The drug is actually not a new creation: Metyrapone is often used to diagnose adrenal insufficiency, but these researchers found that its effect on stress hormones might be its most useful attribute. Metyrapone decreases the levels of cortisol, which is a steroid hormone produced by the adrenal gland in response to stress. These early trials suggest that by messing around with the levels of cortisol in a person's body at the time of a stressful event, memories of that event might be impaired--possibly permanently. It's a very different technique than the neurological manipulations we explored a few years back. There is a sort of reverse of this process that's used to increase memory--at least, in elderly mice.