Retrospectacle: A Neuroscience Blog

Everyone has painful or unpleasant memories in their past, and some of us would welcome the chance to forget them forever. Some debilitating disorders, like post traumatic stress disorder (PTSD), prey on these memories in ways that are often difficult-to-treat. According to some recent research, a drug taken shortly after a traumatic event, or during the recall of traumatic memories, may act to ‘erase’ them from the brain. Does it work, and could it be a useful treatment? What about the potential for abuse (“de-briefing” comes to mind)?

One drug, propranolol, is currently used to treat hypertension, but it has also already been shown to weaken memories of a traumatic experience when given shortly after the event. Propranolol is a beta-blocker: it blocks the action of epinephrine on both β1- and β2-adrenergic receptors (which may block the formation of frightening memories in the amygdala). However, new research from McGill University suggests that this drug may also act on memories in a retro-active way: if propranolol is given while subjects are asked to recall traumatic memories that occured up to 10 years ago. Interestingly, the result is that the emotional content of the memories are drained, without completely ‘wiping the slate clean,’ so to speak. The subjects remember what occurred, but in a factual rather than emotionally-affecting way.

The experiments are being done [at McGill] involve people traumatized as long as 20 or 30 years ago by child abuse, sexual assault or a serious accident.

“It’s amazing how a traumatic memory can remain very much alive. It doesn’t behave like a regular memory. The memory doesn’t decay,” Brunet said.

To try to make it decay, researchers ask people to describe the trauma as vividly as they can, bringing on physical symptoms like racing hearts, then give them propranolol to blunt “restorage” of the memory. As much as three months later, the single dose appears to be preventing PTSD symptoms, Brunet said.

“Each time you retrieve a memory it must be restored,” he said. “When you activate a memory in the presence of a drug that prevents the restorage of the memory, the next day the memory is not as accessible.”

In another study by Joseph LeDoux’s team at NYU, it was shown possible to eliminate a single memory in rats using a different drug, U0126. This occured without affecting any other memories that the rats had, but questions remain as to whether the ‘deletion’ is permanent. The group is now enrolling subjects for a human study.

Most people, including the researchers in these studies, readily admit that fearful memories do serve some purpose. They remind you to avoid certain harmful stimuli or situations, and perhaps play a role in the formation of personalities and tastes. However, such memories may be moot when it comes to experiences far removed from normal life, like war or rape.

Comments

#1 Sven DiMilo
July 25, 2007

wait…

what?
#2 Shelley
July 25, 2007

Put the propranolol down!
#3 Kapitano
July 25, 2007

What about the emotional content of pleasant memories? Has the drug’s impact on these been tested?

And if propranolol reduces the emotional aspect of old memories, might it have the same effect on the formation of new memories? So as well as being used to trear (for instance) PTSD in soldiers, might is also attenuate the formation of PTSD in soldiers going into conflicts for the first time? Again, has this been tested for?
#4 Blas
July 25, 2007

The problem with giving propranolol to a soldier is that he needs the arousal system fully working in battle.

And I would think it also diminish formation of new memories, at least if used in high doses. It can slao cause depression long term and high dose (from anti-hypertensive use).

Funny how the media tells this story making people think you can erase a certain memory.
#5 Biomed Tim
July 25, 2007

Another interesting aspect of this type of drug is who gets to decide if a patient can have it or not? Should a physician have the responsibility to decide what memory constitutes “emotional truama?” What if I just want to forget that one crazy night in Budapest? What if I consider something to be traumatic but others think I’m just whining?
#6 Jeb, FCD
July 26, 2007

IS the U0126 you referenced the MAPK inhibitor? If so, I don’t think I’d want to be in that study.
#7 shane
July 26, 2007

Might I be the first to mention Eternal Sunshine of the Spotless Mind ? I love it when “in the not-so-distant future” sci-fi comes true in the not-so-distant future.
#8 Spirula
July 26, 2007

In addition to it’s widely perscribed post-myofarct usage, propranolol is widely “used” by people with stage fright issues, as it reduces symptoms and anxiety. It is also widely perscribed for persons with anxiety issues. It does not “wipe” out memories, it just reduces the vividness of the experience, something especially associated with memories formed during sympathetic activation (flight or fight).

I have, and know others, who have been put on propranolol for various reasons, and I did not (nor did they) experience “memory loss”.

