The Effect of Trauma on the Developing Brain

Child abuse is a rampant epidemic in the United States with millions of kids getting hurt every day. The ramifications of this abuse and neglect are long-lasting and possibly permanent.

What happens in the brains of traumatized children? The answer is that a traumatized child’s brain shrinks, and certain brain regions become compromised. Also, myelin production is interrupted leading to many mental and physical health disorders later in life.

This article will concentrate on trauma and its effects on young children as they grow.

Delving Deeper into Trauma

The Diagnostic and Statistical Manual of Mental Disorders (DSM) defines psychological trauma as:

“The direct personal experience of an event that involves actual or threatened death or serious injury; threat to one’s physical integrity, witnessing an event that involves the above experience, learning about unexpected or violent death, serious harm, or threat of death, or injury experienced by a family member or close associate.

Memories associated with trauma are implicit, pre-verbal and cannot be recalled, but can be triggered by stimuli from the in vivo (within the living person’s) environment. The person’s response to aversive details of traumatic event involve intense fear, feeling trapped, and feeling helpless. In children it is manifested as disorganized or agitative behaviors.” 

As you can see the DSM’s definition is very broad. However, there are several key elements worthy of mentioning. The definition is correct in saying that the person ears death or serious injury and a threat to their body. Also, please note that they have listed as a response to these emotionally stimulating events intense fear, helplessness, or horror. A person who has been traumatized may experience many of the following psychological and physical symptoms: 

  • Shock, denial, or disbelief
  • Confusion, difficulty concentrating
  • Anger, irritability, mood swings
  • Anxiety and fear
  • Guilt, shame, self-blame
  • Withdrawing from others
  • Feeling sad or hopeless
  • Feeling disconnected or numb  
  • Insomnia or nightmares
  • Fatigue
  • Being startled easily
  • Racing heartbeat
  • Edginess and agitation
  • Aches and pains
  • Muscle tension 

The causes of trauma in childhood are numerous and varied. A short list of possible causes is below: 

  • Unstable or unsafe environment 
  • Separation from a parent
  • Serious illness
  • Intrusive medical procedures
  • Sexual, physical, or verbal abuse
  • Domestic violence 
  • Neglect
  • Bullying 

It is important to remember that there is no right or wrong way to experience or express having endured trauma either as an adult or a child. We all respond differently to our circumstances. One person’s hang nail may be another person’s tragedy. It is all up to our individual abilities to handle stressors in our world.

Neurotransmitters, Hormones, and Stress

To fully understand what severe and repeated trauma does to the brains of young children, one must first learn some about the chemicals that neurons (brain nerve cells) use to communicate called neurotransmitters, and the brain structures most affected by them.

There are many important substances responsible for the activity in our brains, but we shall touch on just a few of these important chemicals and hormones.

Cortisol. Cortisol is a hormone that controls our reactions to stress. This stimulant gives us the energy to fight or flee in the face of danger.

Serotonin and Dopamine. These are neurotransmitters that affect our moods and behaviors. These chemicals trigger an increase in heart rate, blood pressure, and reduces blood flow to the gut. It also inhibits the body from releasing bodily wastes such as urine and feces. These responses are important to be ready to face danger.

Norepinephrine and Epinephrine. These neurotransmitters affect mood, behavior, and create the fight/flight/freeze response. This chemical mobilizes the brain and body for action by stimulating the necessary areas of the body needed to fight or flee. It is for responsible for raising awareness, alertness and vigilance.  It also enhances formation and retrieval of memory, focuses attention, increase restlessness and anxiety.

Glutamate. Glutamate is a neurotransmitter that excites nerve cells. In balance, it is required to organize our perception of our experiences.

Under normal circumstances, these chemicals allow us to move about in our environment very well. However, when young children experience repeated and extreme traumatic events the production of these chemicals is altered. Levels of cortisol are decreased, norepinephrine and epinephrine are elevated, and Serotonin decreases.

Prolonged exposure, such as in repeated and severe childhood trauma, can have dire consequences. There can be behavioral changes such as depression, fear, and lack of impulse control. Also, there can be an impaired perception of reality and changed filing of memories.

Because of existence of severe and repeated trauma, the imbalance of these chemicals interferes with the storage of declarative memories, so the child may not remember what happened, or if they do they do not remember correctly.

