Researchers have long known of a relationship between people with impulsivity and/or thrill seeking traits, and addiction. But what’s causing what? The problem has been that since researchers tend to deal with addicts only after they become addicts – they haven’t been able to say whether getting addicted to drugs like cocaine causes people to act in impulsive ways, or whether impulsive people tend to become addicted to cocaine!
Scientists are now able to measure the character traits of impulsivity and thrill seeking in rats (Which is kind of neat in itself). Here’s how they can differentiate:
Rats with impulsive character traits are those that are unable to follow tasks that involve waiting, like waiting to push a button until signaled – even when they would be rewarded if they did wait.
Thrill seeking rats are those that will enter into a new environment and immediately investigate unfamiliar smells and stimuli. Normal rats will wait until they are comfortable and feel safe before risking such exploration.
So, now that researchers can segregate these behavior types in rats, they can now investigate what effect these character traits exert over things like cocaine usage patterns.
Psychologists David Belin and Barry Everitt, of Cambridge University, decided to take a look. They constructed a study whereby rats with either the impulsive character trait or the thrill seeking character trait were able to inject cocaine directly into the brain as often as they wanted to. They had complete control over this self administration.
In the beginning, the thrill seeking rats injected huge quantities, and injected it often; while the impulsive rats were much more reserved – seeking cocaine only sporadically and in small quantities.
After 40 days of free access though, the tables had turned drastically. The thrill seeking rats no longer had much interest in cocaine – the thrill and novelty was gone, and they rarely self administered. The impulsive rats though were incredibly addicted, and administered the drug in large quantities and with great frequency.
Which tells us…
These character trait effects are likely the same in humans – meaning impulsive people are probably at a greater risk to develop addictions. And since certain anti-depressant medications can reduce impulsivity, the researchers are excited that their research findings may lead to a new methodology in the treatment of addiction.
People with diagnosed impulsivity traits could potentially receive targeted drug prevention programming, and addicts in treatment could also get tested for impulsivity, and perhaps benefit from existing medications that would help to minimize the influence of impulsivity on their addiction.
Rats with impulsivity issues could also be cautioned against experimenting with cocaine.
You can read the full study in the June 06/2008 edition of "Science"