Key indicators of cardiovascular health, such as blood pressure and arterial stiffness, are headed in the wrong direction in "chunky" adolescents, researchers say.
Much as their weight falls in between their thinner and heavier peers, cardiovascular indicators do as well, says Dr. Yanbin Dong, geneticist and cardiologist at the Medical College of Georgia.
"This is a wakeup call to parents and physicians to pay more attention to children who fall somewhere in the middle because they likely are headed toward being fatter and at increased risk of cardiovascular disease," says Dr. Dong.
He presents his findings May 10 during the Inter-American Society of Hypertension and the Consortium for Southeastern Hypertension Control Scientific Sessions in Miami.
"We tend to ignore these people," says Dr. Dong, who looked at cardiovascular measures for 972 healthy adolescents with a mean age of nearly 18. The adolescents were part of the Georgia Cardiovascular Twin Study, led by Dr. Frank Treiber, on how environmental stress impacts cardiovascular health.
About 17 percent of the black and white identical and fraternal twins had mid-range body mass, which is weight divided by height.
"Almost everything was in between," says Dr. Dong. For example, the whites had about a 2-mmHg increase in casual and ambulatory systolic blood pressure (the top number taken when the heart is contracting) as he looked across the three categories of kids from thinnest to heaviest.
Although the incremental increases don't guarantee eventual hypertension, it's not a good sign, says Dr. Dong. "If you become hypertensive when you are 42, it doesn't go up just like that," he says, snapping his fingers. "Blood pressure in your adolescence will track to your adulthood, so it's likely there will be amplification when you get older."
In blacks and whites, incremental increases in blood pressure even showed up at night, when pressures are generally lowest. Also, the heavier the adolescent, the more sodium secreted in their urine, an indicator of higher sodium intake. Excessive dietary intake may increase blood pressure, Dr. Dong notes.
A measure of arterial stiffness in the dorsalis pedis, the artery that supplies the top of the foot, also found incremental increases in whites. Blacks with a healthy weight have higher arterial stiffness than their white peers.
Heart rate increases also were fairly dramatic in blacks and whites: one beat per minute for each category. "Once again, they are young and headed in the wrong direction," says Dr. Dong.
There also was a linear increase in the size of the pumping chamber of the heart - an indicator it's working harder - from the thinnest to heaviest adolescents.
"Youth at risk of overweight compared with healthy-weight youth appear to have increased cardiovascular risks," the researchers write. "Although there is a continuum of cardiovascular risk across all levels of (body mass index), our data suggest that the at-risk-of-overweight status already has clinical implications in youth."
Dr. Dong's research is funded by the National Institutes of Health and the American Heart Association. A Consortium for Southeastern Hypertension Travel Award enabled him to present at the joint research session May 6-10 in Miami.
Co-authors include Dr. Weili Yan, postdoctoral fellow in biostatistics; Dr. Dongliang Ge, former postdoctoral fellow in genetic epidemiology; Dr. Haidong Zhu, molecular geneticist; Dr. Gregory Harshfield, hypertension researcher and director of the Georgia Prevention Institute; Dr. Gaston Kapuku, cardiologist; Dr. Harold Snieder, genetic epidemiologist; and Dr. Treiber, clinical child psychologist and MCG vice president for research.