COLUMBUS, Ohio -- The negative effects of environmental tobacco smoke on a child who lives with parents who smoke continue to linger long after that child has left home, a new Ohio State University study suggests.
In tests, college students who were exposed to high levels of environmental tobacco smoke (ETS) as children maintained higher blood pressure, mean arterial pressure, and heart rate at rest and during psychological stress compared to students who grew up with low levels of ETS.
"We've learned that children who grow up in a smoking household will have small but long-lasting negative effects on their health," said Catherine Stoney, co-author of the study and associate professor of psychology at Ohio State. "You don't have to be the one smoking, but you can still vicariously suffer some of the effects," said Lisa Manzi Lentino, psychology graduate student.
The work appeared in a recent issue of the International Journal of Behavioral Medicine, in a paper co-authored by Stoney, Lentino, and Karen Emmons of the Dana Farber Cancer Institute and Harvard School of Public Heath, in Boston.
Past research has shown that adults who grew up in smoking homes attained higher blood pressure and heart rate during physical stress than did adults who grew up in non-smoking homes. Stoney, Lentino, and Emmons wanted to find out whether the same result held true for psychological stress.
The 78 male Ohio State students who participated in the study were all taking an introductory level psychology course. Their average age was 19 years, so most had been living away from home for approximately one year. Both groups -- those students from smoking homes and those from non-smoking homes -- were healthy and reported little exposure to ETS in their lives at the time of the study; most lived in university dormitories where residents are not allowed to smoke. When subjected to tests designed to induce psychological stress, both groups of students experienced roughly equal spikes in blood pressure, mean arterial pressure, and heart rate.
But one result was surprising: the students who grew up in smoking homes consistently maintained a higher baseline blood pressure, arterial pressure, and heart rate than did their counterparts.
Even though both groups of students responded to stress to the same degree, the students who grew up in smoking homes achieved higher rates for the three measures overall, because their baseline readings were higher to begin with. The study employed two common psychological stress tests. First, researchers showed each student a four-digit number on a flash card and asked him to subtract 13 from that number continuously. The student had to recite his answers while the researchers videotaped him. Halfway through the test, the researchers flipped over a second flash card with a different four-digit number and asked the student to begin again.
For the second test, each student was given an imaginary scenario -- such as being falsely accused of stealing -- and was ordered to give an impromptu three-minute speech in his defense, also while being videotaped. If the student stopped speaking before three minutes had passed, the researchers prompted him to continue.
Students were allowed to rest between tests and let their blood pressure fall back to near-baseline level. The researchers measured the students' blood pressure, mean arterial pressure, and heart rate during the tests and again during each rest period.
The blood pressure tests measured systolic blood pressure, the peak pressure just after the blood pressure cuff first relaxes its grip on the subject's arm. A normal systolic blood pressure for a healthy college student averages about 120 mm of mercury on a sphygmomanometer, or 120 mmHg. At rest, students with low past ETS exposure had an average systolic blood pressure of 112 mmHg. Students with high past ETS exposure had an average blood pressure of 119 mmHg.
For students with low past ETS exposure, the average blood pressure rose to 131 mmHg during the first test and 135 mmHg during the second test. For students with high past ETS exposure, their average blood pressure rose to approximately 135 mmHg and 139 mmHg, respectively.
The study also measured mean arterial pressure and heart rate, with similar results. While students with past exposure to ETS reacted to psychological stress to roughly the same degree, their baseline rates remained higher throughout the tests.
"That was the really striking thing for us," said Stoney. "Even though these students had grown up in smoking homes, they currently weren't exposed to much environmental tobacco smoke at all. But still they had higher baseline rates than the other group."
The researchers explained that a consistently elevated heart rate, blood pressure, and arterial pressure puts stress on the body, and the negative effects are cumulative.
"Because these students have a higher blood pressure and heart rate, 20 to 30 years down the line they might be at risk for hypertension, which puts them at risk for heart disease," said Lentino.
"The message is -- if you've got kids, don't smoke at home, because it will affect them later on," said Stoney.
This study was funded by the National Heart, Lung, and Blood Institute and the National Cancer Institute, both part of the National Institutes of Health. Lentino's work was funded by an Ohio State fellowship award during her first year of graduate school.
Written by Pam Frost, 614-92-9475; Frost.18@osu.edu
Journal
International Journal of Behavioral Medicine