For Markus Heilig, the years of dead ends were starting to grate.
A seasoned psychiatrist, Heilig joined the National Institutes of Health in 2004 with grand ambitions of finding new ways to treat addiction and alcoholism. “It was the age of the neuroscience revolution, and all this new tech gave us many ways of manipulating animal brains,” he recalls. By studying addictive behavior in laboratory rats and mice, he would pinpoint crucial genes, molecules, and brain regions that could be targeted to curtail the equivalent behaviors in people.
It wasn’t to be. The insights from rodent studies repeatedly proved to be irrelevant. Many researchers and pharmaceutical companies became disillusioned. “We cured alcoholism in every rat we ever tried,” says Heilig, who is now at Linköping University in Sweden. “And at the end of every paper, we wrote: This will lead to an exciting treatment. But everything we took from these animal models to the clinic failed. We needed to go back to the drawing board.”
Heilig doesn’t buy that mice and rats have nothing to teach us about addiction. It’s more that researchers have been studying them in the wrong way. Typically, they’ll let the animals self-administer drugs by pressing a lever, which they almost always learn to do. That should have been a red flag. When humans regularly drink alcohol, only 15 percent or so become dependent on the stuff. Why them and not the other 85 percent? That’s the crucial question, and you won’t answer it with an experiment in which every rodent becomes addicted.