Transcript Raine et al (1997) Brain abnormalities in murderers

Brain abnormalities in murderers
indicated by positron emission
tomography
Biological Psychiatry 42 495-508
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain
abnormalities in murderers
Introduction
• is there a biological basis for criminality?
• PET scans
• radioactive labels on:
• blood/blood sugars
• dopamine (neuro-transmitter)
•  gamma ray signals
• 7-8M ps
• also MRI and fMRI
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
PET scans showing ‘hot spots’ for cognitive activities
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
introduction: problems
• colourisation v complex  errors
• 'hot spots' same for 'on & 'off' brain actions
• practiced brain activity declines in that area
• 'hottest spots' = only for newest tasks?
• "it seems we should not let the quality of
evidence get in the way of a good story"
Banyard and Grayson 2000
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
PET scan of a subject
whilst practicing a new
language skill
A scan of the same
subject demonstrating
this skill after it had
become familiar
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
the study: subjects
• 41 people: 39M 2F
• charged with murder
• pleading not guilty by reason of insanity
(NGRI)
• all referred for PET for legal reasons
• average age 34.3
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
the study: subjects’ medical histories
• schizophrenia 6
• head injury/organic brain damage 23
• drug abuse 3
• affective disorder 2
• epilepsy 2
• hyperactivity or learning disorder 3
• personality disorder 2
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Raine et al (1997) Brain abnormalities in murderers
the study: controls
• 1 for each subject
• matched for age / sex
• schizophrenics with non-murderer
schizophrenics
• all controls screened for mental/physical
health
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
the study: the PET process
• injection with glucose tracer
• 32 mins on target recognition task
• NRGI/controls compared re 14 L&R brain areas
• 6 cortical:
• inc prefrontal; parietal; temporal; occipital
• 8 sub cortical:
• inc corpus callosum; amygdala; hippocampus
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
Mark Souter psychlotron.org.uk
the study: ANOVA
• statistical comparison
• ANalysis Of VAriance
• compares a range of factors
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
results: cortical areas
• differences in activity in lobes of cerebral
cortex cf controls;
• parietal & pre-fontal: less activity =?
• occipital: more activity =?
• temporal: same =?
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
results: sub cortical areas
• less activity in corpus callosum cf
controls
• a sub-cortical area =?
• cf Sperry
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
results: sub cortical areas
• imbalance between hemispheres cf controls in;
• amygdala; hippocampus – less activity L /
more R
• thalamus - more activity R / same L
• handedness made no difference
• ethnicity made no difference
• head injury patients’ corpus callosum only
difference
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: authors (1)
• supports previous findings;
1. amygdala (part of limbic system)
differences (linked to emotions; lack of
fear)
2. corpus callosum differences linked to
lack of long term perspective?
• cautious about implications
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: authors (2)
• results;
• do not show violence is only biological in origin
• do not show NGRIs not responsible for their
own actions
• do no say anything about causes of differences
• cannot be generalised from NGRIs to other
violent offenders
• cannot be generalised to other types of crime
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: other issues
• imaging methods still being developed
• pre-scan task no bearing on violent
behaviour
• NGRIs not necessarily charged with
violent act
• cause  effect of brain differences unclear
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: practical applications
• diagnosis of criminality?
• no clear evidence to support this
• treatment of criminality
• no clear evidence to support this
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers
discussion: summary
• data unclear
• differences small
• cause-effect unknown
• meaning of differences unknown
Mark Souter psychlotron.org.uk
Raine et al (1997) Brain abnormalities in murderers