The Rat Park experiment

We may earn a commission from links on this page.

Are drugs addictive? As odd as it might sound, one scientist believes that they weren't — at least not to the degree most people insisted. He thought it had more to do with overwhelming misery and depressing environments, and to prove it he created the ideal environment... for rats.

In the late 1970s, Canadian psychologist Bruce Alexander was distressed by the laws and policies pertaining to opiate drugs. He didn't approve of the harsh penalties dealt out to people in the name of addiction prevention. Generally those penalties were applied in order to prevent drug dealers from pushing their product on new people — at which point the addictive nature of drugs caused people to be hooked.

When Alexander looked at the studies indicating the addictive properties of drugs, he found what he believed to be insufficient evidence. There were plenty of interviews with drug users who self-reported themselves as being addicted, but Alexander reasoned that they had reasons of their own to declare that their affinity for drugs was beyond their control. Meanwhile, the relatively few studies done on addiction were highly technical and all relied on one thing: they were conducted on rats that lived and died in miserable, cramped cages.


It seemed to Alexander that the reported increased rates of addiction in economically depressed areas might have something in common with the consistently high rates of addiction in studies done on rats in distressing environments. Drugs provided relief from pain, and if it was the only relief available, it was no wonder that anything — animal or human — would turn to it with the fervor of an addict. Alexander began to put forward a new hypothesis. If rats were given a beautiful living area that allowed them a relatively happy life, they would not become addicted.


And so he built "Rat Park," a testing facility meant to give the rats inside it plenty of room, exercise and play facilities, good food, lots of bottles and boxes to explore, mixed-gender company, and private areas to raise their young. His group even painted the walls to resemble a forest. Before populating Rat Park, they forced many of its future inhabitants to ingest morphine hydrochloride for a month and a half. Less lucky rats were fed with morphine and then put in standard lab cages. Once the two groups of rats were housed, they were given a choice between morphine-laced water and regular water. Although the caged rats overwhelmingly chose the morphine-laced water, relatively few of the Rat Park residents did.

Alexander began trying to induce the Rat Park rats to take the morphine. His best results were with a sugar solution. Rats love sugar, and if the morphine was heavily sugared the rats did try it, but they still didn't consume nearly as much as the caged rats did. At one point, the caged rats were consuming twenty times as much as the Rat Park residents were. Alexander published his results, declaring that miserable living conditions were the primary cause of addiction to opiates, not the opiates themselves.


His theory did not gain much popularity. His procedure, overall, seems to have drawn more attention than his conclusions. Scientists realized that isolated animals in cages may not provide a useful response in experiments determining human behavior, but few people hold to the theory that drugs are not, for the most part, addictive. A similar experiment that seemed to contradict his results didn't help, although its framers admitted that they might have done the experiment with two different rat subspecies, one of which might be resistant to addiction.

It's understandable that no one wants to say that drugs aren't addictive. If they are, and people get hooked, one announcement might spawn a generation of addicts. And if they're not, they're hardly healthy. Still, the idea of easing up on drug penalties and using any money saved to prevent the societal conditions that may contribute to addiction in the first place has an allure. What do you think of Rat Park?


Top Image: Alexey Krasavin

Second Image: Steve Beger

Via Parliament of Canada, NCBI, LP.