Dementia is a major global public health problem that now affects 50 million people and is projected to reach over 150 million cases by 2050.

Obesity, which is usually measured by body mass index (BMI), is still a worldwide problem. Studies from the past have shown that being overweight in middle age may make you more likely to get dementia.

But it’s still not clear what the link is between BMI and the risk of dementia.

Now, researchers from the Boston University Chobanian & Avedisian School of Medicine and the Chinese Academy of Medical Sciences & Peking Union Medical College have found that different patterns of changes in one’s body mass index (BMI) over the course of one’s life may be an indicator of a person’s risk for dementia.

“These findings are important,” says corresponding author Rhoda Au, as “previous studies that looked at weight trajectories didn’t consider how patterns of weight gain/stability/loss might help signal that dementia is potentially imminent.”

A group of people who took part in the Framingham Heart Study were monitored for a total of 39 years, and the researchers evaluated their weight at regular intervals of around two to four years. Researchers studied weight trends (steady, growth, loss) in demented and non-demented people.

They found that a general drop in BMI was linked to a higher chance of getting dementia. But after more research, they found a subgroup with a pattern of first increasing BMI and then decreasing BMI, both of which happened in midlife. This pattern seemed to be at the core of the link between declining BMI and dementia.

Au says that it’s easy for people, their families, and their primary care doctors to keep an eye on weight.

“If after a steady increase in weight that is common as one gets older, there is an unexpected shift to losing weight post midlife, it might be good to consult with one’s healthcare provider and pinpoint why,” she adds. 

“There are some potential treatments emerging where early detection might be critical in the effectiveness of any of these treatments as they are approved and become available.” 

The researchers hope that this study will show that the seeds of dementia risk are planted over many years, and probably even over a person’s whole life. 

“Dementia is not necessarily inevitable and monitoring risk indicators such as something as easy to notice as weight patterns, might offer opportunities for early intervention that can change the trajectory of disease onset and progression.”

These results were published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

Source: 10.1002/alz.12839

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