FOR RELEASE: 4 p.m. ET, Monday March 19, 2001
CONTACT: For journal copies only,please call: (214) 706-1396For other information, call:Carole Bullock: (214) 706-1279, [email protected]Bridgette McNeill: (214) 706-1135
American Heart Association journal report:Bad habits, non-cholesterol risk factorsin youth linked to fatty plaques
DALLAS, March 20 -- A new study links "non-lipid" risk factors -- obesity, smoking, high blood pressure and diabetes -- to the development of early atherosclerosis in youth with recommended cholesterol levels, according to a report in today's Circulation: Journal of the American Heart Association.
Researchers in the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study examined autopsies of 856 males and females aged 15-34 with normal cholesterol levels. All had died in accidents, homicides or suicides. Those who had risk factors such as smoking, high blood pressure or obesity already had fatty streaks and artery-clogging plaques in the abdominal aorta and in the right coronary artery, even though they had recommended cholesterol levels.
"The strong association between cholesterol levels and heart disease may have given some the false idea that other risk factors are unimportant. We've probably under-emphasized non-lipid risk factors," says Henry C. McGill Jr., M.D., the study's lead author and senior scientist emeritus at the Southwest Foundation for Biomedical Research in San Antonio. "The message of this study is that all cardiovascular risk factors should be controlled in children and adolescents."
Some authorities have questioned the importance of non-lipid risk factors in the young, but this study clearly shows that the presence of non-lipid risk factors in young people is associated with more arterial plaques that lead to coronary heart disease in middle age. Nearly half the individuals possessed at least one non-lipid risk factor, and 13 percent had two, with smoking and hypertension the most prevalent.
Atherosclerosis develops in two stages: the first stage is an accumulation of fat-filled cells in the inner lining of the artery, called a fatty streak. The second stage is a thickened plaque covering a fatty core that gradually blocks the artery and slowly cuts off blood supply to the heart, or provokes a blood clot that rapidly blocks the artery and triggers a heart attack.
Those in the study who smoked had more extensive fatty streaks and three times the extent of plaques in the abdominal aorta, where aneurysms (bulgings of the artery wall) develop in middle age. Obese males had more extensive fatty streaks and twice coronary artery plaques compared to non-obese males. High blood pressure was associated with more extensive coronary artery plaques, particularly among blacks. High blood sugar (an indicator of diabetes) was associated with more extensive fatty streaks in the coronary artery.
The researchers also examined coronary arteries microscopically to determine how advanced the plaques were. Advanced plaques -- those likely to lead to arterial blockage -- were about four times more frequent in men than in women, a result expected because middle-aged men are known to have a higher risk of heart attack than women. Surprisingly, advanced plaques were about four times more frequent in obese men than in non-obese men, whereas no difference was associated with obesity in women. Hypertension and elevated blood sugar tended to be associated with advanced coronary artery plaques, but less strongly.
During the past decade abundant scientific evidence has shown that the established risk factors for coronary heart disease accelerate the development of atherosclerosis in children and adolescents, although symptoms don't generally appear until middle age.
"Several reports have stressed to health care professionals that the prevention of cardiovascular disease should begin in childhood," McGill says. "Preventing heart disease is a pediatric problem, but we still have a long way to go in this approach."
In an era in which smoking, obesity, physical inactivity and diabetes are increasing among the young, he also urges parents to take more responsibility for their children's health-related behavior and for young adults to change bad habits.
"Parents shouldn't wait until more than one risk factor is present before modifying a child's lifestyle," he says. "Your children's health in middle age depends on how you raise them today."
He estimates that a 25- to 34-year-old who quits smoking reduces the risk of a premature heart attack between age 40 and 65 to about one-fourth of what it would be if this person continued to smoke, assuming other lifestyle habits were unchanged. If an obese young adult lost weight and maintained a non-obese state for 10 years, a conservative guess is that they would cut their risk in half. "So the combined effect of both smoking cessation and weight loss/maintenance could reduce this person's risk of heart attack to one-fifth of what it was previously -- and possibly even more," McGill adds.
He notes that the percentage of smokers was "very high" among the study subjects -- 44 percent compared to 25 percent to 30 percent for the same age group in the general population.
"We believe this higher smoking prevalence is due to the association of smoking with traumatic death, as well as to our use of an objective measure of smoking, which has shown to be more accurate than self-reported smoking behavior," McGill says.
Other researchers participating in the study include: C. Alex McMahan, Ph.D.; Arthur W. Zieske, M.D.; Gray T. Malcom, Ph.D.; Richard E. Tracy, M.D., Ph.D; and Jack P. Strong, M.D.
The study was funded in part by the National Heart, Lung and Blood Institute.###NR01-1268 (Circ/McGill)
Media Advisory: Dr. McGill can be reached at (210) 258-9408, by fax at (210) 670-3323, and by e-mail at [email protected]. Dr. Strong can be reached at (504) 568-6033, by fax at (504) 568-6037, and by e-mail at [email protected]. (Please do not publish contact information.)
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