Ketamine dose to reduce heavy drinking shows promise

"One-off ketamine dose may reduce heavy drinking, say scientists," reports The Guardian.

In an experimental study, researchers used a single injection of the drug ketamine to disrupt the pleasurable memories that heavy drinkers associated with drinking alcohol.

Previous studies have shown that ketamine can disrupt, or "rewrite", stored memories. So the researchers wanted to see if a dose of ketamine could help break a cycle of thinking and memory in which alcohol use is strongly associated with feelings of pleasure and relaxation.

The research involved 90 men and women from the UK, with an average age of 27. All the participants drank heavily but had not been diagnosed with an alcohol problem.

They were split into 3 groups. One group was given ketamine as part of a memory trigger and disruption process and they halved their weekly consumption from an average 84 units to 41 units. This was a bigger reduction than the other groups, who were either not given ketamine, or given it without the memory trigger process.

The researchers found the potential effects of ketamine on memory and behaviour could be investigated as a treatment for people dependent on alcohol. However, more work needs to be done to test whether the process is really safe and effective.

It is important to stress that under UK law, ketamine is a class B illegal drug that carries up to a 5-year sentence for possession and 14 years for dealing. Long-term ketamine abuse can lead to serious bladder problems.

Find out more about alcohol and health

Where did the story come from?

The researchers who carried out the study were from:

  • University College London
  • University College Hospital
  • the University of Amsterdam

The study was funded by the Medical Research Council. It was published in the peer-reviewed journal Nature Communications on an open access basis so it's free to read online.

The Guardian gives an accurate and balanced account of the study.

The Mail Online stated that "injecting alcoholics with ketamine" could "help them quit their boozing habits", which is a bit misleading. The people in the study were not diagnosed as alcohol-dependent, and they reduced their alcohol consumption rather than stopping it altogether.

What kind of research was this?

This was a randomised controlled trial (RCT), which is often the best type of study to see which treatment works best.

However, it is a small-scale study and larger studies would usually be needed before a treatment is widely put into use.

What did the research involve?

Researchers recruited 55 men and 35 women through advertisements on social media. All the participants were beer drinkers, who were drinking at harmful levels (consistently more than the recommend 14 units of alcohol per week).

None of the participants had been diagnosed with alcohol dependency and none of them were currently seeking medical treatment for alcohol use.

The study had 3 stages.

During the first stage, people were given a glass of beer and told they could drink it after answering a series of questions. They were shown images of alcoholic drinks and asked about their desire to drink and how much they thought they would enjoy the drink. After drinking the beer, they were asked how much they actually enjoyed it. They were also asked about their drinking in the past week.

In the second stage, the participants were randomly split into 3 groups of 30.

  • Group 1 was given ketamine with memory triggering. They were given a glass of beer and viewed images of alcoholic drinks, as before. However, instead of being allowed to drink the beer, the glass was taken away and they were given a ketamine injection. Removing the beer unexpectedly meant the memory of pleasure associated with beer drinking was vulnerable to being weakened by ketamine, the researchers say.
  • Group 2 was given ketamine without memory triggering. They were given orange juice instead of beer and shown images of orange juice. The orange juice was then taken away and they were given a ketamine injection.
  • Group 3 was given a placebo injection with memory triggering. They were also given a glass of beer and viewed images of alcoholic drinks. The beer was then taken away and they were given a placebo injection of saline.

In the third stage, people were recalled after 10 days and went through the first stage again, where they were given a glass of beer and asked to answer questions before and after drinking it. They were again asked about their drinking in the past week. The researchers followed up with questionnaires about their drinking in the past week after 2 weeks, 3 months, 6 months and 9 months.

The researchers also looked at ketamine levels in their blood to test whether it correlated with later desire to drink.

What were the basic results?

All the participants in each group were drinking heavily at the start of the study, with an average reported 74 units a week. This is 25 to 37 pints of beer, depending on strength.

Those in the group randomly assigned to ketamine and memory triggering were drinking the most, at an average 84 units a week.

10 days after treatment:

  • the group that had ketamine plus memory triggering had reduced their drinking by an average 23.5 units a week
  • the group that had ketamine but no memory triggering reduced their drinking by an average 13.6 units
  • the group that did not have ketamine had not reduced their drinking

The group given ketamine plus memory triggering reported a reduced desire to drink the beer placed in front of them after 10 days, rated their expected enjoyment lower, and enjoyed the beer less than before treatment. The other groups did not show a change in desire to drink or enjoyment of drinking.

All groups reduced their drinking in the 9 months following treatment. In the group given ketamine plus memory triggering, the drop was sharpest during the first 10 days. However, their drinking continued to drop until they had reduced it by an average 43 units a week.

The other groups reduced their drinking more slowly over time. By 9 months, the 3 groups were drinking about the same – around 40 to 41 units a week. Because the ketamine plus memory triggering group had been drinking most heavily at the start of the study, they showed the biggest reduction in drinking.

How did the researchers interpret the results?

The researchers said the study showed that the memory triggering plus ketamine procedure had led to "meaningful, lasting reductions in alcohol consumption outside of the lab after a single brief intervention" that were "unprecedented in alcohol research".

They stressed that "specialist supervision" is needed for administration of ketamine, and it may not be safe enough to use in all cases. They said further work was also needed to assess the most effective memory triggering process.


Drinking too much alcohol can have a devastating effect on health, as well as on people's lives, ability to hold down a job and relationships with friends and family. A quick treatment that seems to help people cut down on excess alcohol sounds great.

However, this is only a single relatively small study, and it is the first time the treatment has been tested. We cannot yet be sure that this treatment is safe or will work if used routinely.

There is also a problem with the results. Because the randomly chosen people in the treatment group were drinking much more than the people in other groups, it is difficult to be sure that the changes to their drinking afterwards came just from the treatment. It could be that their alcohol consumption reduced the most because it was highest to start with.

Additionally, a third of participants did not contribute to the 9-month follow-up – so we do not know what level of alcohol they were consuming.

It is encouraging that people maintained their drop in alcohol consumption over 9 months. However, some people who are dependent on alcohol return to drinking many months or even years after cutting down or quitting, so it would be useful to see longer-term results.

It is also notable that people in all 3 groups reduced their alcohol consumption to about the same level after 9 months. The reason for this reduction is not explained, but it could be that taking part in a study where they spent time thinking about their drinking might have made people decide to cut down.

If you're concerned about your drinking, there is help and support available. Starting with a GP is a good idea.

Read more about where to find alcohol support

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