The Effects of Trauma on the Brain

“The simplest way of defining trauma is that it's an experience we have that overwhelms our capacity to cope.” - Dan Siegel, M.D.

“Fundamentally, every part of the brain, is affected by trauma.” - Bessel van der Kolk, M.D.

What happens in the brain during a traumatic event: The threat or perceived threat is observed, the sympathetic nervous system is activated, the heart rate goes up, blood flow to muscles increases, blood pressure increases, pupils dilate (this is fight or flight), It’s not always possible or safe to fight or escape, that’s when a person will freeze. The parasympathetic nervous system is activated as well, muscles get tight and freeze, gaze and breath may freeze. THIS IS NOT A COGNITIVE CHOICE. These decisions are made at the level of the brain stem and nervous system.

If the threat continues a person will shutdown completely. Their heart rate drops, respiratory rate drops, some will stop breathing, muscles become limp, metabolism shuts down, endorphins are released. The person enters a state of no pain and they are no longer aware of their surroundings. Some say it feels like they’ve left their body, they have disassociated. None of this is in your control, it is your biology.

When we experience trauma, the brain shuts down all nonessential systems and activates the sympathetic nervous system to help us survive the trauma. The brain releases stress hormones, cortisol and adrenaline. These hormones have a direct impact on brain function. Cortisol will shut off the way the hippocampus functions and adrenaline will increase the way the amygdala functions. Adrenaline increases the laying down of certain memories. Cortisol will decrease the integration of those memories because the hippocampus has receptors on it that respond to cortisol and shut it down. The periaqueductal gray, in the mid-brain, is the most primitive danger detection part of the brain. It’s always lit up when you’re a traumatized person, they’re always on alert for danger.

Trauma causes dis-regulation of thoughts and emotions causing one to overreact or underreact. If you’ve seen the movie The Hurt Locker, you observed how the main character kept putting himself, needlessly, in danger. He had no regard for his own safety. Was his job inherently dangerous, yes — however, he would go beyond, not taking any precautions. He also did not feel comfortable in his own home and it appeared he did not know what to do with himself. He inevitably sent himself back to a combat zone because he knew how to live in that state. This is an example of how one would perceive dangerous situations differently than most who have not been in such circumstances. Trauma changes the brain so a soldier is a specialist in danger but cannot handle day to day life at home due to changes in their frontal lobe.

Dr Bessel van der Kolk explains this well in the video - How Trauma Damages Specific Brain Networks. The Default Mode Network helps us process self-relevant information and helps us know what we're feeling inside. It also helps us to process our own memories and to think about the future. The Salience Network helps us figure out what's most important in our environment to respond to. The Executive Network helps us plan, think, concentrate and learn new information. Due to the impact of trauma these three networks do not function properly. A person may often zone out, have a difficult time being present, have a hard time concentrating, have trouble problem solving and have a poor short term memory. Experts believe the way to heal the brain from trauma is to obtain left and right brain integration. Ways this can be achieved is through mindfulness, Eye Movement Desensitization and Reprocessing (EMDR) and Cognitive Behaviour Therapy (CBT), to name a few.



Janine O'Keefe is a retired police officer with 14 years of experience. She has extensive training dealing with trauma, addictions and mental health. Janine was diagnose with PTSD from an Operational Stress Injury in 2020 which led her to leave the force. She continues to help people in a different capacity. Janine is currently working on her Integrative Health Coach Training to become a Mental Health Coach that specializes in helping people heal their trauma and PTSD. Janine is an empath and has training in the Akashic Records and is a Usui & Violet Flame Reiki Master. She currently offers Energy Healing Sessions and leads a Trauma & PTSD Support Group.


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