 Brain Structure Changes Caused by Trauma

The constant submersion of a child’s brain in stress hormones forever alters a child’s brain structure and its ability to function. The sizes of parts of the brain can be altered by continual bathing in the above substances, causing life-long changes that can alter the future of the traumatized child’s life.

One researcher found evidence of how a person’s brain is affected by childhood trauma. In 1993, he found brain abnormalities in 54% of children with histories of physical abuse, but only 27% in children who had no history of abuse. The numbers jump alarmingly when measuring children who have been sexually abused (Teicher 1993).

The research showed 72% of children with histories of this type of abuse with abnormal brains. The regions found to be most affected by trauma, not only in Teicher’s work, but in subsequent research are as follows:

The Hippocampus. This part of our brains is responsible for declarative memory, emotions and critical for learning. It allows us to process memories and manage the emotions that go along with them. Research has found a reduction in size of the hippocampi of adults who were severely traumatized as children of 19% (Bremner 1997) (Teicher et al. 2012).

The Amygdala. This structure is responsible for the unconscious storage and processing of emotions and initiating the flight/fight/freeze response.

The amygdalae of adults who were exposed to extreme and repeated trauma as children are often hypersensitive to the information received through the senses and can trigger a strong fear response even when there is currently no danger present.

A Failure to Communicate

The hippocampus and amygdala are meant to work together to form a cohesive memory of events. When there is extreme and repeated trauma in childhood, this communication is disrupted. Memories can either be enhanced or totally repressed, depending on the way these two vital parts of the brain interact.

There are many effects caused by this disruption of communication. One is the dysregulation of emotions. Since the amygdala senses danger when there is none, the hippocampus is hard-pressed to respond appropriately.

The child senses danger and this changes their molecular organization by changing their sensitivity and response bias. This means normal responses to stressors can be exaggerated. Increased fearfulness, anxiety, and  an enhanced hormonal response to stress.

Changes in the Myelination of the Brain

Changes in stress hormones affects normal myelination. Myelination is a process where a fatty substance, Myelin, is formed to help the brain communicate. Other functions of myelination and myelin are as follows::

  • Myelination affects and programs cell death plus the making new neurons and synapses.
  • Myelin changes the way the brain controls the cell death, an important cleaning and regulating process.
  • Myelin changes the ability of the brain to make new synapses and cells. This inhibits memory and other changes that enhance our experience of life.
  • Myelin acts as an insulator protecting brain cells from shorting out.

When myelin formation and distribution becomes limited or does not form correctly, the brain cells cannot properly communicate. This lack of communication is theorized to play a leading role in the formation of a myriad of mental and physical health problems including schizophrenia and multiple sclerosis.

Tying It All Together

The chemicals that we make in response to stress are important to our being able to escape or confront danger. However, when the developing brain of a young child is bathed in stress hormones that never return to normal levels, the results can be disastrous. Such is the case in children who live in traumatic environments where they are in constant danger physically, emotionally, or sexually.

Trauma affects this normal development of the brain, by interrupting through overstimulation of stress hormones, the ability of the brain to process memory, and the brain to communicate. While the survival center (brain stem) continues to keep us alive, the emotional center cannot regulate correctly what memories are stores where, and the hemispheres of the brain become fragmented in their ability to store information.

These changes are not reversible.

“Life isn’t easy… Sometimes, stuff happens that isn’t your fault, that you can’t control. It doesn’t mean you’ve failed or that or that you won’t fail again. It just means that you have to fight harder. You have to be stronger. You can’t let the bad stuff win. You have to keep getting up and moving forward even when you’re afraid to or you don’t think you can.” ~ Julie Miller


Bremner, J. D., Randall, P., Vermetten, E., Staib, L., Bronen, R. A., Mazure, C., … & Charney, D. S. (1997). Magnetic resonance imaging-based measurement of hippocampal volume in posttraumatic stress disorder related to childhood physical and sexual abuse—a preliminary report. Biological psychiatry, 41(1), 23-32.

Teicher, M. H., Anderson, C. M., & Polcari, A. (2012). Childhood maltreatment is associated with reduced volume in the hippocampal subfields CA3, dentate gyrus, and subiculum. Proceedings of the National Academy of Sciences, 109(9), E563-E572.

Teicher, M. H., Glod, C. A., Surrey, J., & Swett, C. (1993). Early childhood abuse and limbic system ratings in adult psychiatric outpatients. The Journal of Neuropsychiatry and Clinical Neurosciences.

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