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Drug Deletes Fearful Memories
Al writes "Technology Review has an article about a common drug that seems to 'delete' painful memories related to a fearful experience. Experiments carried out by neuro-scientists at Emory University show that propranolol, a drug commonly used to treat high blood pressure, can suppress the emotional part of a fearful memory. The results, published in Nature Neuroscience, suggest a new way to treat anxiety disorders. In recent years, scientists have discovered that the simple act of remembering a past experience requires that the memory be consolidated once again. And both animal research and some human studies have shown that during re consolidation, long-term memories — once thought to be fairly stable — can be more easily meddled with."
Nope, propofol (2,6-diisopropyl phenol) likely works by increasing the response to inhibitory neurotransmitters, and acts as an anesthetic. Propanolol is a non-selective beta-blocker, which blocks the beta-adrenergic receptors (receptors for epinephrine and norepinephrine). As the summary notes, the most common pharmaceutical use for this is to lower blood pressure, which it does by preventing the release of renin. Its effects on memory are completely coincidental to those on blood pressure.
In the brain, a part of the brainstem known as the locus ceruleus is the site of norepinephrine synthesis, and it is activated by stress to send norepinephrine to the amygdalae, the brain's "emotional memory association" centers. It is in the amygdalae that memories are associated with emotions, with the ultimate result being that it is easier to form long term memories of experiences that associated with strong emotions. In blocking norepinephrine transmission to the amygdala, beta-blockers most likely are acting to uncouple the connection between a stressor and its associated memory, such that the brain no longer considers it important enough to keep in long term memory.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
Oh, most definitely- it's still an off-label use of the drug in the US, but people are certainly taking beta-blockers to treat performance anxiety, as well as to prevent nervous fine motor tics. At the most recent Summer Olympics, one of the medalists in pistol shooting had his medals taken away after testing positive for propranolol.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."