Adult Asthma Causes

(Page 5)

Highlights	Adult Asthma Risk Factors	Other Asthma Treatments
Introduction	Adult Asthma Diagnosis	Managing Asthma
Adult Asthma Symptoms	Overview of Asthma Treatment	Resources
Causes of Adult Asthma	Quick-Relief Medications for Adult Asthma sufferers	References
Adult Asthma Prognosis	Long-Term Relief Medications for Adult Asthma Sufferers

Acetaminophen (Tylenol) has been the traditional alternative for relief of minor pain for patients who are aspirin-sensitive. Unfortunately, recent evidence has muddied these recommendations. Some asthmatic episodes have been linked to high consumption of acetaminophen among adults.

Exercise-Induced Asthma

Exercise-induced asthma (EIA) is a limited form of asthma in which exercise triggers coughing, wheezing, or shortness of breath.

Nocturnal Asthma

Asthma occurs primarily at night (nocturnal asthma) in as many as 75% of patients with asthma. Attacks often occur between 2 and 4 A.M. Factors that might play role in nocturnal asthma may include one or more of the following:

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Chemical and temperature changes in the body during the night that increase inflammation and narrowing of the airways
Delayed allergic responses from exposure to allergens during the day
The wearing off of inhaled medications toward the early morning
An increase in acid reflux (back up of stomach acid) that causes airways to narrow
Postnasal drip that occurs during sleep
Conditions relating to sleep, such as sleep apnea or sleeping on one's back, which may worsen any asthma attack that occurs at night

Some experts believe that nocturnal asthma may actually be a unique form, with its own specific biologic mechanisms that occur only at night and which reduce natural steroid hormones (which block inflammation).

Contributing Medical Conditions

Infections. The role of infections in asthma is complicated. Respiratory infections may play a role in some cases of adult-onset asthma, but may be protective against asthma in small children. (In both children and adults with existing allergic asthma, however, an upper respiratory tract infection often worsens an attack.)

Researchers are particularly interested in the organisms Chlamydiapneumoniae and Mycoplasmapneumoniae adenovirus. They are major causes of both mild and serious respiratory infections and are becoming important suspects in many cases of severe adult asthma. (If such respiratory infections occur in young children, they are unlikely to affect adult-onset asthma.)

In one study, patients whose asthma occurred after infections had more severe conditions than those whose asthma was due to other causes. The infection-initiated asthma, however, lasted only 5.6 years compared to 13.3 years in the non-infection group.

In any age group, respiratory infections worsen existing asthma in people who have it already. Rhinovirus (the common cold virus) has been reported to be the most common infection associated with asthma attacks. In one study, it was associated with 61% of asthma exacerbations in children and 44% in adults. Some research suggests that colds promote allergic inflammation and increase the intensity of airway responsiveness for weeks.

GERD. At least half of patients with asthma have gastroesophageal reflux disease (GERD), the cause of heartburn. It is not entirely clear which condition causes the other or whether they are both due to common factors.

Heartburn is a condition where the acidic stomach contents back up into the esophagus causing pain in the chest area. This reflux usually occurs because the sphincter muscle between the esophagus and stomach is weakened. Standing or sitting after a meal can help reduce the reflux that causes heartburn. Continuous irritation of the esophagus lining as in gastroesophageal reflux disease is a risk factor for the development of adenocarcinoma.

Some theories for the causal connection between GERD and asthma are:

Acid leaking from the lower esophagus in GERD stimulates the vagus nerve, which runs through the gastrointestinal tract. This stimulated nerve triggers the nearby airways in the lung to constrict, causing asthma symptoms.
Acid backup that reaches the mouth may be inhaled into the airways (aspirated). Here, the acid triggers a reaction in the airways that cause asthma symptoms.

GERD is sometimes hard to detect and might be a contributor in the following patients:

Those who do not respond to asthma treatments
Those whose asthma attacks follow episodes of heartburn
Those whose attacks worsen after eating or exercise
Those whose coughs follow episodes of acid reflux. (One study found that GERD was associated with about half of the episodes of coughs and wheezes in patients with asthma.)

Treating GERD symptoms with anti-acid drugs may resolve asthma in some (but not all) patients who share both conditions. A small 2005 observational study found that while GERD was common in patients with asthma, treatment of GERD had no effect on asthma symptoms. [See In-Depth Report #85: Heartburn and gastroesophageal reflux disease.]

Sinusitis. Almost half of children and adults with allergic asthma have sinus abnormalities, and in various studies, between 17 - 30% of patients with asthma develop true sinusitis. The presence of sinusitis, however, does not appear to increase the severity of asthma.

Click the icon to see an image of sinusitis.

Exercise-Induced Asthma (EIA)

Exercise-induced asthma (EIA) is a limited form of asthma in which exercise triggers coughing, wheezing, or shortness of breath. This condition generally occurs in children and young adults, most often during intense exercise in cold dry air. Symptoms are generally most intense about 10 minutes after exercising and then gradually resolve.

EIA is triggered only by exercise and is distinct from ordinary allergic asthma in that it does not produce a long duration of airway activity, as allergic asthma does. (It should be noted that some people have both forms of asthma.) People who have only EIA do not appear to require long-term maintenance therapy. A study of military recruits with EIA also reported that the condition does not hinder a person's overall physical performance.

Medications

Cromolyn, a mild anti-inflammatory drug, or short-acting beta2-agonists have been the treatments of choice for preventing EIA. Newer approaches for people who work out regularly include pretreatment with long-acting beta2-agonists, such as salmeterol (Serevent), or the regular use of inhaled corticosteroids.

Hints for Reducing EIA

EIA occurs only after exercise and is more likely to occur with regularly paced activities in cold, dry air. The following are some suggestions for reducing its impact:

Warm-up and cool-down periods are important.
Patients with EIA might do better with activities that involve short bursts of exercise (tennis, football) than with exercises involving long-duration regular pacing (cycling, soccer, and distance running).
Breathing through a scarf or through the nose helps warm up the airways.
Some evidence suggests that restricting dietary salt might help reduce EIA.

Click the icon to see an image of exercise-induced asthma.

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Review Date: 03/18/2006
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

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