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Invisible wounds: How trauma affects the brain

Understanding the physical impact on the brain can help destigmatize trauma-related injury and mitigate the impacts of trauma


“Science proves that trauma exposure has a tangible impact on the brain, and even though we can’t observe it on the surface, the brain can also experience a physical injury,” writes Bartlett.

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By Brooke Bartlett, Ph.D.

It’s no secret that trauma exposure is par for the course for first responders.

Despite the plethora of scientific evidence showing that trauma exposure can cause poor mental and physical health outcomes (e.g., Sowder et al., 2018), there’s still a pervasive misconception in first responder culture that managing trauma-related symptoms is merely a matter of willpower. This misconception only serves to bolster the cultural stigma that merely experiencing trauma-related symptoms and/or seeking help for them is a sign that someone is weak, “crazy,” unfit for duty, or similar judgments.

One way to help overcome this misconception and combat the stigma is to share the science behind how trauma affects the brain. Perhaps then people will understand that willpower is hardly a suitable option.

What is trauma exposure?

There are two types of trauma exposure, which we’ll call “Big T” trauma and “Small T” trauma.

“Big T” trauma is defined as exposure to actual or threatened death, serious injury or sexual violence (American Psychiatric Association, 2022). This exposure can occur through direct experience, by witnessing it happening to others, by learning that it occurred to a close family member or friend, or by experiencing repeated exposure to aversive details of traumatic events through the job.

Examples of “Big T” trauma include:

  • Physical or sexual abuse in childhood or adulthood
  • Recovering dead bodies
  • The suicide of a close friend or family member
  • Dispatching a call from a victim in an active emergency
  • The line of duty death of a crewmember
  • Responding to an active wildfire
  • Using force to resolve a criminal incident that results in physical harm or death to the suspect

“Small T” trauma involves highly distressing events that affect people on a personal level but that are not inherently threatening to life or bodily integrity. They can exacerbate the effects of a “Big T” trauma and over time can accumulate and mimic reactions of “Big T” trauma.

Examples of “Small T” trauma include:

  • Infidelity
  • Divorce
  • Losing a child custody battle
  • Emotional and psychological abuse (e.g., name-calling, manipulation, gaslighting)
  • The death of a loved one (e.g., a grandparent)
  • The death of a beloved pet

Common reactions to trauma

Needless to say, experiencing “Big T” and “Small T” traumas can affect how we feel and act. The following are some common reactions that someone may notice after experiencing some type of trauma:

  • Irritability and anger
  • Intrusive thoughts and memories
  • Diminished pleasure and enjoyment in activities that you used to enjoy
  • Decreased motivation
  • Feeling disconnected from others
  • Forgetfulness
  • Withdrawing from friends and family
  • Engaging in reckless or self-destructive behavior
  • Increased substance use
  • Avoidance of certain people, places and situations
  • Always feeling “on edge”
  • Poor sleep
  • Being extra jumpy

Many first responders experience one or more of these reactions at some point during their career. What’s important to remember is that these reactions do not occur in a vacuum. While the reactions themselves might be noticeable to an outside observer, the neural processes that are causing them are not.

Trauma and the brain

The following three brain structures are the key players when addressing trauma exposure and its impact on the brain.

Amygdala: The amygdala is one of the most primitive parts of our brain. It has one purpose and one purpose only – to protect us from harm and ensure our survival. When the amygdala perceives a threat, it sets off an involuntary, neurobiological stress response. In other words, the amygdala is our body’s natural alarm system. Because the amygdala is tasked with arguably the most important job of all (keeping us alive), it is the loudest structure in the brain, and when activated, its functions take precedence over our other brain structures.

With posttraumatic stress injury, the amygdala becomes overreactive and completely overrides the functioning of other parts of the brain, preventing them from doing their jobs.

Prefrontal cortex (PFC): The PFC helps us think logically and rationally, regulates our emotions so that we don’t succumb to fits of rage, and helps us control our impulses so that we don’t do or say things that we regret, particularly when emotions are high. The PFC also turns off an activated amygdala, which allows the rest of the brain to resume its functioning.

With posttraumatic stress injury, the PFC is weakened due to a decrease in neuronal branching (Bremner, 2006), which makes it under reactive.

Hippocampus: The hippocampus is the memory center of the brain. It can be thought of as a highly organized filing cabinet that regulates learning and helps us store information into long-term memory so that we can retrieve it later. It also assists with concentration, focus and motivation.

With posttraumatic stress injury, the size of the hippocampus literally shrinks, and it is unable to properly store and retrieve memories and information (Bremner, 2006).

