A reduced risk of cardiovascular disease is associated with being more highly educated, but only for those living in high income countries, according to a new study.

While previous studies have found a link between completed levels of formal education and risk of heart disease , few have included populations in low- and middle-income countries.

"We can't simply take studies that are conducted in high-income countries, particularly as they relate to socioeconomic status and health outcomes, and extrapolate them to low- and middle-income countries," said Dr. Abhinav Goyal, lead author of the study and assistant professor of epidemiology and medicine at Emory School of Medicine in Atlanta, Ga.

Goyal and colleagues assessed 61,332 patients from 44 countries who had been diagnosed with heart disease or stroke, or who had several risk factors, including smoking, high blood pressure, clogged blood vessels and obesity . They also collected information about formal education level. Participants were followed up for two years.

The results show highly educated women in low-and-middle-income countries had a slightly higher incidence of heart attack and stroke than less educated women in those countries. Among all other groups, heart disease declined as education increased, with highly educated men in high-income countries showing the lowest level of disease.

Education may confer protective effects against heart disease in high income countries because it leads to higher personal income and improved access to health care. Those with more education may also be better informed about good health practices and may adopt healthier behaviors, according to the researchers.

However, in low- and middle-income countries, higher education may not bring these benefits, especially for women. "Women may be less independent or empowered than men to make healthy lifestyle choices or to seek adequate healthcare," the researchers write.

Another reason higher education doesn't have the same impact on heart disease risk in low- and middle-income countries might be smoking habits. Smoking is known to be a risk factor for cardiovascular disease.

In low- and middle-income countries, 21 percent of the most educated women smoke, while 14 percent of the least educated did.

For men, smoking rates were virtually the same across educational groups in low- and middle-income countries. In affluent countries, however, the most educated men smoked less than men with the fewest years of formal education (66 percent versus 75 percent).

"We can't assume that just because certain groups are more educated than others that they're going to have healthier lifestyles," Goyal said in a statement. "Everyone needs to be educated about the risk of heart disease in particular, and counseled to adopt healthy lifestyles and to quit smoking."

The results will be published in the September issue of the journal Circulation: Journal of the American Heart Association.