Individuals who have impulsive or antisocial traits have an exaggerated response to anticipated reward, according to a study funded by the National Institute on Drug Abuse.
Scientists from Vanderbilt University in Nashville used positron emission tomography (PET) to assess the relationship between traits associated with psychopathy and dopamine release following amphetamine administration in 30 normal volunteers (Buckholtz JW et al. Nat Neurosci. 10.1038/nn.2510 [published online March 14, 2010]). They found a strong correlation between higher scores related to impulsive or antisocial characteristics on the psychopathic personality inventory and dopamine release. Additionally, functional magnetic resonance imaging of 24 individuals (18 of whom also underwent PET testing) indicated that those with such traits had a greater neurological response to the anticipation of a monetary reward.
Kuehn BM. Psychopathy and Reward. JAMA. 2010;303(16):1587. doi:10.1001/jama.2010.458