They are more likely to be depressed, abuse drugs and alcohol, and engage in self-mutilation. They are more likely to be obese, experience post-traumatic stress disorder and fail to complete high school. They are more likely to place their children at risk for abuse, neglect and developmental issues.

They are women who were sexually abused as children.

These dramatic findings emerged from a landmark study led by Penelope Trickett, the David Lawrence Stein/Violet Goldberg Sachs Professor of Mental Health at the USC School of Social Work. For the past 25 years, Trickett and her research team has followed a group of girls, now women, who suffered sexual abuse when they were as young as 2 years old.

She is aware of no other study of this length that has focused on the consequences of sexual abuse, and federal officials recently acknowledged the importance of this ongoing research. A successful application for additional funding from the National Institute of Child Health and Human Development received a perfect score from reviewers.

“There are certainly things you would have never been able to learn without doing a longitudinal study of this length,” Trickett said. “The fact that the reviewers gave us such a good score recognized that there was something particularly valuable about this sample.”

In 1987, Trickett and a psychiatrist named Frank Putnam recruited a racially diverse group of girls living in the Washington, D.C., area to participate in a new study. Half of the girls had been sexually abused by a family member, abuse that lasted an average of two years before child protective services became involved.

During the first few interviews, researchers didn’t ask directly about sexual abuse, instead measuring levels of depression, self-esteem and other indicators of the effects of maltreatment. As the research team began delving into various developmental and psychological issues as the girls grew older, several disturbing findings emerged.

Girls who were abused were more likely to become pregnant as teenagers, exhibited poorer verbal ability and learning aptitude, and reported becoming sexually active much sooner than their nonabused counterparts.

“We’re talking young—14 years old compared to 15 and a half for the comparison group,” Trickett said.

As years passed and more data were collected, the study became a treasure trove of biological, psychological and social information that painted a detailed picture of development during the first few decades of these women’s lives.

At many points, participants who were sexually abused had higher levels of dissociation, aggression, delinquent behaviors and problems in school. By adulthood, these issues had coalesced around increased depression and substance abuse.

When interviewed in their mid-20s, abused women in Trickett’s study were more likely to report experiencing new instances of sexual or physical assault than the women in the comparison group. They were also more likely to report self-harm and suicidal thoughts.

One unique aspect of the study, which garnered recognition from the Society for
Social Work and Research in the form of its Excellence in Research Award in 2012, was its findings regarding levels of cortisol, a hormone released during highly stressful situations.

As children, the girls who had been sexually abused had heightened levels of the hormone. But by the time they reached adolescence, their cortisol levels were below normal. Low levels of cortisol have been linked to problems such as antisocial behavior and post-traumatic stress disorder, as well as physical issues including rheumatoid arthritis, chronic fatigue syndrome and poor cardiovascular functioning.

“They self-report going to the doctor more often, being hospitalized more and experiencing a variety of health issues,” Trickett said.

She credited Putnam, whose background in psychiatry prompted the research team to draw blood from participants during the early years of the study, for recognizing the importance of tracking biological markers over time. Trickett plans to focus more on physical health as the study moves forward in the coming years with its 7th and 8th data collection points.

“In their 30s, they are getting to an age where some of these physical problems are showing up after years of development,” she said.

The sample, which included approximately 160 girls at the beginning of the study, has expanded as original participants had children of their own. At the 6th data collection point, Trickett said the group included about 130 offspring; that figure has increased to nearly 250 children.

The growing sample will enable the researchers to explore the effects of sexual abuse across three generations—the abused and nonabused girls, their mothers or nonabusing caregivers, and their children. Initial forays into intergenerational issues have revealed the lasting influence of abuse on families.

“Our abused girls who have become mothers were already more likely to have been reported to child protective services than the comparison group,” Trickett said. “In most cases, it was for neglect. We think it has a lot to do with mental health outcomes and substance abuse issues, but we’d like to follow up on that.”

Although the consequences of sexual abuse have been severe for a significant portion of participants, Trickett was careful to note that many of the abused girls have coped well with their traumatic childhood experiences.

“There is a lot of variability,” she said. “One of the things we haven’t looked at thoroughly enough is whether we can identify characteristics that result in more positive trajectories.”

Advances in statistical methods during the decades since the study began will enable the research team to explore interactions among various attributes and factors in more detail, allowing them to gain a better understanding of why some girls handled the stress and trauma of sexual abuse better than others.

Another area Trickett hopes to examine during the coming years is how the study’s findings can be translated into policy and practice. She noted that the participants who had been sexually abused received an average of only three or four counseling sessions immediately after the abuse came to the attention of child welfare officials.

That relative lack of immediate treatment was severely inadequate, Trickett said, both from a recovery standpoint and in terms of ongoing societal costs.

“If these girls end up with lower education levels, mental health problems, substance abuse problems and preterm births, then front-end investment in treatment would be very worthwhile,” she said.

Despite the length of the ongoing study, the researchers have been tremendously successful at reducing attrition among participants. At least 85 percent of the original group of girls has agreed to be interviewed at any given data point throughout the 25-year project, and the last three time points have boasted a retention rate higher than 95 percent.

The research team is now led by Trickett and Jennie Noll, a former USC doctoral student who worked with Trickett during the 1990s and served as project director on an earlier grant. Trickett said Noll, now a professor at the University of Cincinnati’s Department of Pediatrics, is a big reason why the team has been able to retain so many participants over the years.

“She has made sure that when we’ve had gaps in funding, and we have had quite a bit over these 25 years, that she keeps in touch with people,” Trickett said, describing her colleague as warm and engaging.

The project has received financial support from an array of federal and private sources, including the William T. Grant Foundation, the National Institute of Mental Health, and the Administration on Children, Youth and Families.

Although financial details are still being finalized, it appears the project will receive close to the $2.5 million over five years that Trickett and her colleagues requested from the National Institute of Child Health and Human Development.

“It’s the only one that got a perfect score, so it’s right at the top of the list,” Trickett said. She added later, “If anybody had told me when I started this study that I’d still be doing it now, I would have never believed them.”