Feb. 14, 2000 (Boston) -- For the first time, a brain defect that could be at least partly responsible for extremely violent criminal actions and antisocial behaviors of some men has been identified, report researchers from the University of Southern California (USC).
Men with antisocial personality disorder (APD) -- a form of mental illness often seen in serial killers and other violent, aggressive, wildly impulsive, or dangerous people -- had an 11% reduction in a certain type of tissue (gray matter) in the part of the brain known as the prefrontal cortex when compared with either normal men or men with a history of drug or alcohol abuse but no APD.
Researchers have pinpointed the prefrontal cortex as the part of the brain where emotion, arousal, attention, moral conscience, and self-control primarily reside.
The link between extremely violent and antisocial behavior and damage to prefrontal cortex from disease or trauma has been long established. One of the most famous cases was that of a Vermont railroad worker named Phineas Gage, who in 1848 survived and, remarkably, recovered rapidly from a horrific accident in which a heavy iron tamping rod more than three feet in length was driven by an explosion completely through his skull. Following the accident, however, he underwent a dramatic personality change, and began to display many of the traits of APD, including antisocial behavior, use of sexually explicit language, apparent lack of moral conscience, impulsiveness, irritability, aggressiveness, and an inability to focus on work or plan for the future.
Although children are not typically diagnosed with personality disorders until they reach adulthood, according to the American Psychiatric Association, children that exhibit signs similar to APD typically violate rules and show signs of extreme aggression, such as the torture of animals or other people, frequent bullying or threatening, use of weapons that could cause serious injury, lying, sexual aggression, vandalism, and theft. Adults with APD frequently commit criminal acts, get into fights, cheat, show a general disregard for the safety of themselves or others, and show a lack of remorse for their own behavior.
But the findings from the USC study raise legal and ethical questions about whether some violent offenders are completely responsible for their actions, and whether they can or should be treated with specific interventions that could curb impulsive behaviors and dampen their aggressive tendencies so that they no longer present a threat to society at large.
"I don't think anyone would argue that you can treat extreme antisocial behavior by locking people away, but then how would we treat them, and is it possible to prevent such behaviors from occurring in the first place?" asks M. Marsel Mesulam, MD, in an interview with WebMD seeking objective analysis. Mesulam is professor of psychiatry and behavioral sciences at Northwestern University Medical School in Chicago.
"The exciting part would be if this could be a marker to identify children who are at increased risk for this troublesome adult outcome, and if it would have sufficient accuracy to pick up children who are at risk for this condition, because that's a prerequisite for any targeted intervention program," agrees David R. Offord, MD, director of the Centre for Studies of Children at Risk at McMaster University in Hamilton, Ontario.
If the causes of the underlying problem can be identified, it could allow doctors to design therapies such as drugs or surgery to treat the specific brain defect, combined with other strategies such as psychiatric treatment and behavioral therapy. Such therapies would be likely to be more effective in children, whose brains are more adaptable to change than those of adults, says researcher Adrian Raine, DPhil, professor of psychology at the USC, in an interview with WebMD.
"We have to try to discover what the causes of the prefrontal damage are, and that's what we can't answer at the moment," Raine says. "The deficit could occur from environmental factors, such as birth complications, which could traumatize the brain. We did research a few years ago showing that birth complications predispose to violent offending in adulthood. Perhaps if we gave under-served mothers better prenatal and postnatal health care, we might be in a better position to do something about reducing one of the sources of prefrontal damage."
"Another source of the damage could be very early infant abuse. If you repeatedly shake an infant, you'll lacerate the white nerve fibers connecting the frontal cortex, effectively shutting it off from the rest of the brain and perhaps leading to some neuronal [nerve cell] degeneration. So the question may be, what do we do to prevent early infant abuse?" he says.
Raine tells WebMD that although there is little hope now of curing adults with APD, "we know that in the next 10 years we'll have the first microchip implant to replace the hippocampus [the area of the brain thought to be involved in emotion and memory], and scientists are working on using microchip implants to replace other damaged brain structures. It's not inconceivable, therefore, that within the next 15 to 20 years we might be able to do something about the tissue loss that occurs in these individuals."
- Antisocial personality disorder (APD) is a form of mental illness often seen in serial killers and other violent, aggressive, wildly impulsive, or dangerous people.
- Researchers have found that men with APD have an 11% reduction in a type of tissue in the prefrontal cortex -- the area of the brain associated with emotion, arousal, attention, moral conscience, and self-control.
- Some suggestions as to what actually causes the damage to this area of the brain include environmental factors, such as complications during birth, or early infant abuse.