People who are jobless at some point during their lifetime becausethey were laid off, fired or quit may be at an increased risk of having aheart attack after age 50, finds a study out Monday.

In fact, thechances of a heart attack associated with multiple job losses may be onpar with the risks people face from factors such as smoking,hypertension and diabetes, says the study's lead author, Matthew Dupre,an assistant professor of medicine at Duke University.

Theresearchers say they don't know from the data if the job losses werebecause people were fired, laid off, had seasonal jobs or voluntarilyleft their jobs. "We believe the greatest risk for heart attacks wouldcome from having been fired or laid off -- in other words involuntaryjob loss," says Linda George, a professor of sociology at Duke and anauthor on the study.

"We do know it's not from retirement," George says. "Retirement poses no increased risk of heart attack."

The findings come as the nation's unemployment rate is 7.9%.

Researchersat Duke looked at the different aspects of unemployment and the risksof heart attacks among 13,451 men and women, ages 51 to 75, whoparticipated in the national Health and Retirement Study. Participantswere interviewed every two years from 1992 to 2010.

Usingstatistical models, the researchers looked at associations betweenmultiple aspects of employment instability and heart attacks. Among thefindings presented online Monday in the Archives of Internal Medicine:

  • Heart attack risks were about 35% higher among the unemployed than employed, and risks increased incrementally from one job loss (22% higher) to four or more job losses (63% higher), compared with those without a job loss in their lifetime.
  • The risk of having a heart attack was highest the first year of unemployment.
  • The harmful effects of unemployment were consistent for men and women, and major race/ethic groups.

Participantshad the same risk of a heart attack from unemployment no matter whattheir education level or socioeconomic situation, Dupre says.

Georgesays the researchers don't know the exact mechanisms for the increasedrisk, but they do know that "anytime we are not as in control of ourlives as we'd like to be, stress goes up."

When that happens,other health habits may slide too - people may eat less healthfully,stay up too late and not sleep as well, she says. There may be morestrain and conflicts in the family. "We believe all these things areamong the reasons why unemployment is linked to this increased risk ofheart attack."

People should "be extra vigilant" about seekingmedical help during times of unemployment, especially if they areexperiencing any signs of a heart attack, George says.

Atlantacardiologist Gina Lundberg, an assistant professor of medicine at EmoryUniversity who was not part of this study, says, "Research shows thatjob stress can cause heart attacks, and now this study shows that nothaving a job causes heart attacks.

"Right now, many Americans have stressful jobs or no job at all - and either way, it isn't good for their heart."