Halting the Legacy of PTSD

Harvard Chan researchers are looking at the emotional, physical, and genetic consequences of post-traumatic stress disorder, which affects 7 percent of the U.S. population—most of them women.

In 1980—with a tide of Vietnam War veterans suffering flashbacks, nightmares, and depression—post-traumatic stress disorder, or PTSD, became an official psychiatric diagnosis.

What researchers didn’t appreciate at the time was that the biggest group of PTSD sufferers is actually women, whose trauma symptoms are often precipitated by rape and abuse. In fact, physical and sexual violence explains the majority of PTSD in the U.S. population—more so than war, natural disasters, or the sudden death of a loved one. Among women who are raped, about half will develop PTSD. Over the course of a lifetime, 10 percent of women are diagnosed with PTSD, compared with 4 percent of men.


PTSD is a hidden epidemic, afflicting more than 7 percent of the U.S. population and some 8 million adults every year. Its victims typically become emotionally numb, lose interest in the things they used to enjoy, and may easily become frightened. While combat is a strong risk factor—an estimated 30 percent of Vietnam War veterans and 11 to 20 percent of soldiers from the wars in Iraq and Afghanistan have suffered PTSD—the majority of cases spring from threats that are, tragically, closer to home.

As a 2015 survey from the Association of American Universities revealed, for example, 26.1 percent of female seniors had experienced sexual contact involving penetration or sexual touching as a result of physical force or incapacitation—yet only a small fraction of these women (from 5 to 28 percent, depending on the type of assault) reported the attacks. These figures suggest that a large population of sufferers, silenced by shame and social stigma, may never receive help—even though timely, evidence-based treatment has proven effective in more than half of cases.

Why do some trauma sufferers develop PTSD while others do not?

Two Harvard T.H. Chan School of Public Health researchers—Karestan Chase Koenen, professor of psychiatric epidemiology in the Department of Epidemiology, and Andrea Roberts, research associate in the School’s Department of Social and Behavioral Sciences—have done groundbreaking studies on PTSD and the surprisingly prolonged effects of trauma generally. Koenen has linked trauma to a wide range of physical ailments and has explored the genetic underpinnings of PTSD. Roberts has demonstrated how the damage from trauma reverberates down the generations and has proposed biological mechanisms that could explain these striking cross-generational effects.

Both researchers hope that by understanding the roots of PTSD and erasing the onus that accompanies the diagnosis, they can help victims find relief sooner. For Koenen—herself a survivor of rape—the scientific challenge is also a personal quest.


In 1991, as a new college graduate who had planned to go into economic development, Koenen joined the Peace Corps in a village in Niger, West Africa. She was working on economic projects with women, helping them sell salt, develop community gardens, and build a clinic to weigh babies.

One morning, while she was traveling with friends in the north, her companions left her alone with a local man they had recently met. The man grabbed her, held her down, fought off her attempts at escape, and raped her.

“I thought my life was over,” Koenen says. “I had what would be considered full-blown PTSD—probably more from how I was treated by the Peace Corps than from the rape itself. And in the process of recovering from that, I got interested in trauma and PTSD research.”

Early in her clinical training at the VA Boston Healthcare System, Koenen observed that combat veterans suffered not only from the emotional fallout of trauma, but also, like her, from cascading physical complaints that seemed to have no obvious medical cause. “I began to wonder: If their PTSD had been treated earlier, would that have prevented these other problems?” She soon shifted her focus to research.

For 20 years, none of her colleagues knew of Koenen’s rape or PTSD. Then in 2011, she was bathing her young son when a friend called to tell her to turn on the TV. On the newsmagazine 20/20, recent Peace Corps volunteers were talking about their own sexual assaults and what they considered an indifferent response from the organization. Koenen was shocked at how similar their experiences were to hers from 20 years earlier and felt an immediate urge to join their effort.

Andrea Roberts, research associate in the Department of Social and Behavioral Sciences (left) and Karestan Chase Koenen, professor of psychiatric epidemiology in the Department of Epidemiology.
Andrea Roberts, research associate in the Department of Social and Behavioral Sciences (left) and Karestan Chase Koenen, professor of psychiatric epidemiology in the Department of Epidemiology. Kent Dayton/Harvard Chan

She went on to become a strong public advocate for other Peace Corps rape survivors. She joined a class action lawsuit, spoke on national television, and in May 2011 spoke before the House Foreign Affairs Committee at a hearing about violence and victim-blaming in the Peace Corps. “As an expert in the field of psychological trauma, I know how dangerous an inadequate response to the rape victim can be,” she told the committee. “Fear of being disbelieved or blamed, as I was by the Peace Corps, is exactly why so many survivors do not report their rapes.”

