A study has found that people with rheumatoid arthritis appear to age faster than people without the disease, a finding that may help to explain why those with the condition have shorter life expectancies.

For this study, researchers at the Mayo Clinic in Rochester, Minn., examined the medical records of 755 patients who were diagnosed with rheumatoid arthritis, or RA, between 1955 and 2008.

Over the course of 12-and-a-half years, 315 patients died. They tracked participants’ ages and causes of death and compared them to the expected survival data for people of similar ages and genders without the disease.

The results showed RA patients were physically two years older at the time they are diagnosed, and then aged even faster after that point.

Researchers believe for every 10 years of chronological aging, people with RA physically age 11.4 years.

Experts don’t fully understand why RA patients have increased mortality rates. They do know that in patients with RA, cells affected by the disease show signs of what’s called accelerated aging. This is damage at the molecular level.

“This research goes together with the basic science where they say there are individual cells aging faster, so it’s another piece in the puzzle to help us learn how RA works and what causes it,” says Cynthia S. Crowson, a statistician and a member of the research team.

Scientists plan additional studies to better understand their findings in light of more recent treatment advances that help many with RA live more normal lives.

“We know treatment is having wonderful effects so maybe it also impacts mortality,” Crowson says. “We are looking at that in other studies to see if mortality is improving."