|Vol. 1, No. 4 , 1995, Page 6|
Crime Times recently reported evidence, from a study by Adrian Raine, that abnormalities in the prefrontal cortex of the brain may be linked to violent crime (See Crime Times, Vol. 1, No. 1/2, Page 1). Now a Canadian study suggests that psychopathic behavior also may be linked to deficits in this region of the brain.
Dominique LaPierre et al. compared 30 psychopaths to 30 non-psychopathic criminals, using tests that measure the functioning of two different areas of the prefrontal cortex (the orbitofrontal and frontal ventromedial areas). Their data, the researchers say, revealed that "the psychopaths were significantly impaired on all the orbitofrontal- ventromedial tasks" in comparison to the non-psychopathic criminal controls. No differences were seen when tests measured the function of other areas of the frontal cortex.
One particularly interesting discovery was that psychopathic subjects were quite impaired on a test requiring them to select the verbal label for an odor. (The test was selected because patients known to have orbitofrontal damage do poorly at this task.) "This... finding is particularly important," the researchers say, "in the sense that it cannot readily be explained socioculturally, thus presenting a new and convincing argument for brain-based etiology of this disorder."
LaPierre and colleagues note that their findings are not surprising in light of the striking similarities between psychopaths and patients with prefrontal cortex damage. "Both the psychopath and the orbitofrontal or ventromedial frontal patient show an exaggerated preoccupation with sexual matters, acting in a promiscuous and impersonal maladaptive way," they say. "Both are remarkable for their lack of social and ethical judgment. Both neglect long-term consequences of their actions, choosing immediate gratification over careful planning."
The researchers caution, however, that the deficits they discovered may not, in and of themselves, explain psychopathic behavior. They note that a number of brain regions are involved in inhibiting inappropriate behavior, and that a disruption in any part of this "behavior inhibition circuit" could cause the disinhibition, distractibility, and sensation-seeking behaviors characteristic of psychopaths.
"Ventral frontal deficits in psychopathy: neuropsychological test findings," Dominique LaPierre, Claude M. J. Braun, and Sheilagh Hodgins, Neuropsychologia, Vol. 33, No. 2, 1995. Address: Claude M. J. Braun, Psychologie (LNC) UQAM, C.P. 8888, Succ. "Centreville" Montreal, P.Q., Canada H3C 3P8.