Late-in-life weight gain or weight loss appears to be associated with an increased risk of dementia, shows a Korean study of 67,219 men and women between 60-79 years old.
The study, which was published earlier this month in BMJ Open, found that a weight change of more or less than 10 percent body mass index (BMI) over two years is associated with a 20 percent increased risk of dementia as compared to men and women who maintained their BMI over the same period.
“Our study demonstrated the detrimental effects of weight gain and loss on dementia in an elderly population,” wrote the authors who were led by Jin-Won Kwon, M.D., of Kyungpook National University, Korea.
The association between late-in-life weight gain and dementia didn’t appear to apply to men and women who had a high BMI of more than 25 kg at the beginning of the study. However, a low BMI of less than 18.5 kg was associated with a significant increase in the risk of dementia in men, but not women.
- The entire group was followed for an average 5.3 years.
- 4,887 men and 6,685 women developed dementia during the 5.3-year follow-up period.
- 51 percent of study participants were men.
- Body mass index measures were documented for two years.
- More women than men had BMIs higher than 25 kg: 40.2 percent of women compared to 28.9 percent of men.
- Modifiable risk factors varied by sex—men were more likely to be smokers and consume alcohol, while women had a higher prevalence of hypercholesterolemia, hypertension, and congestive heart failure.
The authors attributed the main impact of weight gain on dementia risk to an increase in fat mass that provokes chronic inflammation leading to neurodegenerative changes. They suggested that the association between pre-existing middle-age obesity and lower dementia risk, could be due to the survivor effect.
Weight loss in later years, the authors wrote, suggests the presence of underlying preclinical dementia or other conditions that may influence cognitive function. Cardiometabolic risk factors, including hypertension, congestive heart failure, diabetes mellitus and high fasting blood sugar, were found to be significant risk factors for dementia. Diabetes patients with a high fasting blood sugar had a 1.6-fold higher risk of developing dementia. And, a sedentary lifestyle, smoking, and frequent drinking were also associated with the risk of dementia.
Regular moderate exercise at least three times weekly reduced the risk of developing dementia, the authors found.
“Our results suggest that continuous weight control, disease management, and the maintenance of a healthy lifestyle are beneficial in the prevention of dementia, even later in life,” they wrote.
1. Park S, Jeon SM, Jung SY, Hwang J, Kwon JW. “Effect of late-life weight change on dementia incidence: a 10-year cohort study using claim data in Korea.” BMJ Open 2019;9:e021739. doi: 10.1136/bmjopen-2018-021739.