Long-term lung inflammation associated with allergen exposure is linked to the development of anxiety later in adulthood, according to a new study.
Sonia Cavigelli, PhD
But a recent study found that it is not the initial asthma that triggers anxiety, but the sustained lung inflammation that is associated with exposure to an allergen.
"The idea of studying this link between asthma and anxiety is a pretty new area, and right now we don't know what the connection is," Sonia Cavigelli, PhD, associate professor of biobehavioral health, Penn State College of Health and Human Development, said. "What we saw in the mice was that attacks of labored breathing may cause short-term anxiety, but that long-term effects may be due to lasting lung inflammation."
Researchers not only determined that children and adolescents with asthma are 2-3 times more likely to develop an internalizing disorder such as anxiety or depression later in life, they also found a direct correlation between exposure to an allergen and long-term lung inflammation which is linked to the development of anxiety disorders in adulthood, according to the study.
Given that strong causal link between asthma, lung inflammation and anxiety, children being treated for asthma in their youth should remain wary of the condition’s impact on their mental health.
In order to determine the connection between asthmatic events among pediatric patients and anxiety in adulthood, researchers examined key component of asthma, including lung inflammation or airway constriction.
"A person who's having an asthma attack may have inflammation in their lungs and labored breathing at the same time, so you can't separate which is contributing to later outcomes,” lead author Jasmine Caulfield, a graduate student in neuroscience, said. “But in mice, we can isolate these variables and try to see what is causing these anxiety symptoms.”
After 3 months of exposure to allergens, researchers found the mice still had lung inflammation and mucus, which led them to conclude that lasting effects remain in the lungs long after the allergy trigger has been removed. Additionally, researchers determined that the mice that were exposed to the allergen and developed these changes in lung function also had changes in gene expression in brain areas that help regulate stress and serotonin.
Cavigelli said the team’s original belief was that, once allergen was removed, the lungs would quickly clear themselves of inflammation.
"If this translates to humans, it may suggest that if you grow up exposed to an allergen that you're reacting to, even if you get over that, you might still have these subtle, long-term changes in lung inflammation,” she explained.
Given the link between long-term lung inflammation and anxiety later in life, the study suggests that removing the asthma-inducing allergen among pediatric patients is not an efficient solution, nor does it decrease off the likelihood of developing an anxiety disorder.
Thus, logic dictates that if lung-inflammation is treated early on in pediatric asthma patients, the chance of developing anxiety in adulthood should be reduced.
"It makes sense to us, because while labored breathing events may be scary and cause anxiety in the short term, it's the inflammation in the airways that persists into adulthood," Caulfield said. "So, it would make sense that long-term anxiety is linked with this long-term physical symptom."
The study, "Asthma Induction During Development and Adult Lung Function, Behavior and Brain Gene Expression," was published online in Frontiers in Behavioral Neuroscience.