Today, Koenen says her symptoms are mostly resolved, which she attributes to her robust social and family support, a high level of education, and access to psychotherapy, yoga, and acupuncture. But the larger issue continues to trouble her. “Sexualized violence is perpetuated by the shame of its victims, who are instructed by society to suffer privately,” she wrote for Gloria Steinem’s Women Under Siege website. “The only cure for sexualized violence is to make the personal political.”


In 2007, Koenen and Roberts started working with data from the Nurses’ Health Study, the pioneering longitudinal research established in 1976 by Frank Speizer, now professor of environmental science at Harvard Chan. The study had begun with some 121,000 middle-aged nurses who filled out detailed health questionnaires on their lifestyles, health habits, nutrition, and disease history. Koenen realized that by adding questions on the nurses’ PTSD and experiences of trauma, including rape, the data set could be an epidemiological gold mine for trauma studies. Study administrators agreed.

One early analysis showed that after a rape, almost every woman had traumatic symptoms, including nightmares, depression, and sleeplessness—but that more than half recovered. The data further revealed that victims of trauma early in life, from sexual abuse to neighborhood violence, are more likely to suffer from PTSD after a later trauma. It’s as though they’ve been primed to be retraumatized, Koenen says.


Koenen and Roberts also looked for connections between trauma and physical diseases. Comparing rates of type 2 diabetes, cardiovascular disease, and obesity in women with and without PTSD, Koenen and Roberts found that the women with PTSD were twice as likely to suffer diabetes as the general population. The PTSD sufferers also had a 50 percent higher likelihood of stroke or heart attack and a 36 percent greater likelihood of becoming overweight or obese than those without PTSD.

One analysis showed that after a rape, almost every woman had traumatic symptoms—but more than half recovered.

Koenen’s current research in the cohort involves examining biomarkers that indicate risk for cardiovascular disease. Participants donated blood samples a decade apart, and in the interim between the two donations some women developed PTSD. The research project will compare biomarkers in women before and after they developed PTSD.


One of Koenen’s driving scientific questions is: Why do some people develop PTSD after trauma while others do not? To this end, she has helped launch the nascent study of the genetics of PTSD, trying to identify the genes most likely to make an individual susceptible to the disorder. Today, Koenen coleads the PTSD working group of the Psychiatric Genomics Consortium, which has been amassing genetic data from numerous cohorts around the world in hopes of finding genes implicated in PTSD. To date, they have compiled genomewide association data on approximately 5,000 people who developed PTSD after trauma, and 15,000 controls who experienced trauma but have not developed PTSD.

The scientists are not sequencing entire genomes, but rather looking at what are called “SNP chips,” examining common genetic variation. Koenen is also delving into the epigenetics of trauma: how the expression of trauma-linked genes (rather than differences in the DNA itself) can change as a result of environmental stressors.

The research is slow going. Unlike single-gene disorders, such as Huntington’s disease, PTSD resembles complex inherited disorders such as schizophrenia or diabetes, where many genes each exert a small effect. Ideally, and much farther down the line, Koenen hopes that widespread genetic profiling could someday help those who treat trauma survivors—from frontline medics to psychologists—respond more efficiently.

Her colleagues say that Koenen’s work was critical in forging a comprehensive, evidence-based method of PTSD diagnosis and prevention. “In the late 1990s, our understanding of PTSD centered around the trauma itself and how that was the key driver of PTSD,” notes Sandro Galea, dean of Boston University School of Public Health. “Dr. Koenen has been at the forefront of helping us realize that PTSD is a complex phenotype that is as much determined by genetic predisposition and by circumstances encountered through the life course as by the trauma itself. This was a revolution in how we think of PTSD.”


While Koenen is focused on the causes and variable history of PTSD, Roberts has demonstrated that the devastating aftermath of trauma does not stop at the individual. “It’s kind of biblical: ‘unto the third and fourth generation’ and all that. It persists across many generations, not just two,” she says.

