Unveiling the differences between non-violent psychopaths and criminal ones.
Psychopathy, one of the conditions in the notorious dark triad of personality traits, is characterized by a number of complex behaviors, like uncontrollable impulsivity, a lack of empathy, and an inability to connect emotionally with others.
Although some people may fit the psychopath criteria, it doesn’t mean that each individual will go on to commit violent crimes or land themselves in jail. Previous research has implicated impulsivity as the most reliable predictor of violent criminal activity, so in a new study, researchers decided to focus on the brain areas associated with impulsivity and aggression to investigate how the brains of criminal psychopaths are wired.
The team recruited 14 psychopathic criminals and compared them to two groups of non-criminal participants: one group scored highly on psychopathic tests, while the other scored low. The researchers concentrated on a brain area called the ventral striatum (VS) — part of the brain’s reward circuit. Imbalances in the ventral striatum are linked with impulsivity and aggression.
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In the experiment, participants played a game specifically designed to activate the VS. They were shown either a green or red circle at the beginning of each round, which indicated whether money could be won. Then, they were shown a white circle, and had to press a button as quickly as possible.
The VS activity was measured with functional magnetic resonance imaging (fMRI) scans, but surprisingly, the researchers observed no differences in the excitability levels of the VS between the criminal psychopaths and non-criminals.
However, reporting their findings in the journal Social and Cognitive Affective Neuroscience, the researchers describe an abnormality in the connectivity between the VS and another brain region, called the dorsomedial prefrontal cortex, in the criminal group. This brain region is involved in impulse control, self-inhibition, and social processing.
The researchers suspect that this abnormal activity between the two regions in criminal psychopaths could explain why they aren’t able to regulate their behavior, while passive psychopaths can. In fact, some psychopathic traits are even linked with success.
“The difference was remarkable in terms of consistency: there was no overlap between the groups,” the researchers write in the study.
“The present results help us understand why some people act according to their impulsive/antisocial personality while others are able to behave adaptively despite reward-related urges,” they conclude.
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