How Does Therapy Work? Part of the Brain Which Stores Trauma Might Also Heal, Study Suggests

Therapy can treat symptoms of mental conditions from anxiety to depression and post-traumatic stress disorder (PTSD)—but how does it work? According to a study in mice, it may tap into a part of the brain that stores trauma and uses it to heal.

Researchers in Switzerland investigated how therapy tackles even long-term memories of trauma, including those that lead to PTSD. They found fear attenuation may occur in the same group of neurons in the brain that create and store the memories.

Professor Johannes Gräff of the EPFL, Switzerland, whose lab carried out the study, told Newsweek the study is significant because it is the first to show which cells are important in overcoming traumatic memories.

Researchers have investigated the neurons involved in therapy. Getty Images

As scientists don't fully understand how neurons store our general memories, there is currently a debate in the field around whether suppressing the original memory of the event or rewriting it reduces the severity of the trauma.

The study published in the journal Science offers new data that supports the technique of rewriting, rather than suppressing.

"It shows that memory attenuation is indeed mediated by the same population of neurons that used to store the original trauma, which need to be kept active, rather than suppressed," explained Professor Gräff.

The researchers investigated how to lessen long-lasting trauma, known as remote fear, by studying mice genetically modified so their neural activity could be measured. First, the scientists located neurons in the dentate gyrus of the hippocampus, a small organ in the brain in charge of storing, remembering and reducing fear.

The mice underwent an experience triggering long-lasting trauma, then were given the equivalent of exposure therapy that is widely used in humans. This is a form of cognitive behavioral therapy commonly used to treat phobias.

The team were surprised to find that some of the neurons that activated when recalling traumatic memories were still at work when the animals were no longer fearful. What's more, the less scared the mice became, the more the cells were reactivated, leading the scientists to believe they play a key role in storing and tackling traumatic memories.

And when the recall neurons were dampened during exposure therapy, the mice became found it harder to overcome their fear than control animals. When they dampened the neurons in other areas of the dentate gyrus it did not replicate the same effect, suggesting the recall neurons were vital for working through fear.

While the brains of mice and humans are different, the findings offer an important insight into how the brains of mammals work, particularly as a third of people will experience fear or stress-related disorders at some point in their lives, the authors noted.

"Now that we have a tool to visualize cells that are important for reducing traumatic memories, we can screen different interventions methods to overcome traumatic memories for their efficiency," said Professor Gräff.

"Second, now that we know which cells to look into, we can understand at the molecular level what is going on during the successful attenuation of a traumatic memory. The results will thus inspire more refined approaches to look for candidate genes that are important for treating traumatic memories."

The take-home lesson from the research is that "facing your fears is good," stressed Professor Gräff.

"Only then can you attack, and change, a traumatic memory at its roots," he said. "The better you reactivate your original memory trace of fear, the more likely it is that your treatment, such as an exposure therapy or cognitive behavioral therapy, is going to be efficient."

Professor Neil Greenberg, of the Royal College of Psychiatrists, who was not involved in the study told Newsweek: "We know that as memories of traumatic event form, and we begin to attribute some meaning to a traumatic event (is the world still safe, can I still trust people, did I do the right thing etc.), discussions with people we trust can alter our perception of what happened in an event."

"Also, for those who do become ill, talking therapies for PTSD, including trauma-focused cognitive behavioral therapy, often try to help people reappraise what happened during an event so that they take a more logical/evidence based view of an event rather than one fueled by emotions such as fear.

The findings support the idea that recovery happens when we reprogram rather than suppress memories, he added.

This article was updated to include the location of the EPFL.