Using the Nurses’ Health Study, as well as a followup study of participants’ children called the Growing Up Today Study, Roberts aims to determine how women’s early trauma may have shadowed not just them but also their offspring. The volunteers answer such questions as whether they have been punished with a belt, been hit so hard it left bruises, experienced unwanted sexual touching or worse, how they were screamed at as a child, and whether family members said hurtful things. Roberts discovered that just as abuse survivors have higher rates of obesity, smoking, and substance abuse, so do their kids. What surprised her was how much the severity of abuse matters. She describes this as a classic dose-response relationship: the more abuse, the worse the health outcome, starting at a fairly low dose.

Ben Birchall/PA Wire URN:22629105


Roberts and her colleagues also found much higher rates of depression among the children of abuse victims— between 1.5 and 2.5 times higher than children of nonabused mothers. She surmises that the problem could be behavioral: A mother who experienced abuse in childhood is more likely to be depressed in adulthood, and as a result may be less attuned to her children—a neglect that can sow depression.

Roberts adds that the children of abuse victims are also themselves more likely to be abused. One reason is that in adulthood, abuse victims may struggle more with protecting their children, who in turn are more vulnerable to sexual predators. Women who grew up abused are also more likely to have partners who abuse both them and their children. And some abused women abuse their own children, since that’s the parenting model they were taught.

At the extreme end of the abuse spectrum, the women who lived through the worst physical and emotional abuse in childhood were 60 percent more likely to have children with autism than women not exposed to abuse. Teaming up with Marc Weisskopf, SD ’06, associate professor of environmental and occupational epidemiology, Roberts discovered that women who have experienced abuse by their intimate partner in the past two years are twice as likely to have a child with autism as women who did not experience it.

If mothers suffer trauma and PTSD, are their children and grandchildren more at risk for psychiatric disorders?

Roberts wondered if the higher rates of autism could be due to smoking, substance abuse, or poor prenatal care—all of which are higher among child abuse victims. But after controlling for those behaviors, Roberts explains, “they accounted for very little of the connection.” In ongoing research, she is trying to pinpoint the biological mechanism by which abuse passes through the generations, conferring a higher risk for psychiatric disorders.


Koenen and Roberts hope that the unmistakable links their data have uncovered—between mental health and physical health, trauma and chronic disease, a mother’s childhood abuse and her children’s well-being—will translate into policies that can prevent PTSD.

Treatments that have proven most effective for PTSD include trauma-focused cognitive-behavioral therapies and medications such as the class of antidepressants known as selective serotonin reuptake inhibitors, or SSRIs. A 2013 study from Israel—the Jerusalem Trauma Outreach and Prevention Study—offers strong evidence that timely interventions work. Researchers focused on adult survivors of traumatic events who had been admitted to a hospital emergency department and were diagnosed with acute PTSD. Among the patients who received prompt, trauma-focused cognitive-behavioral therapy, 56 percent saw a sharp drop in symptoms over the five months following the trauma.

Translating such findings into clinical care would require overcoming institutional biases that echo cultural biases. “Research into mental health is still stigmatized— it’s just not as sexy as cardiovascular disease or diabetes,” says Roberts. “The stigma has improved a bit, but scientists are balkanized, and people who don’t study violence or mental health are often unaware of the wealth of data connecting trauma with physical health.”

In the near term, Roberts would like to see primarycare doctors ask patients about their trauma history and then screen trauma-exposed women for heart disease, signs of stroke, diabetes, and weight-related disorders early to prevent problems down the road. “Obesity can be trauma-related,” she says, “but just telling people to change their diets without treating the underlying mental health issues is not going to solve the problem.”

Koenen argues for more attention on mental health issues globally. One of her projects, the World Mental Health Survey Initiative, has recruited 150,000 participants in 28 countries to answer questions on their trauma history, health, and mental well-being—building a database that will accurately estimate the prevalence of mental illness and whether people are getting help.

Closer to home, Koenen has also spoken out against sexism and sexual harassment in the Ivy League research culture, against the shortage of studies on gender-based violence, and against what she sees as cultural indifference that downplays women’s reports of sexual violence. While PTSD is a complex disorder, Koenen and Roberts believe their research demonstrates it can be prevented, even after unimaginable trauma.

“You don’t throw up your hands and give up on people who can be helped,” says Koenen. “It’s a tractable problem. It’s an accomplishable goal.”

“It’s easy to say people should fix themselves,” adds Roberts. “But when you look at these data, you realize that some people go through life as if they are carrying another person on their back.”

Karen Brown is a freelance writer and public radio reporter based in Western Massachusetts who specializes in health and mental health issues. She is a 2016 Ochberg Fellow, a program of the Dart Center for Journalism and Trauma.

Cover illustration by Boris Semeniako.