DAVID GREENE, HOST:
In your health today, we're learning about asthma and what can trigger it. We know it can be strong odors, anything from the heavy scent of perfume to household cleaners and industrial solvents. But now researchers are finding that just anticipating an odor, not even really smelling it, can lead to an asthma attack. Here's NPR's Patti Neighmond.
PATTI NEIGHMOND, BYLINE: For Sondra Justice, there are lots of odors that can mean danger.
SONDRA JUSTICE: Aerosol cans, incense, you know, that people burn, certain types of charcoals because I can't use charcoal on my grill, even mixing bleach in water irritates my throat.
NEIGHMOND: If Justice smells these things, an asthma attack is likely - her airways constrict. For healthy people, if that happens, airway muscles relax quickly, but for asthma patients like Justice, they don't, and breathing becomes shallow and difficult.
JUSTICE: I'll get, like, a hacking cough. My throat will feel like it's closing up. I'll break out in hives.
NEIGHMOND: And she's often gasping for air. It's really scary.
JUSTICE: It is awful when it happens, very awful.
NEIGHMOND: Asthma can be fairly easily controlled with medications a patient inhales to relax airway muscles. Even so, for most people with asthma, everyday life can be a constant worry, says Pamela Dalton, a scientist at the Monell Chemical Senses Center in Philadelphia.
PAMELA DALTON: I think asthmatics are probably more at risk of being hypervigilant all the time than almost anyone else.
NEIGHMOND: In fact, they can be so hypervigilant that just the thought of a dangerous odor, she says, makes them more susceptible to an attack. Dalton's found that most people are extremely suggestive. In one study, two groups of people were given the same thing to smell. One was told it was a chemical solvent, the other - a rain forest plant. The group who thought they were smelling a chemical reported feeling sick. The group who thought it was a plant felt good, relaxed, even rejuvenated.
DALTON: When we saw these dramatic effects in normal healthy people, we decided well, maybe they would be even more enhanced in a population like asthmatics who already were afraid of odors.
NEIGHMOND: So Dalton conducted a small study. People with moderate asthma were given the same rose-scented odor to smell for 15 minutes. One group was told it could help them breathe better, the other was told it might cause breathing problems. As expected, the breathe-better group said they liked the odor. The might-cause-problems group said they didn't like it at all. In fact, it made them feel sick.
DALTON: What really surprised us was the simple instruction that the odor might be hazardous for them caused their airways to increase inflammation.
NEIGHMOND: Now, inflammation's really important because that's what causes the airways to get swollen and sensitive and makes breathing difficult. After smelling the rose scent, those who thought it was problematic not only said they felt sick, their airways showed evidence of inflammation.
DALTON: And we measured it immediately after and then two hours after, and we brought people back the next day - 24 hours later - and their airways still showed evidence of inflammation.
NEIGHMOND: An actual, physical reaction; meanwhile, participants who were told the smell could be beneficial had no inflammation at all. At the University of Mississippi Medical Center, Dr. Gailen Marshall researches stress and inflammation. He says the fact that some patients had a physical reaction to the odor could ultimately prove helpful in treating asthma.
GAILEN MARSHALL: If, in fact, there are smells that could make someone's asthma worse, then, perhaps, there are smells that could actually make their asthma better.
NEIGHMOND: By opening a new area of therapy, for example, targeted to a patient's expectations. Take, for example, the scent of lavender.
MARSHALL: Most people think of lavender in a nice context and it's a nice soothing smell. If you could have, say, a sachet of mild lavender and that could be associated with a regular asthma medicine that made them get better, then after a little while it may simply be that if they were having trouble with their asthma, they could simply smell the lavender sachet and it would have the same effect as having to use their inhaler.
NEIGHMOND: By soothing an anxious asthma patient and controlling or even stopping an attack before it begins. Patti Neighmond, NPR News.
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