Body mass index trajectories and the risk for Alzheimer's disease among older adults.

The effect of body mass index (BMI) changes and variability on the risk for Alzheimer's disease (AD) remains unclear. We analyzed 45,076 participants, whose BMI were measured on phase 1 (2002-2003), phase 2 (2004-2005), and phase 3 (2006-2007), of the Korean National Health Insurance Service-Health Screening Cohort. We evaluated the effect of 2- and 4-year BMI changes and BMI variability on the risk of AD using Cox regression models. In men, association between 2-year BMI changes, BMI variability, and the risk of AD was not significant. Risk of AD was higher in men whose BMI had decreased 10.1-15.0% over 4 years. In women, aHRs and 95% CIs for AD were 1.14 (1.02-1.29), 1.44 (1.17-1.79), and 1.51 (1.09-2.09) when 2-year BMI loss was 5.1-10.0%, 10.1-15.0%, and > 15.0%. The HRs for AD in women significantly increased when 4-year BMI loss was > 5.0%. The aHR and 95% CI for AD was 1.31 (1.17-1.46) in the 4th quartile of average successive variability (ASV) compared with the 1st quartile of ASV in women. BMI loss over 2- and 4-year period was associated with increased risk for AD, and risk increased in women with higher BMI variability. Appropriate body weight management is recommended to prevent AD.