A brain that is severely injured by posttraumatic stress will eventually begin to malfunction. The overreactive amygdala will “scream” danger as loud as possible at all times (even when there is no objective threat present), and the one structure that has the power to tell it to stop (the PFC) is no longer capable of doing so. Thus, hypervigilance, anger and impulsivity reign. Moreover, the hippocampus is atrophied, and the contents of its previously meticulously organized filing cabinets are metaphorically strewn across the floor. This makes it difficult to recall and organize information correctly, including how to cope with acute distress in healthy ways.

Trauma takeaways

There are several key points to observe and accept about trauma in this context:

  1. Overcoming the effects of trauma is not a matter of strength or willpower. Traumatic stress has a tangible and observable impact on our most complex organ – our brain.
  2. Being affected by trauma is normal. Having trouble sleeping after a heart-pumping structure fire is normal. Feeling a mixture of difficult emotions after responding to a triple homicide is normal. These are normal reactions to abnormal events. It is completely unrealistic (and, frankly, inhuman) to expect that you will be completely unphased and unaffected by the trauma of the job.
  3. Posttraumatic stress injury is not a lifelong sentence. The brain is malleable and never stops changing in response to learning, thanks to a superpower we are all born with called neuroplasticity. Neuroplasticity promotes the ability to recover from trauma or brain damage, helps us learn new things, and strengthens areas where function is lost or has declined (Kaczmarek, 2020).

Openly discussing these points are key to reducing the stigma associated with experiencing trauma-related symptoms.

How to mitigate the effects of trauma

When we understand the power of our brain activity in response to trauma, we can take actions to help mitigate its impact.

Seek treatment: While trauma symptoms are normal reactions to abnormal events, it’s important to recognize when it’s time to seek help. If symptoms worsen and begin negatively affecting your life, then treatment may be the best approach. There are several treatments that are scientifically proven to reduce trauma-related symptoms, including cognitive processing therapy (CPT), prolonged exposure (PE), and eye movement desensitization and reprocessing (EMDR). These treatments are short-term (6 months or less) and highly effective.

Find a grounding technique: When you feel your stress response ramping up, deploying a grounding technique can help stop it by decreasing your heart rate and helping you regain control of your breathing. Examples of grounding techniques include diaphragmatic breathing, counting backward from 100 in intervals of 7, and using a “stress relieving” tool (e.g., Rubik’s cube).

Engage in relaxing activities: Because of the high stress nature of the job, it’s important to proactively take advantage of opportunities to induce relaxation when off the job. Have a wide variety of activities that (1) relax your brain (e.g., going for a bike ride), (2) relax your body (e.g., doing a crossword puzzle), and (3) relax both (e.g., taking a candlelit bath). Be sure to limit activities that might produce stress, even if they are not directly harmful (e.g., watching the news before every shift).

Exercise regularly: Physical activity reduces the release of stress hormones such as adrenaline and cortisol. It also increases the release of “feel good” hormones known as endorphins, which improves mood, promotes relaxation and sleep, and increases your ability to cope with stressful scenarios.

Final thoughts

If you’ve previously beat yourself up for being affected by the job, stop. Remember, trauma reactions are normal responses to abnormal events. If your trauma-related symptoms are causing issues in your life, know first and foremost that you are not alone, crazy or weak, and there are plenty of options for help.

Science proves that trauma exposure has a tangible impact on the brain, and even though we can’t observe it on the surface, the brain can also experience a physical injury. So, why is it that a sprained ankle that occurred as a direct result of the job is taken seriously, but a brain injury that developed over time as a direct result of the job is not? It’s time we reverse this thinking and start viewing trauma-related brain injuries and job-related physical injuries in the same light. Spreading the word about the science of the brain and trauma is imperative for destigmatizing its effects. When we reduce stigma, we increase help-seeking behavior and protect against worsened mental health issues.

About the author

Brooke Bartlett, Ph.D., is a licensed clinical psychologist and the CEO/owner of Center for Trauma, Anxiety, and Stress Inc. In addition to being a trauma specialist, Dr. Bartlett is highly specialized in working with first responders and military veterans and has contributed extensively to the scientific research of trauma psychology among these two populations. A major focus of her professional work is promoting first responder wellness by assisting agencies in the creation and implementation of mental wellness programs through training, consultation and on-call critical incident services. Dr. Bartlett is also a professor of psychology at several higher education institutions. To learn more about Dr. Bartlett, visit her website or connect with her via LinkedIn or email.


  1. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, Fifth edition, Text Revision. Washington D.C., American Psychiatric Association, 2022.
  2. Bremner J. D. (2006). Traumatic stress: effects on the brain. Dialogues in clinical neuroscience, 8(4), 445–461.
  3. Kaczmarek, B. L. (2020). Current views on neuroplasticity: what is new and what is old?.Acta Neuropsychologica, 18, 1-14.
  4. Sowder, K. L., Knight, L. A., & Fishalow, J. (2018). Trauma exposure and health: A review of outcomes and pathways. Journal of Aggression, Maltreatment & Trauma, 27(10), 1041-1059.