The trial's findings, conducted at the University of Basel in Switzerland and published this week in the Proceedings of the National Academy of Sciences, might seem counterintuitive. But they are built on two lines of research. The first suggests that fearful memories have become inextricably tangled up with the object of one's phobia, and each time we face that stimulus, those memories get dredged up. The second suggests that cortisol, a steroid hormone that is produced by the adrenal cortex but can be produced synthetically, affects memory in two ways: It makes old and especially emotionally-laden memories harder to retrieve (quick! disregard that oncoming train and tell me your mother's birthday), and makes new memories more likely to stick (which is why we often remember extremely stressful moments in our lives with exquisite clarity).
Put these together and it all makes perfect, if unexpected, sense. Getting a dose of cortisol before a gradual exposure to heights (or spiders, bridges or public places) should make it harder for a person with a phobia to retrieve the associated memory that makes certain places or things so scary. At the same time, the new memories being created by that guided exposure to the object of a phobia are more likely to establish themselves. With the bond severed between fearful memory and its object, a phobia loses its power to paralyze.
When put to the test in this clinical trial, acrophobic subjects who preceded their exposure therapy sessions with two 10-milligram hydrocortisone tablets reported a significantly greater reduction in their fear of heights, their expectancy of danger and their inclination to avoid situations that might involve heights than did subjects who got a placebo pill.
The Swiss researchers suggested that cortisol might help boost the effects of exposure therapy in the treatment of a wide range of phobias and anxiety disorders. They found in earlier studies that cortisol-plus-exposure-therapy reduced the fear of those with social anxiety in a social-stress situation, and patients with spider phobia reported progressively less fear on viewing photos of spiders when they took cortisol.