Public Release: 

In humans, an anesthetic rightly timed can weaken the strength of a traumatic memory

Propofol-induced deep sedation reduces emotional episodic memory reconsolidation in humans

American Association for the Advancement of Science

As part of continued efforts to develop treatments for anxiety and stress-related disorders, researchers have shown that reactivating a negative memory in a human patient and then administering an anesthetic to that person made it harder for them to retrieve the memory 24 hours later. This result has implications for developing therapies for disorders including post-traumatic stress disorder (PTSD), suggesting that a routine anesthetic procedure combined with memory reactivation might be an effective, noninvasive approach. Stress-related disorders are often associated with the vivid remembering of traumatic experiences. One avenue for treating these disorders is to selectively weaken specific negative memories but doing so has been challenging. Recent studies in animals have found evidence that reactivating a "consolidated" memory temporarily, when it's about to be "reconsolidated," can briefly return it to a state where the memory is susceptible to modifications, including weakening. Seeking to understand if sedation could disrupt reconsolidation of a negative memory, Ana Galarza Vallejo and colleagues invited fifty healthy people to watch two narrated slide-shows (featuring some aversive content). Then, one week later, the participants' memory for one slide-show was reactivated by a reminder. Immediately after memory reactivation, the participants received one intravenous dose of the anesthetic propofol. To explore if propofol disrupted reconsolidation of the reactivated memory, participants were then randomly assigned to two groups; in the first, the authors tested the participants' ability to recall both stories (reactivated and non-reactivated) 24 hours after propofol, and in the second, they looked at this immediately after propofol administration. Showing that propofol disrupted reconsolidation of a reactivated memory, the researchers reported that people in the first group (in whom the anesthetic had 24 hours to take effect) could not remember the reactivated story as well as they could recall the non-reactivated story. The results point to an effective, noninvasive method for reducing the stressful impact of traumatic events.

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