Erasing Your Traumas
Using these techniques to treat cravings in addiction is very new. In a study published in 2013, researchers tested rats to see if blocking memory reconsolidation with the drug rapamycin could reduce cravings. Led by Segev Barak, then at UCSF and now at Tel Aviv University, after putting alcohol-addicted rats through a 10-day abstinence period, they exposed them to the smell or taste of alcohol. Immediately after, they administered rapamycin, which apparently blocked the pathway that enables protein synthesis. Even without subsequent extinction training, these rats did not “relapse” a full 24 hours later. And, drinking remained “suppressed” for up to 14 days.
There are a handful of pre-clinical trials testing whether propranolol can work in addiction, namely for cocaine and nicotine. MUSC’s Michael Saladin led a study looking at treating cocaine addicts with propranolol during the reconsolidation window to reduce cravings and relapse. The results showed that it did, indeed, work: compared to addicts who received a placebo, those subjects who received an injection of propranolol after being presented with an initial cue “had greatly reduced craving response to [subsequent] cues” that they were exposed to the following day, as well as a variety of other subjective measures, he says, like reduced heart rate and blood pressure. He is currently conducting a follow-up study that will look at longer-term effects of propranolol exposure.
While much hype has been given to the idea of “erasing” memories using interventional techniques, all the researchers interviewed here said that this type of intervention—blocking reconsolidation of cue-based memories—is only going to change the emotional aspect to these memories. In essence, you’re not going to forget that you like the buzz from drinking or the high from doing drugs; the association for the drug with a cue—the craving—is just going to be diminished. The memory itself is not being changed, Saladin says. “What’s going on is that these procedures are impacting the emotional aspect of memory.”
“It’s easy to imagine how this could be used in a treatment setting,” he adds, in that it’s not only practical, but cost-effective—it’s designed to only be used once, or a few times at most. While this area of research is so young, it’s also got a lot of potential, Saladin believes. “We’ll learn more in the next decade, but even before then, we’re going know a lot more about potential treatment.”
Barak thinks rapamycin, which is FDA-approved to prevent organ rejection after a transplant, could be used as an initial treatment for cravings in alcohol addiction, but “if we can get the same or similar result without a drug, it’s always better.” With so few clinical studies, it’s hard to say what, if any, kind of side effects to these treatments there might be.
While much research in rats has shown that memory reconsolidation can be intervened upon pharmacologically, it was Elizabeth Phelps’ group at NYU, led by Daniela Schiller, who showed that in humans, reducing fear memories could be effected by psychological means, not using drugs. In a well-cited study from 2010, the lab showed that human patients who had been conditioned to fear a blue square on a computer screen could be re-trained to not fear the blue square if they were cued with a “reminder” 10 minutes before the usual fear extinction training. And, they were much more apt to not see their fear spontaneously come back—as often happens. In fact, the difference between the test groups persisted a full year on. It’s a new type of learning, says Saladin, compared to simply making memories extinct. “When you open that window [of reconsolidation], you are updating the content of that memory.”
Phelps thinks that psychological intervention is something that can and should be focused on instead of using chemical interventions, like propranolol—she thinks the data is too messy and so far, most of it is in rodents and not humans. Importantly, memory reconsolidation is a natural process, one that’s happening whether or not we manipulate memories in the lab. “This is how your brain works,” she says. “The purpose of reconsolidation is to strengthen memories over time, and the second may be to update memories with new information at the time of memory retrieval—by understanding [this], we can take advantage of that [process].”
Non-invasive techniques to target the reconsolidation of craving memories are just beginning to be investigated. In a most recent study from 2012, Chinese scientists led by Lin Lu at Peking University in Beijing used a retrieval-extinction process similar to Phelps and Schiller’s to reduce cravings and relapse in heroin addicts. They showed that in abstinent heroin addicts, retrieval of drug-associated memories 10 minutes before extinction sessions reduced heroin cravings one, 30, and 180 days later.
To be sure, this doesn’t erase memories. And, it’s still “science fiction,” Phelps warns. “It is really interesting and has great clinical potential, but we really aren’t there.” In other words, don’t get your hopes up; researchers have a lot more work to do. As with most things in life—and addiction—there will be no easy fix. Just because you take away cravings doesn’t mean that you don’t have to work hard at changing your lifestyle, your worldview, or both. Moreover, for many addicts, the inner work only begins when the intense cravings of early sobriety begin to subside—getting past cravings can teach addicts a lot about why they got sober, and how to stay sober.
Jeanene Swanson is a regular contributor to The Fix. She last wrote about the helpful effects of glutamate.