What causes muscles to weaken as we age? Study unlocks mystery behind sarcopenia

EXETER, England — Time waits for no one. As much as we would all love to look and feel 21 forever, that just isn’t the reality of being human. The years pass by and sooner or later and age catches up to everyone. Regarding muscle weakness specifically, though, some people experience much more loss of strength than others. Now, a new study finds the biological risk factors that make some people more susceptible to late-life muscle weakness than others.

Conducted at the University of Exeter, this research also notes that diseases including osteoarthritis and diabetes probably contribute to muscle weakness susceptibility.

Severe muscle weakness that impedes an individual’s ability to live their life is medically defined as sarcopenia. While that may sound extreme, sarcopenia is actually quite common. Approximately one in 10 adults over 50 deal with sarcopenia to varying degrees. Sarcopenia is also associated with a higher risk of death, but the specific biological or genetic reasons as to why certain people experience more intense sarcopenia than others is a mystery.

To shed some light on this topic, researchers performed a comprehensive genetic analysis of 250,000 people (60+ years old), as well as 21 additional analyses focusing on other datasets. Specifically, study authors looked to handgrip strength as an indicator of loss of muscle strength or function.

That process helped the research team identify a series of specific biological mechanisms that appear to “push” certain people into sarcopenia while actually protecting others from muscle weakening. In total, the study identifies 15 genome areas linked to muscle weakness. Notably, 12 of those genome areas have never previously been associated with the deterioration of grip strength over time.

Researchers say certain biomarkers in the blood, such as inflammation and red blood cells, may share sarcopenia-related casual pathways. The findings should be enough to help identify adults at greater risk of developing the condition years down the line.

“The strongest associations we found were close to regions of the genome regulating the immune system, and growth and development of the musclo-skeletal system. However we also discovered associations with regions not previously known to be linked to musclo-skeletal traits,” lead study author Garan Jones says in a release. “We found that our analysis of muscle weakness in older people shared common genetic pathways with metabolic diseases such as tType-2 diabetes, and auto-immune conditions such as osteoarthritis and rheumatoid arthritis. In subgroups of people with increased risk of these conditions, sarcopenia may be a key outcome to look out for and prevent.”

“We hope that by understanding the genetic contributions to muscle weakness with age, we will be able to highlight possible therapeutic interventions earlier in life, which would lead to a happier and healthier old age,” he adds.

The study is published in Nature Communications.