depressed man with hormone issues

Why doesn’t everyone who experiences trauma develop PTSD?

Throughout the world, billions of people live through traumatic events. While some of these individuals develop posttraumatic stress disorder (PTSD), the vast majority don’t.

Through the years, experts have identified a variety of genetic and environmental factors that increase or decrease risk for PTSD. Two recent studies add important factors to this list:

  • A team from Switzerland’s Ecole Polytechnique Fédérale de Lausanne (EPFL) found hormones may play an integral role in PTSD risk
  • Researchers from Texas A&M University found greater activation in the prefrontal cortex after a traumatic event may protect people from the long-term effects of PTSD

If additional research supports these findings, substantial advances in diagnosing and treating PTSD may follow.

How Common Are Trauma & PTSD?

Billions of people around the world experience trauma – that’s no exaggeration.

An analysis of survey responses collected through the World Health Consortium show the global prevalence of trauma:

  • 4% of adults report at least one traumatic experience in their lifetime
  • 5% of adults report four or more traumatic experiences

Most traumatic experiences do not cause PTSD. For example, the National Center for PTSD reports that about 6% of the population will develop PTSD.

Currently, the global population includes about 5.8 billion people ages 15 and above. This means:

  • About 4 billion people over 15 experience trauma
  • Over 1.7 billion people over 15 experience trauma four or more times.
  • About 348 million individuals ages 15 and above develop PTSD.

Applying these percentages to the United States, where the current adult population is about 261 million, yields the following:

  • 183 million may have a history of trauma
  • 79 million may have experienced four or more traumatic events.
  • 6 million are likely to have PTSD

Clearly, PTSD is not rare. Improvements in treatment could increase quality of life for hundreds of millions of people around the world. Understanding why so many people don’t progress from trauma to PTSD may be a key to these improvements.

Can Hormone Levels Predict PTSD?

The EPFL study that we mentioned above assessed the role that glucocorticoids (naturally produced steroid hormones) play in the development of PTSD.

The research team used several evaluation tools, including magnetic resonance imaging (MRI) scans, to evaluate levels of glucocorticoids and other hormones in the brains of rats that had been trained to respond with fear to a certain cue.

  • Previous theories held that trauma causes low glucocorticoid levels, smaller volume of the hippocampus (an area of the brain that is part of the limbic system), and poor sleep patterns.
  • This study suggests these characteristics are present before a traumatic experience, they may be risk factors for PTSD, rather than consequences.
  • The team reported glucocorticoids affect both hippocampal volume and sleep patterns, which reinforces the influential role that these hormones play.

“Our study provides causal evidence of a direct implication of low glucocorticoid responsiveness in the development of PTSD symptomatology following exposure to traumatic experiences,” Carmen Sandi, one of the study’s lead authors, said in a Nov. 7 press release.

“In addition, it shows that low glucocorticoids are causally implicated in the determination of other risk factors and symptoms that were until now only independently related to PTSD,” Sandi added.

How Is Brain Activity Linked to PTSD?

In the second study that we mention above, researchers noted that 40 percent of people develop some symptoms of posttraumatic stress disorder after trauma, but in most cases, the symptoms subside before they develop PTSD.

Their research effort involved conducting brain scans on 104 adults trauma survivors. Each trauma survivor underwent three brain scans. The first scan occurred one month after their accident, the second occurred five months later, and the third took place 14 months post-trauma.

The team found that subjects with increased activation in a specific region of the brain during their first scan were more likely to overcome initial PTSD symptoms. Dr. Israel Liberzon explains the phenomenon in a recent news release:

“[G]reater activation in right inferior frontal gyrus, a region linked to cognitive control and emotional reappraisal, predicts better recovery from early PTSD symptoms. These findings highlight the key roles of cortical/cognitive regions in regulation of fear and in PTSD development.”

The right inferior frontal gyrus, or rIFG, is associated with functions such as inhibition, attention, language processing, and the suppression of emotional memories.

Other research teams previously examined the relationship between this area of the brain and PTSD.

A January 2021 study in the European Journal of Psychotraumatology found the brains of trauma-exposed individuals had a “significantly larger” volume of white matter near the rIFG than subjects without a recent history of trauma.

Based on this data, the research team theorized:

  • Increased white matter in the rIFG may compensate for pre-trauma difficulties with inhibition and emotion regulation.
  • People who exhibited deficiencies with inhibition and emotion regulation prior to a traumatic event may not respond well to trauma.
  • These individuals may rely on avoidance as a coping strategy.

“Practical implications of our results might be specifically targeting and reducing the use of expressive suppression during PTSD treatment,” they wrote. “However, further research is needed to better understand how white matter abnormalities may be associated with inhibitory control processes and maladaptive emotion regulation in the development and maintenance of PTSD.”

Will These Findings Affect PTSD Treatment?

This research may lead to breakthroughs in the prevention, diagnosis, and treatment of PTSD. However, considerable research is needed before insights into glucocorticoid levels, brain activity, and white matter volume are reflected in direct patient care.

That doesn’t mean that these and similar studies don’t offer immediate, present-day benefits, though.

For example, as researchers continue to learn more about the neurobiology of PTSD, these ongoing advances may lead to more widespread understanding of PTSD.

Though public awareness has increased considerably in recent decades, some people still cling to the myth that PTSD is a sign of weakness or flawed character. In addition to promoting stigma, this misinformation prevents people from getting the professional care they need.

These types of studies also help to break down the barrier that some people believe separates physical and mental health.

The phrase “it’s all in your mind” – once used to invalidate the experience of trauma survivors – now means we know that PTSD and many other mental health concerns are related to observable factors such as hormone levels, genetic variations, brain structure, and central nervous system activity – in the mind.

Identifying physical components of mental health disorder add evidence to the fact that seeking treatment is not an admission of weakness,  but rather a sign of wisdom and strength. We don’t judge people who develop diabetes, arthritis, or other medical conditions, and we shouldn’t judge people with mental health disorders.