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April 8, 2013

Thrill Seekers Lack ’Brakes’ in the Brain

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New research gives a possible explanation for why some of us are thrill seekers and others like to play it safe. The study found that some of us can’t control the release of a certain brain chemical.
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Interviewee: David Zald, Vanderbilt University
Produced by Sunita Reed-- Edited by SunitaReed and Chris Bergendorff Copyright © ScienCentral, Inc

"Adrenaline Junkies" Actually Prefer Dopamine

Wouldn’t it be amazing if researchers could scan our brains and see whether we have thrill seeking personality traits? Vanderbilt University psychologist David Zald has come pretty close. He has conducted a study that links thrill seeking behavior with a difference in specific part of the dopamine system in the brain.

“Dopamine does a number of different things. Probably most importantly though it’s involved in motivation and reward,” explains Zald. “And it’s the critical chemical in terms of people really wanting to do things.”


Specific brain cells, or neurons, make and release dopamine. When dopamine is released its target is specific dopamine receptors on other brain cells in the pleasure centers of the brain. There have been some studies of these receptors in people. But Zald wanted to look at a different structure on the dopamine releasing brain cells themselves, called autoreceptors, which function as brakes to stop the release of dopamine.

Zald knew that studies in rodents showed that those with reduced brakes were more likely to explore in novel environments but were also more likely to self-administer cocaine or amphetamines. He also knew there was some limited evidence that individual differences in dopamine functioning was linked to novelty seeking.

He and his colleagues asked 34 healthy male and female volunteers to fill out a questionnaire that measures a person's tendency for novelty seeking.

“The scale that we used measured things like how much the person wants to try new things, how free they are in terms of spending money, and the person’s willingness to be spontaneous or even break rules,” Zald explains.

Then his team scanned the brains of the volunteers using PET scanners. They measured the number of autoreceptors, the structures that act like brakes on dopamine release. As they wrote in the “Journal of Neuroscience” low thrill seekers had many brakes while high thrill seekers had very few. In the brain scans in the image at the right comparing a high and low thrill seeker, the white arrows point to the autoreceptors, which show up as bright blue.

“What we think that means is people who really don’t have the brakes on their dopamine system, they’re really going to release more dopamine and have more of the rewarding effects of dopamine,” says Zald.

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Zald says that there are positive and negative aspects to the novelty seeking personality trait.

“Thrill seeking is one of the things that leads people to explore new things, to discover new things,” says Zald. “The world would be a boring place if we didn’t have people who were willing to take the risks because they were so interested or drawn to the new and exciting.”

But people with the novelty seeking trait are also at a higher risk of doing drugs. Zald wants to do further studies to find out why some people take such deadly risks and others find ways to balance their need for excitement in healthier ways.

And Zald has a word of advice for parents: “For a child who is a thrill seeker, what you really want to do is direct them into activities which will give them those thrills. For instance having them learn to do rock climbing would be a good example. And if they can get those thrills through something where they maintain a reasonable level of safety, that may be a draw that is enough for them so they never feel the need or desire to start experimenting with drugs.”

Publication: Journal of Neuroscience
Authors: David H. Zald, Ronald L. Cowan, Patrizia Riccardi, Ronald M. Baldwin, M. Sib Ansari, Rui Li, Evan S. Shelby, Clarence E. Smith, Maureen McHugo, and Robert M. Kessler
Research funded by: National Institute of Drug Abuse

Elsewhere on the Web:

How Stuff Works: How Your Brain Works

The Science Behind Drug Abuse

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