Rewriting Addiction


In this podcast about how neuroscience is offering new approaches to treatments for drug addiction, science journalist Ryan O’Hare speaks to

  • Harry Shapiro of Drugscope,  the UK organisation supporting professionals working in the field of drug misuse.
  • Dr Amy Milton, a lecturer and researcher in the Department of Psychology at the University of Cambridge
  • Barry Everitt, Professor of behavioural neuroscience at the University of Cambridge.
  • Dr Sunjeev Kamboj, a lecturer in clinical psychology at University College London
  • Andy [not his real name], a recovering addict

[Andy] – “Trying to justify to yourself that you could take it possibly take it very sporadically, but yeah, there’s a lot of mental trickery going on,”

[Sunjeev Kamboj] – “There isn’t really, at the moment, any long-term treatment that you receive and then stop taking and you’re cured,”

[Harry Shapiro] “When someone has collapsed all of their problems into one, to the exclusion and detriment of everything else in their lives, that’s addiction,”

[Amy Milton] – “We need to think of addiction much more as a chronic disorder so it’s more like treating diabetes or hypertension than some short term disease”

Ryan O’Hare:  When it comes to drug and alcohol addiction the numbers speak for themselves. With 800 million pounds a year being spent on drug treatment and recovery services in the UK alone, it’s estimated that one in five of us have experienced addiction or know someone who has.

Although there are a number of treatments to try and tackle the problem in the short-term, such as chemical replacements, and abstinence and psychological therapies for the dependence, relapse in the long-term is still a problem.  Harry Shapiro is head of communications for the UK charity, Drugscope.

 Harry Shapiro:  There’s a bit of a kind of mantra, cliché, whatever, there’s many ways into addiction and many ways out. There is no typical pathway out, and some people won’t go anywhere near a treatment system but might manage to get off the actual drinking or drugs and then might spend much of their time in AA or NA meetings. So, there are several pathways that people will take and they will jump from one to another.”

For someone who has become used to using drugs or alcohol as a way of coping with problems there is always the chance that if more problems present themselves that there’s a kind of learned behaviour there and the way that you deal with this, in terms of coping, is to go back on drugs or start drinking again.

One of the reasons why a lot of residential rehabs are based sited well out of city centres, out in rural communities and all the rest of it, is this idea that you need to be well away from your old haunts and your old habits. Because it’s true, people do start getting cravings, some people do, if they walk past some alley way where they used to shoot up a few years ago, it all kind of starts coming back.

RO’H: We are becoming more and more aware that getting someone off of drugs and alcohol is only half the problem. The challenge for the long-term means trying to target the very mechanism which has evolved to help us make sense of the world around us, our memory.Though, brilliantly adapted to help us find food, a partner and to avoid the dangers of our environment, it can also be one of the biggest barriers to long-term drug treatment.

But in order to understand the underlying pathways used by our brains, we need to start with something a little more every day.

Walk into a bakery and the smell of fresh bread hits you. Immediately it stirs up a thousand memories, you may not even be aware the process is happening, you may start to salivate, and your stomach may even start to rumble with hunger.

But all of this is triggered in a flash, before you’ve even seen a loaf. Just from a simple cue, the smell of the bread.  Dr Amy Milton, is a lecturer and researcher in the Department of Psychology at the University of Cambridge…

Amy Milton:  The smell of food is a Pavlovian cue. So the smell of baking bread, if you walk past a bakers and smell the bread you’re more likely to go in and buy a loaf of bread.  There’s no reason why that smell should be rewarding, I mean you don’t get anything from the smell, but because it’s been paired with the yummy bread in the past, that smell has become effectively a conditioned cue. It’s acquired some reinforcing value, because you’ll behave differently on being exposed to that smell, but also some motivational value because you actually like that smell as well.

RO’H:  Without realising it, you are being conditioned by your environment, throughout your everyday life. Your brain makes the link between the things you see and the things you do, learning to associate cues from the outside world with a response, and keeping a permanent record in your subconscious in the form of memory.

