title: Change in body mass index before and after Alzheimer's disease onset.
abstract: OBJECTIVE
  A high body mass index (BMI) in middle-age or a decrease in BMI at late-age has been considered a predictor for the development of Alzheimer's disease (AD). However, little is known about the BMI change close to or after AD onset.
  
  
  METHODS
  BMI of participants from three cohorts, the Washington Heights and Inwood Columbia Aging Project (WHICAP; population-based) and the Predictors Study (clinic-based), and National Alzheimer's Coordinating Center (NACC; clinic-based) were analyzed longitudinally. We used generalized estimating equations to test whether there were significant changes of BMI over time, adjusting for age, sex, education, race, and research center. Stratification analyses were run to determine whether BMI changes depended on baseline BMI status.
  
  
  RESULTS
  BMI declined over time up to AD clinical onset, with an annual decrease of 0.21 (p=0.02) in WHICAP and 0.18 (p=0.04) kg/m2 in NACC. After clinical onset of AD, there was no significant decrease of BMI. BMI even increased (b=0.11, p=0.004) among prevalent AD participants in NACC. During the prodromal period, BMI decreased over time in overweight (BMI≥25 and <30) WHICAP participants or obese (BMI≥30) NACC participants. After AD onset, BMI tended to increase in underweight/normal weight (BMI<25) patients and decrease in obese patients in all three cohorts, although the results were significant in NACC study only.
  
  
  CONCLUSIONS
  Our study suggests that while BMI declines before the clinical AD onset, it levels off after clinical AD onset, and might even increase in prevalent AD. The pattern of BMI change may also depend on the initial BMI.
authors.forename: Yian
authors.initials: Y
authors.lastname: Gu
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Scarmeas
authors.forename: Stephanie
authors.initials: S
authors.lastname: Cosentino
authors.forename: Jason
authors.initials: J
authors.lastname: Brandt
authors.forename: Marilyn
authors.initials: M
authors.lastname: Albert
authors.forename: Deborah
authors.initials: D
authors.lastname: Blacker
authors.forename: Bruno
authors.initials: B
authors.lastname: Dubois
authors.affiliation: Taub Institute for Research in Alzheimer's Disease and the Aging Brain, Columbia University, 630 W. 168th Street, P&S Box 16, New York, NY 10032, USA. yg2121@columbia.edu.
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Stern
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*; D015992:Body Mass Index; D004522:Educational Status; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D050177:Overweight / Q000453:epidemiology / Q000503:physiopathology; D015995:Prevalence; D062706:Prodromal Symptoms; D011379:Prognosis; D012680:Sensitivity and Specificity