Psychological stress and anxiety can make seasonal allergy attacks worse and linger longer, according to research presented at the annual meeting of the American Psychological Association in Boston.

"People may be setting themselves up to have more persistent problems by being stressed and anxious when allergy attacks begin," said Dr Janice Kiecolt-Glaser, professor of psychology and psychiatry at Ohio State University in Columbus.

To gauge how stress and anxiety affect allergy sufferers, Kiecolt-Glaser and colleagues recruited 28 men and women with a history of hay fever and seasonal allergies to participate in a laboratory study.

On different days, the volunteers were subjected to a low-stress condition - reading quietly from magazines - and to much more stressful conditions - giving a 10-minute, videotaped speech in front of a group of "behaviour evaluators" and solving math problems without paper or pen in front of the group and then watching their videotaped performance.

The researchers assessed participants' levels of stress and anxiety and performed standard skin prick allergy tests before and right after the stressful events, as well as the next day.

Anxiety following the stressful event, the researchers found, heightened the magnitude of the allergic reactions induced by the skin prick tests. These allergic reactions show up on the forearm as slight wounds, or "wheals".

People who were moderately stressed because of the experiment had wheals that were 75 per cent larger after the stressful event compared to the same person's response after the low-stress condition.

People who were highly stressed had wheals that were twice as large after they were stressed compared to their response when they were not stressed. Moreover, these highly stressed people were four times more likely to show allergic wheals a full day after the stressful event.

This suggests, the researchers say, that highly stressed people had an ongoing and strengthening response to the allergy-causing substances.

"The stress seemed to affect them into the next day," explained Kiecolt-Glaser. That is, being stressed seems to cause a person's allergies to worsen the next day.

According to Ohio State immunologist Dr Ronald Glaser who was involved in the study, greater anxiety was associated with increased production in the body of stress hormones called catecholamines and the inflammation-related protein called interleukin-6.

He thinks the elevated levels of these compounds are to blame for the delayed allergic reactions.

This delayed allergic response is "really what's ugly about allergies," Kiecolt-Glaser noted, because they are typically unresponsive to antihistamines. She advises trying to keep stress at a minimum, if possible, during allergy season.

Reuters