People who have recently lost their jobs are more likely to suffer a heart attack than their employed peers, a new study suggests.

Researchers found each successive job loss was tied to a higher chance of heart problems among more than 13,000 older adults. Still, it’s not clear if or how unemployment, itself, might have caused the extra heart attacks.

Matthew Dupre, the lead researcher on the report from the Duke Clinical Research Institute in Durham, North Carolina, said a combination of stress, worsening lifestyle and poor management of chronic conditions without health insurance may be to blame.

“Those without a job may be unable to control their high blood pressure or to manage their diabetes (with their usual medication), or rates of smoking may be exacerbated,” Dupre told Reuters Health.

But it’s too early to know for sure what’s behind the link, he said, which means it’s also too early to recommend ways to ward off heart problems among the recently-unemployed.

The new data came from a large U.S. study of 13,451 adults who were interviewed every other year, for an average of 12 years, about their health, lifestyle and life events such as employment and job loss.

Study participants were 55 years old at the onset, on average, and two-thirds of them were overweight or obese. One in seven people was initially unemployed.

During the research period, 1,061 of all participants – almost eight percent – had a heart attack.

Dupre’s team found the more times people had been let go leading up to the latest survey, the higher their chance of having a heart attack. Unemployment was still linked to a 35 percent increased risk of heart attack after the researchers accounted for the effects of poverty and education, as well as race, age and other heart risks.

“We weren’t surprised to find the association, but we were surprised to find that the effects were so large, on par with classic risk factors such as hypertension and diabetes,” Dupre said.

“The associations are strong, and they remain despite accounting for a whole host of possible explanations.”