Ketamine: a surprisingly long-term and effective treatment for addiction...
Alcohol is a well-known ‘social lubricant’, but it is also one of the most commonly abused drugs in the world and linked to addiction, disease, death and accidents, all of which place an unwelcome strain on stretched healthcare systems like the UK's National Health Service.
In 2018, almost 600,000 people were dependent on alcohol in England alone. That is nearly 1% of the UK’s population. And 8/10 of those people are not accessing treatment.
Now researchers at University College London have shown that a single dose of the anaesthetic drug "ketamine" can be used to weaken memories associated with addictive behaviour right after they are recalled, and this might help problem drinkers to cut down. In their study, participants showed a significant reduction in alcohol intake per week that persisted for up to nine months afterwards.
Ninety adults drinking harmful quantities of alcohol every week were recruited. Each was consuming an average of 74 units of alcohol - roughly equivalent to 30 pints of beer - per week - but had not been formally diagnosed with alcohol addiction.
The researchers worked on the principle that addiction, like other patterns of behaviour, is learned and stored in memory. But how can you kick an addiction if it is stored as a memory?
They used a process called memory destabilisation to erode the subject's recall of their fondness for alcohol. To do this, they placed a glass of beer in front of each participant, with the promise that they would eventually get to drink it. The subject was then tasked to look at images of beer and rate how pleasant they found them.
The unexpected twist is that the beer reward they had been expecting was then snatched away, so they did not get to drink it. This, explains Ravi Das, who led the trial at University College London, “seems to be the key thing for getting memories to destabilise.”
下一步研究需要destabilised memory to be weakened. This is where the ketamine comes in. According to Das, “ketamine blocks a certain receptor that is critical to making memories stable again, so kind of restoring them; so if you block that receptor you can prevent the memories restoring and directly weaken those memories' traces.”
The results of the study showed an average reduction in weekly consumption from 74 units to around 40. The most surprising result was that this single, hour-long treatment produced these impactful results over the entire duration of the study, which was nine months.
The use of ketamine might be surprising for some as it is widely known to be a recreational drug and animal tranquilizer, but, as Das points out, “ketamine is the most effective drug we can use to specifically block this receptor in humans. It's quite safe given the way that we gave it. It's routinely used on the NHS in anesthesia, particularly for children.”
The next step for the UCL team is a clinical trial with participants formally diagnosed with alcohol use disorder. Successfully repeating the results from this study would give further credibility to their approach, which could potentially be used to tackle other addictions too.
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