Young girls who are the victims of sexual abuse experience physical, biological and behavioral problems that can persist for decades after, a new study shows.

Researchers, who tracked a group of girls ranging in age from 6 to 16 at the start of the study in 1987 for the next 23 years, found that they had higher rates of depression and obesity, as well as problems with regulation of brain chemicals, among other issues, compared to a control group of girls who were not abused.

The study, published in the Cambridge University Press journal Development and Psychopathology, was conducted by researchers from the University of Southern California and the Cincinnati Children’s Hospital Medical Center. Those in the study were assessed by researchers six times at varying ages and developmental stages. Researchers hope to continue the study looking at the women, who are now in their 30s, as well as their children.

The racially-diverse group of 80 girls, who lived in the Washington, D.C., area, were victims of incest, broadly defined as suffering sexual abuse by a male living within the home. On average, the girls were abused for about two years prior to the abuse coming to the attention of child protective services. Some girls were abused when they were as young as age 2.

Compared to a non-abused control group, the researchers found the study participants, all of whom were provided three therapy sessions on average in group and individual settings, suffered severe effects during different stages of their lives, which affected their sexual and cognitive development, mental and physical health, as well as their brain chemical profile. Study participants were more likely to be sexually active at younger ages, have lower educational status, and have more mental health problems.

As children, they had higher levels of cortisol, the so-called "stress hormone," which is released in high levels during the body’s "fight or flight" response. But by about age 15, testing showed that cortisol levels were below normal, compared to the control group. Lower levels of cortisol have been linked to a decrease in the body’s ability to deal with stress, as well as problems with depression and obesity. Lower levels of the hormone have also been linked to post-traumatic stress disorder.

“The cortisol levels (of some study participants) wound up looking like Vietnam vets,” says study co-author Dr. Frank Putnam, professor of pediatrics and psychiatry at Cincinnati Children's Hospital Medical Center. “That tells us they are in a chronic state of stress, and never feel safe.”

During the last assessment, when study participants were in their 20s, their cortisol levels remained lower than the control group, on average. “That tells us their stress response system is burned out,” says Putnam, which could explain why some are doing so poorly in life.”

The long-term effects of the abuse “were absolutely profound,” says lead author and child psychologist Penelope Trickett, USC professor of Social Work. “It’s just not mental health issues. Some of these women are suffering from a lot of problems today like sleep issues, poor health utilization, and have a lot of risky behaviors. It’s very disturbing.”

Trickett says some women who have been sexually abused themselves have told her the findings validated their realities. “A woman came up to me once at a talk and identified herself as a childhood victim of sexual abuse and thanked me for these findings and for trying to shed light on this issue.”

She also noted that not all of the 80 women in the study are extremely disabled from their experience. In the abused group, some 40 percent are obese as adults, compared to 20 percent in the control group. “But that still means that almost 60 percent of the abused group are not obese,” says Trickett. “The groups are statistically different, and that’s important. But both groups have variability. The abused group just has more variability within the group.”

Trickett also says the findings don’t mean that once someone is abused they are destined to a lifetime of struggle.

“These women are more likely to have problems in mental health and physical health than those who haven’t been abused,” she said. “But it really varies to what degree they are disabled by these challenges. Some are managing their lives pretty well, considering what they went through.”

Though the study participants received some psychological counseling there was no specific treatment for childhood trauma and sexual abuse in the late 1980s. “Three or four sessions isn’t a lot of treatment; it’s some, but it’s little compared to today,” says Trickett. According to Putnam, evidence-based treatments, such as trauma-focused cognitive-behavioral therapy, came about in the 1990s.

“But the big question is does treatment prevent these things from happening or reverse what has happened,” says Putnam. “And the answer is we don’t know.”

The researchers hope that study data are used to develop more comprehensive treatment programs. “What is clear here is that abuse is not something that’s a one-time fix,” says Trickett.

Prevention and getting kids into treatment early is “the first step,” says Carolyn Landis, a clinical psychologist with Rainbow Babies & Children’s Hospital in Cleveland, Ohio. “To see how these girls suffer into adulthood is extremely troubling,” she says.

“From my perspective, this data, especially regarding cortisol levels, can help professionals identify kids who may be at risk much earlier. We need to sensitize people and then find ways to help kids be safe.”

This article is republished with permission from msnbc.com.