New Study Shows How Glucocorticoid Levels Influence Who Develops PTSD

Despite advances in therapy, PTSD treatment often falls short, leaving many struggling. A new study suggests the answer might lie in our body’s stress hormones, potentially explaining why only some develop PTSD after trauma.

PTSD Patient.

PTSD Patient. Credit: Alex Green

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Because life is so unpredictable most of us will experience trauma at some point in our lives, but only 25 to 35 percent of people exposed to highly distressing events develop post-traumatic stress disorder (PTSD). According to a new study, a person’s vulnerability to this disorder may be determined by the amount of stress hormones in the body, offering a possible explanation for this discrepancy.

What are the symptoms of post-traumatic stress disorder?

People with post-traumatic stress disorder usually experience ongoing anxiety, meaning that their emotional reactions to dramatic events do not diminish over time. Other features of posttraumatic stress disorder include a reduction in the volume of the hippocampus – an area of the brain that plays a key role in memory and emotions – and sleep disturbances.

A study published in Biological Psychiatry has also shown that people suffering from PTSD often have Blunted Glucocorticoid Responsiveness.

“There are significant differences in the levels of glucocorticoids that individuals release into the blood when they are stressed,” study author Carmen Sandi explained. “Low levels of glucocorticoids are often observed in patients suffering from PTSD,” she continued.

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“The possibility that this is a characteristic that constitutes a pre-existing risk factor for posttraumatic stress disorder is a question that has remained unanswered for years,” she adds.

PTSD: the fundamental role of glucocorticoids

To finally get an answer, her team conducted experiments on rats genetically modified to have reduced corticosterone responsiveness to stress.

Brain scans showed that these rats had a reduced hippocampus, and recordings of brain activity also indicated problems with REM sleep. Moreover, after being conditioned to associate a sound with receiving an electric shock, the mice with low cortisol responses were less able to unlearn this association and continued to freeze with fear when they heard the sound.

These results indicate that ongoing anxiety, reduction of the hippocampus and sleep disturbances may be mediated by glucocorticoids and that people with low levels of these hormones may therefore be more vulnerable to post-traumatic stress disorder (PTSD).

To confirm the strength of this conclusion, the study authors injected mice with additional glucocorticoids and found that this reduced excessive anxiety and sleep disturbances in the animals.
The researchers concluded that the low presence of stress hormones “not only predicts but possibly causally contributes to the main symptoms of PTSD.”

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To know for sure whether humans would respond similarly, these results need to be reproduced in humans to confirm these hypotheses.

Final Thoughts

Although more research is still needed, by studying the role of stress hormones in PTSD, treatments can be tailored to regulate these hormone levels. This directly addresses a key factor in the disorder’s development and symptoms, potentially improving treatment efficacy and patient outcomes.


Monari, S., Guillot de Suduiraut, I., Grosse, J., Cash, D., Astori, S., & Sandi, C. (2023). Blunted Glucocorticoid Responsiveness to Stress Causes Behavioral and Biological Alterations That Lead to Posttraumatic Stress Disorder Vulnerability. Biological Psychiatry.



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