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Psychopaths: new evidence of brain abnormalities
New studies add to evidence linking psychopathic behavior
to abnormalities in brain structure and function. Among the
recent findings:
- Edelyn Verona and colleagues found that male offenders
with high scores on affective-interpersonal psychopathic traits
(e.g., superficial charm, manipulativeness, and absence of
remorse or empathy) showed reduced skin conductance
response to both pleasant sounds, such as a baby laughing,
and unpleasant sounds, such as screaming. Their skin
conductance responses also revealed a failure to differentiate
between pleasant and unpleasant sounds. This, the
researchers say, adds to "a growing body of evidence
indicating that high psychopathy individuals do not discriminate
normally between non-emotional and emotional cues, whether
pleasurable or aversive, in basic physiological response
systems."
- Adrian Raine et al. report that psychopaths who are caught
and convicted show an exaggerated asymmetry of the
hippocampus (with the right side larger than the left), compared
to either successful psychopaths or normal controls. This
finding remained significant, they say, when they controlled for
schizophrenic symptoms, head injury, substance use, early
exposure to abuse or other trauma, and additional
demographic and behavioral factors. Their data lend support,
the researchers say, "to a neurodevelopmental model of
unsuccessful psychopathy."
The hippocampus plays a key role in regulating aggression,
as well as in "contextual fear conditioning"- the learned
knowledge of which situations cause fear and should thus be
avoided in the future. Raine et al. speculate that in
unsuccessful psychopaths, disruption of the circuitry between
the hippocampus and the prefrontal cortex may result in
impaired contextual fear conditioning, and in "impulsive,
disinhibited, unregulated and reward-driven antisocial behavior
that is more prone to legal detection."
Earlier studies by Raine et al.
(see Crime Times, 1995, Vol. 1, No. 1, Page 1,
Crime Times, 1997, Vol. 3, No. 4, Page 7,
Crime Times, 2000, Vol. 6, No. 2, Page 1,
and Crime Times, 2004, Vol. 10, No. 1, Page 6)
have revealed a
range of additional brain anomalies in psychopaths.
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"Psychopathy and physiological response to emotionally
evocative sounds," Edelyn Verona et al., Journal of
Abnormal Psychology, Vol. 113, No. 1, 2004, 99-108.
Address: Edelyn Verona, Department of Psychology, Kent
State University, Kent, OH 44242.
-- and --
"Hippocampal structural asymmetry in unsuccessful
psychopaths," Adrian Raine et al., Biological Psychiatry,
Vol. 55, 2004, 185-191. Address: Adrian Raine, Dept. of
Psychology, University of Southern California, Seeley G. Mudd
Building 501, Los Angeles, CA 90089-1061.
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