Carrying my father's service
04:31 - Source: CNN

Story highlights

A new study adds evidence to a possible genetic risk for developing PTSD

The risk arises after a psychologically traumatic experience

No individual genes have been identified, but researchers hope to find out more

CNN  — 

Christal Presley considers herself a survivor of the Vietnam War, even though the war ended years before she was born.

Her father was a Vietnam veteran with post-traumatic stress disorder, or PTSD. At times, he carried his rifle through the house, threatening to shoot himself in the head.

During and after the war, he used alcohol to numb the pain; as Presley grew up, so did she.

“I’ve always felt like I inherited this sadness that wasn’t my own,” said Presley, 38, now a teacher in Atlanta.

Presley was diagnosed with PTSD in 2010, and the idea that trauma can be passed down generations has long hit close to home.

A study published today in Molecular Psychiatry sheds new light on why some people might develop PTSD and others don’t. For some, the key might lie in their DNA.

Christal Presley was born after the Vietnam War but has been affected by it through her father, a veteran with PTSD

Trauma is exceedingly common, but “some people seem to be very resilient to it, and some people seem to struggle with it,” said Karestan Koenen, professor of psychiatric epidemiology at the Harvard T.H. Chan School of Public Health, who led the study.

For those who develop PTSD, the fear and stress of trauma doesn’t go away.

When the stress becomes chronic, people may re-experience traumatic events in the form of nightmares and flashbacks, according to the National Institute of Mental Health. Presley said that she had nightmares of war, even though she never saw it firsthand.

“It’s going to take a village to find genes for PTSD risk if in fact they exist,” said Rachel Yehuda, professor of psychiatry and neuroscience at the Mount Sinai Icahn School of Medicine. “The risk for PTSD is more nuanced than the genes you inherit from your parents.”

Yehuda, another of the study’s authors, was an early researcher of trauma and heritability. Her research on Holocaust survivors found that “epigenetic” changes – not the genes themselves, but how they are turned on and off by other molecules – could be passed down to survivors’ children and change their stress hormones.

“But I have not put all my eggs in the genetic basket,” she said.

What’s in the basket?

Past studies on twins with PTSD suggested that DNA played a major role in the disorder, but those studies didn’t look at the genes themselves, Koenen said. That’s where this study comes in.