Epigenetic Changes After Trauma May Be Adaptive, Contribute to Resilience

In recent years, research throughout the scientific and medical community has suggested a link between trauma and epigenetic changes, chemical modifications that affect gene activity without actually changing the gene’s DNA sequence. The assumption has been that epigenetic changes in the context of trauma are inherently bad, a form of damage that gets passed from generation to generation. But according to Rachel Yehuda, Ph.D., Endowed Professor of Psychiatry and Neuroscience of Trauma at the Icahn School of Medicine at Mount Sinai, these changes may also be adaptations that promote resilience.

“Sometimes the biological changes in response to trauma or intergenerational trauma are there to help deal with the problem of trauma, not compound its effects,” Yehuda said. “The survival advantage of this form of intergenerational transmission depends in large part on the environment encountered by the offspring themselves.”

Yehuda described this phenomenon as a paradox.

“Parental or ancestral trauma may heighten vulnerability to mental health challenges, but epigenetic adaptations may simultaneously facilitate coping mechanisms,” she said. “Trauma increases susceptibility for psychological distress, but also produces adaptations that help us cope with them.”

Yehuda described research she and her colleagues have conducted to tease out how trauma in parents can affect offspring in the context of the biology of posttraumatic stress disorder (PTSD) in Holocaust survivors and their children. As the research unfolded, Yehuda and colleagues found that survivors’ adult children were more likely to have mood disorders, anxiety disorders, and PTSD than Jewish people whose parents did not directly experience the Holocaust. This was especially true of children of Holocaust survivors who had PTSD. The researchers also found that many children of Holocaust survivors had low levels of the stress hormone cortisol, particularly if their parents had PTSD.

Yehuda and colleagues then conducted a series of studies that looked at the role of glucocorticoid receptors — the proteins to which cortisol must bind to exert its effects — and found evidence that these receptors were more sensitive in people with PTSD.

“In practical terms this means that even though someone with PTSD might have lower circulating levels of cortisol in their blood, their cells might react more strongly to the cortisol that is present,” Yehuda said.

Yehuda said that epigenetics provided further insight on the relationship between hypersensitive glucocorticoid receptors, cortisol, and PTSD. She explained the potential role of methylation, which is a chemical reaction in the body in which a small molecule called a methyl group gets added to DNA or DNA-associated proteins.

“Increased methylation generally impedes RNA transcription, whereas less methylation enhances gene expression,” Yehuda said.

In 2015, Yehuda and colleagues conducted a study involving combat veterans who had PTSD and found lower methylation on an important region on the participants’ glucocorticoid receptor gene. The changes were associated with cortisol and glucocorticoid receptor sensitivity in the study participants, suggesting a potential epigenetic explanation for the association between the trauma of combat and PTSD.

Yehuda said that stress-related epigenetic changes may be reversible. For example, one of the studies conducted by her team revealed that combat veterans with PTSD who benefited from cognitive-behavioral psychotherapy showed treatment-induced changes in the methylation of a gene that regulates glucocorticoid receptor sensitivity. Yehuda said that this finding confirmed that healing is also reflected in epigenetic change.

“That we can transform to meet environmental challenge is a superpower. That is resilience,” Yehuda said. ■

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