(…at least, as far as I can recall. Thanks, I’ll be here all week. Try the veal.)
#9 katherine sharpe
July 26, 2007

fascinating fascinating fascinating
#10 Chris
July 26, 2007

This could be pretty useful. So wait… what if I forget where I put the pill?
#11 VInce Noir
July 26, 2007

I took propanolol for a while for migraine, and experienced no adverse effects, except maybe slight drowsiness. People take this drug all the time for public speaking, etc, because it keeps your heart from jumping out of your chest when you’re nervous. And every one of my grandparents took it for blood pressure. So….I’m wondering if this is really as exciting as it sounds. Plus, how on earth do you erase a specific memory?! Unless, of course, the rats were taught something then they immediately got an injection of the drug…
#12 Peterbart
July 27, 2007

It might be prudent to be a tad more skeptical about the U106 study. In particular, concluding that “it was shown possible to eliminate a single memory in rats using a different drug, U0126. This occured without affecting any other memories that the rats had..” might overstate the case. After all, while it is indeed possible to test some of the other memories that the rat had, it is virtually immpossible to test each and every other memory. Indeed, given potential inter-relatedness of the memory trace, it is more than likely that other memories might be affected, albeit with less of an effect than the target memory.

Some form of memory dampening is probably a real phenomenon, but the science depicted in the Eternal Sunshine of the Spotless Mind is unlikely to become a reality in the very near future.
#13 JanieBelle
July 28, 2007

We Can Forget It for You Wholesale anyone?
#14 gus
July 28, 2007

As I understand, at least for the U0126 drug, it is a very short-lived effect. This is not something that you take twice a day. You are exposed to the drug RIGHT AS YOU ARE RECALLING THE MEMEORY in great detail. Because of this, it should not affect other memories. It is pretty specific. There is a good podcast about it that SciAm did or maybe the Science or Nature one. Damn I cant find it. Sorry!

Gus
#15 kemibe
July 29, 2007

Hot damn. I didn’t believe this shite so I checked it out for meself. I spent five hours today memorizing the Greek alphabet and then swallered me a couple, three Inderal. Now I can only remember 23 of the 24 letters. Weird.
#16 daedalus2u
July 29, 2007

I would suggest that:

“However, such memories may be moot when it comes to experiences far removed from normal life, like war or rape.”

only pertains to some places at some times. That humans have evolved strategies to deal with such experiences tells us that those experiences were not “far removed from normal life” during the time of human evolution.

What propranalol does, is attenuate the somatic effects of stress by blocking certain adrenergic receptors. It may be that it is not the “memory” that is lost, rather the “hard wired connection” of that memory to the autonomic nervous system.

Giving this to soldiers would make them lousy soldiers. Unfortunately what makes people good soldiers makes them lousy peaceful citizens and vice versa.
#17 Melissa G
July 29, 2007

Propanolol? Wait, is the LOLcats craze moving into the field of organic chemistry? I can see it now, cute captions over adorable molecular models, suitable for use as LiveJournal icons:

“O HAI I FIXED UR PROPANE”

“I MADE U SOME PROPANOL BUT I EATED IT”

“I M IN UR BRANE FIXIN UR MEMRIES”

…I’ll get my coat.
#18 DaveH
August 1, 2007

My Dad is 91 and having serious short-term memory problems. He is just fine in the moment and his long-term memory is fine but ask him what he had for lunch after an hour or so and he cannot remember most of the time.

He is hypertensive and has been taking Propranolol since God made dirt. Wondering if this might be a contributing factor. This is not Alzheimer’s (no personality shift and great long-term memory) and the other symptoms of vascular dementia are not there…
#19 PDF
February 19, 2009

After remembering repressed memories and being traumatized in my 40′s by the sexual abuse of my childhood to the point of considering suicide, I would certainly and seriously consider a medication which could erase those flashbacks and memories which sometimes incapacitated me. Please don’t judge someone’s decision to consider this possibility until you hear their story and reasoning for wanting/needing to forget or repress these memories for the first time or again . I sometimes feel that I was better off (and certainly, more emotionally functional) for all those years that I was in denial.
#20 Linda Murphy
September 20, 2010

My daughter was raped is it possible for her to have received this drug? because the police are acting as though she is crazy but it appears the police could have raped her from what she has told us.