Differences in the behavior and the brain receptors of rats seem to predict which of the rodents will become cocaine addicted, scientists report. The finding supports the idea that some people are predisposed to drug addiction.
Scientists have long suspected that certain personality traits, including thrill seeking, impulsivity, and a tendency to be antisocial, go hand in hand with drug addiction. Studies have also shown that the brains of monkeys and people addicted to stimulants such as cocaine or amphetamine have significantly fewer receptors for dopamine, a brain chemical that regulates emotion, motivation, and feelings of pleasure.
However, the connection between these mental and physical characteristics and drug addiction has posed a chicken-and-egg problem for researchers. It's unclear whether drug addicts have these qualities before they begin using drugs or whether taking drugs over the long term changes a person's personality and brain properties.