(AFP) – Mar 14, 2010
PARIS — The brains of psychopaths could be hardwired to seek reward even when the consequences are life-threatening to others or themselves, according to a study released Sunday.
A naturally-occurring chemical, dopamine, plays a key role in some forms of pathologically violent behaviour and drug addiction, the study found.
Previous research has focused on what psychopaths tend to lack -- fear, empathy and the ability to maintain normal relationships.
But a team led by Joshua Buckholtz of Vanderbilt University in Nashville, Tennessee examined what there is too much of, namely impulsiveness and an extreme attraction to risk-taking and rewards.
"Lack of sensitivity to punishment and a lack of fear are not particularly good predictors of violence or criminal behavior," said colleague and co-author David Zald.
The new data, published in Nature Neuroscience, suggests that psychopaths "have such a strong draw to reward -- to the carrot -- that it overwhelms the sense of risk or concern about the stick," he said.
The key may be dopamine, a neurotransmitter known to affect cognition and behaviour, especially related to motivation, punishment and gratification.
Cocaine, alcohol and nicotine all stimulate the brain's dopamine circuits.
Other pathological states linked to dopamine dysfunction include autism, schizophrenia, and attention deficit hyperactivity disorder (ADHD).
"Psychopaths are often thought of as cold-blooded criminals who take what they want without thinking about consequences," Buckholtz 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."