Many people who develop asthma during childhood or young adulthood outgrow it by the time they are older. New research suggests that their lungs may be affected even when the symptoms are long gone.
Researchers looked at lung data from over 3,000 people over the age of 45 all over the United States. They compared the lung structure and function of those that had a history of childhood- or young adult-onset asthma to those with no history of asthma.
The results showed a link between asthma early in life and lower lung capacity and function in later adulthood.
Kathleen M. Donohue, MD, of Columbia University, New York, and colleagues wanted to find out if a history of childhood- or young adult-onset asthma changed lung structure and capability later in life.
The data for this study were taken from 3,371 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). This is a large-scale study looking at cardiovascular disease in white, African American, Hispanic and Asian subjects.
MESA recruited men and women between 2000 and 2002 from cities all over the US. All participants were between 45 and 84 years old.
People with heart disease, obesity, pregnancy or who could not commit to participate over a long period of time were not included.
When participants joined the study they were asked if they had any history of asthma or asthma symptoms.
People who had experienced asthma at or below the age of 18 were put in the childhood-onset group. Those who had experienced asthma between the ages of 18 and 45 were put in the young adult-onset group.
Between 2004 and 2006, a lung function test called spirometry was performed for all participants.
A computerized tomography, or CT, scan that gives three-dimensional X-ray images of the lungs was also performed on all participants.
These CT scans were used to measure how much air was in each participant's airway. People with asthma-related lung damage often have smaller or narrower airways that let in less oxygen than the airways of people without lung damage.
Of the 3,371 study participants, 446 had asthma and 2,925 did not. Of those that reported a history of asthma, 217 said that it had begun in childhood and 102 said their asthma symptoms started when they were young adults.
Individuals that had a history of asthma – no matter when it started - had significantly lower lung function at the time of the study when compared with participants without asthma.
On average, people with childhood asthma had 2,365 milliliters less air in their lungs than participants without childhood asthma.
Those who had young adult-onset asthma had an average of 2,343 milliliters less air in their lungs than people without the condition.
As a comparison, study participants who had a history of smoking but no history of asthma only had 282 milliliters less air in their lungs than average non-smoking participants.
“This finding confirms that asthma in childhood and young adulthood is a major correlate of lung function later in life,” the authors wrote.
Additionally, a history of asthma in young adulthood was linked with narrower airways and thicker walls in the lungs, when compared to those without a history of asthma.
Those with a history of asthma had an average of 20.01 millimeters narrower airways than participants without asthma history. Their airway walls were also thicker by an average of .001 millimeters.
For each year that participants had experienced asthma, the researchers found that the effect was greater.
“A history of asthma, particularly in childhood and young adulthood, was associated both with large decrements in lung function in later life and narrower segmental airways,” the authors concluded.
The study was published in the February issue of The Journal of Allergy and Clinical Immunology.
The research was funded by the National Institutes of Health.
Several of the authors report potential conflicts of interest. Some have received research grants from the National Institutes of Health. Others are stakeholders in VIDA Diagnostics, a company commercializing lung image analysis software developed, in part, at the University of Iowa.