WASHINGTON – The more advanced degrees a person has, the lower their blood pressure, a study published online has found.

An analysis of some 4,000 patient records from the 30-year Framingham Offspring Study found that, controlling only for age, women with 17 years or more of education -- a master's degree or doctorate -- had systolic blood pressure readings 3.26 millimeters of mercury lower than female high school drop-outs.

Men who went to graduate school had systolic blood pressure readings that were 2.26 millimeters of mercury (mmHg) lower than their counterparts who did not finish high school, the study, published online in the open access journal BMC Public Health, says.

The same inverse relationship between education and blood pressure was also seen, although to a lesser degree, in men and women who got associate's or bachelor's degrees at university but did not continue on to graduate school.

They showed greater blood pressure benefits than high school drop-outs but lesser benefits than holders of master's degrees or doctorates, the study found.

Even after controlling for influences such as smoking, drinking, obesity and blood pressure medication, the benefits persisted, although at a lower level.

The study could help explain the widely documented association in developed countries between education and lower risk of heart disease, said lead author Eric Loucks, an assistant professor of public health at Brown University in Rhode Island.

Blood pressure is "one of the biological underpinnings of heart disease," said Loucks, urging policy-makers who want to improve public health to think about improving access to education.

The study focused on systolic blood pressure over diastolic blood pressure because "systolic hypertension is substantially more common than diastolic hypertension, and systolic blood pressure contributes more to the global disease burden attributable to hypertension than diastolic blood pressure."