Neuroanatomical Dysconnectivity Underlying Cognitive Deficits in Bipolar Disorder

Abstract Background Graph theory applied to brain networks is an emerging approach to understand the brains’ topological associations with human cognitive ability. Despite well-documented cognitive impairments in bipolar disorder (BD) and recent reports of altered anatomical network organisation, the association between connectivity and cognitive impairments in BD remains unclear. Methods We examined the role of anatomical network connectivity derived from T1- and diffusion-weighted magnetic resonance imaging in impaired cognitive performance in individuals with BD (n=32) compared to healthy controls (n=38). Fractional anisotropy- and number of streamlines-weighted anatomical brain networks were generated by mapping constrained spherical deconvolution-reconstructed white matter between 86 cortical/subcortical bilateral brain regions delineated in the individual’s own coordinate space. Intelligence and executive function were investigated as distributed functions using measures of global, rich-club and interhemispheric connectivity while memory and social cognition were examined in relation to subnetwork connectivity. Results Lower executive functioning related to higher global clustering coefficient in bipolar participants, and lower IQ performance may present with a differential relationship between global and interhemispheric efficiency in BD relative to controls. Spatial recognition memory accuracy and response times were similar between diagnostic groups and associated with basal ganglia and thalamus interconnectivity and connectivity within extended anatomical subnetworks in all participants. No anatomical subnetworks related to episodic memory, short-term memory or social cognition generally or differently in BD. Conclusions Results demonstrate selective influence of subnetwork patterns of connectivity in underlying cognitive performance generally and abnormal global topology underlying discrete cognitive impairments in BD.