I teach a class on the psychology of addiction (Psych 477 at California State University in Long Beach) and as I have been preparing the lectures something has become very clear to me – textbooks patently gloss over important details about the addiction research they cite. One of the most obvious gaps I’ve noticed this semester concerns the population of research subjects most addiction research is conducted on. An example will clarify:
A student group in my class had to read a study assessing the residual effects of methamphetamine on mood and sleep. They were amazed that no changes in mood were observed and that participants slept a full 6-8 hours the night after being administered meth! Would you have been surprised with these results given that we all have been told that crystal meth improves mood and causes insomnia?
Would it matter at all if I told you that the participants in the study were current meth abusers who use an average of 4 times every week?
For anyone not aware of the tainted history of health research in the U.S. (I’m including psychological research in this group), go ahead and read about the Tuskegee Syphilis Experiment and Stanford Prison Experiment (video here). There are other examples including Stanley Milgram‘s obedience studies, and more but as exciting as the discussion of these studies is, it’s time to get back to my main point.
It is mostly due to the ethically-questionable, psychologically damaging, research above that research institutions are now required to vet proposed research studies using Institutional Review Boards (IRBs) to assure that human participants in studies are consenting to participate of their own free will, are not coerced, and are not suffering undue damage. This is also true of addiction research. Rarely does the public consider this fact however when they are being reported on research relevant to addiction. I know this because the kids in my class never gave it a second thought.
Nearly all addiction research, especially studies utilizing “hard” drugs like cocaine, meth, opiates, etc., are required to make use of a very limited part of society – drug using individuals with a history of use of the specific drug of interest who are specifically not interested in treatment. Individuals who have never tried the drug or who want to be treated for drug abuse or dependence (addiction) are excluded due to ethical concerns. In most studies, participants can not qualify if they are addicted to drugs other than those being studies (except smoking, for which exceptions are usually made since we’d be able left with no participants otherwise) or have any associated mental health disorders, which are very common among addicted individuals. I would further assert that for at least a substantial portion of these research participants, the term “addicts” may not be appropriate since many addicts would not willingly give up using their favorite substance for a week or two to be replaces with a hospital bed and an experimenter controlled dose of drug or placebo. Taken together, our research subjects are pretty obviously not representative of all drug users, or all addicts, or all anything else. They make up a very specific group – less than perfect, but what we have to work with.
In some studies that attempt to make a direct comparison between controls (or drug naive participants) and drug users, this is likely less of an issue. This can happen when researchers try to examine brain structure differences, or performance on a specific psychological or physical test. In such cases researchers can at least statistically identify contributions of length of use, method of use, and other relevant data on differences between people who use and those that don’t. There are probably still some serious differences between “true” addicts, recreational users, and semi-chronic users that would be important to understand here, but we can’t so we don’t. But when it comes to assessing mood effects, or indeed any of a number of subjective effects of drugs, drug cravings, and withdrawal, this limitation in the population to be studied is something that often needs to be made explicitly clear to most public consumers of research. Since we can’t assess changes in mood, absorption rate, anxiety, or any other such measure (some exceptions for very low doses in very specific circumstances) among people who are new to the drug, we end up assessing them among people with a lot of experience, but not enough of a problem to want addiction treatment. Again, this should be considered a pretty specific type of drug user in my opinion.
There are other types of studies – those conducted with abstinent ex-users or addiction treatment intervention studies utilizing addicts who want, or who reported to, treatment on their own or in response to advertisements. While these studies make use of populations that can be considered at least closer to the individuals they are specifically aimed at – assessing the return of cognitive function after short or long term abstinence or testing a new intervention on those who want treatment – they still bring on limitations that need to be specifically considered.
An important point – most researchers recognize these issues and make them explicitly part of their research publications, in a specific section called “Limitations” but what seems troubling is that the public doesn’t have any awareness of these issues. So when someone tells you that “they just found out meth doesn’t actually make people lose sleep,” take a second to ask “for who?”