Wednesday, September 9, 2009

Learning can be addictive

One of the toughest problems smokers face when trying to quit is the association of smoking with other activities. For some, it might be wanting a cigarette after a good meal. For others, getting into the car on the way home from work might stimulate the desire to light up. Whatever it is, the urge is often strong, and provides a real barrier to quitting.

If you think about it though, it's not a logical connection. There's no reason why getting into the car should lead you to smoke. Lots of people don't have this urge, even lots of smokers. So what's going on? The key here is learning. For whatever reason, the smoker has learned to associate the activity, the people or the place with the good feelings that come from lighting up a cigarette. And so they continue to smoke, or at least want to smoke.

That's why psychologists who are helping people quit drugs of any kind try to dissociate behaviours from their cues. Whether it's introducing a substitute like gum, or having a person avoid the places where they like to indulge, it's all about changing the behaviour and learning new patterns.

So far, none of this is new. But Dr. John Dani, from Baylor College of Medicine, wanted to look under the hood and figure out what's going on inside the brain when someone takes an addictive drug. Why is it that we're so good at learning to associate addictive substances with cues, when we're not normally that successful?

What he found out is published here.(paper available September 10, 2009)

Find out more about Dr. Dani's Lab here.

In a series of experiments, Dr. Dani and his colleagues were able to show that nicotine (and by extension other addictive drugs) was able to enhance learning. That is, connections in the parts of the brain we associate with learning new things were stronger and more numerous when there was nicotine in they system, compared to controls. Although that needs to be qualified. This only worked when dopamine levels were also raised, showing the connection between the role of dopamine in learning, with the addictive substance.

This is an almost sinister finding. Our brains need to be able to learn, that's what keeps us alive. And dopamine is an important part of this learning process. After all, dopamine is associated with pleasurable experiences, and it makes good evolutionary sense to seek out food, sex and a safe place to sleep. Dopamine helps us find all of these, by making them pleasant. But these addictive drugs are taking over that system, and making drug seeking not just a pleasant experience, but one that we remember vividly. No wonder it's so hard to break an addiction.

This has some important implications. First of all, it reminds us that addiction is a physical thing, not just a weakness of will in the person who's trying to quit. But there's another angle to this, and that's understanding learning itself. By studying how these drugs interact with dopamine and the brain, maybe we can learn what's going wrong in various dementias, or Parkinson's disease (which is characterized by loss of dopamine), and in the long run, come up with treatments for them.

What this isn't, is a suggestion that smoking is good for you. The memories you form encourage you to remember smoking, and not much else, which can lead to all kinds of other health problems.

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