Psychiatrists discover craving centre
Jul 9, 2004 - 10:55:00 PM
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By Ashwin, UK Correspondent,
[RxPG] Psychiatrists have discovered the craving centre of the brain which causes smokers, drinkers, gamblers and drug addicts to relapse just at the sight of someone lighting up, having a scotch or pulling the handle on a slot machine.
Delegates heard that a small pea-shaped area, called the anterior cingulate cortex, in the frontal lobe of the brain, is responsible for long-term cravings which remain with addicts even when they are clean and have not abused drugs, alcohol or drink for years.
It stores up memories of feelings of excitement and pleasure associated with the substance or behaviour, and brings them out afresh when a former addict is faced with the opportunity to take his or her drug of choice.
Professor David Nutt, professor of psychopharmacology at the University of Bristol, told delegates during a session on craving that his experiments with alcoholics showed that cue exposure to alcohol, such as showing them a bottle of their favourite drink or a picture of someone drinking, activated this area of the brain when the addicts had brain scans. Previous research has shown that the anterior cingulate cortex is also linked to other cravings, such as food, gambling and sex.
The anterior cingulate cortex is a primitive brain region which is involved in strong interests, said Prof Nutt. If you show people sex videos it lights up in brain scans too. The cue to craving will always be there in addicts and it gets stronger with time. Once youve acquired an addiction, the memory is always there.
However, another part of the brain, the orbital frontal cortex, determines whether or not people act on these cravings. The addiction is there and you either strengthen the addicts cortical ability to inhibit the cravings or you use drugs to dampen it down, said Prof Nutt. The anterior cingulate cortex is a a primitive part of the brain and the higher frontal cortex is controlling that.
Addicts can be treated with drugs, such as acamprosate or naltrexone, or psychosocial therapies such as cognitive behavioural therapy. Dr Jonathan Chick, a psychiatrist at the University of Edinburgh, told delegates that psychosocial therapies and step programmes, such as the one advocated by Alcoholics Anonymous, were as effective as drug therapies and much cheaper.
Professor Colin Drummond, a consultant psychiatrist and head of the addiction unit at St Georges Hospital, London, said there were two distinct forms of craving the acute feelings of craving, when someone is withdrawing from a substance, and the latent cravings triggered by memories and activated by the anterior cingulate cortex. This explains why many clean addicts relapse when they come out of addiction units.
When they come out hospital they get a shock because that latent reaction cues are still there, he said. As a former smoker, being in the presence of your old smoking buddies is a cue and it triggers off craving, even if there is no nicotine in your body. Its a conditioned response. This knowledge isnt new but the research to show exactly whats going on in the brain is.
Professor Drummonds research at St Georges shows that if addicts are repeatedly exposed to their favourite drink, the cravings lessen. Its the same method used to treat people with phobias, explained Prof Drummond. If you expose phobics to the thing they fear, like spiders, they slowly get better, and its the same with alcoholics. But it has to be a gradual exposure smelling drink, holding a glass etc. If you go and deliberately seek out bars or smokers you increase your risk of relapse.
Prof Nutt is conducting research into specific receptors in the brain that activate the anterior cingulate cortex. People ask us why we are interested in brain circuits, and this is the reason. Instead of flooding the brain with drugs, we want to know where to look for the chemical problems, so we can precisely target the treatment.
Publication:
Royal College of Psychiatrists
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