An interesting study came out in 2014 that caught my eye. I had heard ramblings about it on various podcasts and in a few articles, but I had never seen it. Not too long ago, I finally stumbled upon the research and the details of what they found amazed me.
In a nutshell, researchers sprayed a citrus scent around mice which would be followed by a shock to their feet. This was repeated over, and over, and over. The poor mice were traumatized. Through classical conditioning, they would begin to scramble around their cage every time they smelled that horrifying citrus scent in anticipation of their little feet being shocked .
However, these weren’t just mad scientists torturing mice; they had a clear goal and acquired some astounding results from this. The traumatized mice were allowed to breed and they had healthy litters of baby mice. This new generation of mice didn’t have the lives of ordinary mice, though. When the citrus scent of doom returned, the new generation began to panic .
It seemed as if their parents’ memory of being shocked when exposed to citrus was ‘passed’ down to the next generation. ‘What about the second generation?’, you may ask. Well, they seemed to be quite afraid of the citrus smell as well. At this point, you may be wondering how this is going to relate to human brains. That is exactly what I was wondering too. What if our parents’ traumatic experience could influence how we react to our own traumatic experiences?
To satisfy our curiosity, a few groups of researchers have investigated this and a review by Youssef and colleagues summed it up well. It is well known that our environment can change how our DNA is expressed and it can also go as far as to alter the DNA itself. This is called epigenetics: alterations from the environment to our DNA that don’t mutate the sequence but make other modifications that can change how our bodies interpret our DNA.
Interestingly, it is already known that trauma and PTSD can make these epigenetic changes to DNA. More specifically, researchers have studied the relationship between modifications made to the mother’s DNA from trauma and how these changes are passed along to offspring. Before this type of research came about, it was largely assumed that PTSD strictly arose from the environment.
However, this didn’t make sense since roughly 50-85% of Americans will experience a ‘traumatic’ experience within their lifetime, but only 8% go on to develop PTSD. What causes this difference? The answer is obvious: people handle trauma differently.
This could largely be due to how someone was raised and what they’ve experienced that would allow them to manage the trauma, but new research shows that it could be genetic as well. Moreover, this research shows that the genetic component may be partially based on the traumatic experiences of your parents.
One example of this was a study done among mothers who endured the Tutsi genocide in the 1990’s. The researchers found that both the mothers and their children born after the event had significantly higher levels of depression and PTSD when compared to the control. After genetic testing of the mothers and children, the researchers stated that this could be due to modifications made to the mother’s DNA during the traumatic event that had been passed on to their offspring.
“available literature in humans suggests that children of parents who had suffered from extreme trauma have methylation modifications associated with trauma and PTSD”
Another example is among a Congo population that went through a particularly stressful time. There was found to be a significant correlation between the stress of the mothers and DNA changes in their babies that were born after the traumatic times. Even more, the DNA changes inherited by the babies could also make it harder for their bodies to properly use certain segments of DNA which could lead to further mental and physical harm.
From the few studies covered by the review, it seems like it may be possible that humans can inherit changes to mother’s DNA from PTSD. What isn’t known is if these changes are benign or if we respond like the mice who clearly were afraid of the citrus smell because of what their parents experienced. In order to get a clearer view of what is going on, much more in-depth research needs to be done on this subject.
Even with just preliminary studies, it does give possible insight into one’s own situation and how they handle traumatic experiences. Do you know of a traumatic experience your mother had before you were born? It’s possible your mother wasn’t the only one affected, but you as well. Either way, you can overcome PTSD with proper psychotherapy techniques (like many we have written about in our mental health section), but now you may have learned a bit more about yourself along the way.
What have you heard on this topic? Have anything to add?