This is jaw-dropping news.
Obesity, high blood pressure, diabetes and smoking are among the known risk factors for dementia, a loss of cognitive functioning that affects nearly 7 million Americans.
New research from the Johns Hopkins School of Medicine provides more evidence that muscle mass loss, also known as sarcopenia, can also significantly increase the risk of dementia. The new finding is based on the belief that one particular jaw muscle may indicate skeletal muscle mass throughout the body.
“We found that older adults with smaller skeletal muscles are about 60% more likely to develop dementia when adjusted for other known risk factors,” said neurology professor Marilyn Albert, the study’s co-senior author.
Skeletal muscles comprise about one-third of our body weight, and losing muscle mass is a natural part of aging. After 30, people typically start to lose as much as 3% to 5% of their muscle mass per decade.
Sarcopenia, which is a substantial loss of muscle mass and strength, is estimated to affect 10% to 16% of the world’s elderly population.
Sarcopenia’s link to cognitive decline is not exactly clear, but researchers speculate it may be due to myokines.
Skeletal muscles produce and release small proteins and peptides called myokines that directly influence the brain. Less muscle mass means fewer myokines are released. Also, people with sarcopenia may exercise less and participate in fewer social activities, two major risk factors for dementia.
The Johns Hopkins team focused on the temporalis muscle on the side of the head for its study. The large, fan-shaped muscle is used to close the mouth when chewing.
The researchers say that features of this jaw muscle, like its thickness and size, can paint a picture of muscle mass within the body.
They examined brain images for 621 dementia-free older adults to determine how much muscle loss they had suffered.
The participants were tracked for around six years to see if they got diagnosed with dementia or experienced brain or cognition changes.
Most of the participants had smaller temporalis muscles, which researchers tied to a higher risk of dementia, as well as greater decreases in cognitive test scores and brain size compared to those with larger temporalis muscles.
Dementia is characterized by memory loss and a decline in language, problem-solving and thinking skills.
The Johns Hopkins researchers presented their study this month at a meeting of the Radiological Society of North America. They suggested that when an older adult gets a brain scan for any reason, this imaging should be evaluated for muscle changes.
Early detection helps with treatment options, which include physical activity, such as chair workouts, resistance training and nutritional guidance. It may be beneficial to eat more protein, which is essential for building muscle.
“These interventions may help prevent or slow down muscle loss and subsequently reduce the risk of cognitive decline and dementia,” said Dr. Shadpour Demehri. co-senior study author and professor of radiology.