AM:  So there’s a memory for the cue, which we call the conditioned stimulus after Pavlov, and the unconditioned stimulus which is the thing that actually has the motivational value, whether that’s the bread itself, because that has the caloric value and the taste value, or in the case of drugs of abuse, the pharmacological effect of that drug.”

RO’H:  Barry Everitt is Professor of behavioural neuroscience at the University of Cambridge.

Barry Everitt:  What happens when people take drugs, is they do it again and again and again in a quite restrictive set of circumstances. So if you think of someone smoking crack cocaine or smoking heroin, or rolling up notes to snort cocaine, but also the places people do it or the people they do it with, become always associated with taking the drug and the drug effect.

Even when people are abstinent and they suddenly encounter those drug cues, they elicit memories of drug taking and they make you crave, they elicit cravings. And both of those things can lead to the resumption of the taking of drugs.

AM: So just as in the same way that you can automatically find yourself walking into the kitchen where there’s the smell of baking bread and you’re not consciously aware that you’ve done that. That can also happen in individuals who are trying to remain abstinent. They suddenly find themselves back in a bar where you’re exposed to these alcohol cues again, and the more of these cues that are present, then the more likely it is that somebody is going to relapse.

Each time the drug is taken, be it alcohol, cigarettes or narcotics, the links between the substance and the cues associated with it are strengthened in the brain, compounding the addiction.

RO’H: Andy, not his real name, is a recovering addict and explains how his addiction began.

Andy: I guess through the nightlife really, through people I used to get pissed with and take coke with, and then some of those people would form secret groups within social situations and then go off and take smack and, being young and full of bravado, you’re really up for doing the harder stuff.

I got to a point where maybe for about six years where I was taking heroin and smoking crack everyday, and yeah, being a fully fledged junkie.

RO’H: And was it a physical thing or mental thing? Was there ever a need to have to take it?

Andy: Oh yeah, there’s definitely a need to have to take it, both heroin and crack. But, after that, the period I was talking about when I could not take it for a couple of months and then have a huge binge, that was very mental, a huge mental block about it.

Trying to justify to yourself that you can take it very sporadically, you know, things like that. There’s a lot of mental trickery going on.

RO’H:  But, new research is emerging around targeting the memories linked with addiction. By focusing on two separate processes used by the brain, it can alter the subconscious record of events, and might just be the key to cutting the link between the cues, the memories and the cravings.

One of these processes is called extinction.

By tapping into how the brain links a memory with a response, it’s possible to create a new, better suited memory, without the old association. This new memory then takes the place of the old one.

BE: So extinction, instead of briefly retrieving a memory, by presenting a stimulus, you present the stimulus again and again until the response to the stimulus gradually disappears. So that’s used in cue-exposure therapy, for example, to treat phobias.”

So in the same way you might treat someone with a fear of spiders, by gradually exposing a former addict to their cues, the association with a drug can be weakened.

AM: …so if we take the example of an alcoholic patient, this could be something that looks very much like the drink, so the glass, a fluid that is the same colour, cotton pads soaked in the drink so that you have the smell of the alcohol as well. But it could also be particular environments as well, so if someone always drinks in the same place. Those are the sort of things that we’re talking about”

RO’H:  So it could be as simple as taking someone into a pub and not getting a drink?

AM: Essentially, in cue-exposure therapy, what you’re doing is you’re training the individual that these cues no longer predict the drug.

RO’H: Creating a new memory is all well and good, but what happens to the old memory?

BE: Now, extinction is very context dependent. So if you bring people into the clinic and extinguish their fear or their drug cue, and it’s been tried, when they go into the outside world the extinction hasn’t happened there, so the stimuli retain their power. And worse still, over a period of time, the memories have never been removed from the brain so they can spontaneously recover and impose themselves on the individual’s behaviour.”

RO’H: Andy, Were you ever aware of any of any triggers that would bring on the cravings and make it any stronger?

