Girls' Asthma Risk Tied to Weight Gain
Key is in grade school; may be hormonal
FRIDAY, May 25, 2001 (HealthDayNews) -- Obesity has been linked to asthma, but a new study suggests that weight gained during grade school sometimes may be more important in the development of breathing trouble.
The study found that girls -- but not boys -- who put on too many pounds as they leave early childhood are up to seven times more likely to develop asthma than those whose weight stays the same. The link is particularly strong in obese girls who have their first menstrual period before age 11, indicating that hormonal changes many play a role in the airway disorder.
With both childhood asthma and childhood obesity on the rise in the United States, the findings "suggest another reason that we should avoid putting on those excess pounds," says Anne Wright, an asthma expert at the University of Arizona's Respiratory Science Center in Tucson.
Wright and her colleagues, whose study appears this month in the American Journal of Respiratory and Critical Care Medicine, followed part of a group of 1,300 boys and girls who'd been enrolled at birth in a study of respiratory problems.
The researchers collected information from the children on their body mass, asthma symptoms and allergies starting at about age 6. At about age 11 they added tests of lung function.
Body mass index, a measure of obesity, at age 6 didn't predict wheezing and poor lung function later in childhood, the researchers say. But girls who became overweight or obese by ages 11 to 13 were up to seven times more likely to suffer asthma symptoms in adolescence than those who didn't gain weight as they grew older.
"We don't know what the relationship is based on. They both may be secondary to something else, like a hormonal thing," Wright says.
Intriguingly, Wright says, while boys are much more prone to asthma early in life, girls overtake them as they enter puberty. And as adolescence and adulthood progress, women are more likely than men to suffer severe, even deadly, breathing attacks.
The seven-fold increased risk of asthma in obese girls is substantial, but may underestimate the true effect because body mass index is often tricky to gauge in children, says Dr. Carlos Camargo Jr., a Harvard University asthma expert familiar with the Arizona study. "There's something big going on," he says.
Camargo, who helped lead the first prospective study that connected asthma to obesity in women, says estrogen has been linked to overweight, which might help explain why girls who had earlier onset of puberty were both obese and had a greater risk of asthma. "But that's entirely speculative" at this point, he says.
Camargo says it's also possible that certain types of asthma are more closely tied to obesity. For example, it's difficult to explain why some adults who get asthma at age 30 or 40 showed no signs of breathing trouble as young children. "Adult-onset asthma might be more susceptible to the incidence of obesity, while exposure to allergens might" account for most childhood cases of the condition, he says.
The latest study also found that ethnic background was linked to weight gain, and that children with two Hispanic parents were more likely to be obese at any age than those with one Latino or two white parents.
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