Tuesday, February 17, 2009

Fearful memories 'can be erased by blood pressure drug'

Fearful memories can be erased using propranolol, a drug commonly prescribed for high blood pressure, research has shown. The discovery could lead to new ways of treating people suffering from the emotional after-effects of traumatic experiences such as terrorist attacks or natural disasters.

Previous research on animals had shown fear memories are susceptible to being altered at the time they are recalled, as they are "reconsolidated" in the brain. Studies suggested beta-blockers, a family of drugs normally used to treat high blood pressure, may interfere with the reconsolidation process. Now a trial involving human volunteers has given strong support to the theory.

A team of Dutch researchers artificially created a fearful memory by associating pictures of spiders with a mild electric shock delivered to the wrists of the 60 participants. When the volunteers were shown the spider pictures 24 hours later their "startle" response - a measure of fear - was assessed by testing eyeblink reactions. Administering the beta-blocker drug propranolol before reactivation of the fearful memory led to a marked reduction in the startle response. After taking the drug, volunteers were much less disturbed by the spider pictures. The effect appeared to be permanent, as the spider fear seen in the initial experiment did not return to treated participants.

The findings, reported in the journal Nature Neuroscience, raise the possibility of a new approach to tackling emotional problems and post-traumatic stress disorder. The study leader, Professor Merel Kindt, and colleagues from the University of Amsterdam, wrote: "Millions of people suffer from emotional disorders and the relapse of fear, even after successful treatment. "Our findings may have important implications for the understanding and treatment of persistent and self-perpetuating memories in individuals suffering from emotional disorders."

However Dr Daniel Sokol, lecturer in Medical Ethics at St George's, University of London, sounded a word of caution. He said: "Removing bad memories is not like removing a wart or a mole. It will change our personal identity since who we are is linked to our memories. It may perhaps be beneficial in some cases, but before eradicating memories, we must reflect on the knock-on effects that this will have on individuals, society and our sense of humanity."

John Harris, Professor of Bioethics at the University of Manchester, said: "It is obviously up to the individual whether or not she wishes to risk the possible effects, including psychological discontinuity, of erasing unpleasant memories. "An interesting complexity is the possibility that victims, say of violence, might wish to erase the painful memory and with it their ability to give evidence against assailants. "Similarly, criminals and witnesses to crime may, under the guise of erasing a painful memory (perhaps of another sort), render themselves unable (with a good excuse for being unable) to give evidence."


Decoys drive cancer cells to suicide

French specialists overnight unveiled a new weapon against cancer - a molecular "decoy" that mimics DNA damage and prompts cancerous cells to kill themselves. The research, published in a US journal, Clinical Cancer Research, opens up fresh avenues for attacking tumours that are resistant to conventional therapy, they said. Chemotherapy and radiotherapy aim at inflicting sufficient damage to a cancer cell to unleash a process of programmed cell death, also called apoptosis. But sometimes the onslaught does not cause enough damage to activate the apoptosis trigger, and surviving cancer cells are able to repair themselves.

A team led by Marie Dutreix of the Curie Institute in Paris, developed tiny fragments of DNA that mimic the two broken ends of the double-helix genetic code. The trick prompts these holdout cells into believing they are far more damaged than they really are, and commit suicide. The tricksters - appropriately called "Dbaits" - have been successfully tested on mice, Ms Dutreix said. By injecting lab rodents with Dbaits a few hours before radiotherapy, the team were able to wipe out 75-100 per cent of cancer cells on lab rodents, compared with 30-50 per cent using only radiotherapy, and there was no collateral damage to healthy tissue.

If all goes well, clinical trials on volunteers could start by the end of next year, said Ms Dutreix. The technique is especially promising for treating brain tumours and skin cancer, which are notorious for resistance to radiotherapy. If it works, it could also lead to big reductions in dosage of radiotherapy, which can often be toxic to healthy cells surrounding the tumour.


1 comment:

Anonymous said...

"Fearful memories 'can be erased by blood pressure drug'"

Geez, no chance of anything going wrong/being abused with this drug, is there?