New Israeli study investigates childhood trauma and its prospects for reversal
As concern mounts for the psychological health of young victims of the war and terror, Weizmann Institute researchers look at why some people are prone to triggering later in life
Renee Ghert-Zand is the health reporter and a feature writer for The Times of Israel.
A new study from the Weizmann Institute of Science shows how exposure to trauma in childhood alters the brain, and how such trauma may be reversed to prevent the development of further trauma or mental illness later in life.
The study done on mice in Prof. Alon Chen’s lab was published on December 1 in the peer-reviewed Science Advances journal.
“In my lab, we investigate the neurobiology of stress. We have been working on this study for five or six years, and it is under a very big and long program in which we are trying to understand what happens within the brain and body when you are exposed to stressful stimuli,” Chen told The Times of Israel.
“This is very relevant now because of the trauma that Israelis are experiencing [because of the Hamas atrocities of October 7 and the war]. But it’s really a subject that is always relevant, especially here,” he said.
The study, whose lead authors were Dr. Aron Kos and Dr. Juan Pablo Lopez, aimed to determine if brain mechanisms that go awry due to stress exposure in young childhood can be reversed or mitigated later in life. In other words, will all children who undergo traumatic experiences — such as seeing loved ones killed, being held hostage, or being under constant rocket bombardment — suffer post-traumatic stress disorder (PTSD) or develop other mental illnesses as adults?
Exposure to stress stimuli sets off physiological responses like increased heart and respiratory rates, and increased blood sugar, blood pressure, and cortisol levels. This is normal and part of a healthy “fight or flight” survival response.
“This central stress response is initiated and controlled in the brain, where every main brain structure is either activated or inhibited,” Chen said.

These activations and inhibitions in the brain are expressed not only through changes in the body but also in how the brain itself works. With the horrific events of October 7 still fresh in everyone’s minds, Chen gave examples of such brain changes in terms of the response to a terrorist attack.
“The areas in your brain responsible for fear or anxiety levels will increase. It’s helpful to be fearful when you’re facing a Hamas terrorist. Your cognition will also change. The area in your brain responsible for your memory will work differently — you’re really going to remember this event,” Chen said.
“Your focus and attention will change. If it takes five seconds on average to see the first terrorist, it will take only a few fractions of a second to see the second one,” he continued.

In the wake of an acutely stressful event such as a terrorist attack, this heightened response generally switches off and the brain returns to homeostasis. The time in which it takes to do so varies from person to person based on genetic makeup and environmental factors. When a person’s brain does not return to its previous balance, PTSD or other pathologies can take hold.
Chen’s team investigated mice in their “childhood,” in other words during the four weeks during which they are breastfed by their mothers after birth. Given mice’s short lifespans, this is already halfway to their becoming sexually mature “adults” (the equivalent of age 7 or 8 in humans).
“We used a model in which we made the mother during this suckling period very nervous. She didn’t have bedding, she was very upset and didn’t treat her pups well. Of course, affecting the mother and affecting maternal care has long-term consequences on the developing pups,” Chen said.
The team then used a cutting-edge video and AI system to track the behavior of the mice for days — and even weeks — as they lived in their usual social settings with other mice who had not been subjected to childhood stress.
The mice who had been subjected to childhood stress found themselves at the bottom of the dominance hierarchy.
“Equivalent behaviors in humans might include high levels of introversion, social anxiety, and having an avoidant personality, all known to be characteristic of post-trauma,” said Lopez.
Some of the mice in the study were subjected to another stress stimulus when they were “adults,” in the form of bullying by other mice.

In total, the study involved four groups of mice: mice that were subjected to childhood trauma only, mice that were subjected to childhood trauma and adult trauma, mice that were subjected only to adult trauma, and mice that were not subjected to any trauma at all.
The scientists removed the brains of the mice in all the groups and studied the many types of neurons (nerve cells) in the hippocampus, a part of the brain highly involved in learning, memory, social and anxiety-related behaviors, and more.
“We sequenced the RNA molecules in this area in single-cell resolution. We did not take the hippocampus and make a smoothie out of it. Rather we separated it into the single cells that compose it and we sequenced each one,” Chen explained.
The researchers found that early trauma left a mark on different types of cells, primarily affecting gene expression in two subpopulations of neurons, those belonging to the glutamatergic excitatory system and those belonging to the GABA inhibitory system. This effect was especially strong in mice that had been exposed to both childhood trauma and bullying as adults.
An imbalance between excitation and inhibition found on the molecular level was confirmed by testing the electrophysiological properties in the activity of the neurons.
Knowing that the anti-anxiety drug diazepam (known commercially as Valium) affects the GABA inhibitory system, the researchers gave it to these mice for a week and a half, beginning several days after the initial trauma — while they were still being fed by their mothers.
Not only did the mice not end up at the bottom of the social ladder, but they also appeared to be protected against triggering later on.

Chen said this does not mean at all that children who have had traumatic experiences should be immediately medicated. However, the success of giving Valium to the mice is part of a larger discussion about early intervention to prevent PTSD.
Research has shown that the majority of people who undergo trauma will recover through natural psychological resilience, but there is still up to 20 percent for whom trauma will transform into PTSD. As Chen has found, many will have imbalances in their brains waiting to be triggered.
“There were 3,000-4,000 people at the Supernova Festival. That means that as many as 800 of the survivors could end up with post-trauma. Those are huge numbers,” Chen said.