According to the National Institute of Mental Health, posttraumatic stress disorder, or PTSD, is an anxiety disorder that some people get after seeing or living through a dangerous event.
The intense fear triggers split-second changes in the body to defend against danger. In PTSD, this reaction is changed or damaged. People with PTSD may feel stressed or frightened even when they are no longer in danger.
Anyone can develop PTSD at any age. War veterans and survivors of physical and sexual abuse are commonly diagnosed with the disorder. Not everyone with PTSD has been through a dangerous event. Some people develop PTSD after a friend or family member experiences danger or is harmed.
The sudden, unexpected death of a loved one can also cause PTSD.
It sounds like science fiction, but some researchers are studying whether certain drugs can erase or dim bad memories. The possibility of memory blocking has some ethicists concerned.
Felicia Cohn, Ph.D., is the director of medical ethics at the University of California, Irvine. She said erasing memories may be erasing someone's identity.
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Erasing Memories
News 8’s Todd Boatwright explores the science and ethics behind some controversial therapies.
 
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"If you start changing somebody's memories, you can raise the question of whether or not you're changing their identity in some fundamental way," Cohn said.
According to her, even bad memories teach us important lessons.
"Whether it means we become more protective with our children or we lock our doors more often at night, or you know, even subtle behavior changes can really make a big difference in the way we live," Cohn said.
Researchers in Brooklyn are studying the drug known as "ZIP" in animals. They conducted an experiment where they put the animals on a turntable. One region of the table delivered a mild foot shock, so the animals learned to stay away from that area. After the researchers injected ZIP into their brains, the rats went straight to the spot that shocked them, meaning they forgot what they had learned.
Researchers from Harvard and elsewhere have been studying whether the drug propranolol can dim the emotional response to memories in people with PTSD.
In one preliminary trial, investigators found the pill "significantly reduced physiological responses" in the patients. Researchers said the drug works by influencing the reconsolidation of memories, which is the shaping of already-formed -- or consolidated -- memories.
In another recent study involving the drug, researchers trained 60 people to associate a picture of a spider with an electric shock.
After the conditioning, students who were given propranolol before seeing the picture were not startled, while the other students were.
Researchers are also studying the effects of other drugs for memory editing. Some of these therapies include painkillers, anti-nausea drugs and RU486, which is best known as the "abortion drug."
