The Neuroscience of Epigenetics: Understanding the Inheritance of PTSD and Generational Trauma
Abstract
Intergenerational trauma is the trauma that our ancestors have endured in their lives, and it can affect the mental health, behavior, and emotional regulation of future generations through DNA methylation and mechanisms without changing the DNA sequence itself. In this study, we explore how experiencing trauma can lead to changes in our DNA and affects regions of the brain known to be involved in post-traumatic stress disorder (or PTSD) — such as the amygdala, hippocampus, and prefrontal cortex. These modifications might result in a higher risk of PTSD and psychological problems for future children. Research done on animals and other groups, such as the children of the Holocaust survivors, illustrates how traumas can have a long-lasting impact on stress responses.
Although trauma does not cause permanent changes in your genetics, it can powerfully impact the regulation of stress-related genes. The cycle of intergenerational trauma is not irreversible. By understanding epigenetic patterns and addressing trauma-related modifications, one can begin the process of healing and prevent further transmission of these effects to future generations. The findings in this research highlight the important role played by epigenetics in understanding and ultimately breaking the cycle of generational trauma.
Introduction:
Everybody has problems. No one is immune to hardship, fear, or insecurity, regardless of the issue or how deeply it might affect our lives. These often create harmful habits or behavior patterns making us feel like something is wrong with us. However, this is not always the truth—thinking that we are fully responsible for our struggles can sometimes be a narrow perspective on the issue at hand. A person's trauma, like their facial structures, is passed on genetically from three generations back. The idea stems from epigenetics, which proposes that the traumas of a previous generation can leave an impact on the genetic material of their descendants - affecting their mental health, behavior, and potentially their susceptibility to PTSD (Youssef et al., 2018).
Ptsd and the impact of trauma on brain regions
Post-traumatic stress disorder is a psychological disorder that is caused by experiencing or witnessing a traumatizing event. Common symptoms of PTSD include intrusive memories, heightened anxiety, and emotional numbness, all stemming from alterations in the brain areas that control stress and emotions. When trauma occurs, these regions in the brain are affected:
- The Amygdala, the brain's fear center, is shown to be hyperactive, which hints at the body's hyper response towards fear and stress. In PTSD, this part of the brain is often overactive, which results in constant vigilance and heightened anxiety.
- The Hippocampus, critical for memory and learning, is involved in processing trauma-related memories. The hippocampus is typically smaller in PTSD patients, possibly because epigenetic changes have made it so that the hippocampus can no longer differentiate between past trauma and real current danger.
- The prefrontal cortex helps manage emotions and check on impulses. In individuals with PTSD, the connection between the prefrontal cortex and the amygdala weakens, thus reducing the efficiency of the fear and emotional response control system (Bremner, 2006).
Epigenetic mechanisms and dna methylation
With this in mind, there is now increasing evidence to suggest that trauma is not confined to just the individual but also affects changes in genetic expression for generations to come. This phenomenon is known as epigenetics—a field of study where gene activity gets modified due to environmental causes without changing the DNA sequence of the genes themselves. One of the most common types of epigenetic modification is DNA methylation, where a chemical group (methyl) gets added to our DNA, which can switch specific genes on or off.
This chemical group gets added to specific places on the DNA, which blocks the proteins that attach to DNA to read the gene. Enough methylation will completely inactivate a gene, preventing it from producing protein. This means that the methyl group works like a light switch on DNA. Its presence or absence determines if a gene is "turned off" or "turned on" and thus expressed for transcription, translation, and subsequent protein production. In practice, this usually means that a gene is rendered less active. This group could get removed by de-methylation- a process of "turning genes on."
The discovery of DNA methylation, originally in human cancer in 1983, has opened the way for its detection in various conditions and diseases. The alteration is not genetic, it is epigenetic because DNA methylation alters gene expression without changing the DNA sequence (Kiselev et al., 2021). In PTSD, this can mean that genes responsible for regulating the body's response to stress, such as genes controlling the hypothalamic-pituitary-adrenal (HPA) axis, are altered. This leads to exaggerated stress responses and emotional dysregulation. In Epigenetics, the cells control gene activity without changing the DNA sequence or causing mutations, only altering how the body reads the genes.
Research evidence
A 2013 study discovered that fragrance-related trauma can get passed down through generations. The researchers puffed acetophenone, a cherry blossom-scented chemical, into the cages of adult male mice while simultaneously zapping their feet with an electric current. The mice associated the smell of cherry blossoms with pain. The mice began to breed shortly after that. When their mice pups smelled cherry blossom, they became anxious and agitated, while mice pups whose parents had never been conditioned to fear that scent did nothing. The traumatized mice's grand-pups also showed heightened sensitivity to that scent, although neither generation experienced any direct pain regarding the smell. This study suggests that their sensitivity to the aroma of cherry blossoms is linked to epigenetic changes in their DNA (Dias & Ressler, 2013).
