Smell Sensitivity Linked to Cough

(WebMD)  People who are sensitive to odors also might cough more easily than others.

A new study shows a physical link between chemical sensitivity — or odor intolerance — and increased cough sensitivity, a condition the researchers say should be a newly named disorder.

The Swedish scientists included Åke Johansson, M.D., from the department of lung medicine at Central Hospital in Skövde. They wanted to find out exactly how chemical sensitivity and cough sensitivity are linked because many patients who are sensitive to smells also report a variety of nonspecific symptoms including "cough" and "pressure across the chest."

To get more specific, the researchers performed capsaicin inhalation tests on 103 people. Capsaicin is an ingredient in red pepper; when inhaled it can cause cough by stimulating sensory nerve endings. The number of times a person coughed during the 10-minute test determined a positive or negative result. Sixteen people had a positive result.

The researchers found patients with odor intolerance "react more strongly … to provocation with capsaicin inhalation" — 80 percent of those with a positive inhalation test also had a positive chemical sensitivity score.

Study participants' chemical sensitivity scores had been determined by how they ranked scenarios in a questionnaire, including:

I am easily alerted by odorous/pungent substances.

At movies, other persons' perfume and aftershave disturb me.

In public places, I do not mind some smell of cigarette smoke.

I would not mind living in an apartment that has a weak smell.

Because the researchers "regard the capsaicin inhalation provocation as a fairly objective test," they say the cough response in odor-sensitive people is a "physiologically demonstrable disorder." They call it "airway sensory hyperreactivity," or SHR.

The study appears in the June issue of CHEST, the journal of the American College of Chest Physicians.

SOURCE: Johansson, A. CHEST, June 2006; Vol. 129: pp. 1623-1628.

By Lisa Habib
Reviewed by Louise Chang, M.D.
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