Painful Memories may be Erased by Anti-Fear Drug

by Kathy Jones on Jun 5 2010 6:03 PM

 Painful Memories may be Erased by Anti-Fear Drug
Scientists have said that it is possible to overcome bad memories of painful situations with the help of a chemical that works on the brain.
Researchers suggest that anti-fear medication could help soldiers deal with post-traumatic stress disorder.he new study was carried out on laboratory rats.

According to boffins, instead of working in the same way as a conventional sedative or anti-depressant, the new chemical stimulates the area of the brain thought to be involved in remembering a painful situation from the past. The chemical, called brain-derived neurotrophic factor (BDNF), is naturally produced in the brain and is involved in learning and memory. When given to the rats, the drug caused them to re-learn a painful association so that the memory of it is extinguished - although not lost entirely.

"Many lines of evidence implicate BDNF in mental disorders. This work supports the idea that medications could be developed to augment the effects of BDNF, providing opportunities for pharmaceutical treatment of post-traumatic stress disorder and other anxiety disorders," said Thomas Insel, director of the US National Institute of Mental Health.

Published in the journal Science, the study investigated how laboratory rats freeze when they hear a sound that they have associated with a small electric shock to their feet. It is possible to overcome this fear of the sound by training the animals with a series of similar sounds not associated with painful shocks.

The Independent reports, "But by injecting BDNF, a protein that stimulates the growth of nerve cells, into the brains of the rats, the scientists found they could mimic the effects of the retraining process. This chemical mimicry only worked if they put BDNF into a part of the brain called the infralimbic prefrontal cortex, a structure that appears to be critical for the extinction of memory.

"The drug seems to induce a "memory of safety" in the rats that overrides the fearful memory. In effect, the BDNF drug mimics the effect of retraining the rats to extinguish the memory of the painful situation, said Gregory Quirk of the University of Puerto Rico School of Medicine, who led the investigation."

"The surprising finding here is that the drug substituted for extinction training, suggesting that it induced such a memory [of safety]," Dr Quirk said.