Exams could worsen asthma

Helen Barratt, London

As thousands of students approach finals in the next few weeks, there is now evidence to suggest that the stress at this time may exacerbate symptoms in people with asthma. The American Journal of Respiratory and Critical Care Medicine reports that researchers from the University of Wisconsin have found that stress associated with exams can increase the sensitivity of airways, increasing the local inflammatory response to antigens such as cat dander.

Twenty undergraduates (11 men and 9 women) with mild asthma were exposed to an inhaled antigen on two occasions: during a low stress period—such as the middle of the term or two weeks after exams—and during the week of their finals. The immediate decrease in lung function in response to the antigen was identical during both the examination and low stress periods. Blood tests, however, showed that the inflammatory response was much greater during the exam period—for example, participants produced higher numbers of eosinophils—compared with the low stress period.

They also showed that during the period of stress, participants with a greater increase in the number of eosinophils in their sputum 24 hours after the antigen challenge had a greater fall in their forced expiratory volume in one second. There was no such correlation during the period of low stress.

Psychological stress has been implicated as a significant contributor to the onset of asthma symptoms for many years, and many patients have increased bronchoconstriction in response to distressing experiences. The mechanism linking stress and asthma, however, has not been well defined. The researchers claim that this is the first study to show that eosinophilia induced by allergen can be increased by the psychological stress associated with final exams. They suggest that stress modulates the local immune response, particularly the balance of cytokines. This appears to enhance the sensitivity of the airway to a second stimulus, such as an antigen, potentially increasing the severity of symptoms.

An accompanying editorial, however, points out that the study of the effect of emotions on asthma symptoms has had a chequered history. Although the paper seems to strongly suggest that exam stress worsened at least some of the inflammation associated with asthma, there is evidence for and against the hypothesis and many doctors continue to question the importance of emotional factors.