When asthma symptoms appear and are diagnosed in adults older than 20, it is typically known as adult-onset asthma. About half of adults who have asthma also have allergies. Adult-onset asthma also may be the result of commonplace substances in work (called occupational asthma) or home environments, and the asthma symptoms come on suddenly.
What is Asthma?
Asthma is a disorder of the lungs that causes intermittent symptoms. In the airways there is:
Swelling or inflammation, specifically in the airway linings
Production of large amounts of mucus that is thicker than normal
Narrowing because of muscle contractions surrounding the airways
The symptoms of asthma include:
- Feeling short of breath
- Frequent coughing, especially at night
- Wheezing (a whistling noise during breathing)
What is Adult-Onset Asthma?
When a doctor makes a diagnosis of asthma in people older than 20, it is known as adult-onset asthma.
Among those who may be more likely to get adult-onset asthma are:
- Women who are having hormonal changes, such as those who are pregnant or who are experiencing menopause
- Women who take estrogen following menopause for 10 years or longer
- People who have just had certain viruses or illnesses, such as a cold or flu
- People with allergies, especially to cats
- People who are exposed to environmental irritants, such as tobacco smoke, mold, dust, feather beds, or perfume. Irritants that bring on asthma symptoms are called "asthma triggers." Asthma brought on by workplace triggers is called "occupational asthma."
What is the Difference Between Childhood Asthma and Adult-Onset Asthma?
Adults tend to have lower lung capacity (the volume of air you are able to take in and forcibly exhale in one second) after middle age because of changes in muscles and stiffening of chest walls. This decreased capacity may cause doctors to miss the diagnosis of adult-onset asthma.
How is Adult-Onset Asthma Diagnosed?
Your asthma doctor may diagnose adult-onset asthma by:
- Taking a medical history, asking about symptoms, and listening to you breathe
- Performing a lung function test, using a device called a spirometer, to measure how much air you can exhale after first taking a deep breath' the device also measures how fast you can empty your lungs. You may be asked at some time before or after the test to inhale a short-acting bronchodilator (medicine that opens the airways by relaxing tight muscles and that also help clear mucus from the lungs).
- Performing a methacholine challenge test; this asthma test may be performed if your symptoms and spirometry test do not clearly show asthma. When inhaled, methacholine causes the airways to spasm and narrow if asthma is present. During this test, you inhale increasing amounts of methacholine aerosol mist before and after spirometry. The methacholine test is considered positive, meaning asthma is present, if the lung function drops by at least 20%. A bronchodilator is always given at the end of the test to reverse the effects of the methacholine.
- Performing a chest X-ray. An X-ray is an image of the body that is created by using low doses of radiation reflected on special film or a fluorescent screen. X-rays can be used to diagnose a wide range of conditions, from bronchitis to a broken bone. Your doctor might perform an X-ray exam on you in order to see the structures inside your chest, including the heart, lungs, and bones. By viewing your lungs, your doctor can see if you have a condition other than asthma that may account for your symptoms. Although there may be signs on an X-ray that suggest asthma, a person with asthma will often have a normal chest X-ray.