Changing Memories to Treat PTSD

A controversial area of brain research suggests it may be possible””but is it ethical?

National Journal
Aug. 28, 2014, 12:46 p.m.

Be­fore he lost the abil­ity to sleep through the night; be­fore the pan­ic at­tacks star­ted; be­fore he drove his truck over an im­pro­vised ex­plos­ive device, leav­ing him with trau­mat­ic brain in­jury; be­fore a second road­side bomb did the same thing a few weeks later””be­fore all of that, on the U.S. mil­it­ary base near Kanda­har, Afgh­anistan, sol­dier Kev­in Mar­tin liked to think about the sci­ence-fic­tion movie In­cep­tion.

“My friends and I used to joke dur­ing our time in Afgh­anistan that we were go­ing to take all the money we had and pay someone to Incept us,” he says””ref­er­en­cing the film’s premise of im­plant­ing or ex­tract­ing in­form­a­tion from a per­son’s mind as they sleep”””so that we could put a cool­er, not-as-bad memory of Afgh­anistan in our brains and go on with the rest of our lives.”

Thus far, no such treat­ment ex­ists for Mar­tin, 23, who re­turned to the U.S. in 2012 and was dia­gnosed with post-trau­mat­ic stress dis­order earli­er this year. Now a sopho­more at Trin­ity Col­lege, he’s con­sidered 30 per­cent dis­abled by the Vet­er­ans Af­fairs De­part­ment for his PTSD (he’s also 10 per­cent dis­abled for an un­re­lated shoulder in­jury) and takes pre­scrip­tion an­ti­anxi­ety med­ic­a­tion to ease his symp­toms.

But re­search­ers have be­gun to in­vest­ig­ate a pos­sible treat­ment sim­il­ar to the one Mar­tin ima­gined: A pa­per re­cently pub­lished in the journ­al Bio­lo­gic­al Psy­chi­atry ar­gues that it may be pos­sible to treat PTSD by al­ter­ing pa­tients’ memor­ies.

The pa­per re­views a grow­ing body of sci­entif­ic lit­er­at­ure on memory re­con­sol­id­a­tion, a re­l­at­ively new (and, in hu­mans, still some­what con­ten­tious) concept in which old in­form­a­tion is called to mind, mod­i­fied with the help of drugs or be­ha­vi­or­al in­ter­ven­tions, and then re-stored with new in­form­a­tion in­cor­por­ated””like a piece of met­al that’s been melted down, re­mol­ded, and left to harden in­to a dif­fer­ent shape.

Though dif­fer­ent types of memor­ies are so­lid­i­fied in dif­fer­ent ways””the fear-driv­en memory of driv­ing over a bomb, for ex­ample, will make its way through the brain dif­fer­ently than a mundane memory of yes­ter­day’s break­fast””there are gen­er­al neur­o­lo­gic­al pro­cesses that all memor­ies fol­low.

“In memory re­search, we talk about three parts,” ex­plains Ken Paller, dir­ect­or of the cog­nit­ive neur­os­cience pro­gram at North­west­ern Uni­versity. “The first part is the ac­quis­i­tion or cod­ing of a memory,” in which our brains pro­cess the in­form­a­tion our senses are send­ing, “and the last part is re­triev­ing a memory. And in between, we talk about con­sol­id­a­tion,” the pro­cess by which sens­ory in­form­a­tion””a sight, a taste””so­lid­i­fies in­to fully formed memor­ies to be stored for the long term.

Typ­ic­ally, the more of­ten memor­ies are re­called, the stronger they be­come. “If you’re try­ing to mem­or­ize something in a book, you sit there and re­peat it over and over,” ex­plains Wendy Su­zuki, a re­search­er at New York Uni­versity’s Cen­ter for Neur­al Sci­ence. “That’s also an ex­ample of how things get con­sol­id­ated. You re­peat [them] over and over.”

But with re­con­sol­id­a­tion, the re­search­ers ex­plain, con­sciously re­call­ing a memory is also what al­lows it to be ma­nip­u­lated. “[Memor­ies] are not ne­ces­sar­ily fixed but can be changed long after stor­age,” they write. “Seem­ingly stable memor­ies may re-enter an un­stable state when they are re­trieved, from which they must be re-sta­bil­ized.”¦ Dur­ing re­con­sol­id­a­tion, memor­ies are sus­cept­ible to modi­fic­a­tion again.”

