16 September 2013

How addictive is morphine?

Research previously conducted on rats did not adequately control for the environment in which the rats were studied:
Alexander's hypothesis was that drugs do not cause addiction, and that the apparent addiction to opiate drugs commonly observed in laboratory rats exposed to it is attributable to their living conditions, and not to any addictive property of the drug itself. He told the Canadian Senate in 2001 that prior experiments in which laboratory rats were kept isolated in cramped metal cages, tethered to a self-injection apparatus, show only that "severely distressed animals, like severely distressed people, will relieve their distress pharmacologically if they can."

To test his hypothesis, Alexander built Rat Park, an 8.8 m2 (95 sq ft) housing colony, 200 times the square footage of a standard laboratory cage. There were 16–20 rats of both sexes in residence, an abundance of food, balls and wheels for play, and enough space for mating and raising litters. The results of the experiment appeared to support his hypothesis. Rats who had been forced to consume morphine hydrochloride for 57 consecutive days were brought to Rat Park and given a choice between plain tap water and water laced with morphine. For the most part, they chose the plain water. "Nothing that we tried," Alexander wrote, "... produced anything that looked like addiction in rats that were housed in a reasonably normal environment." Control groups of rats isolated in small cages consumed much more morphine in this and several subsequent experiments. 
Via garry's subposthaven.  There is a relevant discussion at Reddit.

Addendum:   A hat tip to Fletcher in Portugal for noting that the research described above has been summarized in a well-illustrated 40-page cartoon.


  1. This is not surprizing. There's a well argued book which is lost in a pile near at hand, which points out similar observations of people. Two key takeaways:
    1. Genetics matter. Even heroin isn't addictive to anything like 100% of the population - many people don't like it at all. (I personally didn't much care for morphine in hospital settings and can't imagine using it except for physical pain control.)
    2. Environment and context matter - and hence the "socially acceptable" alcohol appears to have a higher addiction rate than Heroin. (You can be a high functioning alcohol addict for decades - it's very common - and never be arrested..)

  2. Minnesotastan, this story has also been written up in comic form here:


    It's a great, visual way to educate on this topic. Amazing how often researchers, their peer reviewers, and journal readers can all be blind to a confirmation bias that, in hindsight, seems blindingly obvious.

    On a similar topic, Portugal decriminalized ALL drugs in 2001, becoming a leading nation in the real war on drugs (as opposed to the one that merely enriches cartels, arms dealers and private prisons, while making everyone else's lives worse). Instead of being given jail time, Portuguese users under the legal limit -- and there are now legal limits for marijuana, hashish, cocaine, heroin, ecstasy and meth, in the amount of a 10-day supply -- must report to a drug commission that may impose a fine, assign counseling/rehab, or simply hand out a warning.

    The results after a decade show less usage among teenagers, dramatically lower HIV rates among addicts, far higher rehab rates, and a massive savings for the government due to not pursuing, prosecuting, and incarcerating citizens for taking a puff in their living rooms. Such a sane policy! -- and it's now being closely examined by other nations who had been waiting to see whether or not it would explode in our faces. Alas, I do not believe that the US is one of those nations.

    1. "this story has also been written up in comic form"

      - and impressively so. I've added the link to the post. Tx, Fletcher.

  3. Hello. I read your post with a great deal of interest as well as confusion. Is it saying that because the rats moved in to some nicer digs they were no longer addicted? I am a morphine addict. I do not confess this with pride. My addiction is a prison-hell. Is this article telling me that if I move out of my crappy double-wide and into a nice 3 bedroom, 2.5 bath house I will no longer want morphine? As much as I would love that to be true, I'm pretty sure that wouldn't be the case. If I abstain more than 24 hours without morphine, no matter where I am, I will be in a very ugly world of hurt. Did I read it wrong? Is my drug soaked brain just not getting it? I would greatly appreciate an explanation.

    PS - Please no lectures on drug abuse. I already know.

    1. I would interpret the research as being relevant to how addiction develops rather than how addiction can be resolved or treated.

      I think they showed that during initial encounters with morphine, rats who had other options (companionship, recreation etc) were less likely to develop dependency on morphine. The same would not necessarily apply to escaping from a morphine addiction once it is already established.

      Other readers may be able to offer additional insights. And you won't get any lectures from me. Good luck.

    2. Hi anonymous, I recommend reading the book "Globalization of Addiction", by Bruce Alexander (the main scientist of the Rat Park studies).

      He describes his theory that the 'Rat Park effect' isn't necessarily due to the physical spaces that addicts find them in, but also the psycho-social spaces that addicts find themselves in.

      I'm not a psychologist, and can't vouch that Bruce has the correct answer. But he does mount a lot of research to back himself with. And the book is written with a great sense of humanity, and compassion towards addicts.

      Hopefully you can find the book at a library near you.

    3. A good Day to You, anonymous morphine addict! Don't move out from your double-wide, your addiction feels cosy there.

  4. Behavioural Sciences (Ethology) and books about it used to be very popular during the 50s and 60s and 70s, From Pavlov's dogs to Konrad Lorenz. People simply couldn't help themselves and jump to conclusions. Since then a lot of this stuff has been rebutted and adjusted, though the major discovered principles of imprinting, conditioning and instinct remain.

    Ethologists found and described patterns by observing animals, however a lack of a result isn't actually really helpful, it's not a pattern the best thing that could be derived from the experiment is somewhat of a no-brainer: social and living conditions matter... Let's also not forget that they managed to reproduce previous results by getting caged rats hooked on morphine. Not surprising that war veterans after severe physical and psychological trauma got hooked on morphine, essentially chained to a hospital bed.

    It's one thing to test toxicity on rats, since we share the same bio-chemisty, but another thing to test the effects of psychoactive drugs, where we have less in common: behaviour and brain.


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