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Psychopaths' brains don't learn from punishment- 30-Jan-2015
Toronto: Psychopathic violent offenders have abnormalities in the parts of the brain related to learning from punishment, according to a new study.
"One in five violent offenders is a psychopath. They have higher rates of recidivism and don't benefit from rehabilitation programmes," said Professor Sheilagh Hodgins of the University of Montreal and Institut universitaire en sante mentale de Montreal.
"Our research reveals why this is and can hopefully improve childhood interventions to prevent violence and behavioural therapies to reduce recidivism," Hodgins said.
"We have found structural abnormalities in both gray matter and specific white matter fibre tracts among the violent offenders with psychopathy," Hodgins said.
Grey matter is mostly involved with processing information and cognition, while white matter coordinates the flow of information between different parts of the brain.
The study included 12 violent offenders with antisocial personality disorder and psychopathy, 20 violent offenders with antisocial personality disorder but not psychopathy, and 18 healthy non-offenders.
The offenders had been convicted of murder, rape, attempted murder and grievous bodily harm, and were recruited from Britain's probation service.
"We observed reductions in gray matter volumes bilaterally in the anterior rostral prefrontal cortex and temporal poles relative to the other offenders and to the non-offenders," Hodgins said.
These brain regions are involved in empathy, the processing of pro-social emotions such as guilt and embarrassment, and moral reasoning.
"Abnormalities were also found in white matter fibre tracts in the dorsal cingulum, linking the posterior cingulate cortex to the medial prefrontal cortex that were specifically associated with the lack of empathy that is typical of psychopathy," said Dr Nigel Blackwood, who is affiliated with King's College London.
These same regions are involved in learning from rewards and punishment.
While inside the brain scanner, the violent offenders and non-offenders completed a task that assessed their ability to adjust their behaviour when the consequences of their responses changed from positive to negative.
The task was an image matching game - sometimes points were awarded for correctly pairing images, sometimes they were not.
"When these violent offenders completed neuropsychological tasks, they failed to learn from punishment cues, to change their behaviour in the face of changing contingencies, and made poorer quality decisions despite longer periods of deliberation," Blackwood said.
The study appears in the journal Lancet Psychiatry.
