Though Patrick Bateman may have become the fictional poster boy for psychopaths everywhere, the reality is that not everyone who qualifies as psychopathic would be at home in a Bret Easton Ellis novel. There are in fact non-violent psychopaths, and researchers believe they may have figured out what distinguishes the brains of these more pleasant individuals from their criminal counterparts.
Psychopathy is a complex condition that consists of several traits, such as a lack of empathy, an inability to connect emotionally to others, and uncontrollable impulsivity. Studies have shown that impulsivity ratings are the single most reliable predictor of violent criminal activity among psychopaths, indicating that those who most strongly display this particular characteristic are the most likely to fit the Bateman mold.
To understand how the brains of violent psychopaths are wired, researchers recruited 14 psychopathic criminals and 20 non-criminals who scored highly on psychopathy tests. Since previous research has suggested that imbalances in a brain area called the ventral striatum – which forms part of the reward circuit – are strongly associated with impulsivity and aggression, the study authors focussed their attention particularly on this part of their subjects’ brains.
Participants took part in a game that was specifically designed to activate the ventral striatum by messing with players’ reward expectations. At the beginning of each round, participants were shown either a green or a red circle, indicating whether or not monetary prizes were available. They were then shown a white circle, at which point they had to press a button as quickly as possible.
The connectivity between the brain's reward circuit and behavior control regions was significantly altered in criminal psychopaths. Johan Swanepoel/Shutterstock
Using functional magnetic resonance imaging (fMRI), the researchers measured the activity in each player's ventral striatum, finding that there were in fact no differences in the excitability levels of this region between the two groups.
However, they did discover that the connectivity between the ventral striatum and another brain region called the dorsomedial prefrontal cortex was significantly higher in the criminal group than the non-criminal group. Since this part of the brain is strongly associated with self-inhibition and impulse control, the researchers believe that this abnormality in the connectivity between the ventral striatum and the dorsomedial prefrontal cortex could explain why passive psychopaths are able to regulate their behavior, while criminal psychopaths aren’t.
Significantly, the study authors explain in their write-up – which appears in the journal Social Cognitive and Affective Neuroscience – that “the difference was remarkable in terms of consistency: there was no overlap between the groups.”
As such, they claim that the results of this study “help us understand why some people act according to their impulsive/antisocial personality while others are able to behave adaptively despite reward-related urges.” In other words, some psychopaths are unable to inhibit their reward-related impulses, while others have greater restraint.