- Vincent Clark, of the University of New Mexico in Albuquerque, thinks he has something like a crystal ball for drug addicts. By applying traditional psychiatric evaluation and modern fMRI brain imaging to people recovering from drug addiction, he claims to be able to spot who is likely to relapse — months before the relapse actually happens.
- Clark puts people recovering from cocaine and methamphetamine addiction in an fMRI machine, then asks them to play a game called 'oddball task' which is common in addiction research. Participants hit a button when they see an 'X' on a screen, but not when they see a 'T'. Mixed in are a few distracting 'C's: when these appear, they trigger activity in the posterior cingulate region of the brain in some addicts. Clark later meticulously tracks the volunteers, taking hair and urine samples, to see if they have begun using drugs again.
- With more than 80% accuracy, Clark says, the test predicted who would relapse (those whose posterior cingulate did not light up) and who would stay straight (those whose posterior cingulate did) over the next six months. Combined with a simple test for a history of mania, it was 89% accurate, he says.
- Clark presented the results during the annual meeting of the Organization for Human Brain Mapping in San Francisco, California, on 19 June. Nature News
talked to him about how he keeps such research going.
Would it be crass to call this measuring willpower?
- It's kind of the highest level of the same constellation. When people do the task and they see the 'distracter' they tend to get very annoyed — all they are supposed to do is press when they see the 'X', and the 'C' comes up. These brain areas are involved in your emotional response. But in this case there is just a transient kind of … not depression, but more annoyance.
- The relapsing group really didn't show any response. One hypothesis about addiction relapse is that individuals who don't react strongly to their environment get in situations that are much more disruptive to themselves. They kind of wander into it blindly.
What's the significance of a history of mania?
- Mania, chemically, is probably very similar to what stimulants do to you. Drugs really just mimic what you already have. So these people who have evidence of a potentially overactive internal stimulant system have this possibility of relapse that's higher later.
But that in itself isn't enough for these people to relapse.
- No, not at all. But that combined with imaging gives you this close-to-90% [predictive power].
So you envision someone checking into a clinic, playing this game in the scanner and getting tested for mania in their past. If both come out positive, then they would get more intensive care.
- It would suggest that this person needs more attention. Up to half of our population of addicts is not being that well served by treatments that are available. We've looked at a number of different populations. Individuals in drug court, they do a crime and the judge says, "You go get treatment and if you use again you are going to jail." In that group, at six months, about 50% use [drugs]. They know they are going to get caught and they do it anyway. Residential treatment centres, where they are living in a special environment and getting treated every day – that's [also] about 50% at six months. We recruited for this study at outpatient treatment, where they were living at home and getting some kind of treatment a couple of times a week – that's 50% [too]. It suggests that there is this native property in these people that results in relapse which isn't being touched all that well by treatment.
Getting more than that together would be difficult?
- But not impossible. What we would like to propose to the National Institute on Drug Abuse — which funded this originally — is to go into local prisons in New Mexico, scan people in prison and then monitor them after they are released. The Mind Research Network [that I work with] has the world's first mobile MRI system that can do functional brain mapping.
Did the patients know what this study was about?
- Absolutely. We said we were looking for ways to predict who is going to relapse. They do care. These people want to be a part of the solution.
Did you catch those who relapsed through drug testing, or did they confess?
- Many people came back and said, "Sorry, I relapsed." In the worst cases, we could not find them and we called their families or friends.
Predicting relapse is not the same as targeting the part of the brain that is causing it, though, is it?
It could be. If we find a brain network that is causal, then learn how to affect its behaviour, we can help keep people sober longer. Maybe even cure [the addiction].
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