Overview of Addiction Research in NYT Magazine

http://www.treatmentonline.com/treatments.php?id=782

So what made all those lab rats lose their minds? Bruce Alexander and his research team had a rather simple hypothesis: The rats had awful lives. They were stressed, lonely, bored and looking to self-medicate. To prove it, Alexander created a lab-rat heaven he called Rat Park. The 200-square-foot residence featured bright balls and tin cans to play with, painted creeks and trees to look at and plenty of room for mating and socializing.

Alexander took 16 lucky rats and plopped them into Rat Park, where they were offered water or a sweet, morphine-based cocktail (rats love sweets). Alexander offered the same two drinks to the control group of rats he left isolated in cages. The results? The rat-parkers were apparently having too much fun to bother with artificial highs, because they hardly touched the morphine solution, no matter how sweet Alexander and his colleagues made it. The isolated and arguably depressed rats, on the other hand, eagerly got high, drinking more than a dozen times the amount of the morphine solution as the rats in paradise.