Wow, that "addictiveness index" looks mighty precise.

I read a Re-Twitt from our good blog friend Abel Pharmboy of Terra Sigillata which pointed to a most amazing bit of online drug information. The originator was @mjrobbins of The Lay Scientist blog*. The answer to "What are the most addictive drugs" on some Q/A site called blurtit. And dude, do they have answers! For example, the "addiction likelihood" of cocaine is 78%, of heroin is 87.5% and of crystal meth is 89.5%. Wow, what precision! And they cite some science-y sounding dudes including some that I recognize as being experts. Great stuff, all kinds of people want to know the objective addictiveness of different drugs right? From parents to policy makers, users to scientists.
...but what's all this? The "addiction likelihood" of cannabis is 42%, of LSD is 32% and of psilocybin and mescaline are 16-18%? Hmm.....


Luckily the answer on blurtit contains citations to their sources. And tracking back to one of the data sources, we find a clue. . At least some of the backing data are derived from a study described as follows:

"To rank today's commonly used drugs by their addictiveness, we asked experts to consider two questions: How easy is it to get hooked on these substances and how hard is it to stop using them? Although a person's vulnerability to drug also depends on individual traits -- physiology, psychology, and social and economic pressures -- these rankings reflect only the addictive potential inherent in the drug. The numbers below are relative rankings, based on the experts' scores for each substance:

Hmm. And nicotine is at 100 so in the parlance of the blurtit answer, nicotine is "100% addictive". Which is patently false. This blurtit answer fails to communicate that the numbers given are subjective rankings and relative rankings at that. I think a very large swath of people would read that blurtit answer and infer that these numbers are intended to reflect some sort of objective, absolute "addictive" quality of the drugs.
As my readers know, getting at questions of "addictiveness" and conditional probability of dependence (as I like to frame the question) is a tricky business and it is essential to tie the seemingly objective rankings / percentages / whathaveyou to the underlying analysis or data. So that the reader can infer "If you look at these numbers, the answers are..." instead of "This is something which reflects fundamental truth..."
Additional data sources cited in the blurtit "answer" seem to refer back to a similar ranking procedure described here. You will notice these data use a 1-6 scale ranking, not a percentage. Of course deploying these particular data might give the reader a clue that what was being discussed was relative addictive potential, not some sort of objective truth. If you tell someone a drug has addictive likeliness of "5", they are quite naturally going to ask "5? Relative to what?". If you tell them it is "85.5%", some large fraction of the audience is going to assume something or other about the underlying population- any users, consistent users, 'those losers', etc. But they are not going to automatically assume "...on a subjective opinion scale of a limited number of experts wherein the most addictive substance is set to 100%".
It is a horrible answer to the question.
__
*Updated, forgot to include this link and h/t when originally published.

17 responses so far

  • becca says:

    So is there anything about the order of relative addiction you would change?

  • fullerenedream says:

    You should submit this post as an answer on the blurtit site. At least that way people will see that the answer with the super-precise "addictiveness index" isn't some kind of gospel expert wisdom.

  • DrugMonkey says:

    So is there anything about the order of relative addiction you would change?
    c'mon now becca, you know better than that.
    I would say that there is nothing about the rankings that is glaringly out of kilter.
    If you want me to endorse any specific position for a given drug, well it all depends on what exactly you mean by "addictiveness" and, if you are weighing multiple aspects, what weight you place on various factors. What are your criteria for deciding on the denominator for your user population (ever tried?, last 12 mo?, last 30 days?, treatment seekers?...)?

  • jamie says:

    This critique does not question the premises of the claims made by the blurtit article. You merely debate the question of how they could arrive at their "pin point" percentages. I'd love to see the evidence that there is any addictive potential for true psychedelics such as LSD, psilocybin, 2CB,or mescaline. I have never seen any good studies supporting these claims.

