I had read about the Rat Park experiment and the analog of the Vietnam war a few times before this week. Either in a documentary, NPR broadcasting, or another like article, the story is told often almost identically. They begin with the cocaine water experiments, offer a few words to Nixon's War, move to Rat Park, and then end with Vietnam heroin users. But there are a few things many of these articles seem to leave out.

The first detail left out is that, unlike the original experiment, cocaine was not used in rat park; morphine was. This might seem like a nitpick--both cocaine and morphine are highly addictive--but it is worth noting that morphine's high works by pumping the brain full of the same chemical released when both humans and rats exercise. Along with the comfortable social settings, the rats in the Rat Park experiment were also given exercise equipment: balls and wheels.

Rats have been shown to become addicted to exercise (http://www.nytimes.com/2002/05/21/health/runner-s-high-endorphins-fiction-some-scientists-say.html) and it is possible that the exercise afforded to them in Rat Park could have been doing much of the heavy lifting in keeping them clean. But this isn't surprising. Recent medical literature has been pointing to this with studies in lab rats showing self-administration of cocaine dropping after exercise (https://www.ncbi.nlm.nih.gov/pubmed/18585870 & https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3276339/).

Although I would hardly call the results of Rat Park misleading, the greater takeaway from this experiment might be the effects of exercise on addiction.