In A Web Of Family Trauma. What Is Epigenetic Inheritance - Research

2023 Author: Oswald Adamson | [email protected]. Last modified: 2023-05-21 20:18

It is only recently that scientists have begun to understand the biological processes involved in the inheritance of traumatic experiences. To find out more about this, they turned to animal research. Humans and mice have a surprisingly similar genetic makeup - 99% of human genes have their counterparts in mice. Therefore, studies in mice provide us with a lens through which we can see the effects of inherited stress on humans. Such experiments are valuable for one more reason: since mice are capable of reproducing the next generation approximately twelve weeks after birth, the study of several generations takes place in a relatively short time. And the same research on humans can take about sixty years. Chemical changes in the blood, brain, eggs and sperm of mice have been associated with behavioral patterns (such asas anxiety and depression) of later generations. For example, studies of offspring have shown that traumatic experiences, such as weaning, caused a change in gene expression that could be traced back to three generations.

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In one such experiment, scientists stopped females from feeding their young for three hours a day for the first two weeks of their lives. Later, these offspring displayed behaviors similar to what we call depression in humans. Moreover, the symptoms worsened as the mice got older. Surprisingly, some of the males themselves did not exhibit this behavior, but epigenetically transmitted the changes to their female offspring. Scientists have also found changes in methylation and gene expression in stressed mice. Among them was the CRF2 gene, which is responsible for regulating anxiety in both mice and humans. Scientists found that the stress of separation from their mothers affected the germ cells (the precursor cells of eggs and sperm) and the brains of the offspring. In another experiment involving rats, cubsthose who received little maternal care were more anxious and more stressed as adults than those who were cared for sufficiently by their mothers.

It is now common knowledge that babies who are weaned early may experience more difficulties in life

In studies in male mice, mice weaned from their mothers showed increased susceptibility to stress throughout their lives and gave birth to offspring that showed similar stress patterns over several generations. In one such study, which was conducted at the University of Zurich's Brain Research Institute in 2014, scientists subjected male mice to periodic and prolonged stress, weaning them from their mothers. Subsequently, they developed symptoms similar to depression. Then, when these mice gave birth, the scientists found that the second and third generation mice showed the same symptoms of trauma, although they had never experienced such an experience.

The researchers also found abnormally high levels of microRNA - the genetic material that regulates gene expression - in the semen, blood and hippocampus of stressed mice. (The hippocampus is an area of the brain involved in the stress response.) Abnormal microRNA values have also been found in the blood and hippocampus of second-generation mice. And although mice in the third generation showed the same symptoms of trauma as their fathers and grandfathers, there were no elevated miRNA values. This allowed the researchers to speculate that the behavioral effects of a traumatic event may last for three generations, but perhaps no further. “By discovering an imbalance in microRNAs in semen, we uncovered a key factor in how traumatic experiences can be passed on,” explains Isabelle Mansui, co-author of the study. She and colleagues are currently studying the role of miRNAs in inheriting traumatic experiences in humans.

In a later study published in 2016, Mansui and her colleagues were able to show that trauma symptoms are reversible in mice if they lived in a positive, stress-free environment as adults. It wasn't just the behavior of the mice that improved. They also showed changes in DNA methylation, which prevented transmission of symptoms to future generations. The value of these studies is very important. In later chapters, we will learn how to create positive images and experiences that will help us change stress patterns that have affected our family for generations.

Research in mice has become so important because science can now back up the evidence that adversity experienced by one generation can become a legacy that can be passed on to others. In 2013, in a study of offspring of mice exposed to stress, researchers at Emory University School of Medicine discovered that traumatic memories could be passed on to subsequent generations through epigenetic changes in DNA. Mice of one generation were taught to fear the smell of acetophenone, similar to the smell of cherry flowers. Each time, simultaneously with him, they received a current discharge. Over time, the mice developed more olfactory receptors tuned to this particular smell, which allowed them to smell it at much lower concentrations. Their brains also have an enlarged area responsible for these receptors. In addition, the researchers were able to identify changes in the semen of mice.

However, the most curious thing about this study was what happened to the mice over the next two generations. When mice of both the second and third generations were given the smell of acetophenone, they began to jump, trying in every possible way to avoid it, although they had never encountered it before. At the same time, the same changes occurred in their brains as were observed in the first generation. Mice inherited not only sensitivity to this smell, but also the accompanying fear response.

