Adult-onset Asthma May Herald Heart Consequences
A 2016 study published in The Journal of the American Heart Association suggests that individuals who develop asthma later in life are at higher risk of also developing heart disease or having a stroke.
**Before we get into the details of the study, let's revisit the various types of asthma. Those include:**Early-onset asthma or ** child-onset asthma**begins in childhood, and usually occurs when the child becomes sensitized to common allergens in the environment. A genetic component may make the child more susceptible to the allergens, which can include animal proteins, fungi, pollen, house dust mites, and other types of dust.
Exercise-induced asthma is defined as coughing, wheezing, or feeling out of breath during or after exercise (as distinct from someone who is simply unfit and struggles to breathe when attempting to exercise). In exercise-induced asthma, a person will struggle to get air in and out of the lungs because of inflammation of the bronchi and mucus accumulation. If you have another type of asthma, you may also experience exercise-induced asthma.
Cough-induced asthma is a challenge to diagnose. Coughing can occur with or without other asthma symptoms. Doctors need to first rule out chronic bronchitis, postnasal drip, or sinus disease causing the cough, before considering this type of asthma diagnosis.
Occupational asthma is triggered by exposure to something in the workplace. Instigators can include chemicals, vapors, dust, fumes, gases, or other particles. It also can occur due to exposure to molds, animal products, pollen, indoor humidity, or temperature. Stress also can be a trigger.
Nocturnal asthma usually occurs between midnight and 8 a.m. and is often triggered by allergens in the home like dust and pet dander. It can also be caused by a sinus condition. Symptoms occur when the person lies down. (Note that there might be no symptoms during the daytime, which can make it difficult to diagnose.)
Steroid-resistant or severe asthma is resistant to the standard glucocorticoid or steroid treatment. A recent post discussed a new novel treatment for this type of asthma.
Late-onset asthma or adult-onset asthma typically develops in adulthood, after age 18. It is often a more severe type of asthma and can be more difficult to control. Adult-onset asthma has been strongly linked to air pollution exposure, but has also been linked to exposure to certain plastic chemicals or particles, metals, medications, or wood dust. Women are more at risk than men, and it can be triggered by allergens. When allergens are not involved, it is classified as non-allergic, adult-onset asthma.
What the study found
The American Heart Association study, part of the ongoing Wisconsin Sleep Cohort, which began in 1988, followed about 1,270 adults, average age 47, without heart disease, for more than 14 years. For the purposes of the study, the average age of adult-onset asthma diagnosis was 39.5 years, compared to early-onset asthma, which was diagnosed at 8.9 years of age.
At the beginning of the study, 166 of the subjects had asthma (111 had late-onset and 55 had early-onset). The researchers focused on tracking heart events including heart attacks, strokes, heart failure, angina, cardiac revascularization, and death due to cardiac causes. The researchers did factor in risk factors for heart disease in the subjects including smoking, being overweight, having diabetes, or hypertension. After the 14-year period, researchers found that:
Subjects with late-onset asthma were 57 percent more likely to have a heart event compared to individuals without asthma** Subjects with late onset asthma** (compared to non-asthmatics) were more likely to be female and to have a higher BMI
Subjects with early-onset asthma had similar rates of cardiovascular event to non-asthmatics
Why does late-onset asthma seem to encourage higher risk of heart disease and stroke? The researchers theorize that the nuanced differences between early and late-onset seem to be at play here. In addition to the heightened difficulty of controlling late-onset asthma with standard medications that typically resolve early-onset flare ups, late-onset asthma may be specifically linked to air pollution and often involves a more rapid decline of lung function. A 2012 study published in the European Journal of Heart Failure links airflow obstruction and compromised lung function with a higher risk of incident heart failure. Limitations of the study include the fact that most of the subjects were Caucasian, and details on air pollution exposure and stressful life events, which can raise heart disease risk, were not accessible.
If you’ve been diagnosed with late-onset asthma, you and your doctor should work diligently to limit any additional risk factors for heart disease, including being overweight or obese, high blood pressure, hypercholesterolemia, and diabetes.
Remember: Even though your late-onset asthma diagnosis raises your risk of developing heart disease, you have the power to modify your other risk factors.
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Eli Hendel, M.D. is a board-certified Internist and pulmonary specialist with board certification in Sleep Medicine. He is an Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, Qualified Medical Examiner for the State of California Department of Industrial Relations, and Director of Intensive Care Services at Glendale Memorial Hospital. His areas of expertise in private practice include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases.