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   Psychopaths' brains wired to seek rewards, no matter the consequences   
   Date:   
   March 15, 2010   
   Source:   
   Vanderbilt University   
   Summary:   
   The brains of psychopaths appear to be wired to keep seeking a reward at any   
   cost, new research finds. The research uncovers the role of the brain's reward   
   system in psychopathy and opens a new area of study for understanding what   
   drives these    
   individuals.   
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   FULL STORY   
      
   Abnormalities in how the nucleus accumbens, highlighted here, processes   
   dopamine have been found in individuals with psychopathic traits and may be   
   linked to violent, criminal behavior.   
   Credit: Gregory R.Samanez-Larkin and Joshua W. Buckholtz   
   The brains of psychopaths appear to be wired to keep seeking a reward at any   
   cost, new research from Vanderbilt University finds. The research uncovers the   
   role of the brain's reward system in psychopathy and opens a new area of study   
   for understanding    
   what drives these individuals.   
      
   "This study underscores the importance of neurological research as it relates   
   to behavior," Dr. Francis S. Collins, director of the National Institutes of   
   Health, said. "The findings may help us find new ways to intervene before a   
   personality trait    
   becomes antisocial behavior."   
      
   The results were published March 14, 2010, in Nature Neuroscience.   
      
   "Psychopaths are often thought of as cold-blooded criminals who take what they   
   want without thinking about consequences," Joshua Buckholtz, a graduate   
   student in the Department of Psychology and lead author of the new study,   
   said. "We found that a hyper-   
   reactive dopamine reward system may be the foundation for some of the most   
   problematic behaviors associated with psychopathy, such as violent crime,   
   recidivism and substance abuse."   
      
   Previous research on psychopathy has focused on what these individuals lack --   
   fear, empathy and interpersonal skills. The new research, however, examines   
   what they have in abundance -- impulsivity, heightened attraction to rewards   
   and risk taking.    
   Importantly, it is these latter traits that are most closely linked with the   
   violent and criminal aspects of psychopathy.   
      
   "There has been a long tradition of research on psychopathy that has focused   
   on the lack of sensitivity to punishment and a lack of fear, but those traits   
   are not particularly good predictors of violence or criminal behavior," David   
   Zald, associate    
   professor of psychology and of psychiatry and co-author of the study, said.   
   "Our data is suggesting that something might be happening on the other side of   
   things. These individuals appear to have such a strong draw to reward -- to   
   the carrot -- that it    
   overwhelms the sense of risk or concern about the stick."   
      
   To examine the relationship between dopamine and psychopathy, the researchers   
   used positron emission tomography, or PET, imaging of the brain to measure   
   dopamine release, in concert with a functional magnetic imaging, or fMRI,   
   probe of the brain's reward    
   system.   
      
   "The really striking thing is with these two very different techniques we saw   
   a very similar pattern -- both were heightened in individuals with   
   psychopathic traits," Zald said.   
      
   Study volunteers were given a personality test to determine their level of   
   psychopathic traits. These traits exist on a spectrum, with violent criminals   
   falling at the extreme end of the spectrum. However, a normally functioning   
   person can also have the    
   traits, which include manipulativeness, egocentricity, aggression and risk   
   taking.   
      
   In the first portion of the experiment, the researchers gave the volunteers a   
   dose of amphetamine, or speed, and then scanned their brains using PET to view   
   dopamine release in response to the stimulant. Substance abuse has been shown   
   in the past to be    
   associated with alterations in dopamine responses. Psychopathy is strongly   
   associated with substance abuse.   
      
   "Our hypothesis was that psychopathic traits are also linked to dysfunction in   
   dopamine reward circuitry," Buckholtz said. "Consistent with what we thought,   
   we found people with high levels of psychopathic traits had almost four times   
   the amount of    
   dopamine released in response to amphetamine."   
      
   In the second portion of the experiment, the research subjects were told they   
   would receive a monetary reward for completing a simple task. Their brains   
   were scanned with fMRI while they were performing the task. The researchers   
   found in those    
   individuals with elevated psychopathic traits the dopamine reward area of the   
   brain, the nucleus accumbens, was much more active while they were   
   anticipating the monetary reward than in the other volunteers.   
      
   "It may be that because of these exaggerated dopamine responses, once they   
   focus on the chance to get a reward, psychopaths are unable to alter their   
   attention until they get what they're after," Buckholtz said. Added Zald,   
   "It's not just that they don't    
   appreciate the potential threat, but that the anticipation or motivation for   
   reward overwhelms those concerns."   
      
   The National Institute on Drug Abuse funded the research.   
      
   Zald is an investigator in the Vanderbilt Kennedy Center for Research on Human   
   Development.   
      
      
   Story Source:   
      
   The above post is reprinted from materials provided by Vanderbilt University.   
   Note: Materials may be edited for content and length.   
      
   Journal Reference:   
      
   Joshua W Buckholtz, Michael T Treadway, Ronald L Cowan, Neil D Woodward,   
   Stephen D Benning, Rui Li, M Sib Ansari, Ronald M Baldwin, Ashley N   
   Schwartzman, Evan S Shelby, Clarence E Smith, David Cole, Robert M Kessler &   
   David H Zald. Mesolimbic dopamine    
   reward system hypersensitivity in individuals with psychopathic traits. Nature   
   Neuroscience, 2010; DOI: 10.1038/nn.2510   
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   Vanderbilt University. "Psychopaths' brains wired to seek rewards, no matter   
   the consequences." ScienceDaily. ScienceDaily, 15 March 2010. .   
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