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Understanding a Childhood Asthma Epidemic

New research is investigating the underlying causes behind high asthma rates in U.S. kids.
Maria Godoy, NPR /
New research is investigating the underlying causes behind high asthma rates in U.S. kids.

In the 1980s and 1990s, childhood asthma rates in the United States reached epidemic proportions. Although research indicates rates are now leveling off, the numbers remain high. Around 6.3 million U.S. children have been diagnosed with the respiratory illness. Overall rates for African-American and Hispanic children are not declining; they're 30-percent to a 100-percent higher than for white children. In fact, a growing body of research indicates the effects of asthma, including death and hospitalization, seem to fall disproportionately on minorities and urban populations.

As Madge Kaplan of member station WGBH in Boston reports, many in the research community feel a new urgency about the epidemic and are turning their attention to poverty, stress and mental health as potential underlying causes.

Harvard Medical School researcher Rosalind Wright is investigating the long-term consequences of stressful inner-city life. She suspects that when new parents in difficult circumstances feel helpless and worried, this triggers anxiety in young children. This worrying, Wright says, can prompt the brain to send out hormones and neurotransmitters, such as cortisol and adrenaline, that affect immune-system functions.

"If that's ongoing, you may have changes in your immune system that are longer lasting and may translate into asthma," Wright said.

The intense stress can throw the immune system off kilter, Wright explains, causing the lungs to be overly sensitive and easily inflamed starting at a very young age.

Wright is now recruiting 1,000 pregnant women of African-American, Haitian and Hispanic backgrounds for a five-year government-funded study. She plans to track physiological changes in women and children in relationship to their life circumstances and indoor and outdoor environmental quality. Genetic susceptibility will also be studied. This is the first time anyone has tried to explore the potential causes of asthma by examining so many factors simultaneously. Wright's results could show that the mental wear and tear of dealing with poor housing, lack of money and often-violent neighborhoods not only makes an existing asthma diagnosis worse, but also helps the disease take hold in the first place.

Other researchers, such as Alex Ortega of the Yale School of Public Health, are asking different questions. Ortega is investigating why asthma rates among Puerto Rican children are the highest of all -- 30 percent of kids who live on the island and 11 percent of children of Puerto Rican descent who live on the U.S. mainland have been diagnosed with asthma. Based on previous research, Ortega theorizes psychological factors may be at work.

"For example, breathlessness is a very common symptom in both asthma and anxiety, particularly in panic attacks in children," Ortega said. "If parents and doctors are perceiving breathing problems as physiological as opposed to psychiatric, that has major clinical implications."

In other words, treating the asthma could allow underlying mental-health problems to get worse. It could be that asthma and psychiatric disorders feed off each other in one vicious circle. Rather than having to choose one over the other, Ortega says the first step is to find out if some young Hispanic asthmatics benefit from psychological counseling.

Adding psychological issues to the question of what's driving America's childhood asthma epidemic complicates matters, but at the moment, most in the research community welcome the inquiry. Genetics may prove to be a bigger issue than now known, along with other factors. But the growing sentiment seems to be that asthma is a syndrome caused and fueled by many things.

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