Why 'Peritraumatic Reactions' Are A Critical Piece Of The PTSD Puzzle

New research offers a new way of conceptualizing PTSD.

By Mark Travers, Ph.D. | October 5, 2021

A new article appearing in the Journal of Abnormal Psychology attempts to understand why certain memories from traumatic experiences are more likely to reappear as intrusive memories than others. The answer, according to the researchers, has to do with a difference in the way intrusive memories are encoded into long-term memory.

"Cognitive theories of post-traumatic stress disorder suggest that later intrusive memories of a traumatic event are partly caused by specific changes in how people felt, thought, and behaved during the event," comment the authors, led by Alessandro Massazza of University College London. "We provide support for this hypothesis by showing that the specific moments of the traumatic event later experienced as intrusive memories are characterized by different 'peritraumatic' reactions to those moments from the same trauma that did not intrude later."

A peritraumatic reaction, according to the scientists, describes the thoughts, emotions, and behaviors that people have during or immediately after a traumatic event. Some can be severe, such as dissociation (for example, thinking that what one is experiencing is not real or is a dream), distress (experiencing fear, horror, and/or helplessness during the event), and tonic immobility (not being able to move during the event).

To test whether intrusive memories about traumatic experiences were more likely to stem from certain types of peritraumatic reactions, the researchers recruited 104 survivors of the 2016-2017 Central Italy earthquakes to take part in an in-person study. They asked participants whether they had experienced any intrusive memories about the trauma and, if so, to rate the memory on the following five dimensions of peritraumatic reactions: somatoform dissociation, mental defeat, cognitive overload, distress, and immobility.

"Intrusive memories can only be remembered involuntarily and are triggered by internal (e.g., thoughts or emotions) or external (e.g., objects) things that bear some connection to the traumatic event," states Massazza. "For example, an earthquake survivor might experience an intrusive memory of their collapsed house when passing by a construction site."

The scientists also asked survivors to identify and describe other memories of the earthquakes that were just as distressing as intrusive memories but that had never spontaneously intruded. This way, they could compare the peritraumatic reactions of the intrusive traumatic memories to the peritraumatic reactions of the non-intrusive traumatic memories.

They found that severe peritraumatic reactions were more likely to appear in intrusive memories than non-intrusive memories.

"As hypothesized, moments experienced as intrusive memories were associated with higher levels of all peritraumatic reactions, except for mental defeat, when compared to moments from the same trauma experienced as distressing, but non-intrusive, by the same participants," state the authors. "These findings support the importance of peritraumatic encoding for intrusive memories."

The scientists believe these findings hold promise for developing new and effective forms of PTSD treatment.

"Our results have various practical implications for clinicians and people with lived experience of PTSD or trauma," says Massazza. "They suggest that peritraumatic reactions may play an important role in the development of intrusive memories, a hallmark symptom of PTSD. Therefore, interventions that aim at diminishing negative peritraumatic reactions during or immediately after a traumatic event (e.g., psychological first aid) are likely to hold potential in preventing the development of intrusive memories."

An interview with Alessandro Massazza discussing his research on PTSD and intrusive memories can be found here: Where do intrusive thoughts and memories come from?