8
$\begingroup$

A study by White et al. (2012) using a large UK sample concludes that

In this cohort, high childhood IQ was related to illegal drug use in adulthood.

Note that this does not refer to habitual use, but to have ever having tried illegal drugs:

Preliminary analyses revealed that, at the 42-year follow-up, the use of drugs in the past 12 months was rare [...] We therefore used assessments of the lifetime prevalence.

The same paper of White cites another UK study Batty et al. (2007) in which regular smoking and heavy alcohol consumption ware negatively correlated with childhood IQ.

Is this type of finding, namely positive correlation of IQ with what I'd call experimental drug use [I think the medical term is drug abuse], but negative correlation of IQ with heavy/regular use [which I think is called dependency or addiction] generalizable across countries? Or [if this is far too ambitious to ask] at least reproducible in other countries?

And if so, are there other confounding variables that might explain some of it better, e.g. openness to experience for ever having tried an illegal drug?

$\endgroup$
  • 1
    $\begingroup$ ...generalizable across cultures - Can you define cultures? As of now I wouldn't even know how to start answering this question - there are innumerable cultures and multiple definitions; e.g. "...the arts and other manifestations of human intellectual achievement regarded collectively. like "20th century popular culture" or - "the ideas, customs, and social behaviour of a particular people or society. e.g. "Afro-Caribbean culture". $\endgroup$ – AliceD Dec 24 '17 at 21:20
  • 1
    $\begingroup$ In other words culture can be defined according to geography, but also in time etc. $\endgroup$ – AliceD Dec 24 '17 at 21:21
  • 1
    $\begingroup$ @AliceD: very good points. I've done some quick editing, but I'm heading out in like 5 mins, so if it's still not clear enough, I would not mind either editing from someone else or putting it on hold. $\endgroup$ – SX welcomes ageist gossip Dec 24 '17 at 21:25
  • 1
    $\begingroup$ Also, asking about the past or how it might vary with generations is potentially interesting.. although IQ tests haven't been around for that long, so we can't go very far in the past with that (although 100 years or so is still a lot). Still I suspect there's nowhere near enough data to be this ambitious. $\endgroup$ – SX welcomes ageist gossip Dec 24 '17 at 21:31
3
$\begingroup$

First, thank you bringing that White et al. (2009) paper to my attention -- I am currently accumulating a whole bunch of cohort studies focusing on cognitive epidemiology, or health outcomes associated with cognitive ability. Here I will share with you some of what I have collected so far with respect to drug-related outcomes.

Is this type of finding, namely positive correlation of IQ with what I'd call experimental drug use [I think the medical term is drug abuse],

To my understanding, I do hear about similar findings from time to time, but this isn't where the research funding goes. You tend not to get research grants unless you can sell drugs = death and destruction.

negative correlation of IQ with [...] dependency

Yes, this is generally the case. Dependency, and other adverse health outcomes resulting from said depedency. Moreover, the relationship tends to be non-linear. The following data is from a cohort study of 1 million Swedish conscripts, with the health outcomes being the risk for hospital admission for various disorders including alcohol-related disorders and other substance-related disorders as a function of childhood intelligence. Obviously, the use of a hospital admission endpoint means that the disorder was on the more serious end of the disorder:

enter image description here

Gale, C. R., Batty, G. D., Tynelius, P., Deary, I. J., & Rasmussen, F. (2010). Intelligence in Early Adulthood and Subsequent Hospitalization for Mental Disorders. Epidemiology, 21(1), 70–77. https://doi.org/10.1097/EDE.0b013e3181c17da8

Here's another one of a similar vein. This cohort study comprised 1.4 million Swedes, looking at "substance-misuse events" as a function of stanines (this is a way of grouping your cohort into nine groups, each comprising a 1 SD increment in ability).

How these guys defined "substance-misuse events" does warrant further clarification, however:

Substance misuse events were assessed with an omnibus measure combining information about alcohol- and drug- related criminal convictions, medical treatments and deaths. This measure, which has been used previously [10,26,27], captures a wide range of alcohol and drug re- lated negative outcomes but does not include all individ- uals with substance abuse, as many substance abusers are not registered in any medical or governmental registry.

Again, you see that the risk is greatest in the the stanine with the lowest cognitive ability (estimated IQ <74), and the curve is non-linear:

enter image description here

Latvala, A., Kuja-Halkola, R., D’Onofrio, B. M., Larsson, H., & Lichtenstein, P. (2016). Cognitive ability and risk for substance misuse in men: genetic and environmental correlations in a longitudinal nation-wide family study. Addiction, 111(10), 1814–1822. https://doi.org/10.1111/add.13440

And last, but not least, some mortality data, again from the Swedes (n = 50,000). This one doesn't examine cognitive ability, but demonstrates that substance abuse and dependency, particularly in adolescence, seems to be a mediating factor in injury-related mortality. We also note that alcohol abuse as an adult also represents a significant risk:

enter image description here

Stenbacka, M., Leifman, A., Dalal, K., & Jansson, B. (2011). Early predictors of injury mortality among Swedish conscripts: A 35-year cohort study. Accident Analysis and Prevention, 43(1), 228–234. https://doi.org/10.1016/j.aap.2010.08.014

generalizable across countries? Or [if this is far too ambitious to ask] at least reproducible in other countries?

As you can tell, the best data seems to come from the Scandinavian countries... no prizes for which country ranks #1. The whole problem with these sorts of studies is that you need to be organised and preferably have national conscription, meaning its simply untenable for most Western countries.

However, if you dig around, the best studies will come from the Swedes, Danes, and Norwegians. And to a lesser extent, the Scots followed by perhaps the Unites States.

And if so, are there other confounding variables that might explain some of it better, e.g. openness to experience for ever having tried an illegal drug?

Good question. Perhaps high cognitive ability results in greater disposable income? Most of the drugs reported are reminiscent of the substances you would find floating around a nightclub, where people are queuing up at the toilets in order to snort lines of coke off a toilet seat. And amyl nitrite is very much a gay party scene drug. However, we also note that even after controlling for adult SES, the effect is attenuated but still remains.

Who knows -- perhaps getting totally fucking high from time to time is part of the normative human experience, while those with lower cognitive ability are too busy drinking the bad thoughts away with alcohol. It is, nevertheless, a great find :p

| improve this answer | |
$\endgroup$
2
$\begingroup$

I don't know how reproducible those findings are, but this study (Schretlen, van der Hulst, Pearlson, & Gordon, 2010) found a moderate association between fluid intelligence and openness to experience:

The two separate samples yielded strikingly similar associations between trait Openness and cognitive test performance. In both samples, Openness showed strong positive correlations with Gc, intermediate correlations with Gf and fluency, and relatively weak correlations with executive functioning.

If we add to that the claim that the use of certain drugs is positively correlated to openness to experience, then we have some support for your idea of this trait as a confounding variable in your study results.

However, we should also keep in mind that drug use itself may influence openness to experience (MacLean et al, 2011), which should complicate things further.

| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.