Background

Although body weight (Bwt) variability is an accepted risk factor for cardiovascular disease and mortality, the effect of Bwt variability on dementia is not yet clear.

Methods

The study population included 19,987 subjects age 60 years and older, who participated in a Korean National Health Screening Examination from January 1, 2005 to December 31, 2009. Cox proportional hazard analysis was used to calculate adjusted hazard ratios (HRs) and 95% confidence interval (CIs) for all-cause dementia and dementia subtypes, including Alzheimer’s dementia and vascular dementia from 2009 to 2015 according to Bwt variability and baseline BMI. For the analysis, Bwt variability was measured as variability independent of the mean (VIM).

Results

After multivariate adjustment, the HRs for all-cause dementia and Alzheimer’s dementia were 1.39 (95% CI 1.206–1.603; P <0.001) and 1.46 (95% CI 1.240–1.724; P <0.001), respectively, when comparing the highest and lowest Bwt variability quartiles. Using a single reference group (lowest Bwt variability (Q1) with normal baseline BMI), we found that subjects with the highest Bwt variability (Q4) and underweight BMI had a significantly increased risk of developing dementia (HR 1.994, 95% CI 1.302–3.054). Meanwhile, subjects with low Bwt variability (Q1 and Q2) and obese BMI had decreased risk of developing dementia (HR 0.664, 95% CI 0.505–0.872 and HR 0.648, 95% CI 0.493–0.852, respectively).

Conclusions

The present study revealed that high Bwt variability was associated with an increased risk of dementia in the elderly. Reducing Bwt variability may help to lower the risk of dementia in older people, especially those are underweight or obese.