MONTREAL, 5 December 2006 - According to new MUHC-led research, adolescent boys have a significantly increased risk of high systolic blood pressure (SBP) compared to adolescent girls. This finding is consistent with a higher prevalence of hypertension often observed among men compared to women and suggests that the origins of the sex difference in adult hypertension may develop during adolescence. The new study, which involved collaboration between researchers from McGill University and the Centre hospitalier de l'Université de Montréal (CHUM) and the MUHC, will be published in Circulation: Journal of the American Heart Association on Tuesday. The study also reveals that being overweight and having a sedentary lifestyle increases the risk of higher SBP in both sexes. Video games, TV and internet use specifically were found to raise blood pressure, while involvement in sporting activities had the opposite effect.

For the first time, these findings document a gender difference in likelihood of developing higher SBP during adolescence, with boys clearly at higher risk than girls. The five year study, which involved more than 1,200 male and female Canadian students, reveals that risk of higher SBP increased 19 percent annually for boys, but remained stable for girls. Being over weight was a major driving factor for higher SBP in both sexes. The study also revealed that sedentary behaviour and physical activity had differing effects on SBP. "The more hours kids spent playing video games, watching TV and using the internet, the greater their risk of higher blood pressure levels," says Dr. Kaberi Dasgupta, a physician at McGill University Health Center, assistant professor of medicine at McGill University, and lead author of the study. Conversely, the more time kids spent doing sporting activities, the more their blood pressure was lowered. "This suggests that there are non-medicinal treatment options for tackling higher blood pressure levels in teens. Turning off the computer or television and going out to kick around a ball can be helpful, as can wise dietary choices," says Dr. Dasgupta.

The researchers are members of GENESIS, a pan-Canadian multidisciplinary group studying the sex and gender differences related to cardiovascular disease - the leading cause of death in Canada. The project involves a team of more than thirty researchers from across Canada, investigating key unknowns in the way cardiovascular disease affects women and men. The co-authors of this study are Jennifer O'Loughlin, Ph.D.; Shunfu Chen, M.Sc.; Igor Karp, Ph.D.; Gilles Paradis, M.D.; Johanne Tremblay, Ph.D.; Pavel Hamet, M.D., Ph.D.; and Louise Pilote, M.D., Ph.D.

Systolic blood pressure (SBP) is the larger of the two numbers that make up a blood pressure reading. SBP represents the blood pressure when the heart is fully contracted. The smaller number, the diastolic pressure, occurs when the heart relaxes. A normal blood pressure reading is considered approximately 120 over 80 mmHg (millimeters of mercury) or lower. High blood pressure is a risk factor for hypertension, which in turn can lead to atherosclerosis, heart disease and stroke. Among adults, men generally have a higher prevalence of hypertension than women. Detecting hypertension early allows early and effective intervention, often by simply altering a person's diet and increasing his or her exercise. Until now, however, no one had explored gender differences in adolescent blood pressure.

This study was funded in part by the National Cancer Institute of Canada, the Canadian Cancer Society, the Canadian Institutes of Health Research (CIHR) and the Heart and Stroke Foundation of Canada.