Reduced hippocampal activity has been linked to increased PTSD risk
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The mechanisms of trauma in the human brain are numerous and results from numerous studies have proven than trauma can, in fact, change the structure of the brain. How we each individually respond to trauma in the days following a traumatic experience can shape how we go on to process and heal from that trauma. Now a research team has identified a pattern of reduced activity in the hippocampus that might be linked with increased risk of developing PTSD.
Written by Bryony Porteous-Sebouhian
The key to increased risk from trauma
Researchers from the University of North Carolina’s School of Medicine in the US have conducted the ‘largest prospective study of its kind’ regarding trauma and the brain’s response to trauma, their findings point to the initial days following a traumatic experience being a vital part of determining how a person will continue to deal with and process that trauma.
Researchers found that:
‘Individuals facing potentially threatening situations who has less activity in their hippocampus – a brain structure critical for forming memories of situations that are dangerous and that are safe – developed more severe posttraumatic stress disorder (PTSD) symptoms.’
Interestingly, there was an even greater association between reduced hippocampal activity and risk of PTSD in participants who displayed more severe involuntary defensive reactions to being startled, this is also known as the ‘startle response’, which can become overactive in people who have PTSD or complex PTSD (CPTSD).
What did the study find about startle responses and PTSD?
This new research, which has been published in the JNeurosci journal suggests that this overactive startle response in people with PTSD displays a possible inability to determine whether something is actually dangerous or safe.
Participants in the study who displayed this overactive startle response and reduced activity in the hippocampus were found to be more likely to experience severe forms of PTSD, which often include symptoms such as:
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This research is part of a national, multi-institution project that is looking into trauma, how it works and how people can recover from it: the AURORA Study.
Heading up the project is Samuel McLean, MD and professor of psychiatry and emergency medicine at the UNC School of Medicine, he is also the director of the UNC Institute for Trauma Recovery.
AURORA is utilising date from patients who enter emergency departments at hospitals to use that environment to identify people who could be helped with preventative treatment for trauma and PTSD.
Senior author of this particular study, Vishnu Murty PhD has spoken to UNC’s news team about the findings, saying:
“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.”
The study used brain-imaging techniques as well as surveying and tests, and found that there is a clear link between reduced activity in the hippocampus and a greater defensive response and startle response.
Bü?ra Tanriverdi, lead author on the study said that this link and the “greater defensive reactions”, “may bias them against learning information about what is happening so that they can discern what is safe and what is dangerous.”
Speaking to how this latest research fits into the wider scope of AURORA, Samuel McLean said:
“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. 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.”
PTSD and CPTSD can be extremely debilitating mental health conditions, and when untreated can lead to other diagnoses and issues such as substance misuse. However, if treat properly early on, and identified, a person can be helped to process their trauma and recover from it. It is because of this that research into preventative treatments for PTSD is essential.?