I get asked this question a lot, both by people who are fully committed to the biological (or brain) model of addiction and ones who thinks it’s crap and that it’s all about psychology, experience, and motivation.
The thing is that it is absolutely impossible to separate the influence of the brain, environment, and psychology since they all intertwine and interact to deliver the final condition… I was reading an article about marketing in the new Internet age yesterday and it included a joke that I thought was relevant, so I’ll steal it. Instead of focusing on addiction, this joke centered on the question of which part of the body is most important? Maybe it’ll do a good job of explaining why asking the question of which of the above is most important is to some extent useless.
So – The brain, blood, lungs, and Legs were all fighting each other on the question of which of them was most important in the human body. Along came the anus and argued for its own place as The King of all that is human. The first four all laughed in its face, thinking the idea that the anus is King a funny joke. In protest, the anus shut down, a little upset at being made fun of. Three days later the rest of the body sent a notice that the anus has won the debate and begged it to get back to business.
You see, the brain runs the body, upon which it relies for everything and together those two interact with the environment in ways that alter them both. Then you place thousands and millions of people together in the environment and they interact to create a psychological reality that affects everything else that’s already there. It’s completely impossible to separate the parts sice they all rely on each other and are affected by the others.
This is why behavioral interventions, medical interventions, and environmental conditions have all been shown to affect the probability of addiction developing and of addiction ceasing. They all contribute so they all have the power to affect it, though the mix is probably different in different people based on their own experiences, biology, etc…