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  1. chillinwill
    Risk-taking, by definition, defies logic. Reason can't explain why people do unpredictable things — like betting on blackjack or jumping out of planes — for little or, sometimes, no reward at all. There's the thrill, of course, but those brief moments of ecstasy aren't enough to keep most risk takers coming back for more — which they do, again and again, like addicts.

    A new study by researchers at Vanderbilt University in Nashville and Albert Einstein College of Medicine in New York City suggests a biological explanation for why certain people tend to live life on the edge — it involves the neurotransmitter dopamine, the brain's feel-good chemical.

    Dopamine is responsible for making us feel satisfied after a filling meal, happy when our favorite football team wins, or really happy when we use stimulating drugs like amphetamines or cocaine, which can artificially squeeze more dopamine out of the nerve cells in our brain. It's also responsible for the high we feel when we do something daring, like skiing down a double black diamond slope or skydiving out of a plane. In the risk taker's brain, researchers report in the Journal of Neuroscience, there appear to be fewer dopamine-inhibiting receptors — meaning that daredevils' brains are more saturated with the chemical, predisposing them to keep taking risks and chasing the next high: driving too fast, drinking too much, overspending or even taking drugs.

    David Zald, a professor of psychology and psychiatry at Vanderbilt, studied whether the brains of those thrill seekers differed in any way from those of the less adventuresome when it comes to dopamine. He gave 34 men and women a questionnaire to assess their novelty-seeking tendencies, then scanned their brains using a technique called positron emission tomography to figure out how many dopamine receptors the participants had. Zald and his team were on the lookout for a particular dopamine-regulating receptor, which monitors levels of the neurotransmitter and signals brain cells to stop churning it out when there's enough.

    Earlier studies in rats had shown that animals that tend to explore and take more risks in new environments also tend to have fewer of these inhibitory receptors, and Zald wanted to find out if the same was true in people.

    "This is one of those situations where the data came out essentially perfectly," he says. "The results were exactly as we predicted they would be, based on the animal data." That is, like the rats, humans who were more spontaneous and eager to take risks had fewer dopamine-regulating receptors than those who were more cautious.

    The findings support Zald's theory that people who take risks get an unusually big hit of dopamine each time they have a novel experience, because their brains are not able to inhibit the neurotransmitter adequately. That blast makes them feel good, so they keep returning for the rush from similarly risky or new behaviors, just like the addict seeking the next high.

    "This finding is really interesting," says Dr. Bruce Cohen, director of the Frazier Research Institute at McLean Hospital in Boston and a professor of psychiatry at Harvard Medical School. "It's a piece of the puzzle to understanding why we like novelty, and why we get addicted to substances ... Dopamine is an important piece of reward."

    Cohen suggests that a better understanding of novelty-seeking behavior may even help researchers find more effective treatments for addiction. If future studies validate Zald's findings and show that addicts also have fewer dopamine-inhibiting receptors than average, then medicines designed to replace the function of those receptors may help bring their dopamine levels down to normal and weaken their addiction.

    On a more theoretical level, Zald's results may also help inform a long-ranging debate in the addiction field. Some experts believe that addicts suffer from a natural deficit of dopamine and self-medicate with drugs; others think addicts' brains make normal amounts of the neurotransmitter but just can't break it down and regulate it properly.

    "We think a person who finds novelty and excitement more rewarding does so because he gets more dopamine release, or more of a boost," says Zald. "But it's one of the big controversies in the field of addiction research now." And it's yet another area for researchers to explore in trying to come up with a better treatment for substance abuse.

    By Alice Park
    Tuesday, Dec. 30, 2008
    Time
    http://www.time.com/time/health/article/0,8599,1869106,00.html?imw=Y

Comments

  1. PsychoActivist
    Not much of a surprise here as I've always kind of figured this to be true. However, it is nice to see it tested, proven, and documented and was interesting little read. I like in particular the part about finding more effective treatments now that this study has taken place. I for one, think it may help find these treatments. After all, it's hard to find the right answers when you don't know the questions.

    Thanks for sharing this post.
  2. bcubed
    Well, I suppose this explains why lizard never met a pilot who could fly worth a damn who wasn't a boozer...

