Overweight Boys Show
More Blood Pressure Problems
Excerpt by Alison McCook, Reuters Health

Among boys, those who weigh more experience a greater increase in blood pressure under stress, and are slower to return to normal pressure levels once relaxed, new research reports.

However, in girls, having excess pounds did not increase the risk of blood pressure problems in response to stress.

It is normal for blood pressure to increase during periods of stress, but larger and longer increases in blood pressure can, over time, damage the kidneys, blood vessels and other organs, study author Dr. Gregory A. Harshfield stated.

"The more load you have on your system the more damage you have," Harshfield said.

Harshfield, who is based at the Medical College of Georgia in Atlanta, said he was surprised that stress-related problems in blood pressure occurred only in overweight boys. Experts are often more concerned about weight issues in girls, he noted, because they tend to have more body fat than boys.

However, "even though girls have more weight, the effect on the cardiovascular system (of being overweight) is greater in boys," he said.

During the study, published in the journal Hypertension, Harshfield and his team measured blood pressure changes in 151 boys and 141 girls of different weights between the ages of 15 and 18. To determine how their blood pressure responded to stress, the researchers asked participants to play a video game with money at stake for one hour.

Along with showing a higher increase and a slower decrease in blood pressure under stress, boys who weighed more also tended to rid their bodies of less salt, relative to boys who weighed less.

Harshfield explained that when blood pressure increases under stress, the kidneys respond by increasing output in order to get rid of excess salt. With the salt comes excess fluid, thereby decreasing the volume of fluid in the blood, and lowering blood pressure, he noted.

Once again, girls who weighed more were just as able to excrete salt after a spike in blood pressure as normal weight girls, the researcher noted, suggesting that something is "protecting" overweight girls from stress-related blood pressure problems.

Harshfield explained that the protection may come from the female hormone estrogen, which blunts the effects of stress hormones and increases levels of substances that open up blood vessels.

In contrast, male sex hormones tend to increase the blood pressure response to stress, perhaps making it "a bigger problem in boys," Harshfield noted.

He added that many questions remained unanswered, and more research is needed to better understand the role of stress in cardiovascular disease linked to obesity.

SOURCE: Hypertension, November 2003.

Reference Source 89

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