My friend was abused as a child and grew into a socially awkward, suspicious, anxious, and shy adult. She had nightmares and flashbacks of the abuse and, when I met her, was beginning to experience panic attacks. She wanted to feel better but feared the work of trauma recovery, so she refrained from seeking help.

Then she fell in love. Together, the two dreamed of marriage and starting a family. What would happen to her children, she wondered, if they gestated inside a body that was frequently stressed to the max? How would they adjust to the world if they were raised by a woman who couldn’t even be alone at home at night? For the sake of these unborn beings, my friend finally sought professional help to relieve her symptoms of post-traumatic stress disorder.

While achieving a less stressed/more calm state of mind will definitely help, recent research suggests that my friend’s childhood traumas may live in places more difficult to change than her basic daily behavior. A team at the University of Zurich and ETH Zurich has discovered a key to trauma’s physiological puzzle and suspect that it can be passed on through an imbalance in parental microRNA.

Experiential Multigenerational Trauma

Every traumatic experience activates survival and coping mechanisms. From nervous system arousal to emotional dysregulation, from turning gene expression on or off to developing aberrant behaviors, from shock and surprise to the development of a belief system that expects shock and surprise, the will to be safe and in control is a primal response to threat and danger. When left uninterrupted, however, the changes trauma instigates become habitual and often survive into the next generation. The simplest way to observe these effects is through a causal behavioral paradigm. For example:

• Survivors of physical abuse often abuse their own children, acting on the belief that abuse is an acceptable form of discipline. They also frequently engage in abusive romantic relationships and perpetuate in their new nuclear families the idea that “love” and abuse go hand in hand.

• Survivors of emotional abuse experience relational problems and often enter into relationships in which they are abused by, or abuse, their significant other. Common parental problems that affect the well-being of children include anxiety, anger, substance abuse, and depression.

• Survivors of neglect often exhibit underdevelopment in the areas of nurturance and intimacy, which causes a failure to meet the emotional needs of their children.

Years of these reinforced mechanisms can change the brain structures and neurophysiology of every generation as attitudes and actions become second nature and are inherited through experience.

Non-Genetic Multigenerational Trauma

Isabelle Mansuy, professor at ETH Zurich and the University of Zurich, knows there are multigenerational diseases (such as bipolar disorder) in families that can’t be traced back to a particular gene. Along with her research group at the Brain Research Institute of the University of Zurich, she’s dedicating her time to exploring the molecular processes connected to non-genetic inheritance of behavioral symptoms caused by childhood trauma.

Studying mice, the researchers subjected one group to early life trauma against a control group. Afterward, they observed that the traumatized mice expressed behavioral changes, exhibiting depressive-like behaviors and partly losing their innate dislike of open spaces and bright light. While traumatizing circumstances were not experienced by the offspring of these mice, sperm of the traumatized mice transferred behavioral symptoms to the next generation. This transfer, identified through an alteration in the amount of microRNAs of the original mice generation, is the major finding of Mansuy’s experiment.

Here’s how it happens:

Enzymes synthesize RNA from DNA by reading specific sections of genes and using them as templates for producing corresponding RNAs. Their primary role being that of a messenger, RNAs carry instructions from DNA regarding the control of the synthesis of proteins. Separate enzymes trim RNA so they reach maturity. All cells carry a number of short RNA molecules: cellular RNA fragments, which are microRNAs that engage in regulatory functions. To prevent the production of a particular protein, for example, they bind to and destroy the messenger RNA that would have produced it.

What Mansuy and her team discovered is that compared to non-traumatized mice, the original generation of traumatized survivors exhibited stress-altered amounts of many microRNAs in the brain, sperm, and blood. While some microRNAs were lower, others were produced in excess. This alteration resulted in the misregulation of the cellular processes usually managed by these microRNAs.

Mansuy explains, “With the imbalance in microRNAs in sperm, we have discovered a key factor through which trauma can be passed on.”

Indeed, even the metabolism of the stressed mice’s offspring was affected, as their blood sugar and insulin levels were lower than those in control groups.

What This Means for Trauma Survivors and Their Children

Mansuy believes that the changes in microRNAs occur as part of a chain of events that begins with the body’s overproduction of stress hormones.

“The environment leaves traces on the brain, on organs, and also on gametes,” she explains. “Through gametes, these traces can be passed to the next generation.”

This news only introduces new areas to explore. While the chain of behaviorally induced inherited trauma can be interrupted through conscious choices, actions, and interventions, if Mansuy’s results correlate in humans (that’s the focus of her current work), how would the cycle of inheritance be interrupted? As with so many facets of trauma and its effects, finding one answer leads to many more questions.

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