Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: NEUROPSYCHOLOGIC APPROACH
of patients with uncontrollable violence. Other symptoms have been targeted for psychosurgical treatment, as well. Favorable outcomes are reported, but clinical improvement has been variable; moreover, the basis for assessing success is controversial (see Mirsky and Siegel, in this volume; O'Callaghan and Carroll, 1987). Several studies suggest a link between violence and temporal lobe epilepsy, although violence occurring during a seizure is extremely rare (Mirsky and Siegel, in this volume). The question remains unanswered as to whether some patients with seizure disorders are more violence prone (because of their putative heightened emotionality) than other persons. Another important question that remains unanswered to date concerns whether these limbic system structures (portions of the temporal lobe, hippocampus, amygdala, hypothalamus) are also implicated in ostensibly "normal" criminally violent offenders who are not preselected under the suspicion of neural abnormalities. Brain imaging techniques constitute one relatively new methodology for addressing such questions.
Clinical case studies of patients with damage to the prefrontal lobes provide some support for a link between this area and features of psychopathic behavior; however, the overlap between these two syndromes is only partial. Given the animal data implicating the prefrontal cortex in the inhibition of aggression, together with neuropsychologic data on frontal dysfunction in violence, it would seem important to pursue research linking this brain site with violence. Studies are needed that combine brain imaging and social, cognitive, emotional or affective measures in order to assess both direct and indirect relationships between the prefrontal cortex and violence in humans.
NEUROPSYCHOLOGIC APPROACH
A large number of studies have found that violent offenders have brain dysfunction as reflected in deficits on neuropsychologic tests (e.g., Bryant et al., 1984; see review in Mirsky and Siegel, in this volume). Although the etiological implications of these deficits are not fully understood, there is converging evidence that cognitive deficits may underlie early school failure, dropouts, alcohol and drug use, and ultimately, encounters with the legal system as violent offenders.
An important issue requiring resolution concerns whether neuropsychologic disturbances are a cause or an effect of violence. Left-hemisphere dysfunction that disrupts linguistic processing may be causal with respect to violence in that poorer verbal comprehension
