Monday, December 18, 2017

Persistence of Drug Use

Here are some numbers from the 2014 National Survey on Drug Use and Health by the Substance Abuse and Mental Health Services Administration. (Henceforth the SAMHSA survey.) It's available here. (Pages 120 and 2071; it is a very large pdf.)





[Click the table for a clearer view.] As a first-blush look at drug use persistence, we can take some ratios. How many lifetime users used in the past year? How many past-year users had an "abuse disorder", suggesting some kind of problem controlling their behavior? I don't want to pretend this will tell us which drugs are truly addictive and which aren't, but I thought it might be suggestive.



A few things jump out at me. The once-and-your-hooked thing is utter nonsense and isn't true of any drug. Compare past month use to lifetime use, or past year abuse disorder to lifetime use. These are all very small numbers. It looks like heroin and tobacco are particularly addictive by these measures. No surprise there, I hope. No other class of illegal drugs seems to come close.

Persistent use does not equate to addictiveness, so we need to be careful here. Looking at past month users per lifetime users, marijuana stands near the top of the list of illicit drugs (though alcohol and tobacco have it beat). Marijuana isn't addictive in the same sense that heroin and cocaine are addictive; at most it is "habit-forming" in the same way that video games are habit-forming. 19% of lifetime marijuana smokers imbibed within the past month, compared to 9% for lifetime heroin users. Somewhat paradoxically, the high persistence of marijuana use may be related to its non-addictiveness. If users can pick it up and set it back down easily, why not? On the other hand, someone who once had a cocaine or heroin habit might realize that imbibing now is making a categorical choice about their lifestyle and plunging back into the abyss.

There is a very high persistence for alcohol use, but a relatively small number of people with an abuse disorder. I think the concept of controlled but persisting recreational use needs to be introduced into the drug policy conversation. Plainly there are a lot of casual drinkers. These people will never have issues with their drinking and some of them may never even get drunk. Surely there are analogs to this behavior pattern for the other drugs. Maybe someone smokes a bowl once a week, but puts it down for the rest of the week. Maybe someone uses methamphetamine/Adderall to concentrate and meet a deadline, but cycles off it after the project is done. See my previous post on Unbroken Brain, which mentions that many heroin users are on a very strict schedule of once a week. This is probably not frequent enough to develop a tolerance or persistent withdrawal symptoms. The point here is that controlled use of a substance is possible, and even periodic use does not inexorably devolve into full-blown addiction.

I really wish that they had more questions about frequency of use, maybe a "past week" question and then a "number of days in the past month" question. Once a month is really nothing. Even if someone stayed in the "used in the past month" category for years, it wouldn't necessarily indicate a drug problem. A "past month" user could still be an infrequent user. It might be policy-relevant to know who is using a few times a week or on an almost daily basis. And once again, even frequent use doesn't necessarily mean the person has a problem.

I wonder if the criteria for an "abuse disorder" might be overly broad. 12% of people who used marijuana in the past year had a "marijuana abuse disorder?" Yeah, right. 6% for hallucinogens? Bull. Hallucinogens aren't habit forming. People who like tripping balls quickly learn that they can't take, say, LSD or psilocybin on consecutive days because it stops working. I wonder if people who get arrested and sent to forced treatment for some of these non-harmful substances are automatically counted in the total? From the link:
The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), no longer uses the terms substance abuse and substance dependence, rather it refers to substance use disorders, which are defined as mild, moderate, or severe to indicate the level of severity, which is determined by the number of diagnostic criteria met by an individual. Substance use disorders occur when the recurrent use of alcohol and/or drugs causes clinically and functionally significant impairment, such as health problems, disability, and failure to meet major responsibilities at work, school, or home. According to the DSM-5, a diagnosis of substance use disorder is based on evidence of impaired control, social impairment, risky use, and pharmacological criteria.
So there are gradations of abuse disorders. If I was hung over and missed a class, does that count as "mild?" I'm guessing that the distribution of "severity of abuse disorder" is like almost every other social problem: the mild cases are the most common, moderate less so, and severe even less so. Again, it would be good for the SAMHSA survey to have finer gradations. The mild, perhaps even moderate, abuse disorders might not be "policy-relevant" in the sense of causing massive social harms. Incidentally, I hate this little trick. Someone defines a problem by pointing to the worst possible cases, but then lower the threshold to include stuff no reasonable person would worry about in order to get a big, scary number. I'm tempted to take the 6% for hallucinogens or the 12% for marijuana and simply subtract it from the other numbers as a "bullshit adjustment factor." (Not really. I'd rather just say, Here's the best we can do with bullshit numbers, and here are the caveats. Making "adjustments" to fundamentally bad data doesn't seem valid.) I'd go so far as to say that the "abuse disorder" figures are almost completely useless, or at best than merely suggestive of what they claim to measure. This annual SAMHSA report frequently uses these numbers to say, "Only [worryingly small percentage] of people with an abuse disorder actually sought treatment in the past year." I'm sympathetic to the idea that some severe addicts who need help can't get it, but my overall impression is that most of these people don't need serious help.

I think there is a selection bias at work here, so I would be hesitant to compare the legal drugs to the illegal ones. I strongly suspect that the kinds of people who use illegal drugs are distributionally/demographically different from the kinds of people who use legal drugs. Someone who tries heroin or cocaine is likelier to be highly impulsive, low-conscientiousness, habit-forming, and risk-neutral or risk-seeking. That certainly isn't to say all illegal drug users are like this, just that whenever you take a tiny sub-sample of the population who by definition are law-breakers, you're going to pick up a larger fraction of people with social and behavioral problems. Dip your ladle into the pool of "alcohol users" (~2/3+ of the entire population) and you basically get a representative subset of the population. Dip your ladle into the pool of "heroin or cocaine drug users", and you're going to get lots of very nice, normal people plus a disproportionate number of anti-social types. Given that, I think the "substance abuse disorder" figures probably overstate how dangerous these substances would be in a regime of legalization. The kinds of impulsive risk-seekers who are likely to have drug problems are already using drugs; they aren't deterred by the law. Those nice, normal people who don't form nasty habits, we don't need to worry about. Perhaps a few of these people might become occasional pot smokers or even heroin users, but very few of them are likely to become full-on addicts.

I'd like to see caffeine on here as a sort of test case. It's not really harmful, often quite the opposite, but definitely addictive.

Prohibition advocates often cite the pervasive use of tobacco and alcohol as an argument for keeping other drugs illegal. Certainly you can see that the legal substances are more widely used. But people don't just pile-on, they trade-off. People wouldn't just start imbibing all manner of substances on top of what they're currently doing. People face constraints like money, time, limited willingness to endure damage to their own health, and negative interactions between substances (some simply unpleasant or buzz-killing, some positively deadly). This argument by drug warriors never made sense to me. It seems more likely that people's willingness to tolerate self-harm is the limiting factor, and expanding their means of accomplishing it doesn't change the total harm done. There just aren't that many people who think, "I'm not going to destroy myself with alcohol or tobacco. But if meth and crack become viable options, I'm in!" Or rather, I should say there are such people but for the billionth time this kind of person is not responsive to legal penalties. Drug prohibition doesn't work for them.

That's all I got for now. What do you see?

No comments:

Post a Comment