Brian Diaz, one of the study participants, suggests that "there is something in the semen that carries information and allows it to be inherited." He and his team noted abnormally low DNA methylation in both the daddy's and his offspring's sperm. While the exact mechanism of how parental traumatic experiences persist in DNA is still being explored, Diaz says he "allows ancestors to inform their offspring that a certain environment was negative for them."

The study provides us with compelling evidence for the existence of what scientists call "intergenerational epigenetic inheritance." It refers to the way in which behavioral patterns can be passed from one generation to the next

When I work with families in my practice, I see recurring patterns of illness, depression, anxiety, financial or relationship difficulties, and I always want to look deeper. What unexplored event from the life of past generations drives the behavior of a man who loses all his money on the run, or a woman who always prefers to enter into relationships only with married men? What influenced their genetic heritage?

Diaz and his team hope to continue working to determine if similar effects are occurring in human genes. So far, human research data is only being collected, as it should affect many generations.

But the information we have today from animal experiments makes us stop and think about how we are still born, inheriting the stress of grandfathers and great-grandfathers

In 2013, in the journal Biological Psychiatry, a number of scientists from the University of Haifa - Hiba Zaydan, Mika Leshem, and Inna Geisler-Salomon - published a study. In the course of it, they found that even relatively little stress before conception and pregnancy can affect the offspring. Several rats were exposed to mild stress (eg, temperature changes) forty to forty-five days after birth, which is equivalent to adolescence in human life. The effect of this impact was traced in the next generation.

Focusing on the CRF1 gene, which is responsible for the molecules involved in the body's response to stress, the researchers found an increase in the amount of the molecular substance of this gene in the brains of female rats exposed to stress. They also found a significant increase in the concentration of the same molecular substance in the eggs of stressed females, as well as in the brains of their offspring. This demonstrates to us that information about stressful experiences is transmitted through the ovum. Scientists insist that the altered behavior of newborn rat pups is not related to the care they received from their mothers. This study suggests that even if a person receives nurturing care from their parents in infancy, we are still recipients of the stress that our parents experienced prior to our conception. In the next chapter, we explorehow children born to the same parents can inherit different traumatic experiences and live different lives, despite having the same upbringing.

In 2014, scientists at the University of Lethbridge in Canada studied the effects of stress on pregnant rats and preterm labor. Their findings showed that stressed female rats gave birth early, and females in their offspring, in turn, also had a shorter gestation period. And in the third generation, the gestation period of females was even shorter than that of their mothers. The third generation impressed the most researchers. In rats "granddaughters" due to the stress of rats "grandmothers", the gestation periods were even shorter, despite the fact that their mothers were not exposed to negative influences. Gerlinda Metz, the main author of the article, writes: “It was surprising to find that exposure to stress, small to medium, has had an impact on a number of generations. And with each generation, the effect of this influence increased. " Metz believesthat epigenetic changes are due to non-coding RNA molecules. These findings can be important for women who struggle with pregnancy or childbirth due to the stress they experience.

Considering that in humans, a generation is counted every twenty years, the study of similar processes in humans for several generations is still ongoing. However, with studies in mice showing that stress can be transmitted over at least three generations, scientists suggest that in humans, children born to parents who have experienced a traumatic or stressful event will also transmit the corresponding psychological pattern, and not only to their children, but also to their grandchildren. It is scary to say that the Bible, namely the Book of Numbers 14:18, confirms what is revealed by modern science, saying that sins, iniquities or the consequences of evil deeds (terms depend on which translation you read) parents can fall on descendants until the third or the fourth knee. In particular,the modern translation of the Bible says: "The Lord is long-suffering and many-merciful, forgiving iniquities and crimes, but not leaving without punishment and punishing the iniquity of fathers in children up to the third and fourth generation."

While the exact mechanism of how parental traumatic experiences persist in DNA is still being explored, Diaz says he "allows ancestors to inform their offspring that a certain environment was negative for them."

As new discoveries in epigenetics emerge, ways to reduce the intergenerational effects of traumatic experiences may soon become standard practice. Researchers nowadays are seeing how thoughts, inner images, and daily practices such as visualization and meditation can alter gene expression.

Fragment of the book “It didn't start with you. How do we inherit negative scenarios from our family and how to stop their influence. " Mark Walinn. - Moscow: Publishing house "Bombora", 2020.