Scientists find drug to banish bad memories
12:01am BST 01/07/2007
Researchers have found they can use drugs to wipe away single, specific memories while leaving other memories intact. By injecting an amnesia drug at the right time, when a subject was recalling a particular thought, neuro-scientists discovered they could disrupt the way the memory is stored and even make it disappear.
The research has, however, sparked concern among parliamentary advisers who insist that new regulations are now needed to control the use of the drugs to prevent them becoming used by healthy people as a "quick fix".
But the US scientists behind the research insist that amnesia drugs could be invaluable in treating patients with psychiatric disorders such as post-traumatic stress. In a new study, revealed in the Journal of Psychiatric Research, psychiatrists at McGill University, in Montreal, and Harvard University, in Boston, used an amnesia drug to "dampen" the memories of trauma victims.
Prof Karim Nader, of McGill University, said: "When you remember old memories they can become 'unstored' and then have to be 'restored'. "As the memory is getting restored, we gave patients a drug that turns down the emotional part of the memory. It left the conscious part of the memory intact, so they could still remember all the details but without being overwhelmed by the memory."
The research suggests memories can be manipulated because they act as if made from glass, existing in a molten state as they are being created, before turning solid. When the memory is recalled, however, it becomes molten again and so can be altered before it once more resets. The drug used by the scientists is thought to disrupt the biochemical pathways that allow the memory to "harden" after it is recalled.
The researchers used propranolol, a drug normally used to treat hypertension in heart disease patients but also known to cause memory problems. They treated 19 accident or rape victims for 10 days with the drug or with dummy pills, while they asked to describe their memories of a traumatic event that happened 10 years earlier. A week later, they found that the patients given the drug suffered fewer signs of stress such as raised heart rate when recalling their trauma.
Scientists at New York University have published another new study where they claim to have erased a single memory from the brains of rats while leaving the rest of the animals' memories still intact. The rats were trained to associate two musical tones with a mild electrical shock so that when they heard either of the tones they would brace themselves for a shock. The researchers then gave half the rats a drug, called U0126 and known to cause limited amnesia, when playing one of the musical tones. After the treatment, the rats that had been given the drug no longer associated that particular tone with an imminent shock but still braced themselves upon hearing the second tone, demonstrating only one memory had been deleted.
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