  • David says:

    addictiveness is in part dependent on the molecule, in part on the delivery method, in part on individual factors of the particular user, and in part on the social context within which the drug is used.
    For instance, nicotine is highly addictive when inhaled (rapid rush) but nicotine gum isn't scheduled - it has essentiall no addictive potential. I've never heard of inhaled LSD.
    individuals may have genetic variants in particular receptor systems, or metabolizing systems, making them more susceptible to addiction to specific agents.

  • Scicurious says:

    Yeah, I'm glad you took this one, I don't have the energy to go into why all this stuff is fuzzy.

  • Benno Hansen says:

    Interesting. Drug information is often dubious.
    I belive I read somewhere that LSD is broken down at temperatures way below smoking degrees.

  • becca says:

    I don't think the description of the data on blurtit sounded overly misleading. The point that there is individual variability is a valid one, discrete from whether the rankings are *subjective* and *relative* rankings.
    Then again, I find excessively-precise numbers to be quite amusing, as long as it's clear where the number is actually coming from, or it doesn't really matter (as in "how are you today?" "7.82").
    I was just curious if the relative rankings do in fact seem reasonable to people- as far as I can tell, they "pass the giggle test".

  • DrugMonkey says:

    I don't think the description of the data on blurtit sounded overly misleading.
    I do. To claim that a drug has a "addictive likeliness" of close to 100% sounds to me very much like saying "try it once and you will be ADDICTED!!!1111!!! (instantly)". This is, of course, not generally true for any drug. (And I very much doubt it is true for any individual, although we do have to grapple with some of the memoirs / anecdotes about "I knew from the first time I tried DrugX that this was the one for me...", etc. )
    If you have been paying attention at all to the commentators around these parts who foam at the mouth any time I post *anything* that suggests that ecstasy or cannabis might not be perfectly benign you will have been faced with the reason this is not a wise way to communicate information.

  • Isabel says:

    "foam at the mouth any time I post *anything* that suggests that ecstasy or cannabis might not be perfectly benign"
    You're a fucking evil asshole DM! You KNOW this is not why the vast majority of people here are arguing with you- but, there you go again! Most people are not saying anything is "perfectly benign." I've certainly never said anything like that. It is YOU who keeps making this assertion. YOU cannot deal with a complex picture, and YOU refuse to look at the evidence.
    You have to totally lie about others in order to make it sound like your point of view has any merit!
    Really sad, especially for the people who are really suffering because of arrogant dweebs like you.
    Stop posting propaganda (or links to it, saying you think it's Outstanding) and dubious little studies where the authors themselves warn the results should not be extrapolated to the general user, etc., and you might get a different reaction.
    And review the literature already! You will sound less ignorant.

  • becca says:

    DM- it's hard for me to know how I would have read the "100% addictiveness rating" if I hadn't been following from here (i.e. already *knowing* what they meant by it), so I can't really comment if it's misleading to most people.
    I coulda sworn this whole "precise yet inaccurate numbers are misleading!" argument has been put forth by you in some other context. I tend to think that you find that particular aspect *more* dishonest than most people, and I view it as *less* dishonest than most people (because I never assume random extra digits = more scientific or correct). But I could be wrong. Maybe these things really confuse the heck out of people.
    "If you have been paying attention at all to the commentators around these parts who foam at the mouth... "
    I generally don't. If there's foaming at the mouth going on, I like to be the one foaming. It's why CPP and I don't get on.

  • DrugMonkey says:

