May 3, 2011

Obesity in Middle Age May Increase Risk of Dementia

Being overweight or obese in middle age may increase your odds for Alzheimer's disease and dementia by as much as 80 percent.

Alzheimer's Reading Room

"Our results contribute to the growing evidence that controlling body weight or losing weight in middle age could reduce your risk of dementia," Weili Xu, of the Karolinska Institute in Stockholm.

The findings showed that the individuals who had been overweight/obese during middle age were 80% more likely to develop dementia, Alzheimer's disease or vascular dementia during old age, compared to the normal weight participants. The risk difference was calculated after taking into account such factors as diabetes status, vascular disease and education.

Obesity in middle age may increase risk of dementia

A new study from Karolinska Institute shows that overweight and obesity in midlife increases the risk of developing dementia later in life. The study, based on data from the Swedish Twin Registry, published in the American scientific journal Neurology.

The researchers analyzed data from 8534 twins 65 years of age and older. Of those, 350 people diagnosed with dementia and 114 with probable dementia. Data on weight and height were registered already, when participants were in their 30s. Participants were divided into four groups based on BMI: underweight, normal weight, overweight and obese. Obesity was defined as BMI between 25 and 30 and obesity as BMI over 30. Of the participants in the study were 2541 people, or nearly 30 percent are overweight or obese in middle age.

It turned out that people who had been overweight or obese in mid-life had 80 percent increased risk of developing dementia, Alzheimer's disease or vascular dementia compared with normal weight. The result remained after the researchers took into account other factors that could affect outcomes, such as education, diabetes and cardiovascular disease. Of those not suffering from dementia were 26 percent overweight, and 3 percent fat. Among those who had dementia, 39 percent were overweight and seven per cent obese.

The researchers also analyzed data from twin pairs where one twin had dementia and the other does not. It then appeared that there was no longer possible to see a significant link between overweight / obesity and dementia.

This suggests that genetic factors and surrounding environment early in life affects the link between obesity in middle age and risk of dementia later in life, "said Weili Xu.

The study was funded by grants from the National Institute of Aging, Research Council, Swedish Brain Power, The Foundation for old maids, Gun and Bertil Stohner Foundation, Dementia Foundation, Loo and Hans Oster's foundation for geriatric diseases. Weili Xu is also active at the Aging Research Centre in Stockholm, a collaboration between Karolinska Institutet and Stockholm University.

W. Xu, AR Atti, M. Gatz, NL Pedersen, B. Johansson & L. Fratiglioni
Midlife overweight and obesity Increase late-life dementia risk: A population-based twin study
Neurology ®, the medical journal of the American Academy of Neurology, 3 May 2011 paper issue


Objective: The relation of overweight to dementia is controversial. We aimed to examine the association of midlife overweight and obesity with dementia, Alzheimer disease (AD), and vascular dementia (VaD) in late life, and to verify the hypothesis that genetic and early-life environmental factors contribute to the observed association.

Methods: From the Swedish Twin Registry, 8,534 twin individuals aged ≥65 (mean age 74.4) were assessed to detect dementia cases (DSM-IV criteria). Height and weight at midlife (mean age 43.4) were available in the Registry. Data were analyzed as follows: 1) unmatched case-control analysis for all twins using generalized estimating equation (GEE) models and 2) cotwin matched case-control approach for dementia-discordant twin pairs by conditional logistic regression taking into account lifespan vascular disorders and diabetes.

Results: Among all participants, dementia was diagnosed in 350 subjects, and 114 persons had questionable dementia. Overweight (body mass index [BMI] >25–30) and obesity (BMI >30) at midlife were present in 2,541 (29.8%) individuals. In fully adjusted GEE models, compared with normal BMI (20–25), overweight and obesity at midlife were related to dementia with odds ratios (ORs) (95% CIs) of 1.71 (1.30–2.25) and 3.88 (2.12–7.11), respectively. Conditional logistic regression analysis in 137 dementia-discordant twin pairs led to an attenuated midlife BMI-dementia association. The difference in ORs from the GEE and the matched case-control analysis was statistically significant (p = 0.019).

Conclusions: Both overweight and obesity at midlife independently increase the risk of dementia, AD, and VaD. Genetic and early-life environmental factors may contribute to the midlife high adiposity–dementia association.

Subscribe to the Alzheimer's Reading Room
Enter Your Email Address

More Insight and Advice for Caregivers

Bob DeMarco is the Founder of the Alzheimer's Reading Room and an Alzheimer's caregiver. The blog contains more than 2,680 articles with more than 512,100 links on the Internet. Bob lives in Delray Beach, FL.

Original content Bob DeMarco, the Alzheimer's Reading Room