“Do you lose some part of your­self if you get rid of a pain­ful memory? Would that be worth the trade?”

One way is by dis­tract­ing the brain as it re­calls, or “ac­tiv­ates,” memor­ies: People who were asked to mem­or­ize two sep­ar­ate lists of ob­jects, for ex­ample, did worse on the second list after they were re­minded of con­tent from the first, while people who were asked to mem­or­ize a folk tale be­fore re­call­ing auto­bi­o­graph­ic­al events de­scribed their memor­ies in less de­tail than those who had not seen the story.

Per­haps more com­pel­ling for the treat­ment of PTSD, though, are the ex­per­i­ments that in­volve tam­per­ing with fear-driv­en memor­ies us­ing phar­ma­ceut­ic­als. In one study, pub­lished in Nature Neur­os­cience, vo­lun­teers were stim­u­lated to gen­er­ate fear memor­ies after be­ing sub­jec­ted to loud noises and im­ages of spiders; later on, one group was giv­en pro­p­ran­o­lol (a beta-block­er used to slow heart­beat and some­times used in the treat­ment of anxi­ety dis­orders) be­fore be­ing made to re­call the fear­ful ex­per­i­ence, while the oth­er was giv­en placebo pills. When the two groups were again re­minded of the memory days after the ex­per­i­ment began, those who had taken the pro­p­ran­o­lol showed markedly less fear than those who had not.

A study from the journ­al Psy­cho­neur­oen­do­crino­logy found a sim­il­ar ef­fect with pro­p­ran­o­lol in sub­jects who were asked to ima­gine a fear­some event that hadn’t ac­tu­ally happened””when they were made to re­call the ima­gined scen­ario, the chem­ic­al eased their re­sponse much as it had done in ex­per­i­ments with real fear memor­ies. (People with PTSD, it bears not­ing, can ex­hib­it symp­toms of the dis­order even if it was someone close to them who ac­tu­ally ex­per­i­enced the trauma; journ­al­ists fre­quently ex­posed to vi­ol­ent im­ages can de­vel­op PTSD even from the safety of their news­rooms.)

Com­pared to Mar­tin’s hy­po­thet­ic­al In­cep­tion scen­ario, the types of modi­fic­a­tion dis­cussed in the re­search re­view are de­cidedly less dra­mat­ic. Based on the stud­ies presen­ted, re­con­sol­id­a­tion ap­pears to be much less heavy-handed than its sci­ence-fic­tion ana­logue””a lessen­ing of the emo­tions as­so­ci­ated with the memory or the dulling of its de­tails, rather than the total men­tal erad­ic­a­tion of an event or the cre­ation of a new one from scratch.

But still, the idea of re­con­sol­id­a­tion broaches new ter­rit­ory for pos­sible re­lief from PTSD, which af­fects an es­tim­ated 7 to 8 per­cent of Amer­ic­ans, by ad­dress­ing its root cause rather than its symp­toms. Cog­nit­ive pro­cessing ther­apy and ex­pos­ure ther­apy, two com­mon be­ha­vi­or­al treat­ments, fo­cus on cop­ing skills and con­trolling fear, and ac­cord­ing to the Na­tion­al In­sti­tutes of Men­tal Health, only two med­ic­a­tions“”the an­ti­de­press­ants Zo­loft and Pax­il””are cur­rently ap­proved by the U.S. Food and Drug Ad­min­is­tra­tion ex­pli­citly for the treat­ment of PTSD, though oth­er an­ti­de­press­ants and anti-anxi­ety med­ic­a­tions are of­ten pre­scribed to treat the emo­tion­al ef­fects char­ac­ter­ist­ic of the con­di­tion.

“The nat­ur­al in the realm of memory does in­volve re­shap­ing and for­get­ting. Maybe the in­jury is more like the un­nat­ur­al.”

