The hallucinogenic drug may help treat addiction by weakening past memories of drinking
By Laura Sanders
A single dose of ketamine may cut down problematic drinking. Taken in the right context, the hallucinogenic drug may be able to weaken the pull of the cues that trigger people to drink beer, researchers report November 26 in Nature Communications.
Ketamine’s influence on people’s drinking was modest. Still, the results might be a time when “small effects tell a big story,” says addiction researcher David Epstein of the National Institute on Drug Abuse in Baltimore. “If a seemingly small one-time experience in a lab produces any effects that are detectable later in real life, the data are probably pointing toward something important.”
The study hinges on the idea that addiction, in a way, is a memory disorder. People learn to associate a drug or alcohol with the good feelings it brings. Cues in the world, such as the smell or picture of a beer, can trigger those memories — and cravings. “We’re trying to break down those memories to stop that process from happening, and to stop people from relapsing,” says study coauthor Ravi Das, a psychopharmacologist at University College London.
Ketamine is an anesthetic, that at lower doses, has also shown promise as a treatment for severe depression (SN: 3/21/19). The drug can also affect memories. One of ketamine’s effects in the body is to interfere with a molecule called NMDA, which is involved in reforming memories after they are called up.
Das and his colleagues recruited 90 people who said they drank too much beer, though none was formally diagnosed with alcohol addiction. First, participants were exposed to pictures of beer and even got to drink one in the lab. During the experience, they rated their beer cravings, enjoyment of drinking, and after the beer was gone, the desire to have another one.
A few days later, the participants returned to the lab and were split into three groups. People in one group were again shown pictures of beer to jog their memories. To make the memory recall extra strong, the researchers served up actual beer, but then, in a twist, took it away before participants could drink it. The bait-and-switch maneuver was key, Das says. “You have to generate the element of surprise,” he says.
As a comparison, a second group was shown images of orange juice instead of beer. Then people in both of these groups got an intravenous dose of ketamine. A third group had beer memories called up, but received no ketamine.
A week after the procedure, the people who had their beer memories jogged before receiving ketamine reported less desire to drink, and less enjoyment of beer — a reduction that wasn’t as strong for the other two groups of participants. The people who had their beer-drinking memories jogged and received ketamine also reported drinking less.
The results were surprising, Das says, because attempts to curb people’s drinking in their daily lives are rarely successful (SN: 8/9/17). “You get jaded. Not a lot seems to work,” he says.
Nine months after the procedure, all of the participants, including those who hadn’t received ketamine, had roughly halved their beer drinking — an across-the-board drop that could be explained by the self-awareness that comes simply from enrolling in a study, says Epstein. “Behavior can change for all sorts of reasons that aren’t specific to the experimental treatment,” he says. The interesting thing here, he says, is the initial decline in drinking among people who had ketamine while they were reminded of beer.
More research is needed to confirm ketamine’s short-term effect on drinking, and see how long it might last. Das and his colleagues plan on testing ketamine on more people with problematic drinking habits in clinical trials. The researchers are also trying to weaken other sorts of problematic memories, such as those involved in post-traumatic stress disorder.
As a drug that can be abused, ketamine comes with baggage that may make people reluctant to see it as a way to treat addictions. But if a single dose of ketamine can slow excessive drinking, “then that’s quite an easy trade-off from a health perspective,” Das says. “If it works, it works.”