Saturday, August 03, 2002
Study Links a Gene To Impact of Child Abuse washingtonpost.com - August 02, 2002 Scientists have discovered a gene that appears to help explain why some boys who are abused or mistreated are more likely than others to grow up to be aggressive, antisocial or violent.
The finding, which for the first time links a gene and an upbringing to a specific behavior, could help shed light on why some children who suffer trauma never seem to recover, while others are resilient. By showing that a particular environment can have devastating consequences for children with certain genes, the new research might one day identify children at greatest risk and help direct services to them.
While the implications for social policy could be profound, researchers warned against assuming that genes alone determine behavior, and said that any effort to peg certain children as potentially violent was simplistic and unethical.
Indeed, in the interplay between this particular gene and the environment, researchers found the environment played a dominant role. Absent abuse, the gene, which is involved in regulating brain chemicals, did not help predict whether a boy would grow up to be violent or aggressive. And some boys without the genetic variation became aggressive if they grew up in an abusive setting.
"On the one hand, the study is a wonderful example of this new frontier of science that provides us with what influences differential outcomes" in people, said Jack Shonkoff, a child development and social policy expert at Brandeis University who helped write an influential 2000 report by the National Research Council and the Institute of Medicine called "From Neurons to Neighborhoods."
"There is also this huge warning sign on the horizon that says: 'Be careful about premature conclusions; be careful about the misuse of science; be careful about oversimplistic conclusions that translate into reckless social policy; be careful about premature labeling and self-fulfilling prophecies,'" he said.
Rather than viewing the gene as a risk factor for violence, the researchers suggested the gene may be designed to play a protective role. One variant of the gene may remove that layer of protection. Only one third of the population has this "high-risk" version. Researchers said this might explain why most adults who suffer accidents and violence emerge emotionally unscathed.
"The unique thing that we found is a gene that seems to protect abused children, and it ought to, in theory, protect other people who experience protracted trauma," said Terrie Moffitt, a psychologist at King's College London and the University of Wisconsin in Madison. "People who experience war, for example -- we know there is huge individual variation in how people to respond to trauma. Some people who came out of the concentration camps were ill, but most were not. What is it that protects?"
Moffitt and a team of researchers in England, New Zealand and the United States concluded that people fortunate to have the "protective" version of the gene may come through terrible experiences intact. Simultaneously, 85 percent of children who suffered mistreatment and had the other version of the gene later became violent offenders. Although these children made up only 12 percent of the population, they later accounted for 44 percent of violent crime.
The environments that increased risk for boys included situations of outright abuse and violence, but also neglect and mistreatment.
Moffitt said she expected that other genes with links to violence will be discovered. Ultimately, experts believe human behavior is a complex interplay between several genes, the environment and an individual's own choices.
The study, published in today's issue of the journal Science, was based on 442 boys in New Zealand who were tracked from birth to age 26. The scientists correlated statistics about abuse and mistreatment among the children with variations of a gene that coded for an enzyme called monoamine oxidase A, or MAOA. The enzyme helps regulate the level of chemicals called neurotransmitters, which carry signals in the brain.
Moffitt said that variations in the gene had previously been linked to aggression in mice, and a small 1993 study had showed a rare mutation in the gene across three generations of one family in the Netherlands, was linked to violence and mental retardation.
Variations in the MAOA gene may give some people certain advantages, even as it causes them risks in the presence of trauma or abuse. This could be similar to African populations, for instance, who have a genetic variation that increases the risk of anemia but protects against malaria.
What people cannot control about their genes they might be able to alter in their environment. Ira Schwartz, provost at Temple University in Philadelphia and an expert on child welfare issues, said child abuse is often associated with young, single parents who are under severe stress as a result of poverty or a loss of employment. Services for mothers expecting babies, good prenatal care and followup home visits after the birth of the baby are all important in reducing the risk of child abuse, he continued.
Schwartz urged that discussions about ethics keep up with advances in science. "The ethical and moral issues ought to be addressed early on so it keeps pace with the science instead of having the research going so far down the road that a politician says, 'I want to pass a law saying that parents of every child with a genetic risk of antisocial behavior must learn to be good parents, and if they don't comply, there will be repercussions.' That's not too far out."
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