Want to stay sharp well into old age? Keep an eye on your waistline, suggests a recent study from the University of Arizona. Having a higher body mass index (BMI) can negatively impact brain functioning in older adults, researchers say, and there’s evidence that inflammation is to blame.
Maintaining a healthy weight can protect against a variety of health issues; it can reduce the risk of cancer, heart disease, and diabetes, to name a few. Previous studies have also linked weight to brain health, but there’s been little research into exactly how one affects the other.
Figuring out that “how” could potentially help scientists develop interventions to better prevent cognitive decline, says Kyle Bourassa, a psychology doctoral student and co-author of the new study.
Bourassa and his co-author suspected that systemic inflammation—a chronic overreaction of the body’s immune system—might be to blame, since previous research has shown that inflammation in the brain can negatively impact cognitive functioning. It’s also well established that being overweight contributes to inflammation throughout the body. “The higher your BMI, the more your inflammation goes up,” he says.
To further explore these connections, Bourassa and his co-author analyzed data from more than 21,000 British people, ages 50 and older, who had their BMI, inflammation levels, and cognition scores tested several times over the course of six years.
BMI, a measure of weight in relation to height, is often used to determine whether a person is normal, underweight, or overweight. For individuals, BMI is not always an accurate measure of healthiness—but for large populations like this, it’s a good way to estimate averages. In general, a BMI of 18 to 25 is considered normal weight, and any number over 25 is considered overweight.