    This critique does not question the premises of the claims made by the blurtit article. You merely debate the question of how they could arrive at their "pin point" percentages.
    sorry, just found this one in the filter. I question the premise that any drug is close to "100% addictive" in the posts linked under "conditional probability of dependence". It is a topic I take up now and again. If you ask me about this sort of thing I will point out that, e.g., the population that meets criteria for dependence is X% as large as that that has used the drug. You can cast both as within the past year or lifetime and it doesn't change the estimate much. a bit harder to knock around the idea of what counts as "using" but you can get pretty close. The value of X ranges from about 8% (cannabis) to the mid-teens (stimulants) to maybe 25% (i.v. heroin) to top at about 30% for nicotine.
    I have never seen any good studies supporting these claims.
    What claims? Hallucinogens are way down in the few percent levels at best- and before anyone starts carping, take a look at what it means to meet criteria for dependence. Hallucinogen dependence is not going to look anything like stimulant dependence, for example, even though on DSM-IV there is just the one set of core criteria. The fact that you have never seen any "good studies" is hard to deal with absent specifics- are you contesting that anyone is actually meeting criteria for hallucinogen dependence? They do but you have to read papers closely because of the low frequency relative to other drugs. Things like this
    http://www.ncbi.nlm.nih.gov/pubmed/17019896?ordinalpos=8&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum
    call MDMA a hallucinogen but it isn't what you are talking about here. Still, there was a measurable rate for LSD.
    Nobody serious claims that the classical hallucinogens are highly addictive but there are indeed people who end up meeting criteria for dependence on them.
    This illustrates the problem with presenting the apparent source of rankings the way the person in the blurtit answer chose.

  • David Harmon says:

    foam at the mouth any time I post *anything* that suggests that ecstasy or cannabis might not be perfectly benign"
    And "Isabel" #10 proceeds to demonstrate....

  • DuWayne says:

    For instance, nicotine is highly addictive when inhaled (rapid rush) but nicotine gum isn't scheduled - it has essentiall no addictive potential.
    Just because it isn't scheduled, doesn't mean it isn't addictive. Nicotine gum is most certainly addictive, though not as addictive as smoking cigarettes.
    I've never heard of inhaled LSD.
    That would be because you can't smoke it - it is completely broken down in seconds when put to flame. For that matter, it breaks down over time even when frozen (at normal freezer temps) - the warmer the temperature, the quicker is breaks down.
    However, it can be used in different delivery systems. It is active in intermuscular injections and is a fucking intense experience at that. It is rapidly assimilated when taken in the nasal membranes or as a suppository. It is only a little less rapidly assimilated when taken in the eye, though that is extremely risky (and about the only delivery system I have never used).
    Nobody serious claims that the classical hallucinogens are highly addictive but there are indeed people who end up meeting criteria for dependence on them.
    I would be one of those people. I have used LSD to the extreme of becoming incoherent for several days after the last dose - not once, but twice. That is twice that I went for several days at a time, incrementally increasing my dose, so I could continue tripping - to the point that it caused extreme detriment. And the two times I completely lost it, weren't the only times I did that - they were just the times it was really, really bad for me. It was two years after the last time I lost it, that I finally quit using hallucinogens altogether - except that a couple years after that, I broke down and drank mushroom tea, because I am an addict.
    I also used a wide range of plants that are highly neurotoxic. During that whole period of heavy hallucinogen use, I regularly ingested plants knowing that there was a significant chance that doing so might kill me. If that isn't addiction, I don't know what is.
    Is such as addiction rare? Absolutely. But it is no closer to zero possibility, than any drug is to a hundred percent.
    And just to make this very clear, acute dependence does not equal addiction. Addiction is what keeps people coming back, even after they are entirely detoxed from the substance of abuse. Acute dependence can certainly contribute to addiction, but it doesn't mean addiction.

  • Matthew says:

    When the word "index" is used in some sciency sounding context, it should always set off a mental alarm. It often means something completely arbitrary and only peripherally related to what you think it means on first reading. Of course, this isn't always the case, but use of the word should at the very least warrant further reading.

  • luke says:

    no they foam at the mouth when people like you advocate the continued criminalization of cannabis when more addictive and dangerous substances are legal.

  • DrugMonkey says:

    no they foam at the mouth when people like you advocate the continued criminalization of cannabis
    By all means point to where I advocated anything at all about the legal status of recreational drugs? After you are done not finding anything of the sort, perhaps you could explain why from your perspective anything having to do with actual information about the health effects of cannabis is magically transferred into a statement about legal status?
    (I know, I know DuWayne, because it is magical!)

Leave a Reply