According to the Asthma and Allergy Foundation of America, 40 percent of U.S. children suffer from allergies. It is the third most common chronic disease in kids under the age of 18.
A new study suggests that children who have allergies at an early age are more likely to have problems with anxiety and depression than those that do not.
One reason may be that children with allergies tend to keep their troubles to themselves or “internalize” them.
“I think the surprising finding for us was that allergic rhinitis has the strongest association with abnormal anxiety/depression/internalizing scores compared to other allergic diseases,” said lead author Dr. Maya K. Nanda of the division of Asthma, Allergy, and Immunology, at Children’s Mercy Hospital in Kansas City, Missouri.
Rhinitis is more commonly called “hay fever” and includes symptoms such as a runny nose, sneezing, and itchy or watery eyes.
The researchers studied 546 children who had skin tests and exams at age one, two, three, four and seven and whose parents completed behavioral assessments at age seven. They looked for signs of sneezing and itchy eyes, wheezing or skin inflammation related to allergies.
Parents answered 160 questions about their child’s behaviors and emotions, including how often they seemed worried, nervous, fearful, or sad.
Researchers found that the four-year–old children with hay fever symptoms or persistent wheezing tended to have higher depressive or anxiety scores than others at age seven.
The more allergies a child had, the higher the anxiety and depression scores.
“This study can't prove causation. It only describes a significant association between these disorders, however we have hypotheses on why these diseases are associated,” Nanda told Reuters Health by email.
Another reason for the association may be that children with allergic diseases may be at increased risk for abnormal internalizing scores due to an underlying biological mechanism, or because they modify their behavior in response to the allergies, she said.
Other studies support the idea that that a biologic mechanism involving allergy antibodies trigger production of other substances that affect the parts of the brain that control emotions.
In a 2005 study, Teodor T. Postolache, MD, associate professor of psychiatry and director of the mood and anxiety program at the University of Maryland School of Medicine in Baltimore found that peaks of tree pollen increased with levels of suicide in women.
Postolache says allergic rhinitis is known to cause specialized cells in the nose to release cytokines, a kind of inflammatory protein. Animal and human studies alike suggest that cytokines can affect brain function, triggering sadness, malaise, poor concentration, and increased sleepiness.
The new study took race, gender and other factors into account, “so the strong association between allergic disease and internalizing disorder we found is definitely present,” Nanda said.
The severity of mental health symptoms varied in this study. Some children had anxiety and depression that needs treatment, while others were at risk and required monitoring, she said.
“We think this study calls for better screening by pediatricians, allergists, and parents of children with allergic disease,” Nanda said. “Too often in my clinic I see allergic children with clinical anxiety (or) depressive symptoms; however, they are receiving no care for these conditions.”
“We don't know how treatment for allergic diseases may effect or change the risk for internalizing disorders and we hope to study this in the future,” Nanda said.
Experts hope that if parents know that allergies may contribute to their child’s mood or behavior, they will be more likely to keep a closer eye on their child for signs of depression or anxiety and seek treatment if necessary.
The study was presented in The Journal of Pediatrics.
Sources: Kathryn Doyle, http://www.reuters.com/article/us-health-kids-allergies-depression-idUSKBN0UC1TW20151230
David Freeman, http://www.webmd.com/allergies/features/allergies-depression