The brains of men given to psychopathic violence show unusual features on fMRI scans in areas that relate to learning and punishment. The finding indicates that current approaches to dealing with many serious criminals are ineffective, if not counter-productive.
The term psychopath is controversial in psychiatry, but is usually defined as a lack of empathy and remorse.
"One in five violent offenders is a psychopath,” said Professor Sheilagh Hodgins of the University of Montreal. “They have higher rates of recidivism and don't benefit from rehabilitation programmes.”
"Psychopathic offenders are different from regular criminals in many ways. Regular criminals are hyper-responsive to threat, quick-tempered and aggressive, while psychopaths have a very low response to threats, are cold, and their aggression is premeditated," said Dr. Nigel Blackwood of King's College London.
Hodgins and Blackwood are part of a team that compared the fMRI scans of the brains of violent offenders—12 with psychopathy and 20 without—to a group of 18 people with no history of violence. Their work is published in Lancet Psychiatry.
Subjects played an image matching game while inside an MRI machine. However, the game's rules were inconsistent, with the way points were awarded changing without warning. The offenders failed to learn from “punishments” when the rules changed, and differences in brain responses were revealed by the imaging.
“We have found structural abnormalities in both gray matter and specific white matter fiber tracts among the violent offenders with psychopathy," Hodkins said. This is despite the fact that the non-psychopathic offenders had been diagnosed with antisocial personality disorder, suggesting they would be the most likely population to resemble those with psychopathy.
When an achievement that had previously been rewarded with points instead led to a deduction, the functioning of the non-psychpathic offenders' posterior cingulate cortex and anterior insula were similar to that of the control group. However, these parts of the psychopaths' brains responded differently. Although both brain regions are thought to have multiple roles, they are important in learning and empathy.
"These results suggest the violent offenders with psychopathy are characterized by a distinctive organization of the brain network that is used to learn from punishment and from rewards," Blackwood said.
"Offenders with psychopathy may only consider the possible positive consequences and fail to take account of the likely negative consequences,” said Hodgins.
Blackwood noted that the findings may explain why parental skills programs lead to reductions in aggressive behaviors among most children, but not “those who are callous and insensitive to others.”
"Since most violent crimes are committed by men who display conduct problems from a young age, learning-based interventions that target the specific brain mechanisms underlying this behaviour pattern and thereby change the behaviour would significantly reduce violent crime," Hodgins said.
The study was done on offenders with convictions for murder, rape and attempted murder, but not all psychopaths are violent. Further studies will be required to see how relevant this research is to people whose psychopathy is expressed in other ways.