Could Anxiety About Odor Irritants Trigger Airway Inflammation in Asthmatics?

For asthmatics, simply believing that an odor will cause harm—even if it contains no irritants—can increase inflammation of the airways, according to a recent study.

While various health organizations list may fragrances and scents as asthma triggers to be helpful, experts believe individuals with asthma have become more anxious about exposure to environmental odors.
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In order to determine whether these negative expectations play a role in worsening asthma symptoms, researchers exposed 17 participants to the odor phenylethyl alcohol (PEA)—a pure, rose-smelling odorant with no irritant qualities—for a 15-minute duration.

The participants were divided into 2 groups: 8 individuals were told the PEA had therapeutic properties, and 9 patients were told that the odor could cause mild respiratory problems. The investigators measured airway inflammation and lung function in participants before exposure, immediately after, 2 hours after, and 24 hours post exposure.

Participants were asked to rate the odor in intensity, annoyance, and irritancy while researchers recorded results of electrocardiogram, respiratory rate, and end tidal carbon dioxide. Subjective assessment of asthma symptoms were also recorded before, immediately after, and 2 and 24 hours after the study.

The results showed that the group of participants who believed the odor could potentially cause respiratory issues rated the odor as more irritating and reported worse perceived asthma symptoms than those who were told the odor had therapeutic capabilities, and the perceived risk did affect airway inflammation.

“Introducing a negative bias led to a rapid change in airway inflammation,” said Pamela Dalton, PhD, senior author of the study, and a cognitive psychologist at Monell Chemical Senses Center.

“What really surprised us was that this response lasted for over 24 hours. The increased inflammation during this period likely makes asthmatics more sensitive to other triggers,” she said.

Dalton and colleagues further noted that there was no increased inflammation in participants informed that the odor was therapeutic, even though some of them said they were typically sensitive to perfumes and odors.

The complete study is published in the July issue of the Journal of Psychosomatic Research.  

-Michelle Canales

References:

Jaén C, Dalton P. Asthma ad odors: the role of risk perception in asthma exacerbation. JCEM. 2014 July [epub ahead of print] doi: 10.1016/j.jpsychores.2014.07.002.

Monell Chemical Senses Center. In asthma, it’s not just what you smell, but what you think you smell. July 22, 2014. http://www.eurekalert.org/pub_releases/2014-07/mcsc-iai072214.php. Accessed July 23, 2014.