Studying epigenetics allows scientists to determine the mechanisms by which gene expression is modified, facilitated or suppressed, although genes themselves, along with the underlying DNA sequences, remain unchanged. Epigenetic mechanisms are conducted via chemical modifications of chromatin, and are induced by environmental factors. In an article entitled “Cultural trauma and epigenetic inheritance,” Amy Lehrner and Rachel Yehuda collate and analyze research regarding the effects of trauma on varying groups of people, from Holocaust survivors to famine victims, and the subsequent psychological effects on their offspring.
The study focused specifically on cultural trauma, which has been defined as occurring “when members of a collectivity feel they have been subjected to horrendous event that leaves indelible marks upon their group consciousness, marking their memories forever and changing their future identity in fundamental and irrevocable ways.” This subject is imbued with controversy, as many countries continue to grapple with historical traumas and the ways they may continue to function in the present moment.
Research of Holocaust survivors demonstrated startling diversity. While some people were described as extremely psychological resilience, others experienced trauma that left lasting psychological scars, impacting their quality of life, along with that of their children. Holocaust survivors were found to have increased vulnerability to PTSD, specifically heightened sensitivity of the neuroendocrine stress response and in the glucocorticoid receptor. In a 1988 study, Israeli soldiers actively involved in combat were found to be more likely to develop PTSD if they had Holocaust survivor parents.
Interestingly enough, a subsequent study found that Holocaust survivor offspring reported greater satisfaction with life, along with greater hope and optimism when compared with controls, but also experienced higher blood pressure, cholesterol, and sleeping problems. Yehuda affirms these results, referencing her own study regarding the biological findings of altered HPA axis reactivity of offspring of survivors. The activation of the HPA axis is crucial to the acute stress response. This axis, which is regulated through varying systems, including brain, nervous, and sympathetic systems, is highly adaptive. The HPA axis alterations found in the offspring of trauma survivors and combat veterans is comparable to those observed in people with PTSD. Research on the transgenerational impacts of other genocides, and other collective traumatic events such as war, slavery, and colonization, affirms this research that trauma can span across generations and pervade a community’s identity.
The role of the glucocorticoid receptor gene was further analyzed with research in rats, which demonstrated that in accordance with variations in maternal care, specifically established with the ‘operationalized’ licking and grooming of offspring, DNA methylation in the gene was altered. As adults, these rats showed alterations in their HPA axis functioning. This study was then translated to the hippocampal glucocorticoid receptor in human suicide victims, which found higher “methylation at the glucocorticoid receptor 1F promoter in postmortem tissue in victims with a history of childhood abuse.” Variations were found between the offspring of Holocaust survivors in accordance with the sex of their holocaust surviving parent. Those with maternal PTSD had lower methylation of the exon 1F promoter gene, while those with paternal PTSD experienced higher methylation. Yeshuda and Lehrner propose that the differential effects of parental sex suggest that gametes are intimately involved in the epigenetic transmission of trauma.
Teen Vogue published an article in May of 2016, specifically citing Yehuda and her research, entitled: “Trauma From Slavery Can Actually Be Passed Down Through Your Genes: you can get PTSD from your ancestors.” One researcher has even popularized the term “post-traumatic slave syndrome” in an attempt to advocate for ending continued structural violence against people of color in the United States. This article, along with other popular reports of Yehuda’s research, somewhat unclearly suggest that memories and trauma are inherited beyond the molecular level, indicating the transmission of actual, experiential trauma. Still, the popular press has managed to call attention to very important aspects of transgenerational trauma beyond the study, including the implications for the reparations debate in the United States.
Although this paper only achieved an impact factor of 4.357, I believe that it was very well done, as Yehuda and Lehrner combined several of their previous studies in an attempt to give a well-rounded picture of up-to-date research in the field of epigenetics. However, I believe that the current research fails to address the possibility that the trauma in offspring is due to hearing about traumas. As such, I believe that future research should study the HPA axis in adopted offspring of trauma survivors to determine the impact of a specific cultural upbringing, devoid of biological linkage, as well as isolate the biological offspring of trauma survivors who were raised within different communities to determine the extent that both epigenetics and cultural trauma affect the psychological health of offspring.