Andy: Definitely, environment would be one of the main ones. I mean I moved back to Scotland for a while to try and end that part of my life. I mean I couldn’t come to London without geting off the train and instantly going and scoring crack and heroin, or whatever.

BE: Sooner or later, most smokers want to stop and most drinkers want to stop and most addicts actually want to stop. At that point where that’s what they’re trying to do, exert their will to stop using drugs, the thing that works against them are these things in the environment that creep up on them and make them crave and push them towards relapse.”

RO’H: So intertwined are the associations in the brain between the external and the internal that they can affect how the body reacts to a drug.  Dr Sunjeev Kamboj is a lecturer in clinical psychology at University College London

Sunjeev Kamboj: Heroin addicts who are used to taking their drug in a particular place and then take their drug in a different environment are much more likely to overdose. And that’s this process of learning. Because in their normal environment some responses are being produced in the body, independently of the drug being present, and these processes tend to oppose the drug action in anticipation of the person taking the drug. When they are in a new environment those oppositional effects aren’t present, so the drug has a much more powerful effect.

RO’H: Scientists used to think that when a memory was made, it was stored in a permanent form that couldn’t be changed, like text written in the pages of a book.

But, research over the last few years has shown that memories act more like documents in a word processor – they can be edited, overwritten and potentially, even deleted.

When a new memory is made, the information is stored away in the brain in a stable state.

But, when this memory is reactivated under certain conditions, it enters into an unstable state, where it can be updated with new information.

Once the new information is incorporated, the memory is effectively saved and returned to the stable state again. Just like saving the document after editing.

This process is called reconsolidation.

AM:  even these old and well established, very strong memories are susceptible to destabilisation at retrieval and the reconsolidation process.  The memory is only unstable for a short period of time and within six hours your window for updating that memory should have closed.

RO’H: So, could this be the breakthrough needed to tackle relapse in the long-term – by catching and rewriting the memories in this brief window, before they restabilise.

AM: If you take the memory in the unstable state and then you put somebody through extinction / cue exposure therapy, you may be able to update that memory so that you actually overwrite the original memory rather than creating this competing memory. There’s a really interesting study that came out a year, or eighteen months ago, published in Science

BE: …one study in China, in Beijing, of heroin addicts, which has used that exact same procedure. Where there has been a diminished report of relapse.  [NB: the same issue of Science alsocarried an accompanying summary article by Barry Everitt and Amy Milton]

AM: They brought them into the lab and gave them into the lab and gave them a brief re-exposure session, so essentially exposure to videos of people using heroin. What they then did was give them a short break and then brought them back in and gave them cue exposure therapy and six months later they found that the response to the drug cues and the relapse rates were lower than in their control groups.

BE: If you put together those two procedures, so briefly present a stimulus that reactivates the memory at retrieval, and then wait about 10 minutes, or 15 or 30 minutes, so you’re in that window of restabilising the memory, which is reconsolidation, you seem in fact to replace the original association with the new one and erase the memory…

SK: It’s early days, but it remains to be seen whether it can be effective, again in heroin addicts, but also across different addictions.”

RO’H: Although the early results are promising, it may not be the approach for everyone.  And people

Andy: Absolutely no way, not a chance, no…. it all sounds a bit Clockwork Orange for my taste. No, I don’t think I would, no. And I would hope that a human being could do it without having to do that.

AM: At the moment, we’re not bad at treating the short and medium term, but I think that long-term is somewhere there is a real opportunity for therapies to start reducing relapse risk. So these sort of pro-abstinence, anti-relapse therapies would be a really good edition to what’s currently available for treating addiction.

RO’H: Although the Chinese trial is the first of its kind,  the results show the method has potential for use in the real world, as long as people are willing to put themselves forward for treatment.

This approach to targeting memory could break the links which lead people back to addiction, helping more people to get off drugs, and stay off.

It offers some hope that although the cues in the environment will always be there, the associations may not have to be.

Podcast produced and presented by Ryan O’Hare. Ryan is one of the founders of Elements, a great science website.


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