years.

Results: We found extensive DC changes in brain activity, with lower DC values in the left medial frontal gyrus, inferior frontal gyrus, and middle frontal gyrus, and increased DC values in the left insula, bilateral precentral gyrus, and right medial frontal gyrus in BD patients compared to HC. Furthermore, we observed positive or negative correlations between DC values of the inferior frontal gyrus, insula_L, precentral gyrus (L), precentral gyrus (R), and medial frontal gyrus and multiple-domain cognitive assessment scores. Additionally, we identified intranetwork and internetwork functional connectivity alterations in the default mode network (DMN), fronto-parietal network (FPN), and central executive network (CEN) in euthymic BD patients compared to HC.

Conclusion: Our findings highlight abnormal neuronal networks involving multiple frontal brain regions and thalamus, which may contribute to cognitive deficits in individuals with euthymic BD. These findings may serve as potential hallmarks of BD, contributing to a better understanding of the neural mechanism of cognitive impairment during euthymia.