Dec. 7, 1999 (New York) -- A new study has found a possible link between abn
Dec. 7, 1999 (New York) -- A new study has found a possible link between abnormal electrical activity in the brain and violent behavior -- a topic of interest to both doctors and lawyers alike.
Electroencephalography (EEG) is a process whereby the brain's electrical activity is measured by placing electrodes on a person's head. According to a study in the fall issue of the Journal of Neuropsychiatry and Clinical Neurosciences, 13% of a group of violent criminal offenders had evidence of abnormal brain activity based on EEG readings. Those prisoners who had even more specific problems within the brain's left hemisphere committed significantly more violent offenses.
"Our findings lend some support to the concept of a connection between left hemispheric cerebral lesions and the propensity for violence. At the same time, they indicate that this association may be caused by a relatively small subgroup of subjects," write Frank Pillmann, MD, and colleagues in the department of psychiatry at Martin Luther University Halle-Wittenberg in Germany.
The investigators studied over 200 defendants seen at a university clinic for pretrial assessment and evaluation of criminal responsibility. More than 90% of the subjects were male and the average age was 30 years old (ages ranged from 15 to 77 years). Two-thirds of the group were charged with violent offenses such as murder and manslaughter, aggravated assault and battery, robbery, and sexual offenses.
Of the 151 with histories of violence, about one-third had abnormal EEGs. Twenty subjects (13%) had specific types of localized damage, 10 in the brain's right hemisphere and 10 in the left. The average number of violent offenses was slightly higher in those with EEG abnormalities than in those without abnormalities. Breaking it down even further, those who had some type of damage to their left hemisphere, in a specific region of the brain called the temporal region, had significantly higher rates of violent criminal acts than those with damage to the right hemisphere.
Can criminals with certain brain abnormalities use this kind of research as part of their criminal defense? "It's a complex area," Thomas G. Gutheil, MD, tells WebMD in an interview seeking objective commentary. "In determining criminal responsibility, the issue is criteria. You might have extremely powerful evidence that a neurological condition exists but ... the question is whether the condition impinges on a person's functioning enough so that it meets legal criteria which are usually about understanding wrongfulness and inability to control one's actions." Gutheil is with the program in psychiatry and the law at Harvard Medical School in Boston.
"In the United Kingdom, temporal lobe epilepsy is called the defense of desperate cases. No one is absolutely clear that it has, in fact, a role in criminality," says Gutheil.
Angela M. Hegarty MD, who is affiliated with NYU Medical Center and director of forensic services at the Sagamore Children's Psychiatric Center, agrees. "Just because someone has a history of seizures per se, that has minimal or no relevance to their ability at the time of the crime. Most crimes involve complex activities and behaviors. ... It would be hard to imagine a scenario where the fact that one has EEG abnormalities or seizures would actually effect [the committing of] a homicide."
"Abnormal electrical activity in the brain cannot be taken to explain alone why somebody is violent," Hegarty tells WebMD. She suggests that neurological dysfunction in general may lead to cognitive dysfunction that, in turn, may increase the likelihood that somebody would resort to violence because of frustration, inability to concentrate, or other problems.
While Hegarty believes having a history of a seizure disorder would not help an insanity defense, it might be considered as a mitigating factor. "If someone has mental retardation, seizures, and gets explosive and does something unfortunate in that context, that's clearly a very different picture than someone who calculatingly plans a homicide," says Hegarty.
Hegarty suggests that a more meaningful study would have compared focal EEG abnormalities in violent and nonviolent offenders. "The take-home message for clinicians is that neuropsychiatric studies like this one really tell us more about process than content. They tell us there is some brain dysfunction and they tell us to look further. But there are plenty of people with EEG abnormalities who are not violent and there are many people who are very violent but do not have EEG abnormalities. The EEG abnormalities per se cannot be causally linked to violence."
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