LONDON (Reuters) - Scientists who scanned the brains of men
convicted of murder, rape and violent assaults have found the strongest
evidence yet that psychopaths have structural abnormalities in their brains.
The researchers, based at King's College London's Institute
of Psychiatry, said the differences in psychopaths' brains mark them out even
from other violent criminals with anti-social personality disorders (ASPD), and
from healthy non-offenders.
Nigel Blackwood, who led the study, said the ability to use
brain scans to identify and diagnose this sub-group of violent criminals has
important implications for treatment.
The study showed that psychopaths, who are characterised by
a lack of empathy, had less grey matter
in the areas of the brain important for understanding other peoples' emotions.
While cognitive and behavourial treatments may benefit
people with anti-social personality disorders, the same approach may not work
for psychopaths with brain damage, Blackwood said.
"To get a clear idea of which treatments are working,
you've got to clearly define what people are like going into the treatment
programmes," he said in a telephone interview.
Essi Viding a professor in the psychology and language
sciences department of University College London, who was not involved in
Blackwood's study, said it provided "weighty new evidence" about the
importance of distinguishing psychopathic from non-psychopathic people rather
than grouping them together.
The findings also have implications for the justice system,
because linking psychopathy to brain function raises the prospect of arguing a
defence of insanity.
Interest in what goes on inside the heads of violent
criminals has been sharpened by the trial of Anders Behring Breivik, the
Norwegian who massacred 77 people last July.
Two court-appointed psychiatric teams who examined Breivik
came to opposite conclusions about his mental health. The killer himself has
railed being called insane.
LESS GREY MATTER IN BRAIN'S "SOCIAL" AREAS
Blackwood's team used magnetic resonance imaging (MRI) to
scan the brains of 44 violent adult male offenders in Britain who had already
been diagnosed with anti-social personality disorders.
The crimes they had committed included murder, rape,
attempted murder and grievous bodily harm.
Of the 44 men scanned, 17 met the diagnosis for ASPD plus
psychopathy and 27 did not. The researchers also scanned the brains of 22
healthy non-offenders.
The results showed that the psychopaths' brains had
significantly less grey matter in the anterior rostral prefrontal cortex and
temporal poles than the brains of the non-psychopathic offenders and
non-offenders.
These areas of the brain are important for understanding
other people's emotions and intentions, and are activated when people think
about moral behaviour, the researchers said.
Damage to these areas is linked with a lack of empathy, a
poor response to fear and distress and a lack of self-conscious emotions such
as guilt or embarrassment.
Lindsay Thomson, a professor of forensic psychiatry at the
University of Edinburgh who was not involved in this study, said Blackwood's
findings add to evidence that psychopathy is a distinct neurodevelopmental
brain disorder.
Research shows that most violent crimes are committed by a
small group of persistent male offenders with ASPD.
In England and Wales, for example, around half of male
prisoners meet diagnostic criteria for ASPD. A major review of studies covering
23,000 prisoners from 62 countries conducted in 2002 found that 47 percent had
anti-social personality disorder.
Such people typically react in an aggressive way to
frustration or perceived threats, but most are not psychopaths, the researchers
wrote in a summary of their study, which was published in the Archives of General
Psychiatry journal.
There are clear behaviour differences among people with ASPD
depending on whether they also have psychopathy. Their patterns of offending
are different, suggesting the need for a separate approach to treatment.
"We describe
those without psychopathy as 'hot-headed' and those with psychopathy as
'cold-hearted'," Blackwood explained.
"The 'cold-hearted'
psychopathic group begin offending earlier, engage in a broader range and
greater density of offending behaviours, and respond less well to treatment programmes in adulthood compared to
the 'hot-headed' group."
(Reporting by Kate Kelland; Editing by Rosalind Russell)
