It’s scientifically proven that smoking is bad for your health, but what happens if you also have high blood pressure and a low education level? Danish researchers found there is a significantly high risk of stroke among groups with the three deadly factors in combination. They published their study in Stroke, a journal by the American Heart Association.

"We found it is worse being a current smoker with lower education than a current smoker with a higher education,” said the study’s lead author Helene Nordahl, researcher at the Department of Public Health at the University of Copenhagen in Denmark, in a press release. People with lower education levels included those who had a grade school or lower secondary school education, which adds up to 10 years of education since kindergarten.

The researchers examined the education levels of 68,643 participants between the ages of 30 to 70 years old, and compared them to their smoking and blood pressure levels. They found that 16 percent of the men and 11 percent of the women they looked at had a high risk of stroke when they were smokers with the deadly combination of a low education level and high blood pressure. During the 14-year follow-up, 10 percent of those men and nine percent of those women were found to have had a stroke within the time period.

When researchers disregarded the blood pressure factor, they found that smokers with low education levels still had a higher risk of stroke than smokers with high education levels. Approximately 800,000 people in the United States have a stroke each year, and of those, a person dies from a stroke every four minutes, according to the Centers for Disease Control and Prevention. Strokes occur when the blood supply to the brain is blocked or when the brain's vessels rupture, causing bleeding, and eventually killing brain tissue.

Toxins in cigarettes harden arteries, which carry blood throughout the body. They also cause fatty plaques to deposit along the blood vessels, causing scarring and thickening of the artery walls. Smokers continue to increase their risk of stroke, as it obstructs blood flow,  which can also cause heart attacks. Smoking will almost double their risk of stroke, and even after they quit. it takes a total of 15 years for their dangerous stroke risk to decrease.

"The distribution of stroke risk factors may vary across various contexts and study populations," Nordahl said. "However, since the most disadvantaged groups are often exposed to a wide number of stroke risk factors, it seems plausible that these people are at higher risk of stroke not only in Denmark, but also in other industrialized countries."

Source: Nordahl H, Osler M, Anderson I, et al. Combined Effects of Socioeconomic Position, Smoking, and Hypertension on Risk of Ischemic and Hemorrhagic Stroke. Stroke. 2014.