The brains of psychopaths release four times as much dopamine in response to rewards as normal people. Imagine how much more pleasure they get from taking whatever they want.
Dr Joshua Buckholtz, the study's lead author, said:
"Psychopaths are often thought of as cold-blooded criminals who take what they want without thinking about consequences.Psychopaths are also known to have a lack of fear and empathy. But this study emphasised their strong focus on reward.
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."
Dr David Zald, study co-author, said:
"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.The results come from a study in which people - some psychopaths - were given a dose of amphetamine (speed), then had their brains scanned. The aim was to see how people's brains reacted to the stimulant.
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."
Dr Buckholtz explained:
"Our hypothesis was that psychopathic traits are also linked to dysfunction in dopamine reward circuitry.In the second part of the study, participants had their brains scanned while getting a monetary reward for doing a task. Again, the psychopaths showed much higher levels of brain activity in anticipation of getting the reward.
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."
Dr Buckholtz said:
"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."The study was published in the journal Nature Neuroscience (Buckholtz et al., 2010).
"Nicotine and Dopamine
Nicotine activates the same reward pathways in the brain that other drugs of abuse such as cocaine or amphetamines do, although to a lesser degree.Research has shown that nicotine increases the level of dopamine in the brain, a neurotransmitter that is responsible for feelings of pleasure and well-being.The acute effects of nicotine wear off within minutes, so smokers must continue dosing themselves frequently throughout the day to maintain the pleasurable effects of nicotine and to prevent withdrawal symptoms."