Abuse in early childhood dramatically changes the brain chemistry of women for life, making them more vulnerable to anxiety disorders and more easily frustrated by stress as adults, a study suggests.

Researchers said the results could lead to profound advances in treatment for depression for women and men. The study was published Wednesday in the Journal of the American Medical Association.

Dramatic differences in women based on whether they had been physically or sexually abused as children came to light when they were asked to speak in front of a poker-faced audience and to solve tricky math problems.

In women who had been abused, a key hormone that regulates the body's response to stress responded six times as strongly as in women with no abuse history. The early trauma makes the hormone hypersensitive, researchers said.

"We've known for a long time that if you enrich the environment during early development, you can get critical, positive long-term effects," said Dr. Charles Nemeroff of Emory University, one of the study's authors. "This is the other side of the coin, the dark side."

Anti-depressant medication available now indirectly targets the body's hormonal response to stress. But researchers said Wednesday the new information bolstered ongoing studies on whether anti-depressants can target specific stress-reaction hormones.

They also said it could help victims of abuse prevent falling into deep depression.

"This should be beneficial is seeing whether we can reduce that sensitivity," said Dr. Jeffrey Newport, a study author.

A professor from the University of Georgia disagreed with the conclusions from the Emory report.

"It's not always so," said Allie C. Kilpatrick, a professor of social work at the University of Georgia. "There are so many intervening factors. Who was the person providing the abuse, how long did the abuse continue, how much force and trauma occurred at the time? All those factor in to how someone reacts later in life."

Kilpatrick said she did a study of her own with 500 women, including some who had sexual relations with their fathers when they were children.

"The effects were all varied," she said. "There were some women who had no traumatic effects and there were women who had a lot. It all depends on those intervening variables and the resiliency of the individual."

The Emory study examined 49 women ages 18 to 45, dividing them into four groups by whether they had been abused as children and whether they suffered depression as adults.

They were told to speak before a panel of observers who had been told not to show any reaction, and they were asked to subtract 17 from 4,000 continually.

Blood tests measured the response of cortisol and adrenocorticotropic hormone, or ACTH, two hormones closely related to another hormone called CRF that controls the body's reaction to stress.

Cortisol and ACTH are much more easily measured in blood than CRF.

Researchers said they focused on women because both abuse and adult depression are more widely reported among women than men. But they said similar tests on animals have shown almost no difference in the responses of males and females.

"I have no doubt that this will be the case for both men and women," Nemeroff said Wednesday. "It just highlights the importance of public education about child abuse."

(By Erin McClam from the Associated Press)