Some psy­cho­lo­gists, however, re­main skep­tic­al that this par­tic­u­lar area of memory re­search is the an­swer.

Des­pite the find­ings of some of the stud­ies ad­dressed in the Bio­lo­gic­al Psy­chi­atry re­view, the bulk of the re­search on re­con­sol­id­a­tion thus far has in­volved lab an­im­als rather than hu­mans, ex­plains Paul Re­ber, dir­ect­or of North­west­ern Uni­versity’s Brain, Be­ha­vi­or, and Cog­ni­tion pro­gram””and map­ping ro­dent brains doesn’t provide ad­equate in­sight to the in­tric­ate, messy work­ings of hu­man memory, where something as seem­ingly in­con­sequen­tial as a smell or a snip­pet of mu­sic can pull for­ward a rush of emo­tions from events past.

“In an­im­al stud­ies, you have the greatest con­trol over the neur­al sys­tems, but you don’t have any ac­cess to the sub­ject­ive ex­per­i­ence of memory,” he says. “So you can build mod­els of things you think might be re­lated to what hu­mans ex­per­i­ence with PTSD, but you don’t really know how they’re con­nec­ted.”

Paller, too, ques­tions the faith that some have placed in re­con­sol­id­a­tion, ar­guing that it stems from an over­sim­pli­fied un­der­stand­ing of the way that memor­ies are pro­cessed in the first place. Rather than something that must be de-sta­bil­ized in or­der to change, a memory is a con­stantly shift­ing en­tity, con­tinu­ally up­dated with new con­text even when it isn’t be­ing con­sciously re­called.

“It’s a lot dif­fer­ent than when you put some in­form­a­tion in your com­puter and just ex­pect to get that out in the same form,” he ex­plains. “If you learn something on a Wed­nes­day and you learn new in­form­a­tion the next day, that can change the memory that you stored. So every time that we learn something, sub­sequent events can col­or it dif­fer­ently.”

“The more soph­ist­ic­ated view of con­sol­id­a­tion is, [it] can strengthen a memory, but it doesn’t reach a per­man­ent stage ever,” he says.

Wheth­er or not re­con­sol­id­a­tion is a vi­able pos­sib­il­ity for PTSD treat­ment may still be up for de­bate; wheth­er or not it should be a pos­sib­il­ity, though, is an­oth­er ques­tion al­to­geth­er.

Slip­pery philo­soph­ic­al quandar­ies abound: Does the act of tak­ing a pill to change memory re­quire dif­fer­ent eth­ic­al con­sid­er­a­tions than something like psy­cho­ther­apy or hyp­not­ism? Could it pave the way for more omin­ous ap­plic­a­tions? And is the al­ter­ing of memor­ies a hu­mane way of help­ing those who suf­fer, or is it some fun­da­ment­al vi­ol­a­tion of what makes hu­mans, well, hu­man?

But on the flip side, if some people are bio­lo­gic­ally pre­dis­posed to PTSD, wouldn’t this be a way of lev­el­ing the play­ing field, of help­ing people un­lucky enough to be­come vic­tims of their bod­ies’ own chem­istry?

“People say, ‘Well, it’s just wrong to in­ter­fere with the nat­ur­al in the realm of memory,’” says Peter Kramer, a psy­chi­atry pro­fess­or at Brown Uni­versity who stud­ies med­ic­al eth­ics, “but the nat­ur­al in the realm of memory does in­volve re­shap­ing and for­get­ting. Maybe the in­jury is more like the un­nat­ur­al.”

As the body of ex­ist­ing re­con­sol­id­a­tion re­search ex­pands””and as sol­diers con­tin­ue to re­turn home burdened by the trauma of their ex­per­i­ences””it’s an is­sue that those who study the brain are likely to grapple with more and more of­ten.

“I was at a con­fer­ence not that long ago where the idea was brought up,” Re­ber says, “and it led to a lot of an­im­ated dis­cus­sion: If you could edit your own memor­ies, are there any memor­ies you’d want to get rid of? If you have a memory of a pain­ful event, do you lose some part of your­self if you get rid of it? Would that be worth the trade?”

“Ob­vi­ously,” he adds, “it’s not a simple ques­tion.”

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