For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Neuroplasticity is being used to explain addictive behaviors. The Bible says that we become "slaves to sin", presumably this is not on the first time we committ the sin but we become slaves when we do it repetitively.
Neuroplasticity seems to support this Biblical truth. Neuroplasticity actually alters the physical structure of the brain over time and makes you want whatever you are addicted (or a slave) to. This stuff is learned behavior.
I can testify that Jesus is extremely good at defeating sin if you only ask him. He defeated my alcohol abuse/alcoholism. (25 years a drunk, 5 years sober)
There is a decent article that explains it better that was recently published in the National Institute of Health. You can look it up if you would like:
O’Brien, C. P. (2009). Neuroplasticity in addictive disorders. Dialogues in Clinical Neuroscience, 11(3), 350–353.
Paul's writings tell us that drunkards (addicts) will not enter the Kingdom of Heaven. As far as I know God doesn't disallow entry to his Kingdom because someone is sick. That means it must be a heart and behavioral problem. It is definatelya sin. And. It is a sin that we can control if we want to. If we were really powerless over addiction I doubt that we would be explicitly excluded.
Again, the best person to deal with a sin problem a person might have is Jesus. We also know that God will help us whenever we are acting according to his will. Not sinning is according to his will. And the one who is in us is more powerful than anything.