Latest study shows that your mind can play tricks on you. And if you happen to be asthmatic, this is a dangerous thing.

A research study exposed 17 asthmatics to a nonirritating, harmless odor. Eight participants were told the odor was therapeutic, and nine were told it was harmful and could cause respiratory issues. After the odor exposures, participants rated intensity, irritancy and annoyance, and the researchers measured how well their lungs functioned and the amount of airway inflammation.

Airway inflammation increased significantly in those who believed the odor was harmful. The levels of inflammation stayed higher than normal for 24 hours. These participants also rated the odor as more irritating and annoying.

"Introducing a negative bias led to a rapid change in airway inflammation," said senior author Pamela Dalton, Ph.D., cognitive psychologist at the Monell Center where the study was conducted. Dalton was most surprised by how long the inflammation lasted -- up to 24 hours later. She explained that the increased inflammation probably increases sensitivity to other triggers. 

Even more surprising was that the participants who believed the odor to be therapeutic exhibited no increase in airway inflammation. Individuals within the "therapeutic" group who said they were highly sensitive to many odors didn't exhibit increased inflammation either, surprising researchers.

The study's results suggest that some of the asthmatic responses to fragrances actually occur because the person expects harm.

"It's not just what you smell, but also what you think you smell," said Cristina Jaén, Ph.D. and lead study author.

Asthma has no cure, so people with the disease must know how to manage and control it and avoid attacks. Health organizations offer extensive lists of odors that can trigger attacks, possibly putting asthmatics on edge around many scents and fragrances. As this study suggests, it may be possible that being too anxious around odors could cause more harm than good.

The study was published in the Journal of Psychosomatic Research. The odor used in the study was phenylethyl alcohol, a "rose-smelling," "pure" scent with no physiological harmful properties.

The authors of the study hope to conduct future research to understand the exact processes behind how the brain's expectations lead to inflammation. They are also interested in whether or not the reverse of this process is possible.

"Can we improve health outcomes by reducing concern or fear in a disease where emotional arousal is counter-productive?" Dalton and colleagues wonder and aim to find out.

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