Why do some adults suddenly develop allergies? James Sublett, president-elect of the American College of Allergy, Asthma and Immunology, and a practicing immunologist in Louisville, Ky., tells the Wall Street Journal
genetics may be a key factor, but so is a person's exposure to pollen.
If a parent has allergies, chances are good the children will too. But that doesn't necessarily mean they will have symptoms as children. What is inherited is an immune system that is predisposed to allergic reactions. Dr. Sublett explained. And sometimes the symptoms don't emerge until later in life, when exposure to allergens, such as pollen, dust mites or mold, build up over time and reach a critical mass.
Dr. Sublett cites a study of college freshmen who tested positive for the presence of immunoglobulin E, a type of antibody generally associated with allergies, but showed no symptoms. The subjects were checked twice more during their lives.
"Within their college career, about 20 percent of the students developed some allergies," Dr. Sublett said. When the researchers checked the subjects again 20 years later, they found that 40 percent had allergies.
The conclusion: It takes environmental exposure for people to develop full-blown allergies, even if they are genetically predisposed, Dr. Sublett said.
Dr. Sublett said many factors can trigger the onset of allergies in adults, including high levels of pollution exposure, moving to a home that has mold, adopting a pet, or working in a setting where lots of allergens are present. Hormonal changes that come with pregnancy and menopause can also bring on allergies, he says. And in the process of aging, the body's immune system might become more sensitized, which can bring on allergies, he says.
"There are even some viruses that can trigger allergies," Dr. Sublett said, noting the respiratory syncytial and even the common cold can tip the allergy scales in people who are already genetically inclined.