"So the social isolation leads to addiction more quickly, and it's harder to extinguish," said Whitaker.
Whitaker said that the implications of these findings for addiction in humans are obvious. There is a rich literature that documents the negative effects of social isolation in humans, as well as a great deal of evidence that addiction in rats and humans is functionally similar at the neurological level.
"It's not a one-to-one correlation, but there are socially impoverished human environments," she said. "There are children who are neglected, who have less social input. It's reasonable to make guesses about what the impact of that is going to be."
Morikawa points out that their findings may also have implications for how social isolation during adolescence affects conditionability when it comes to other kinds of rewards.
"We think that maybe what's happening is that the brain reacts to the impoverished environment, to a lack of opportunities to be reinforced by rewarding stimuli, by increasing its sensitivity to reward-based conditioning," said Morikawa. "The deprived brain may be overinterpreting any reward it encounters. And if that's the case, it's likely that you are more conditionable not only to drugs but to any sort of reward, including food reward. One interesting possibility is that it might also make adolescents more prone to food 'addiction,' and then to obesity."
|Contact: Daniel Oppenheimer|
University of Texas at Austin