Why do some people experience PTSD after trauma?

Key points:

• 5.7 percent of Australians have experienced post-traumatic stress disorder in the last year

• The National Disability Insurance Scheme does not fund the treatment of psychosocial disability, but people may be eligible for access to NDIS-funded support services to carry out day-to-day tasks

• New research has found that some people may be more likely to develop PTSD in response to trauma than others based on hormones in the human body

Researchers studying post-traumatic stress disorder have revealed new behavioural and biological traits associated with PTSD vulnerability, offering insight into why some people develop the anxiety disorder after trauma while others don’t.

The research, centred on the body’s stress hormone response, could pave the way for more targeted treatments for PTSD.

The new study focused on ‘glucocorticoids,’ which are hormones produced from the cortex of adrenal glands, that the human body releases in response to stressful situations. Scientists found that patients with PTSD frequently had low glucocorticoid levels following a response to trauma.

Glucocortioids help to bring the body back to a state of normalcy after a stressful event — leading scientists to believe that people who develop PTSD have lower levels of the hormone after they develop the condition.

“Low glucocorticoid levels are frequently observed in PTSD patients following trauma exposure and were initially suspected to be a consequence of trauma exposure,” Carmen said.

Spanish and Swiss behavioural neuroscientist Carmen Sandi, who led the study alongside Simone Astori at the Swiss Federal Institute of Technology in Lausanne, wondered whether some people who had naturally lower levels of the hormone could be at risk of developing PTSD.

“The possibility that this could be a trait constituting a preexisting PTSD risk factor has been an outstanding open question for many years, but tackling it has been challenging due to the difficulties of both collecting biological measures before trauma exposure and having access to relevant animal models in which the causal role of these traits can be investigated.”

The study involved training a genetically selected group of rats to mimic the human brain and its response to fear, using scans of the human brain as a model.

They found that a reduced hormonal response to fear led to issues with ‘fear extinction,’ which means an inability to process and let go of something scary or traumatic. The rats also showed other signs of PTSD, including less deep sleep each night and disturbances in brain region volume that are tied to behaviour, emotion and thoughts.

However, the research went one step further and sought to treat the rats for their PTSD-like symptoms, using methods that could be significant for treating human patients.

Neuroscientists treated the rats with the equivalent of human cognitive and behavioural therapy to reduce their learned fears. After that, they gave the rats corticosterone, which is the rat equivalent to cortisol in humans. As a result, both excessive fear and disturbances in rapid-eye-movement sleep had improved, as did the stress levels.

The study’s first author, Silvia Monari, summarised that the discovery was groundbreaking for future treatment and shared understanding of PTSD, as it identified who may be at risk of developing the condition and why.

“In a nutshell, we present [new evidence] that having low glucocorticoids, such as cortisol in humans, is a condition for causally predisposed individuals to present all to-date vulnerability factors for developing PTSD and causally involved in deficits to extinguish traumatic memories.”

How do you deal with fear? Let the team at Talking Disability know your tips and tricks to calm down when faced with anxiety.