Does BMI affect your Alzheimer’s risk?

Research suggests a BMI of 30 may impact your Alzheimer's risk. Photo: Getty

When it comes to your risk for Alzheimer's disease, you probably already know what to eat (and what not to), how to sleep, and even which cooking methods to avoid.

Now, experts are saying that your weight in middle age may predict if and when you'll develop the disease.

For the study, published in the journal Molecular Psychiatry, researchers from the US National Institutes of Health (NIH) tracked nearly 1,400 individuals using data from the Baltimore Longitudinal Study of Aging. Of those individuals, 142 ended up with Alzheimer's.

The NIH team examined how the participants' cognitive abilities changed during the roughly 14-year study period. They found a higher body mass index (BMI) at age 50 correlated with earlier onset of Alzheimer's. For each unit increase in BMI at 50, Alzheimer's set in an average of 6.7 months sooner.

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BMI is only a rough measure of body fat. But a person with a BMI at or above 25 is usually considered overweight; anyone with a BMI at or above 30 is considered obese. According to the study data, a 50-year-old with a BMI of 30 could experience the onset of Alzheimer's more than a year earlier than someone with a BMI of 28.

Even among those who didn't develop Alzheimer's, high BMIs were associated with the accumulation of amyloid plaques - toxic proteins that can harm your brain's ability to function at its best. The NIH researchers say the kind of chronic inflammation associated with higher body weights may play a role. (More bad news: It may also up your risk for breast cancer.)

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While more research is needed to back up these findings, the study authors say keeping your weight under control in midlife could delay or even prevent the onset of Alzheimer's disease. One healthy way to go about this: Eating a Mediterranean-style diet is a proven way to control body weight and safeguard your brain.

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