Asthma Linked To Allergies, NIH Study

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Asthma Linked To Allergies, NIH Study

http://www.sciencedaily.com/releases/2007/09/070927143302.htm

Science Daily — Researchers at the National Institutes of Health

(NIH) have found that more than 50 percent of the current asthma

cases in the country can be attributed to allergies, with

approximately 30 percent of those cases attributed to cat allergy.

" It has long been debated whether people who develop asthma have a

genetic propensity to develop allergies, or atopy, " said Darryl C.

Zeldin, M.D., a senior investigator at the National Institute of

Environmental Health Sciences (NIEHS). " This new research shows that

56.3 percent of asthma cases are attributed to atopy. " Atopy is a

condition that results from gene-environment interactions and can be

measured by a positive skin test to allergens (or allergy causing

substances in the environment).

The study, in the Journal of Allergy and Clinical Immunology, was

conducted by researchers at the National Institute of Environmental

Health Sciences (NIEHS) and the National Institute of Allergy and

Infectious Diseases, both parts of the NIH. The data come from the

Third National Health and Nutrition Examination Survey (NHANES III),

a nationally representative sample of the population of the United

States.

" Sensitization to cat appears to be a strong risk factor for asthma

in this study, " said Zeldin. Zeldin and his co-authors, however,

point out that some research shows that exposure to cats,

particularly early in life, may be a protective factor. " We are not

advocating parents get rid of pets, but if you suspect that you or

your child might have cat allergies or get asthmatic-like symptoms,

you should consult with a physician about the best course of action

for your family, " added Zeldin.

The NIH researchers looked at skin test data for ten allergens. A

positive skin test reaction to cat allergens accounted for 29.3

percent of the asthma cases, followed by the fungus Alternaria at

21.1 percent and white oak at 20.9 percent. " Each of 10 allergen-

specific skin tests was strongly associated with asthma; however,

after adjustment by a variety of subject characteristics and all the

allergens, only skin tests to cat, Alternaria and white oak were

independently and positively associated with asthma, " said

Gergen, M.D., M.P.H, of NIAID's Division of Allergy, Immunology and

Transplantation, a co-author on the paper.

Other allergens tested include: Ragweed, dustmites, Russian thistle,

Bermuda grass, peanuts, perennial rye and german cockroach.

Approximately 10,500 individuals participated in the skin testing.

During these tests, skin was exposed to allergy-causing substances

(allergens) and a positive test was determined by the size of the

reaction on the skin.

" This study tells us that allergy is a major factor in asthma, "

Gergen said. " But this study also tells us is that there are many

people who get asthma who don't have allergies. We need to do more

research to understand what is causing the asthma that is not

related to allergies. "

" This study confirms that the environment plays a major role in the

development of asthma, " said Zeldin. " Given the complexity of this

disease it won't be easy, but if we can prevent, block or reverse

atopy, we could reduce a large proportion of asthma cases. "

Reference: Arbes SJ, Gergen,PJ Vaughn B, Zeldin DC. Asthma cases

attributable to atopy: Results from the Third National Health and

Nutrition Examination Survey. Journal of Allergy and Clinical

Immunology. September, 2007.

Note: This story has been adapted from material provided by NIH,

National Institute of Environmental Health Sciences.