Erasing Memories

Continued from page 1

Preliminary studies of one drug, currently used to treat heart problems and anxiety, show that it seems to do just that. Researchers administered the drug, known as propranolol, to volunteers after they recalled a traumatic event. The drug appeared to subtly change the way they remembered the event: while they could still recall the details, the emotional response that normally accompanied the memory was dulled. Scientists haven't yet studied the effect of this drug on the brain with fMRI.

While it's not yet clear how the drug works, scientists believe it interferes with the way memories are stored after being recalled. Recent research has shown that memories are not set in stone. Unlike a video, every time a memory is "replayed," it needs to be organized and stored anew, making it vulnerable to change. "We believe during that process, some kind of interference occurs, and the memory is degraded," says Alain Brunet, a psychologist at McGill University, in Canada, who led the study, published last week in the Journal of Psychiatric Research. (The mechanism behind the memory reconsolidation process appears to be different than that behind memory suppression, but both involve reactivating the memory and then reshaping it in some way.)

While both studies are exciting, scientists caution that they are still far from clinical practice. In the case of propranolol, larger studies are needed to assess how well the treatment works and for how long. In the case of nondrug therapy, it's not yet clear whether the techniques used in the memory-suppression study will be applicable to trauma victims. "The effects are small, about 10 percent, so they are not on scale of what we imagine true clinical suppression of a traumatic event would have to be," says Gabrieli. "But that doesn't mean they don't give us hints. Making a patient 20 percent happier is significant."