Neuroanatomical Dysconnectivity Underlying Cognitive Deficits in Bipolar Disorder

BACKGROUND: Graph theory applied to brain networks is an emerging approach to understanding the brain's topological associations with human cognitive ability. Despite well-documented cognitive impairments in bipolar disorder (BD) and recent reports of altered anatomical network organization, the association between connectivity and cognitive impairments in BD remains unclear.METHODS: We examined the role of anatomical network connectivity derived from Ti - and diffusion-weighted magnetic resonance imaging in impaired cognitive performance in individuals with BD (n = 32) compared with healthy control individuals (n = 38). Fractional anisotropy- and number of streamlines-weighted anatomical brain networks were generated by mapping constrained spherical deconvolution-reconstructed white matter among 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 participants with BD, and lower IQ performance may present with a differential relationship between global and interhemispheric efficiency in individuals with BD relative to control individuals. 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. We gratefully acknowledge the participants, the support of the Welcome-Trust HRB Clinical Research Facility, the Centre for Advanced Medical Imaging at St. James Hospital Dublin and funding support from the Irish Research Council Government of Ireland Postgraduate Scholarship. We would also like to thank Andrew Hoopes, Research Technician I, MGH/HST Martinos Center for Biomedical Imaging for Freesurfer software support, Christopher Grogan, MSc, for his contribution to data processing and Jenna Pittman, BSc and Fiona Martyn, BA for their contribution to data handling. This research was funded by the Health Research Board (HRA-POR324) awarded to Dara M. Cannon, PhD. peer-reviewed 2020-09-18