The idea of intergenerational trauma is not limited to animals alone. Studies conducted with the offspring of survivors of the Holocaust show intergenerational transmission of trauma. Anxiety, depression, and symptoms akin to those of post-traumatic stress disorder are enhanced in children and grandchildren of survivors who have never experienced the traumas firsthand (Scharf, 2007). Additionally, further studies conducted on survivors of war and famine have reported that epigenetic alterations in the brain might indeed contribute to increased anxiety and dysregulation of emotions in subsequent generations (Jawaid et al., 2018). These findings support the hypothesis that trauma, through epigenetic mechanisms, is indeed heritable.
Intergenerational trauma and emotional transmission
We are profoundly impacted by what our mother experienced while pregnant with us. Every event, emotion, and stressor she encountered during that time can influence how our DNA expresses itself. If a person's mother faced chronic stress or anxiety during pregnancy, those stress signals could alter the development of their brain, increasing the likelihood that they might experience anxiety or emotional dysregulation later in life. This can even extend to attachment styles—if a person's mother struggled with anxious attachment, they may inherit a predisposition for it as well.
It can reach back even further than that. Your future was set in motion, in part, while your grandmother was pregnant with your mother. Inside your developing mother were her ovaries, which contained all the eggs she would ever have—including the one that would become you. This means that any trauma or hardship your grandmother endured during her pregnancy could epigenetically influence not just your mother but you as well (Serpeloni et al., 2019). This cycle repeats itself with each generation, where the traumatic experiences of one generation ripple through the lives of their descendants, subtly altering their biology, mental health, and behavior.
Conclusion
Growing up, we may unconsciously hold the pain and patterns of our mother or grandmother. The effect of such generation-to-generation transmission is profound because it may reshape our view of ourselves and the response of our brain and body to the world. Many of our emotional challenges are not our fault, but they become our burdens to bear nonetheless. Once we grasp the way that trauma is passed down, whether epigenetically or emotionally, we begin to let go of the pain that was never rightfully ours.
Thankfully, trauma does not cause permanent genetic mutations. Instead, it alters how specific genes are expressed, particularly those linked to stress and emotional regulation. The good news is that this cycle of suffering can be broken. By recognizing these patterns and addressing inherited trauma, we can heal, allowing future generations to live free from the unresolved pain of the past.
Written by: Kayan Munim Mbarki
Works Cited
Jawaid, A., Roszkowski, M., & Mansuy, I. M. (2018). Transgenerational epigenetics of traumatic stress. Progress in Molecular Biology and Translational Science, 273, 273–298. https://doi.org/10.1016/bs.pmbts.2018.03.003
Dias, B., & Ressler, K. (2014). Parental olfactory experience influences behavior and neural structure in subsequent generations. Nature Neuroscience, 17, 89–96. https://doi.org/10.1038/nn.3594
Kiselev, I. S., Kulakova, O. G., Boyko, A. N., & Favorova, O. O. (2021). DNA Methylation As an Epigenetic Mechanism in the Development of Multiple Sclerosis. Acta Naturae, 13(2), 45–57. https://doi.org/10.32607/actanaturae.11043
Bremner, J. D. (2006). Traumatic stress: Effects on the brain. Dialogues in Clinical Neuroscience, 8 (4), 445–461. https://doi.org/10.31887/DCNS.2006.8.4/jbremner
Youssef, N., Lockwood, L., Su, S., Hao, G., & Rutten, B. (2018). The effects of trauma, with or without PTSD, on the transgenerational DNA methylation alterations in human offspring. Brain Sciences, 8 (5), 83. https://doi.org/10.3390/brainsci8050083
Weinhold, B. (2006). Epigenetics: The science of change. Environmental Health Perspectives, 114 (3), A160–A167. https://doi.org/10.1289/ehp.114-a160
Serpeloni, F., et al. (2019). Does prenatal stress shape postnatal resilience? An epigenome-wide study on violence and mental health in humans. Frontiers in Genetics, 10, 269. https://doi.org/10.3389/fgene.2019.00269
Nestler, E. J. (2014). Epigenetic mechanisms of depression. JAMA Psychiatry, 71 (4), 454–456. https://doi.org/10.1001/jamapsychiatry.2013.4291
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