Study suggests gene may influence anti-social behavior of abused children

Thursday, August 1st 2002, 12:00 am
By: News On 6

WASHINGTON (AP) _ Abused children who become violent criminals as adults may be influenced by a gene that fails to make enough of an essential brain chemical, a study says.

Based on a 26-year analysis of the lives of 442 males in New Zealand, the study found those men who had a combination of abuse and a less active brain chemical gene were about nine times more likely to commit criminal or anti-social acts as adults than others in the group.

Experts say the finding, appearing this week in the journal Science, could lead to new ways of helping abused children become responsible, nonabusing adults.

The men in the study group were tested for the activity of a gene, called monoamine oxidase A, or MAOA. It produces an enzyme that regulates chemicals in the brain which transmit signals between neurons. Among those studied, 279 were found to have normally active MAOA genes, while 163 showed a low level of action from the gene.

The study found that 64 percent of the men were not abused in childhood, while the balance experienced either ``severe'' or ``probable'' maltreatment _ defined as rejection by the mother, frequent changes in primary caregivers and physical or sexual abuse.

At the conclusion of the research, the researchers found that the abused children with low MAOA gene activity _ 12 percent of the study group _ accounted for 44 percent of the violent crime convictions among all of those in the group, said Terrie E. Moffitt, a psychologist at the University of Wisconsin, Madison, and a co-author of the study.

``As adults, 85 percent of the severely maltreated children who also had the gene for low MAOA activity developed anti-social outcomes, such as violent criminal behavior,'' Moffitt said in a statement. The abused children with normal MAOA genes were no more likely to be anti-social than those who were not abused, the study found.

The findings provide evidence that genetic characteristics ``can moderate children's sensitivity to environmental insults'' such as abuse, Moffitt said in an e-mail. ``These findings may partly explain why not all victims of maltreatment grow up to victimize others.''

She said the findings also suggest a new tool for evaluating the risk that a person may become a problem for society.

``The combination of the low-activity MAOA genotype and maltreatment predicts anti-social behaviors about as well as high cholesterol predicts heart disease,'' Moffitt said.

Dr. John M. Leventhal, professor of pediatrics at Yale University School of Medicine and medical director of the child abuse program at the Yale-New Haven Children's Hospital, said the study was interesting and important because it suggests a biological factor may play a role in causing some abused children to become abusive adults.

``If this paper is confirmed by other studies and we have a better understanding about what the biology means, then this may play a role in clinical evaluations in the future,'' he said.

``We know that not all abused children grow up to be violent. This study supports that observation,'' said Sid Johnson, president of Prevent Child Abuse American, a Chicago-based group that conducts child abuse research and has chapters in 39 states. ``This finding could to lead to a very effective prevention approach.''