It is well known that people who have experienced traumatic events such as assault, sexual assault or domestic violence can experience symptoms of post-traumatic stress disorder (PTSD), including terrifying flashbacks, intense anxiety and uncontrollable thoughts about the incident.
In sufferers of this disorder, the recall of traumatic memories is often intrusive and differs significantly from the processing of "ordinary" negative memories. What exactly happens in the brains of PTSD patients when they recall these events? Do they remember them in the same way as, for example, the loss of a beloved pet or a leisurely walk on the beach?
A new study led by Yale researchers finds that the brain activity evoked by memories of traumatic experiences in people with PTSD is actually significantly different than that seen by memories of sad or "neutral" life experiences.
In the study, which involved 28 different patients diagnosed with PTS, the researchers found that the brain patterns were consistent across all individuals when they recalled their more typical life experiences. But when recalling past traumatic events, neural responses vary widely among individuals.
Methodology and results
The study is the first to examine real-life personal memories, rather than looking at underlying cognitive mechanisms, to link personal experience to brain function. Their results support the notion that the traumatic memories that cause PTSD are an alternative cognitive entity that deviates from ordinary memory, and may provide a biological explanation for why the recall of traumatic memories often manifests as an intrusiveness that is profoundly different from "ordinary " negative memories in PTS patients.
Analysis of the brain activity of people with PTSD is also the first to reveal that traumatic memories are represented in the brain in a completely different way than sad personal memories.
"When people recall sad or neutral events from their past experiences, the brain exhibits highly synchronous activity among all PTSD patients," said Yale Professor of Psychiatry and Psychology Ilan Harpaz-Rotem, co-author of the paper. "However, when they are presented with stories about their own traumatic experiences, brain activity is highly individualized, fragmented and disorganized."
For the purpose of the study, the researchers asked each of the 28 participants a series of questions related to their traumatic experiences, events in their lives that caused sadness (such as the death of a family member), and moments when they felt calm. Each one's narrative was recorded and then read while they underwent an fMRI (functional magnetic resonance imaging) scan, which is used to map brain activity based on blood flow.
The researchers found that activity in the hippocampus—the area of the brain that forms memories of our experiences—followed similar patterns of activity in all participants when they were reminded of sad or relaxing experiences from their lives, suggesting typical normal memory formation. .
But when they were read stories about traumatic experiences, the similarities in hippocampal activity among group members disappeared. Instead, each subject's hippocampus demonstrated highly individualized and fragmented activity, in contrast to the more synchronous patterns of brain activity during normal memory formation.
The findings could explain why PTSD patients have difficulty recalling traumatic experiences in a coherent manner and offer an explanation for why these past experiences can trigger triggering symptoms, the researchers explain. These insights could help psychotherapists help PTSD patients develop narratives about their experiences that can help them eliminate the sense of immediate threat caused by the trauma. /BGNES
