Traumatic experiences affect gene activity
The reasons for mental illnesses have been the subject of scientific research for decades. Most psychiatrists and psychologists suspect the origin of depression, phobias and other mental disorders in the patient's childhood. It is assumed here that mental injuries (trauma) that have not been adequately processed cannot “let go” of people in later life and can lead to psychological problems as a result. But not only your own life seems to be decisive for whether a person has an increased risk of a mental illness or not. Instead, scientists have now found evidence that the biography of family members also has an impact on the health of our souls.
Childhood trauma as a cause of mental disorders
What causes a mental illness? Science has been dealing with this question for decades. So far, it has primarily been assumed that drastic, psychological injuries in childhood (so-called “trauma”) lead to people developing mental disorders - some of which only really become noticeable for the first time in adulthood. The focus was on the biography of the individual, their own experiences and the individual processing of these experiences.
Ancestral experiences leave traces in the genome
Now, however, there seems to be evidence that the lives of our direct ancestors also have an impact on our soul life. As the American scientists Brian Dias and Kerry Ressler from the Emory University School of Medicine in Atlanta found out, things that our grandparents, for example, have experienced can also leave a trace in the genetic material of their descendants. As part of an animal study, the researchers administered electric shocks to mice to keep them away from the harmful substance acetophenone. As a result, the animals quickly flinched as soon as the smell of the organic chemical compound appeared - even without an electric shock.
Mice "inherit" learned aversion to a chemical
But the real surprise only came when the scientists also examined the next generation of mice in the next step: the descendants of the mice of the first experiment also reacted significantly more strongly to a smell of acetophenone than a control group - even though they never used electric shocks or the substance in them Had come into contact. But not only the next generation, but even the grandchildren of the first experimental animals still showed visible "aftermath" of their grandparents' experiences by reacting to the smell of acetophenone. The learned flinching in the smell of acetophenone was thus somehow anchored in the DNA of the animals and was thus passed on to the next generations.
Traumatic experiences are stored on "fine structures"
For the researchers, this was a clear indication of the influence of genetics, because passing on the experience of "acetophenone = pain", for example due to similar external influences, did not provide a conclusive explanation in further studies: "The fact that these changes also occur when artificial insemination occurs, rearing the young by foster parents and surviving over two generations indicates a biological origin, "says the US scientists in the journal" Nature Neuroscience ". According to the researchers, however, it is probably not the genes themselves that are affected by changes, but rather the so-called" Fine structures ”that control the activity of the genes, according to which the experts would apparently save traumatic experiences and in some cases lead to lifelong impairments.
The results provide a framework for further research
For the researchers, this is an important step in the field of epigenetics, which focuses on the question of which factors are responsible for gene activity and thus the development of the cell, or whether certain changes are passed on to the next generation as in the current experiment : "Our results provide a framework for further addressing the question of how environmental information is inherited across generations at the behavioral, neuroanatomical and epigenetic level," the researchers said in the abstract of their study.
Altered activity of the genes even in post-traumatic stress disorder
The development of a so-called "post-traumatic stress disorder" (PTSD) also appears to be directly related to a change in the activity of the genes. This is the result of a study by the Max Planck Institute for Psychiatry in Munich in cooperation with the Mount Sinai School of Medicine in New York, in which the late effects of the terrorist attacks of September 11, 2001 are currently being investigated.
It was shown here that for those who suffer from PTSD as a result of the traumatic experience, “adaptation genes” and “stress genes” have a different form of activity than those who remained healthy. Accordingly, this unique experience had apparently meant that the negative experience had “burned” itself into the genome of some of those affected, thereby having far-reaching consequences for future life.
Aftermath of the “Hunger Winter” 1944 can still be seen across generations
However, a change in the activity of the genes can not only affect the soul; instead, the descendants may also experience physical impairments. According to the Dutch depression researcher Florian Holsboer, this can be derived, for example, from intergenerational, epidemiological studies in which, among other things, the health of the Dutch born during the "Hunger Winter" in 1944 was observed. For example, children and mothers who had suffered from extreme malnutrition and malnutrition at the time had recovered over the years - but the bad experience had apparently “passed on” to the next generation, because they too continued to bring underweight children with one increased risk of illness to the world, even though they themselves had not suffered emergency. "Apparently, the grandchildren's genetic material contained epigenetic markings, which can be traced back to the grandparents' life experiences," said Professor Holsboer in a lecture on "Depression and its cure".
Epigenetics is said to provide more clarity
However, there is still no clarity as to how the “transfer” of traumas experienced into the genetic material of the descendants works exactly. Epigenetics should therefore provide more and more information in the next few years in order to better understand what causes post-traumatic stress disorder or other mental disorders. (No)
Image: Gerd Altmann / Shapes: Graphicxtras / pixelio.de