According to the findings of the biggest prospective study of its type, persons encountering potentially risky scenarios who had less activity in their hippocampus experienced more severe posttraumatic stress disorder (PTSD) symptoms in the days and weeks after trauma.
This link between decreased hippocampal activity and the incidence of PTSD was more evident in people who had more automatic defence reflexes when shocked. This study, published in the journal JNeurosci, reveals that those who have stronger defensive reactions to potentially hazardous events may have a more difficult time determining whether an experience is harmful or safe.
They are also more prone to suffer from severe types of PTSD, which include symptoms such as being constantly on the lookout for danger, self-destructive behaviour such as binge drinking or driving too fast, difficulty sleeping and focusing, irritability, furious outbursts, and nightmares.
“These findings are important both to identify specific brain responses associated with vulnerability to develop PTSD, and to identify potential treatments focused on memory processes for these individuals to prevent or treat PTSD,” said senior author Vishnu Murty, PhD, assistant professor of psychology and neuroscience at Temple University.
This study is part of the nationwide Advancing Understanding of RecOvery afteR traumA (AURORA) Study, a multi-institution effort sponsored by the National Institutes of Health, non-profit funding groups like One Mind, and collaborations with leading technology firms. Samuel McLean, MD, MPH, professor of psychiatry and emergency medicine at the University of North Carolina School of Medicine and head of the UNC Institute for Trauma Recovery, is the organising primary investigator.
AURORA enables researchers to access data from patient volunteers who present to emergency departments at hospitals across the country after being involved in a vehicle accident or other significant occurrence. AURORA’s ultimate purpose is to encourage the creation and testing of prevention and therapy treatments for people who have been through traumatic situations.
Only a minority of trauma survivors develop PTSD, and PTSD is connected with greater susceptibility to dangers and a diminished capacity to engage brain regions storing emotional memories, according to AURORA scientists. However, it is unclear how these two processes combine to enhance the chance of developing PTSD. Murty and colleagues studied brain and behavioural responses in people two weeks after trauma to better understand these processes.
Researchers discovered that those with the least activity in their hippocampus and the largest defensive responses to shocking events following trauma had the most severe symptoms, using brain-imaging techniques in conjunction with laboratory and survey-based testing for trauma.
“In these individuals, greater defensive reactions to threats may bias them against learning information about what is happening so that they can discern what is safe and what is dangerous,” said Busra Tanriverdi, the lead researcher on the study and graduate student at Temple. “These findings highlight an important PTSD biomarker focused on how people form and retrieve memories after trauma.”
“These latest findings add to our list of AURORA discoveries that are helping us understand the differences between individuals who go on to develop posttraumatic stress disorder and those who do not,” said McLean, an author on the paper. “Studies focusing on the early aftermath of trauma are critical because we need a better understanding of how PTSD develops so we can prevent PTSD and best treat PTSD.”
“Since initiating our financial support of the AURORA Study in 2016, we remain steadfast in our commitment to helping AURORA investigators make important discoveries and to bridge the gaps that exist in mental health research funding and patient support,” said Brandon Staglin, president of One Mind.
