title: Effects of Body Mass Index and Body Fat Percent on Default Mode, Executive Control, and Salience Network Structure and Function.
abstract: It is well established that obesity decreases overall life expectancy and increases the risk of several adverse health conditions. Mounting evidence indicates that body fat is likely also associated with structural and functional brain changes, reduced cognitive function, and greater impulsivity. However, previously reported differences in brain structure and function have been variable across studies and difficult to reconcile due to sample population and methodological differences. To clarify these issues, we correlated two independent measures of body composition-i.e., body mass index (BMI) and body fat percent (BFP)-with structural and functional neuroimaging data obtained from a cohort of 32 neurologically healthy adults. Whole-brain voxel-wise analyses indicated that higher BMI and BFP were associated with widespread decreases in gray matter volume, white matter volume, and white matter microstructure (including several regions, such as the striatum and orbitofrontal cortex, which may influence value assessment, habit formation, and decision-making). Moreover, closer examination of resting state functional connectivity, white matter volume, and white matter microstructure throughout the default mode network (DMN), executive control network (ECN), and salience network (SN) revealed that higher BMI and BFP were associated with increased SN functional connectivity and decreased white matter volumes throughout all three networks (i.e., the DMN, ECN, and SN). Taken together, these findings: (1) offer a biologically plausible explanation for reduced cognitive performance, greater impulsivity, and altered reward processing among overweight individuals, and (2) suggest neurobiological mechanisms (i.e., altered functional and structural brain connectivity) that may affect overweight individuals' ability to establish and maintain healthy lifestyle choices.
authors.affiliation: Department of Radiology, University of ManitobaWinnipeg, MB, Canada; Biomedical Engineering Graduate Program, University of ManitobaWinnipeg, MB, Canada; Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Winnipeg Health Sciences CentreWinnipeg, MB, Canada; Department of Psychological and Brain Sciences, Johns Hopkins UniversityBaltimore, MD, USA.
authors.forename: Chase R
authors.initials: CR
authors.lastname: Figley
authors.affiliation: Department of Psychological and Brain Sciences, Johns Hopkins UniversityBaltimore, MD, USA; Department of Neurobiology and Behavior, University of CaliforniaIrvine, CA, USA; Center for the Neurobiology of Learning and Memory, University of CaliforniaIrvine, CA, USA.
authors.forename: Judith S A
authors.initials: JS
authors.lastname: Asem
authors.affiliation: Department of Psychological and Brain Sciences, Johns Hopkins UniversityBaltimore, MD, USA; School of Medicine and Dentistry, University of Rochester Medical CenterRochester, NY, USA.
authors.forename: Erica L
authors.initials: EL
authors.lastname: Levenbaum
authors.affiliation: Department of Psychological and Brain Sciences, Johns Hopkins UniversityBaltimore, MD, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins UniversityBaltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger InstituteBaltimore, MD, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Courtney
keywords: brain; cognition; functional connectivity; gray matter; neuroimaging; obesity; structural connectivity; white matter