It's official: trauma can be hereditary after all. Epigenetic changes caused by severe trauma can be passed on to subsequent generations, leaving a profound mark on the way in which they cope with stress and trauma.
This conclusion comes from a new, ground-breaking, study led by Rachel Yehuda, one of the world's foremost experts on post-traumatic stress. Yehuda, director of the Mental Health Patient Care Clinic at the Peters Medical Center, and a professor of psychiatry and neuroscience at the Icahn School of Medicine at Mount Sinai Hospital, devoted decades of her life to studying the impact of the trauma of the Holocaust within the Jewish community. The latest research she and her colleagues conducted may change the way we see trauma forever.
The team conducted a genetic study of 32 Holocaust survivors who were imprisoned in concentration camps, witnessed torture and muder, or hid during the war. It was already known that their children were more prone to stress disorders, but a genetic analysis of the children of these Holocaust survivors revealed that "the gene changes in the children could only be attributed to Holocaust exposure in the parents", Yehuda said. The genetic results found in this group of people was compared to those from Jewish people whose parents lived outside of Europe during the Holocaust and who were, therefore, not Holocaust survivors. This group did not show the same epigenetic changes.
Epigenetics is a relatively new field. It explores how external and environmental factors change the way in which genes function. To express this in layman's terms, epigenetics refers to genes being switched on and off as the result of things that happen to people, and this process can be passed on through generations. It has been clear that trauma impacts a person's mental health for a very long time, but studying epigenetics makes it clear that trauma also actually changes a person's genes.
What Did The Study Find?
Yehuda and her team were specifically interested in a gene region associated with the regulation of stress hormones. Yehuda said: "If there’s a transmitted effect of trauma, it would be in a stress-related gene that shapes the way we cope with our environment." The team did find epigenetic tags in this area both in the genes of Holocaust survivors and their offpsring, but not in the control group of Jewish people who didn't live through the Holocaust, nor in their children.
Further epigenetic analysis of the people whose parents were Holocaust survivors excluded the possibility that the changes were caused by trauma they themselves had experienced. The conclusion? Yehuda pointed out: "To our knowledge, this provides the first demonstration of transmission of pre-conception stress effects resulting in epigenetic changes in both the exposed parents and their offspring in humans."
Neither Yehuda and her team nor any other resarcher currently knows exactly how these epigenetic changes are passed on from parent to child, so that's something we can expect to learn more about in the future as this area continues to be subject to scientific study. Meanwhile, it has now become clear that "second-generation" trauma is due to much more than nurture alone.