title: Abdominal Obesity and Brain Atrophy in Type 2 Diabetes Mellitus.
abstract: OBJECTIVE
  Type 2 diabetes mellitus (T2D) is associated with gray matter atrophy. Adiposity and physical inactivity are risk factors for T2D and brain atrophy. We studied whether the associations of T2D with total gray matter volume (GMV) and hippocampal volume (HV) are dependent on obesity and physical activity.
  
  
  METHODS
  In this cross-sectional study, we measured waist-hip ratio (WHR), body mass index (BMI), mean steps/day and brain volumes in a community dwelling cohort of people with and without T2D. Using multivariable linear regression, we examined whether WHR, BMI and physical activity mediated or modified the association between T2D, GMV and HV.
  
  
  RESULTS
  There were 258 participants with (mean age 67 ± 7 years) and 302 without (mean age 72 ± 7 years) T2D. Adjusting for age, sex and intracranial volume, T2D was independently associated with lower total GMV (p = 0.001) and HV (p<0.001), greater WHR (p<0.001) and BMI (p<0.001), and lower mean steps/day (p = 0.002). After adjusting for covariates, the inclusion of BMI and mean steps/day did not significantly affect the T2D-GMV association, but WHR attenuated it by 32% while remaining independently associated with lower GMV (p<0.01). The T2D-HV association was minimally changed by the addition of BMI, steps/day or WHR in the model. No statistical interactions were observed between T2D and measures of obesity and physical activity in explaining brain volumes.
  
  
  CONCLUSIONS
  Abdominal obesity or its downstream effects may partially mediate the adverse effect of T2D on brain atrophy. This requires confirmation in longitudinal studies.
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Rachel E D
authors.initials: RE
authors.lastname: Climie
authors.affiliation: Stroke and Ageing Research Group, Monash Medical Centre, Monash University, Clayton, Victoria, Australia.|Aged Care, Caulfield General Medical Centre, Alfred Health, Melbourne, Victoria, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Moran
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.|Stroke and Ageing Research Group, Monash Medical Centre, Monash University, Clayton, Victoria, Australia.
authors.forename: Michele
authors.initials: M
authors.lastname: Callisaya
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Leigh
authors.initials: L
authors.lastname: Blizzard
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: James E
authors.initials: JE
authors.lastname: Sharman
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Alison
authors.initials: A
authors.lastname: Venn
authors.affiliation: Stroke and Ageing Research Group, Monash Medical Centre, Monash University, Clayton, Victoria, Australia.
authors.forename: Thanh G
authors.initials: TG
authors.lastname: Phan
authors.affiliation: Stroke and Ageing Research Group, Monash Medical Centre, Monash University, Clayton, Victoria, Australia.|Developmental Imaging, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Beare
authors.affiliation: Mater Research Institute, University of Queensland, TRI, Brisbane, Queensland, Australia.
authors.forename: Josephine
authors.initials: J
authors.lastname: Forbes
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: Nicholas B
authors.initials: NB
authors.lastname: Blackburn
authors.affiliation: Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia.|Stroke and Ageing Research Group, Monash Medical Centre, Monash University, Clayton, Victoria, Australia.
authors.forename: Velandai
authors.initials: V
authors.lastname: Srikanth
mesh_terms: D050154:Adiposity; D000368:Aged; D001284:Atrophy / Q000150:complications; D015992:Body Mass Index; D001921:Brain / Q000503:physiopathology*; D001927:Brain Diseases / Q000150:complications / Q000503:physiopathology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D048909:Diabetes Complications / Q000503:physiopathology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000503:physiopathology*; D005260:Female; D005838:Genotype; D066128:Gray Matter / Q000473:pathology; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D009765:Obesity; D056128:Obesity, Abdominal / Q000150:complications*; D012044:Regression Analysis; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013648:Tasmania; D049629:Waist-Hip Ratio