Trauma Can be Passed Down in Our Genes
Below is a post I wrote for TEDxAmsterdam. Reproduced in full:
Post-traumatic stress disorder (PTSD) is something we are now accustomed to attributing to the effects of war. We used to call it "shell shock." Today we know that trauma is not only experienced individually, but shared through generations as well. Researchers have known for awhile that trauma experienced by mothers during pregnancy can affect children and even alter the way DNA is expressed without changing its sequencing. A recent study shows that it can also alter microRNA in the sperm of mice, causing anxiety and depression in offspring. The experiences of your parents and grandparents may influence the person you are today.
You can inherit memories
Scientists Michael Meaney and Moshe Szyf have proven that the experiences of female rats could change the DNA passed on to children without altering its sequencing. Now scientists in Zurich have shown that the father also contributes to passing on the effects of trauma to his offspring.
A recent study published in Nature Neuroscience conducted by neuroscientist Isabelle Mansuy and her colleagues at the University of Zurich in Switzerland showed that the offspring of mice who experienced high levels of trauma experienced high levels of stress and depression. The sperm of traumatized mice had a higher expression of microRNA (small RNA) linked to anxiety, depression, and stress. The scientists showed that the stress and depression were passed on genetically, rather than socially, by injecting sperm into mice who had not undergone trauma.
The notion that traumatic experiences influence the children of survivors is not entirely new. Writing in Nature, Virginia Hughes notes that:
People who were traumatized during the Khmer Rouge genocide in Cambodia tended to have children with depression and anxiety, for example, and children of Australian veterans of the Vietnam War have higher rates of suicide than the general population.
Post 9-11 Babies Pre-Disposed to PTSD
About a year after 9/11, researchers examined a group of women who were pregnant when they were exposed to the World Trade Center attack. In the babies of those women who developed post-traumatic stress syndrome, or PTSD, following their ordeal, researchers discovered a biological marker of susceptibility to PTSD -- an effect that was most pronounced in infants whose mothers experienced the catastrophe in their third trimester. In other words, the mothers with post-traumatic stress syndrome had passed on a vulnerability to the condition to their children while they were still in utero.
"Trauma is a great equalizer"
In a talk given at TEDxYYC, Dr. Megan McElheran discussed her experiences dealing with veterans returning to Canada from war in Afghanistan. She warned against the current flirtation with what she calls the "happiness myth," stating that it leads to increased alienation because of the notion that "...if you are not happy there is something wrong with you..."
She finds it important to understand the full range of human experience. "We are all capable of anything," she stated. She urged us all to operate with empathy:
If, on a day-to-day basis, we as individuals and as members participating in our communities are better able to operate from a position where all experience is valued, I think we will be healthier and better able to address the challenges in our lives from a place of being willing and able to have an experience whatever those challenges should entail.
Can PTSD also be contagious?
As the family members of veterans with PTSD increasingly show signs of the disorder themselves, researchers are asking if PTSD is contagious. In an article in Mother Jones, Mac McClelland writes:
"Trauma is really not something that happens to an individual," says Robert Motta, a clinical psychologist and psychology professor at Hofstra University who wrote a few of the many medical-journal articles about secondary trauma in Vietnam vets' families. "Trauma is a contagious disease; it affects everyone that has close contact with a traumatized person" in some form or another, to varying degrees and for different lengths of time. "Everyone" includes children...
Trauma is not only experienced individually, but shared in families and through generations.
