If you stay up to date on cognitive decline you may already know that obesity and loss of muscle mass have been identified as risk factors for dementia. But new research points to adiposity that’s infiltrated skeletal muscles—specifically muscle fat in the thighs—as an indicator for the risk of cognitive decline in older adults.

The Study’s Results

A team of researchers at the University of Pittsburgh’s School of Public Health used computerized tomography (CT) scans to measure muscle fat in more than 1,600 adults—both Black and White—between 69 and 79 at year 1 and year 6 of the study. In addition, the seniors’ cognitive function was assessed at years 1, 3, 5, 8, and 10.

The team found that increased thigh-muscle fat over the five years was a risk factor not only for greater cognitive decline, but also faster cognitive decline. The cognitive decline was independent of other factors, including other fat deposits in the body, muscle strength or mass, and total weight, as well as traditional dementia risk factors.

Why would fat affect the brain? Because fat stored in the body can cause inflammatory conditions that, in turn, affect the brain. (To be clear, it’s not that thigh fat is the only place on the body where muscle tissue fat can be measured. The researchers chose to study fat in the thighs in particular because deposits in these large muscles can be seen on CT scans more easily.)

“Our data suggests that muscle adiposity plays a unique role in cognitive decline, distinct from that of other types of fat or other muscle characteristics,” explains study author and University of Pittsburgh School of Public Health epidemiology professor Dr. Caterina Rosano. “If that is the case, then the next step is to understand how muscle fat and the brain ‘talk’ to each other, and whether reducing muscle adiposity can also reduce dementia risk. Fat is more than meets the eye. It’s something that hides in the body.”

Reducing Muscle Adiposity

Although Rosano points out that dieting may not reduce muscle fat, people with muscle adiposity need to be especially careful in controlling other risk factors for dementia, such as diabetes, smoking, high blood pressure, and excess weight.

And because intramuscular fat can accumulate with age and obesity, preventing excess fat accumulation with diet and exercise is the best course of action.

Although the team of researchers is looking into pharmaceuticals that might reduce muscle adiposity, including the natural muscle protein myostatin, they do encourage doctors to talk to their patients about ways to prevent or slow cognitive decline.

“Medical professionals should emphasize healthy lifestyle behaviors with a focus on weight management, nutrient-dense eating patterns, and muscle strength/mass maintenance. To maintain muscle health, individuals must consume adequate dietary protein and engage in physical activity, including progressive resistance training.”

The study was published in June 7, 2023 issue of Journal of the American Geriatrics Society.

MBJ

Wendy Burt-Thomas writes about the brain, mental health and parenting.

Check out the original research:

https://agsjournals.onlinelibrary.wiley.com/doi/10.1111/jgs.18419