title: Increased body mass index is associated with specific regional alterations in brain structure.
abstract: Although obesity is associated with structural changes in brain grey matter, findings have been inconsistent and the precise nature of these changes is unclear. Inconsistencies may partly be due to the use of different volumetric morphometry methods, and the inclusion of participants with comorbidities that exert independent effects on brain structure. The latter concern is particularly critical when sample sizes are modest. The purpose of the current study was to examine the relationship between cortical grey matter and body mass index (BMI), in healthy participants, excluding confounding comorbidities and using a large sample size.
  
  
  
  A total of 202 self-reported healthy volunteers were studied using surface-based morphometry, which permits the measurement of cortical thickness, surface area and cortical folding, independent of each other.
  
  
  
  Although increasing BMI was not associated with global cortical changes, a more precise, region-based analysis revealed significant thinning of the cortex in two areas: left lateral occipital cortex (LOC) and right ventromedial prefrontal cortex (vmPFC). An analogous region-based analysis failed to find an association between BMI and regional surface area or folding. Participants' age was also found to be negatively associated with cortical thickness of several brain regions; however, there was no overlap between the age- and BMI-related effects on cortical thinning.
  
  
  
  Our data suggest that the key effect of increasing BMI on cortical grey matter is a focal thinning in the left LOC and right vmPFC. Consistent implications of the latter region in reward valuation, and goal control of decision and action suggest a possible shift in these processes with increasing BMI.
authors.affiliation: Department of Psychiatry, University of Cambridge, Cambridge, UK.|Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK.
authors.forename: N
authors.initials: N
authors.lastname: Medic
authors.affiliation: Department of Psychiatry, University of Cambridge, Cambridge, UK.|Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK.|Cambridgeshire and Peterborough NHS Foundation Trust, University of Cambridge, Cambridge, UK.
authors.forename: H
authors.initials: H
authors.lastname: Ziauddeen
authors.affiliation: Department of Psychiatry, University of Cambridge, Cambridge, UK.
authors.forename: K D
authors.initials: KD
authors.lastname: Ersche
authors.affiliation: Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK.
authors.forename: I S
authors.initials: IS
authors.lastname: Farooqi
authors.affiliation: Department of Psychiatry, University of Cambridge, Cambridge, UK.|Medicines Discovery and Development, GlaxoSmithKline, Clinical Unit Cambridge, Cambridge, UK.
authors.forename: E T
authors.initials: ET
authors.lastname: Bullmore
authors.affiliation: Department of Psychiatry, University of Cambridge, Cambridge, UK.|School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Nathan
authors.affiliation: Department of Psychiatry, University of Cambridge, Cambridge, UK.
authors.forename: L
authors.initials: L
authors.lastname: Ronan
authors.affiliation: Department of Psychiatry, University of Cambridge, Cambridge, UK.|Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK.|Cambridgeshire and Peterborough NHS Foundation Trust, University of Cambridge, Cambridge, UK.
authors.forename: P C
authors.initials: PC
authors.lastname: Fletcher
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D001931:Brain Mapping; D056324:Diffusion Tensor Imaging; D005247:Feeding Behavior; D005260:Female; D066128:Gray Matter / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology; D050177:Overweight / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D055815:Young Adult