Caution urged for brain research on violence

graphic July 28, 2000
Web posted at: 5:22 p.m. EDT (2122 GMT)

CNN Medical Corrrespondent Eileen O'Connor contributed to this report


WASHINGTON (CNN) -- Research into brain patterns linked to violent behavior is important, but should be approached with caution, mental health authorities said Friday.

"Efforts to try and identify people who are likely to be violent ... could result in labeling people," said Dr. Farris Tuma, chief of the traumatic stress program at the National Institute of Mental Health. "The research ... provides a window into the many factors that influence behavior. Early experiences are important but not necessarily fixed."

On Thursday, University of Wisconsin-Madison psychologist Richard Davidson and colleagues reported that convicted murderers and other violence-prone individuals show distinct brain patterns that are measurable in diagnostic imaging scans. Results of studies of more than 500 people who were diagnosed with aggressive personality disorder or childhood brain injuries or were convicted murderers appear in this week's issue of the journal Science.

Brain scans for the study group were compared to a normal control group.

"We are placing the question of violence right in the middle of our basic research on the neurobiology of emotion," said Davidson. "Our previous insights in this area give us tremendous leverage to understand the root causes of violence."

Abnormalities found

The studies' findings indicate a relationship between three brain regions that influence emotions and behavior -- the orbital frontal cortex, the anterior cingulate cortex and the amygdala.

The orbital frontal cortex helps to restrain impulsive outbursts of emotion, and the anterior cingulate cortex recruits responses to conflict from other regions of the brain. The tiny amygdala is a key player in the fear response and other negative emotions.

The Wisconsin researchers found that brain activity in the orbital and anterior cortex regions was greatly diminished and even absent in many of the violent people studied, while the amygdala showed normal, and sometimes increased action.

The inability of the orbital and anterior cortex regions to restrain the amygdala's activity may help to explain why some people become explosive in threatening situations, the researchers contended.

"Emotion regulation is extremely significant for a whole constellation of problems people encounter," said Davidson.

Nature vs. nurture

Davidson's research is important, said neurosurgeon Dr. Pamela Blake of Georgetown University Hospital, because it may help doctors find physical traits that could identify children at risk for violent behavior.

During the sentencing phase of convicted student-killer Kip Kinkel's trial, a psychologist testified that scans of Kinkel's brain showed abnormalities consistent with schizophrenia. Kinkel was convicted of killing his parents and two students, and wounding 25 other schoolmates, during a rampage in Oregon in 1998. He is serving a 112-year sentence.

But Blake and others warn that such an approach must be used carefully, and other factors must be considered.

While there is a "natural desire" to develop a "child violence profile," over- reliance on such scientific data risks negative labeling, NIMH said in a published report on the institute's research in child and adolescent violence.

It also risks "missing the quiet, troubled child with a series of problems who may actually become the most violent," the report said.

"It's just not that simple to say genes determine behavior," Tuma told CNN. "We have to take this kind of science and always put it in context."

In other words, human behavior is the sum of nature and nurture, with environmental factors weighing at least as heavily as genetic ones, if not more so.

"We need to be thinking in terms of prevention and intervention to reduce violence," said Tuma, adding that conditions such as attention deficit-hyperactivity disorder, depression and impulsivity need to be treated. "Efforts need to focus on multiple aspects" of violence, he said.

Concomitant factors such as parenting influences or drug and alcohol abuse also must be addressed, Tuma cautioned.

'Double whammy'

Davidson's work also seems to point to a reclassification of impulsive violence as a mental health issue, however.

Genetics and a poor environment present a "double whammy" that puts people at greater risk for trouble. "These parts of the brain are particularly responsive to" environmental influences, Davidson said.

The long-term implications of such brain research could lead to new treatments that combine behavioral modification and drug therapies, in much the same way that depression and anxiety disorders now are treated.

"Given what we know about brain plasticity and the fact that the brain really can change in response to experience, we have good reason to believe that these treatments may, in fact, have beneficial consequences," the Wisconsin psychologist added.