Genetic Generational Transmission of Trauma: Is It Real?
This is a writing sample from Scripted writer Wendy Hoke
The Holocaust. World War II. Domestic violence. Child sexual abuse. All of these traumatic experiences leave visible and invisible marks on the survivors. In addition, these survivors may have epigenetic marks left on the chemical coating on their chromosomes. Some call it a biological memory of the trauma. According to the Veterans Affairs National Center for PTSD, approximately 8% of trauma survivors will eventually develop post-traumatic stress disorder (PTSD). These people seem to have greater vulnerabilities to stress than the general population. Past studies suggest that the vulnerabilities are due to environmental factors like how the person was raised as a child. However, new research is shedding light on the potential for transgenerational effects that might be transmitted genetically to children. Studies in epigenetics are pointing to both environmental and hereditary factors to explain the transgenerational transmission of trauma, which adds a layer to the understanding of psychobiological dimensions. In short, epigenetics may lead to clearer data on why latent transmission manifests itself when an individual experiences unusual stress. Research is suggesting that children of parents with PTSD, from whatever cause, may be more vulnerable to developing inappropriate responses to stress. The individuals experiencing PTSD may be survivors of combat, refugees, victims of childhood sexual abuse, torture, or other extreme forms of stress. And, studies are suggesting that genetic transmission may go beyond the next immediate generation, impacting grandchildren and great-grandchildren as well. Academic literature has described the transgenerational transmission of trauma (TTT) for about the last 50 years, and TTT specifically looks at heredity and the potential to transmit trauma characteristics from parents to children. At least 500 studies have been published on the subject. Yet, we are still unclear on how the unconscious trauma of a parent with PTSD may be genetically passed on to a child. The idea itself does not present any clear, logical hypotheses. Are forgotten memories passed on from generation to generation? Can any neurobiological evidence exist that scientifically proves that the phenomenon is real, such as an MRI scan or a blood specimen? While science is still unclear on TTT, new research suggests that traumatized parents may produce children with an increased disposition to PTSD if subjected to extreme stress. Twin and family studies have pointed to an underlying genetic component and as much as 30% of that component may be due to an inheritable trait. Some studies have found that children of Holocaust survivors have horrific nightmares that replicate their parents' experiences during World War II. They may suffer from debilitating depression and anxiety that negatively impact their ability to function in daily life. Do these individuals absorb the repressed Holocaust trauma of their parents? Or have they learned it from hearing their parents' stories? Can Trauma Be Inherited? It is a very relevant question, and researchers typically take one of four theoretical approaches to understanding TTT: (1) sociocultural and socialization models; (2) psychodynamic relational models; (3) family systems and communication models; and (4) biological or genetic models. Some research is looking beyond the first three approaches to examine the fourth and discover how biological influences produce TTT. A genetic mechanism alone is not a comprehensive explanation. Any hypothesis that attempts to describe TTT must account for the hereditary variations that would clarify how parental trauma can be transmitted genetically to a child while still in gestation. The data must show how a child who has not been traumatized shows a tendency for inherited emotional problems. This is where epigenetics is stepping in to consider more comprehensive explanations of TTT. The discipline includes both environmental and genetic factors to provide a psychobiological dimension that may ultimately integrate clinical observations and empirical data. Let's take a deeper look into this fascinating field of study. Epigenetic Transmission ** Recent developments in epigenetics point to a molecular basis to explain how heritable traits can influence gene function. For instance, DNA methylation may result from environmental stress, which can alter the functional expression of genes in such a way that the alteration becomes transmissible intergenerationally. This may explain both the enduring impact of trauma exposure and individual variations. Epigenetics seeks to understand the heritable changes in gene expression not due to alterations in the underlying DNA sequence. These changes occur from major emotional trauma or environmental stress, which leaves marks on the chemical coating, or methylation, of the chromosomes. The coating acts as a memory that is a constant physical reminder of the trauma, which then is transmitted to offspring. So, the question becomes this when we consider children of Holocaust survivors: does their neurobiological susceptibility to stress make it easier for them to imagine the actual suffering of their parents? Do they actually experience the sounds and smells because of acquired genetic traits? Do they relive their parents' experiences because such extreme environmental conditions such as torture, starvation, or persecution leave an indelible mark on parental genetic material that is passed down? Can extreme circumstances such as these alter genetic material in eggs and sperm to be passed down along the generations? Can epigenetics explain the switch or trigger that must occur in the offspring to then relive the inherited traumatic traits? Part of the challenge to answering these questions lies with showing that a parent with PTSD has some sort of genetic trait that is specific to developing PTSD, which then can be demonstrated in the children. This trait in traumatized populations would manifest as a latent susceptibility to PTSD and result in greater vulnerabilities to extreme stress. The new stress becomes the trigger to the inherited neurobiological response. Some studies have produced very interesting results. In Canada, a series of post-mortem studies on the brains of men who had committed suicide showed that the chemical coating on genes appeared to have been influenced by childhood abuse. The Dutch Famine Birth Cohort study offered more indirect evidence and concluded that exposure to acute, severe famine during pregnancy affected the birth weights of women born during the famine and their own offspring through a phenotypic response. These findings are prompting additional investigations into TTT and the complex mechanisms that surround the phenomena. Other studies of children of survivors of the Holocaust with PTSD show that these offspring had significantly lower urinary cortisol excretion and salivary cortisol levels as well as enhanced plasma cortisol suppression in comparison to children of survivors without PTSD. Lower cortisol levels were found in mothers who developed PTSD after exposure to the attacks on September 11 compared with similarly exposed mothers who did not develop PTSD. And, an array of neurotransmitters have been looked at in relation to a predisposition to PTSD, including dopamine, serotonin, the glucocorticoid receptor, and neuropeptide Y, brain-derived neurotrophic factor. **Final Thoughts Finding hard evidence of TTT would have quite a few consequences. It would spur the shift in scientific thought that extreme stress has physiological effects on the survivors and their offspring. In addition, a clearer understanding of the epigenetic transmission of PTSD to children of survivors would support more accurate diagnosis, targeted treatments, and better prevention. Specific epigenetic therapies could produce a range of applications beyond trauma. Finally, the epigenetic transmission models make it easier to reconcile the observed secondary traumatization effects found in psychotherapy with the epidemiological studies that could not show any differences in populations. Children of parents with PTSD may be able to benefit early from psychotherapeutic interventions or through new psychopharmacological drugs, or both. The knowledge alone will enable them to take charge of their lives and set off on a personal transformative path to greater meaning in their lives.
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