One dose of ketamine could help heavy drinkers cut their alcohol intake, a study has suggested. When a shot of the sedative was given to heavy drinkers after reactivating their drinking-related memories, it led to a rapid decrease in urges to drink and a prolonged decrease in alcohol intake over nine months. Ninety participants were given a glass of beer and told they could drink it after finishing a task. They rated their urge to drink and were shown images of beer and other drinks, while rating their anticipated pleasure, thus retrieving the reward memories surrounding beer drinking. On the first day of the study, the heavy drinkers were then allowed to drink the beer to establish their baseline drinking urges. But on the second day, the beer was unexpectedly taken away from them. Lead author Ravi Das, of University College London’s Clinical Psychopharmacology Unit, said: “We found that heavy drinkers experienced a long-term improvement after a very quick and simple experimental treatment. “Learning is at the heart of why people become addicted to drugs or alcohol. “Essentially, the drug hijacks the brain’s in-built reward-learning system, so that you end up associating environmental ‘triggers’ with the drug. These produce an exaggerated desire to take the drug. “Unfortunately, once these reward memories are established, it’s very difficult to relearn more healthy associations, but it’s vital in order to prevent relapse.” Researchers say unexpectedly removing an anticipated reward is known to be a key factor in destabilising a retrieved reward memory. Typically the brain then undergoes an active process to restabilise and store the memory. However, ketamine prevents this memory re-storage process by blocking a receptor in the brain that is needed to restabilise memories. The study involved 55 men and 35 women who had harmful drinking behaviour – drinking the equivalent of 30 pints of beer a week – but had not been diagnosed with alcohol addiction and were receiving no treatment. On the key day, a third of participants were given an intravenous infusion of ketamine after the beer was taken away. Another group was given an infusion of a placebo, while the other third were given ketamine, but without previously completing the drinking memory retrieval task. The study published in Nature Communications found that over a 10-day follow-up, the people who were given ketamine combined with memory retrieval showed significant reductions in their urge to drink. They also drank less alcohol and on fewer days than the other participants. Given a small sample of beer, they had less urge to drink it, enjoyed it less and had less desire to continue drinking than the other groups. The researchers also conducted blood tests, and found the treatment was more effective in people where the sedative was most readily available in their blood. Dr Das added: “This is a first demonstration of a very simple, accessible approach, so we hope that with more research into optimising the method, this could be turned into a helpful treatment for excessive drinking, or potentially for other drug addictions.” However, the scientists cautioned that the study is experimental and is not a clinical trial. They said further research is needed to optimise the treatment method and determine who it could benefit, and specialist supervision would still be required as the treatment may not be advisable for people with some conditions.