Recovery Michigan

To find out, Mehta’s team studied blood cells from 169 people in Atlanta who were participating in the Grady Trauma Project.  Most were in their late 30s to mid 40s and were African American; some had been abused as children but all had suffered at least two other significant traumatic events, such as being held at gun- or knife point, having a major car accident or being raped. On average, the participants experienced seven major traumas. Despite these events, however, the majority were resilient: 108 participants never developed PTSD.

Among the 61 that did, 32 had been abused as children and 29 had not.  The authors examined their blood cells, looking for genetic changes that distinguished people with the disorder who had been abused from those who had not. To focus on changes associated with PTSD diagnosis rather than trauma exposure alone, they looked for differences not seen in the resilient group.

These genetic alterations are known as epigenetic changes: chemical differences that don’t mutate the DNA itself but affect how actively and efficiently the genes are made into proteins. By either silencing or activating genes, epigenetic changes can influence everything from brain development and functioning to the risk for certain diseases. While not necessarily permanent, some of these changes can last a lifetime and some can even be passed on to the next generation.

“In PTSD with a history of child abuse, we found a 12-fold higher [level] of epigenetic changes,” says Mehta.  In contrast, people who experienced trauma later in life showed genetic effects that tended to be short-lived, and did not permanently alter the function of the genes.