title: Midlife and late-life obesity and the risk of dementia: cardiovascular health study.
abstract: BACKGROUND
  While high adiposity in middle age appears to be related to greater dementia risk, studies exploring this association in the elderly are conflicting.
  
  
  OBJECTIVE
  To evaluate associations between midlife and late-life obesity and risk of dementia.
  
  
  METHODS
  Prospective study with mean follow-up of 5.4 years (1992-1994 through 1999).
  
  
  METHODS
  Community-dwelling sample in 4 US sites recruited from Medicare eligibility files.
  
  
  METHODS
  A total of 2798 adults without dementia (mean age, 74.7 years; 59.1% women) participating in the Cardiovascular Health Study who underwent magnetic resonance imaging were measured for height and weight at baseline at age 65 years or older (late life), and self-reported weight at age 50 years (midlife). Body mass index (BMI) (calculated as weight in kilograms divided by height in meters squared) was calculated at both times.
  
  
  METHODS
  Dementia, Alzheimer disease, and vascular dementia classified by a multidisciplinary committee using standardized criteria.
  
  
  RESULTS
  Classification resulted in 480 persons with incident dementia, 245 with Alzheimer disease (no vascular dementia), and 213 with vascular dementia (with or without Alzheimer disease). In evaluations of midlife obesity, an increased risk of dementia was found for obese (BMI >30) vs normal-weight (BMI 20-25) persons, adjusted for demographics (hazard ratio [HR], 1.39; 95% confidence interval [CI], 1.03-1.87) and for cardiovascular risk factors (1.36; 0.94-1.95). The risk estimates were reversed in assessments of late-life BMI. Underweight persons (BMI <20) had an increased risk of dementia (1.62; 1.02-2.64), whereas being overweight (BMI >25-30) was not associated (0.92; 0.72-1.18) and being obese reduced the risk of dementia (0.63; 0.44-0.91) compared with those with normal BMI.
  
  
  CONCLUSIONS
  These results help explain the "obesity paradox" as differences in dementia risk across time are consistent with physical changes in the trajectory toward disability.
authors.affiliation: Department of Epidemiology, University of Washington, Collaborative Health Studies Coordinating Center, Seattle, 98115, USA. fitzpal@u.washington.edu
authors.forename: Annette L
authors.initials: AL
authors.lastname: Fitzpatrick
authors.forename: Lewis H
authors.initials: LH
authors.lastname: Kuller
authors.forename: Oscar L
authors.initials: OL
authors.lastname: Lopez
authors.forename: Paula
authors.initials: P
authors.lastname: Diehr
authors.forename: Ellen S
authors.initials: ES
authors.lastname: O'Meara
authors.forename: W T
authors.initials: WT
authors.lastname: Longstreth
authors.forename: José A
authors.initials: JA
authors.lastname: Luchsinger
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000544:Alzheimer Disease / Q000209:etiology*; D000886:Anthropometry / Q000379:methods; D015992:Body Mass Index; D015140:Dementia, Vascular / Q000209:etiology*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000453:epidemiology; D011446:Prospective Studies; D012306:Risk; D016019:Survival Analysis