TUESDAY, May 4, 2004 (HealthDayNews) -- Weight isn't the only thing that's risen dramatically among children in the last decade: So has their blood pressure.
Across-the-board increases in the blood pressure of boys and girls of different ethnic and racial backgrounds could set the stage for an explosion of hypertension, heart disease and stroke in as little as 20 years, according to a study in the May 5 issue of the Journal of the American Medical Association.
And that's not the only bad news. A study in the May issue of the Archives of Pediatrics and Adolescent Medicine found caffeine may increase blood pressure and, therefore, the risk of hypertension, in adolescents, particularly among blacks. It's also possible caffeine intake may simply be associated with other dietary and lifestyle habits that have a harmful effect on blood pressure.
Previous research has shown the proportion of overweight boys has grown from 11.3 percent in 1988-1994 to 15.5 percent in 1999-2000. For girls, the increase was from 9.7 percent to 15.5 percent. No one had yet looked at possibly related changes in blood pressure.
A team led by Paul Muntner, an assistant professor of epidemiology and medicine at Tulane University School of Public Health and Tropical Medicine, analyzed data on 5,582 children and adolescents aged 8 to 17 collected during the government's National Health and Nutrition Examination Survey. Blood pressure data for 3,496 kids in the 1988-94 period was compared to data for 2,086 kids in the 1999-2000 period.
Between the two time periods, systolic (the upper figure, which indicates the number of heartbeats) increased an average of 1.4 millimeters of mercury (mmHg), while diastolic blood pressure (the lower number, indicating the between-beat intervals) increased 3.3 mmHg.
The mean systolic blood pressure levels increased 1.9 mmHg among non-Hispanic blacks, 2.3 mmHg among Mexican-Americans, and 1.9 mmHg among children aged 8 to 12 years old.
"Blood pressure has increased over the past 15 years in children," Muntner said. "These increases are both significant and substantial, and the increases we saw were across the board -- among blacks, among Mexican-Americans, among boys, among girls."
About 30 percent of the increases could be attributed to increases in body mass index, a ratio of height to weight. "We can't be certain that it's not more," Muntner said. "We have uncertainty around the estimate, so I think it's larger, but hard to pinpoint the exact percent."
Other factors could be dietary changes as well as declines in physical activity.
"We see the roots of adult hypertension in childhood," said Muntner. "Although we're not talking about the need to treat these children with drugs, we need to be aware that more children are at a higher risk for developing high blood pressure over the next 20 years as they become adults. It doesn't mean that we have to be treating these children. However we do have to track blood pressure in children. We have to encourage lifestyle modifications such as weight loss, since our body size is a major determinant of blood pressure."
Any attempts to change behavior and health in this age group are going to be challenging. "We know that there are interventions that can help, but with adolescents it gets a little difficult," said Dr. Mary Jo DiMilia, an assistant clinical professor of medicine and pediatrics at Mt. Sinai School of Medicine in New York City. "The best treatment for hypertension is diet and exercise."