Today I had the opportunity to hear a presentation by Nora Volkow, director of the National Institute on Drug Abuse, at a neuroscience symposium. I came prepared to pick any fight I could with The Man. Her presentation was on dopamine reward pathways and addiction, with specific examples of studies using methylphenidate, cocaine and amphetamines in stimulant addicts. She also discussed an experiment where they used a modified adenovirus to increase expression of dopamine D2 receptors in alcohol-drinking rats, showing that it dramatically (70%) decreased alcohol intake for as long as the new receptors were in effect. The picture she was painting was one of addiction being the result of decreased dopamine transmission and decreased D2 receptor density leading to an overall deficit of reward stimulation, which presumably leaves people feeling like something is lacking, which is made up for by strong reward stimulus such as drugs.
However, there was nothing in the presentation to demonstrate that the dopamine system deficits were the cause of, rather than the result of heavy drug use, and at first it seemed to me much more plausible that the real picture her data were painting was one of long-term addiction leading to tolerance, mediated by decrease in dopamine signalling, and that the adenovirus was simply bringing the rats back to where they started, where the buzz was just as good as it used to be and they didn't need as much substance to feel high. Now there might be some very practical applications to tolerance-reversing, buzz-rejuvenating treatments, but that was really beside the point.
In the end, I realized that because addiction is most fundamentally a feedback loop, downregulation of dopamine transmission is actually neither a cause nor an effect, but rather a part of the loop. Therefore it does, indeed, make sense to target its mechanisms for treatment. She talked about potential treatments, and did not at all overstate her case; she mostly limited it to suggesting that this could lead to useful treatments for preventing relapse in addicts who were already recovering. Everything I understood about the mechanisms she described, as well as everything I know from my own field research on addiction and drug use leads me to believe that this position, as far as it goes, is quite reasonable and likely to lead to therapeutic benefit.
I limited myself to asking her for her thoughts on any kind of policy implications of her new understanding of addiction. Her opinion was that the most important thing was to convince insurance companies to cover addiction treatment just like they would cover treatment of any other disease, rather than singling addiction out for exclusion for essentially moralistic reasons. She had an ongoing theme of pushing a medical view of addiction as a "disease of the brain" rather than a behavioral choice or moral issue. I didn't have the chance to ask her point blank whether she thought it made sense to put people in jail for having a disease in the brain, and it may be that as director of a major federal agency she would have either avoided answering or stuck to the party line, but I can't help but feel like she was truly a reasonable and insightful person, much more of a scientist than a politician, and suspect that she really doesn't feel like the current system makes sense. All in all I was very impressed with her presentation and her personal attitude, and glad that she is in the position she is.
Of course, there were still some problems with the story. On her intro slide she talked about addiction as being a problem because it takes away "free will", but if you're describing behavior as generated by brain function then you've already given up your right to talk about free will. But that is much more philosophical depth than such an event could possibly entertain.
