Resting-State Network Patterns Underlying Cognitive Function in Bipolar Disorder: A Graph Theoretical Analysis.

BACKGROUND: Synchronous and antisynchronous activity between neural elements at rest reflects the physiological processes underlying complex cognitive ability. Regional and pairwise-connectivity investigations suggest perturbations in these activity patterns may relate to widespread cognitive impairments seen in bipolar disorder (BD). Here we take a network-based perspective to more meaningfully capture interactions among distributed brain regions compared to focal measurements and examine network-cognition relationships across a range of commonly affected cognitive domains in BD in relation to healthy controls.

METHODS: Resting-state networks were constructed as matrices of correlation coefficients between regionally averaged resting-state time series from 86 cortical/subcortical brain regions (FreeSurferv5.3.0). Cognitive performance measured using Weschler Adult Intelligence Scale, Cambridge Automated Neuropsychological Test Battery (CANTAB) and Reading the Mind in the Eyes tests was examined in relation to whole-brain connectivity measures and patterns of connectivity using a permutation-based statistical approach.

RESULTS: Faster response times in controls (n=49) related to synchronous activity between frontal, parietal, cingulate, temporal and occipital regions while similar response times in BD (n=35) related to antisynchronous activity between regions of this subnetwork. Across all subjects, antisynchronous activity between frontal, parietal, temporal, occipital, cingulate, insula and amygdala regions related to improved memory performance. No resting-state subnetworks related to intelligence, executive function, short-term memory or social cognition performance in the overall sample or in a manner that would explain deficits in these facets in BD.

CONCLUSION: Our results demonstrate alterations in the intrinsic connectivity patterns underlying response timing in BD that are not specific to performance or errors on the same tasks. Across all individuals, no strong effects of resting-state global topology on cognition are found, while distinct functional networks supporting episodic and spatial memory highlight intrinsic inhibitory influences present in the resting-state that facilitate memory processing.