Longevity Briefs: Muscle Loss Is Associated With Dementia Years Later

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

As we age, our bodies undergo various changes, one of which is the loss of skeletal muscle mass. This phenomenon, known as sarcopenia, is a common aspect of aging and can lead to decreased mobility, increased risk of falls, and overall decline in physical health. Sarcopenia is also common among those with dementia. In this study, researchers wanted to investigate whether people with less skeletal muscle mass were more likely to get dementia years down the line.

The discovery:

Researchers recruited 621 participants without dementia who had undergone MRI scans as part of an ongoing longitudinal study of Alzheimer’s disease. Participants had an average (mean) age of 77 years at the time of the MRI scans. Researchers used these scans to measure the cross-sectional area of the temporalis muscle, which moves the jaw and has recently been shown to correlate well with overall skeletal muscle mass throughout the body. Participants were then followed up for an average of 5.8 years.

The study found that, after controlling for confounding factors such as age, participants classified as having a small temporalis cross-sectional area were around 60% more likely to develop dementia than those with larger cross-sectional areas. Not only that, but participants with smaller muscles also experienced greater declines in memory and brain volume over the follow-up period.

The implications:

Loss of temporalis muscle mass, which correlates with muscle loss throughout the body, appears to precede the onset of dementia. This means that early detection of muscle loss might enable timely interventions to delay dementia onset. Since this study was observational in nature, we don’t know to what extent low muscle mass contributed to the development of dementia – muscle loss could be caused by undetected early disease processes in the brain, or they could both be caused by other factors unaccounted for. That said, lack of physical exercise is very likely to significantly increase dementia risk. Research published this year suggests that around 45% of dementia cases are preventable, and that a large proportion of these cases are caused by physical inactivity or factors linked to inactivity such as obesity and diabetes.