Trauma, once experienced, seems to never want to let go. It can invade our thoughts and unleash mood swings, anger, depression and an exhausting sense of hyper vigilance. A recent study adds a new layer to our understanding: The behavioural changes that can come with emotional trauma are not only difficult to overcome; they can be passed down from generation to generation.
The study, conducted by researchers at the University of Zurich and ETH Zurich, attempted to pinpoint the processes underlying this “hereditary trauma.” This type of trauma has long been observed by psychologists, who saw that children can sometimes show the same behavioural issues as traumatised parents, even if that trauma occurred far in the parent’s past.
Using mice, the researchers discovered that traumatic stress alters the amount of what are called “microRNAs” in the blood, brain and sperm. This can lead to misregulation of cellular processes controlled by the microRNAs.
The traumatised mice showed markedly different behaviour than the non-stressed mice, and these behavioural symptoms were passed on to the next generation via sperm, even though the offspring weren’t exposed to the trauma themselves. The offspring of the stressed mice also had lower insulin and blood sugar levels.
In an analysis of the study, Professor Isabelle Mansuy noted, "We were able to demonstrate for the first time that traumatic experiences affect metabolism in the long-term and that these changes are hereditary.” And these effects on metabolism and behaviour went beyond immediate offspring, persisting even into the third generation.
The implications are troubling. Trauma has the power to reach out from the past and claim new victims. That makes it even more urgent that those affected by trauma are helped as soon as possible, before the body can sabotage itself and future generations.