November 2, 2015

Passing on the memory of trauma

I don't know what to make of this study - it's very small -  nor do I accept the controversial idea of "epigenetic inheritance”, but I am open to the possibility that some memory of trauma, such as the black plague, can be passed on to later generations. 

Study of Holocaust survivors finds trauma passed on to children's genes

Genetic changes stemming from the trauma suffered by Holocaust survivors are capable of being passed on to their children, the clearest sign yet that one person’s life experience can affect subsequent generations.

The conclusion from a research team at New York’s Mount Sinai hospital led by Rachel Yehuda stems from the genetic study of 32 Jewish men and women who had either been interned in a Nazi concentration camp, witnessed or experienced torture or who had had to hide during the second world war.

They also analysed the genes of their children, who are known to have increased likelihood of stress disorders, and compared the results with Jewish families who were living outside of Europe during the war. “The gene changes in the children could only be attributed to Holocaust exposure in the parents,” said Yehuda.

Her team’s work is the clearest example in humans of the transmission of trauma to a child via what is called “epigenetic inheritance” - the idea that environmental influences such as smoking, diet and stress can affect the genes of your children and possibly even grandchildren.

The idea is controversial, as scientific convention states that genes contained in DNA are the only way to transmit biological information between generations. However, our genes are modified by the environment all the time, through chemical tags that attach themselves to our DNA, switching genes on and off. Recent studies suggest that some of these tags might somehow be passed through generations, meaning our environment could have and impact on our children’s health.
The team were specifically interested in one region of a gene associated with the regulation of stress hormones, which is known to be affected by trauma. “It makes sense to look at this gene,” said Yehuda. “If there’s a transmitted effect of trauma, it would be in a stress-related gene that shapes the way we cope with our environment.”

They found epigenetic tags on the very same part of this gene in both the Holocaust survivors and their offspring, the same correlation was not found in any of the control group and their children.
Marcus Pembrey, emeritus professor of pediatric genetics at University College London commented,  “Yehuda’s paper makes some useful progress. What we’re getting here is the very beginnings of a understanding of how one generation responds to the experiences of the previous generation. It’s fine-tuning the way your genes respond to the world.”
Cherry blossoms and mice
Scientists at Emory University in Atlanta trained male mice to fear the smell of cherry blossom by pairing the smell with a small electric shock. Eventually the mice shuddered at the smell even when it was delivered on its own.

Despite never having encountered the smell of cherry blossom, the offspring of these mice had the same fearful response to the smell - shuddering when they came in contact with it. So too did some of their own offspring.

On the other hand, offspring of mice that had been conditioned to fear another smell, or mice who’d had no such conditioning had no fear of cherry blossom.
Posted by Jill Fallon at November 2, 2015 2:28 PM | Permalink