Obesity and Increased Risk of Dementia

By: Mark Lange, PhD

Dementia costs us dearly in more ways than one, and these costs are increasing around the globe. While current research marks obesity as a modifiable risk factor for the development of dementia, research findings have given mixed results. In a recent article, however, a relationship was found between body mass index (BMI) and dementia risk. 

The Study:

In a study published in Alzheimer’s & Dementia journal, researchers gathered data from eligible large-scale prospective cohort studies that included data on BMI and dementia. Of these, 39 longitudinal population studies from the USA, UK, France, Sweden, and Finland were chosen to equal a total of 1,349,857 participants with no history of dementia. BMI of all participants was assessed before determining dementia. These participants had no record of hospital-treated dementia or dementia deaths and had accrued a minimum of 3 years of follow-up.

The Results:

Analysis of 1.3 million adults over 38 years saw 6894 develop dementia.  Two decades before symptomatic dementia, higher BMI predicted dementia occurrence: each 5-unit increase in BMI was associate with a 16-33% higher risk of this condition.


What It Means:

Past research on how a person’s weight influences their dementia risk has produced conflicting results.  This is because most studies do not look at a person’s BMI over a long period of time or because of an association that is confounded by weight loss during the preclinical dementia phase, which causes the harmful exposure to seem protective. Dementia is a well-recognized source of weight loss.  As symptoms appear, appetite decreases as well as BMI.  Maintaining a healthy BMI throughout life may prevent, or at least delay, dementia.





Source:  Kivimaki, M. et al.  Body mass index and risk of dementia: Analysis of individual-level data from 1.3 million individual.  Alzheimer’s & Dementia 2017: DOI 10.1016/j.jalz.2017.09.016