Cutting edge

Understanding why the anxiety-sensitive think the worst of innocuous sensations could shed light on panic disorders

We have all been in situations where we may be more conscious of bodily sensations, but people who are high in anxiety sensitivity - the tendency to be fearful of anxiety-related sensations -seem to interpret these sensations as potentially life-threatening. For example, a rapidly beating heart may be interpreted as a heart attack. Those low in anxiety sensitivity are more likely to say that such sensations are merely unpleasant.

We have been investigating the thought processes that may be involved in anxiety sensitivity. Anxiety sensitivity seems to be closely related to panic disorder. Indeed, it seems to precede future panic attacks. Since panic disorder is associated with the negative misinterpretation of innocuous bodily sensations, understanding how and why anxiety-sensitive people interpret such sensations should give us insight into how panic disorder may develop and be maintained.

In a recent study, Catherine Dillon and I tried to see if we could manipulate such negative interpretative biases. Given that people high in anxiety sensitivity are particularly fearful of anxiety-related bodily sensations, we decided to manipulate such sensations experimentally by administering a moderate dose of caffeine to 120 healthy students. We chose caffeine because it is known not only to increase physiological arousal (heart rate, blood pressure) but also to affect mood (eg anxiety). The main aim was to see if such caffeine-related changes would affect the interpretative processes of those who are high in anxiety sensitivity.

We presented participants with a series of ambiguous scenarios and asked them to decide what the most likely explanation for them was. For example, we asked people to decide the most likely reason for being aware of their rapid heart beat. We found that those high in anxiety sensitivity rated negative interpretations such as a heart attack as more likely than those who were low in such fears. We also found that caffeine moderated this effect. As expected, caffeine was found to increase cardiovascular activity and mood (anxiety and arousal). However, rather than increasing the likelihood of anxiety-sensitive people making more negative interpretations, caffeine actually seemed to decrease this bias. This would seem to suggest that a moderate dose of caffeine may actually calm anxious people, in that it makes them less likely to interpret their world in a negative way.

An additional and somewhat unexpected finding was that caffeine decreased the tendency for males to make negative interpretations, whereas for women it made such interpretations more likely. The fact that caffeine produced differences in the way in which men and women interpreted such ambiguous events shows that there may be key differences between men and women in cognitive and emotional processes.

We are investigating how the fear of bodily sensations influences perceptions of stressful life events. For example, we are teaching stress-management skills to children taking GCSEs, with the aim of targeting anxiety-related thoughts. We are also investigating how anxiety sensitivity may influence the perception of painful events, such as childbirth. Indeed, researchers in Sweden have shown that the fear of childbirth may actually increase the likelihood of an emergency caesarean section. By predicting who is most likely to react negatively to physically demanding situations, we should be better able to develop specific interventions to reduce the negative impact of such events.

Edmund Keogh is lecturer in psychology, Goldsmiths College, University of London.