(CN) — People suffering from hay fever or asthma face a 166 percent higher risk of developing psychiatric disorders, according to a new study that is the first to propose a link between common allergies and mental illness.
The authors of the report, published Monday in the journal Frontiers in Psychiatry, say the findings could affect how doctors treat and monitor patients with allergic diseases.
After searching a database of health insurance claims in Taiwan, the team found that nearly 11 percent of patients with common allergic diseases developed a psychiatric disorder within 15 years, compared to 6.7 percent of those without.
Over a year, lead author Nian-Sheng Tzeng noticed something unexpected about patients suffering from dermatitis (eczema), allergic rhinitis (hay fever) and asthma — known as the three “A”s.
“As a clinician, I observed that some patients with the three ‘A’s appeared to suffer emotionally,” said Tzeng, who practices at Taiwan’s Tri-Service General Hospital. “Therefore, I wanted to clarify whether these allergic diseases are associated with psychiatric disorders.”
Searched the literature, the team found that previous research had reported connections between allergic diseases and certain psychiatric disorders or emotional issues. For example, a study in Denmark found that children with allergic diseases experienced more behavioral and emotional issues.
But not all research corroborated this positive link, with one study in Taiwan suggesting hay fever is less common in schizophrenia patients. This prompted Tzeng and his colleagues to launch their own study.
They found that none of the studies examined the connection between the three “A”s and the risk of developing psychiatric disorders. To study this in a broad swath of people, the team used a massive database of health insurance in Taiwan, spanning a 15-year period.
The authors identified 46,467 people with allergic diseases and 139,941 without. Unlike previous research, they included patients of all ages.
Over the 15 years, 10.8 percent of people with allergic diseases, compared to 6.7 percent of people without, developed a psychiatric disorder: a 166 percent higher risk.
Examination of the data showed eczema patients had a reduced risk of developing a psychiatric disorder, while those with hay fever or asthma had an elevated risk.
The team also found that using certain asthma medications was linked to a diminished risk of psychiatric disorders in asthmatics.
The study did not examine the potential causes of this phenomenon, but recent studies suggest inflammation is connected to psychiatric issues such as depression and anxiety disorders.
Since allergies involve inflammation, it is possible that they contribute to psychiatric disorders. The psychological stress of a mental health issue may also contribute to physical symptoms.
However, Tzeng says recognizing that there is a connection alone could improve care.
“We would like to let clinicians who care for patients with allergic diseases know that their risk for psychiatric diseases may be higher,” he said in a statement. “Assessing their emotional condition and monitoring their mental health could help to avoid later psychiatric problems.”