Scientists have discovered that a dose of one of the body's own stress chemicals can neutralise a fear of heights.
Writing in PNAS, University of Basel researcher Dominique de Quervain and his colleagues recruited 40 patients with confirmed height phobia. The patients were divided an intervention group and a control group.
Over several days, both groups were then subjected to a series of three graded height exposure therapies using a virtual reality headset to fool the wearer into believing he or she was traversing a series of above-ground walkways and platforms.
While this was happening, the subjects were also asked to rate their subjective levels of discomfort, and skin conductance measurements, another measure of stress, were collected from some of the participants. The subjects paused at each "station" along the way until their self-reported stress levels fell.
Critically, prior to each of these three treatment sessions, the members of the intervention group also received a small oral dose of the chemical cortisol, one of the body's own stress hormones produced by the adrenal gland.
Following the treatment sessions, all of the subjects were then followed up with two assessments 3 days and 28 days later at which their levels of height phobia were reassessed.
The subjects all benefited from the exposure therapy, with the controls showing about a 30% reduction in fear responses during the later assessments. But amongst the cortisol-treated group, fear had fallen by over 60%.
The reason for this, the researchers argue, is that cortisol causes impaired recall of established memories whilst simultaneously strengthening the formation of new ones.
So by exposing the acrophobics to a stressful virtual height situation and permitting them to get used to the sensation at each stage, in the presence of cortisol, the subjects recalled fewer of their fear memories and re-wrote stronger imprints of the experience being less stressful, causing their fear responses to be "extinguished".
The team also point out that the method might be generalisable to other anxiety states too.