Addiction, time preference, and intrusive thoughts.

I’m having a hard time finding time to write new blog posts lately, so I’m going to start scavenging things I’ve written informally.

I was talking with someone the other day about whether it’s useful to model addiction as a rational behavior.  Now, I’m torn as to whether to even use the word “rational” in this way, because the word also has normal-English-language connotations beyond its narrow use by economists and philosophers.  So maybe the better way to ask the question – a way that makes it clear we’re using technical jargon – as “Can we model addiction through time preference?”
 A very naive version of this model would be “Getting drunk feels good right now, but the consequences of getting drunk feel bad in the long term, and alcoholics drink when their discount rate makes the short-term payoff seem preferable.”  This certainly describes many a regrettable night, but I don’t think it’s a close match to the experiences described by addicts 1.  The person I was talking to mentioned nicotine cravings: “I know I’m not going to enjoy the cigarette very much, but I want it anyway.”

So maybe instead we put cravings at the center of the model.  “Cravings are unpleasant right now, and the consequences of getting drunk feel bad in the long term, so alcoholics drink when their discount rate makes the short-term payoff seem preferable.”  If this were how addiction worked, you’d expect to see recovering addicts find other ways to manage their cravings – exercise, meditation, less harmful addictions like caffeine or methadone, and so on.  And we do indeed see that, so I think we’re getting close to reality here.  But this model is still missing something, and this is where I think time preferences alone can’t do the whole job.

You never hear someone say, “I weighed the costs and benefits of drinking and meditation, and decided that meditation was a better way to get rid of the craving.”  Or at least, you never hear them describe their moments of short-term choice like that – I guess you do hear people describe that kind of decision as a long-term thing.  The distinctive thing about cravings is “intrusive thoughts” – even if going to the gym would get rid of their cigarette cravings just as effectively as smoking a cigarette, the addict’s brain is chanting “cigarette!  cigarette!  cigarette!”, not “work out!  work out!  work out!”

Now, we’re still missing some things – withdrawal symptoms, self-medication in the non-euphemistic sense (it’s no coincidence that insomniacs have extremely high rates of alcoholism), peer pressure, drugs actually feeling good, and so on.  But most of these things can be rolled up under the “time preference” banner, so I think the “addiction = time preference + intrusive thoughts” model is reasonably complete 2.

1 A negative twist on this model would be “Things in my life feel bad right now, and drugs or alcohol will make that feeling go away in the short term but not the long term.”  And…I mean, there’s some of that, but there are also plenty of people whose lives are average-or-better who nevertheless get hopelessly addicted to substances.  The same people who drink to drown their sorrows usually also drink to celebrate their victories, which suggests that the drinking and not the sorrows are the central issue.

Also, a general disclaimer: My thinking here is based almost entirely on the experiences of people with addictions that caused them problems, but were not so consuming that their lives fell apart.  It’s possible things are different at the extremes.

2 Complete in terms of explaining how addiction works in the mind, anyway; you’d need other models to explain why some substances are addictive and others aren’t; why some people are more genetically vulnerable than others; why some social circumstances protect against addiction and others don’t, and so on.

At some point I may need to re-read this book, which has partially inspired my thoughts on the matter.

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