    Random testing pretty much keeps pilots from drugs...though once, lizard was at a party with some of his flying peers, everyone "three sheets..." The host turns to lizard and says, quote:

    "The last flight I make before 60 [aka mandatory retirement], the second I shut down the engines, I'm pullin' a 3oz. spliff outta my flight bag...[stares into lizard's eyes]...ya know what I mean?!?"

    "Oh, absolutely!"

    Make of this what you will...
  3. robin_himself
    Risk Takers, Drug Abusers Driven By Decreased Ability To Process Dopamine

    For risk-takers and impulsive people, New Year's resolutions often include being more careful, spending more frugally and cutting back on dangerous behavior, such as drug use. But new research from Vanderbilt finds that these individuals--labeled as novelty seekers by psychologists--face an uphill battle in keeping their New Year's resolutions due to the way their brains process dopamine. The research reveals that novelty seekers have less of a particular type of dopamine receptor, which may lead them to seek out novel and exciting experiences--such as spending lavishly, taking risks and partying like there's no tomorrow.

    The research was published Dec. 31, 2008, in the Journal of Neuroscience.

    The neurotransmitter dopamine is produced by a select group of cells in the brain. These dopamine-producing cells have receptors called autoreceptors that help limit dopamine release when these cells are stimulated.

    "We've found that the density of these dopamine autoreceptors is inversely related to an individual's interest in and desire for novel experiences," David Zald, associate professor of psychology and lead author of the study, said. "The fewer available dopamine autoreceptors an individual has, the less they are able to regulate how much dopamine is released when these cells are engaged. Because of this, novelty and other potentially rewarding experiences that normally induce dopamine release will produce greater dopamine release in these individuals." [imgr=white]http://www.drugs-forum.com/forum/attachment.php?attachmentid=6757&stc=1&d=121210467 3[/imgr]

    Dopamine has long been known to play an important role in how we experience rewards from a variety of natural sources, including food and sex, as well as from drugs such as cocaine and amphetamine. Previous research has shown that individuals differ in both their number of dopamine receptors and the amount of dopamine they produce, and that these differences may play a critical role in addiction. Zald and his colleagues set out to explore the connection between dopamine receptors and the novelty-seeking personality trait.

    "Novelty-seeking personality traits are a major risk factor for the development of drug abuse and other unsafe behaviors," Zald and his colleagues wrote.

    "Our research suggests that in high novelty-seeking individuals, the brain is less able to regulate dopamine, and this may lead these individuals to be particularly responsive to novel and rewarding situations that normally induce dopamine release," Zald said.

    Previous research in rodents showed that some respond differently to novel environments. Those who explore novel environments more are also more likely to self-administer cocaine when given the chance. Dopamine neurons fire at a higher rate in these novelty-responsive rodents, and the animals also have weak autoreceptor control of their dopamine neurons. Zald and colleagues speculated that the same relationships would be seen in humans.

    The researchers used positron emission topography to view the levels of dopamine receptors in 34 healthy humans who had taken a questionnaire that measured the novelty-seeking personality trait. The questionnaire measured things such as an individual's preference for and response to novelty, decision-making speed, a person's readiness to freely spend money, and the extent to which a person is spontaneous and unconstrained by rules and regulations. The higher the score, the more likely the person was to be a novelty seeker.

    The researchers found that those that scored higher on the novelty-seeking scale had decreased dopamine autoreceptor availability compared to the subjects that scored lower.

    The National Institute of Drug Abuse funded the research. Zald is a Vanderbilt Kennedy Center for Research on Human Development investigator and is a member of the Vanderbilt Center for Integrative and Cognitive Neuroscience. His Vanderbilt co-authors were Ronald Cowan, Ronald Baldwin, M. Sib Ansari, Rui Li, Evan Shelby, Clarence Smith, Maureen McHugo and Robert Kessler from the departments of Psychology, Psychiatry and Radiological Sciences. Patrizia Riccardi, Albert Einstein College of Medicine in Bronx, New York, was also a co-author of the paper.

    More Vanderbilt news is available on VUCast, http://www.vanderbilt.edu/news.

    Vanderbilt University
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