Change in Body Mass Index Before and After Alzheimer’s Disease Onset
Objectives: 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.
Keywords: Alzheimer's disease, body mass index, prospective study, weight.
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