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What does repeated trauma do to the brain?

Trauma, especially when repeated or chronic, can have profound effects on the brain. Trauma occurs when a person experiences an overwhelming amount of stress that exceeds their ability to cope. Trauma can be caused by a single distressing event or repeated exposure to severe stressors over time. Examples of traumatic events include combat, sexual assault, physical abuse, accidents, natural disasters, and other threats to life or safety. When trauma happens repeatedly or continuously, it is considered chronic trauma. Some examples of chronic trauma are ongoing abuse, poverty, neglect, or growing up with family dysfunction.

The effects of trauma on the brain are complex and can lead to long-lasting changes in brain structure and function. Repeated trauma, especially during childhood when the brain is still developing, can alter the normal trajectory of brain maturation. This can have impacts on cognitive, emotional, and behavioral development that persist into adulthood. Understanding the neurological impacts of trauma is an important part of caring for trauma survivors and developing effective interventions.

How Does the Brain Process Trauma?

To understand how repeated trauma affects the brain, it is helpful to first consider how the brain normally processes and copes with stress. When faced with a threat, the body’s automatic stress response kicks in. The sympathetic nervous system activates the fight-or-flight response, leading to the release of stress hormones like cortisol and adrenaline. Blood pressure, heart rate, and breathing rate increase to prepare the body to fight the threat or flee to safety. The prefrontal cortex, the brain’s center for reasoning and decision-making, focuses the brain’s attention on assessing the threat.

Once the threat passes, the parasympathetic nervous system activates the rest-and-digest response to calm the body down. Stress hormone levels return to normal baseline levels. The prefrontal cortex shifts attention back to everyday activities. This coordinated process allows the body and brain to respond to threats when necessary, without remaining in an overly aroused state for too long.

Hyperarousal and the Traumatized Brain

In response to trauma, especially when it is repeated or prolonged, this coordinated stress response process can become dysregulated. The body and brain remain in a state of hyperarousal, with stress response systems activated much of the time. Cortisol and other stress hormones remain elevated, rather than returning to baseline. The prefrontal cortex stays hyperfocused on assessing threats in the environment. This ongoing hypervigilance and hyperarousal takes a toll on physical and mental health. It also fundamentally alters how the brain processes information and encodes memories.

Effects on Brain Structures

Chronic trauma exposure literally changes the structure of the brain. Brain imaging studies show alterations in the volume, connectivity, and activity of several areas of the traumatized brain, including:

  • Amygdala: This brain structure is central to detecting threats and triggering emotional responses. Repeated trauma leads to overactivation of the amygdala. It becomes hyperresponsive to even minor stressors, making it difficult to ever feel calm and safe.
  • Hippocampus: This brain region is involved in learning, memory formation, and spatial awareness. Chronic stress impairs hippocampal neurogenesis, the growth of new brain cells. This can impair memory capabilities.
  • Prefrontal cortex: As the brain’s center for complex thinking and decision-making, this area is pivotal to regulating emotions and behaviors. Trauma exposure leads to decreased volume and functional capacity of the prefrontal cortex, making it harder to manage stress reactions.
  • Corpus callosum: This band of nerve fibers connects the brain’s left and right hemispheres. Research shows it tends to be smaller in traumatized brains, reducing communication between hemispheres.

These structural brain changes correlate with the severity of post-traumatic symptoms, like hyperarousal, flashbacks, and difficulties with emotion regulation, attention, and decision-making.

Altered Neurotransmitter Function

The brain’s chemical messengers, called neurotransmitters, are also affected by trauma. Two key examples are:

  • Glutamate: This excitatory neurotransmitter is released in excess during the stress response. Too much glutamate can damage or kill neurons by overstimulating them. This neurotoxicity may play a role in some of the brain volume loss seen with chronic trauma.
  • Serotonin: Likely due to elevated cortisol, trauma survivors tend to have lower levels of serotonin. Since serotonin regulates mood, appetite, sleep, memory, and more, this can compound trauma-related mental health issues like depression, disordered eating, insomnia, anxiety, and cognitive problems.

Effects on Neurogenesis

The hippocampus contains neural stem cells that support neurogenesis. This process of growing new brain cells is pivotal to learning, memory, and overall brain plasticity throughout life. Chronic stress powerfully suppresses neurogenesis in the hippocampus and other limbic system structures. This impairs the brain’s ability to adapt – an effect that is visible on brain scans of trauma survivors. Boosting neurogenesis may be an important goal in treating trauma.

Childhood Trauma Affects Brain Development

The developing brains of infants and children are especially vulnerable to the effects of trauma. Early childhood is a time of rapid brain growth. Trauma interrupts crucial developmental windows, and the effects linger even after the child grows up.

Toxic Stress in Childhood

Stable, responsive relationships and safe environments are essential to healthy child development. If a child instead endures chronic trauma like abuse, neglect, extreme poverty, parental substance abuse, or family dysfunction, they experience “toxic stress.” Toxic stress activates the body’s stress response for prolonged periods during critical windows of brain development. This disrupts neural connections and the structural integrity of the developing brain.

Domains of Impairment

Research shows that children who suffer chronic toxic stress are likely to experience lifelong problems in several domains, including:

  • Cognitive functioning: Impaired learning, memory, attention, language, and executive functions like reasoning, problem-solving, and decision-making.
  • Emotional processing: Poor emotional control, anxiety, depression, anger issues, post-traumatic symptoms, and substance abuse.
  • Behavioral regulation: Difficulty managing impulses, aggression, high-risk behaviors, defiance, and conduct problems.
  • Social skills: Difficulties with healthy attachment, relating to others, recognizing social cues, and building interpersonal skills.

Physical Health Effects

Toxic stress during childhood also impacts physical health across the lifespan. It is linked to increased risk for:

  • Heart disease
  • Obesity
  • Diabetes
  • Cancer
  • Autoimmune diseases
  • Inflammation
  • Faster cellular aging

Intergenerational Trauma

Sadly, the adverse effects of childhood trauma often echo through generations. When parents have unresolved trauma, their dysregulated stress response systems and impaired self-regulation capabilities get passed down to their children biologically and environmentally. Trauma exposure in one generation diminishes resilience in the generations that follow. Breaking this cycle requires healing trauma at its roots.

Healing the Traumatized Brain

While trauma certainly changes the brain in detrimental ways, the brain also maintains the capacity for healing, adaptation, and growth throughout life. Understanding how trauma impacts the brain points to promising directions for treatment and recovery.

Therapeutic Approaches

Therapies that directly treat trauma’s disruption of the nervous system hold great promise for reversing the brain changes wrought by chronic stress. These include:

  • EMDR: This therapy uses bilateral stimulation like eye movements or tapping to “reprocess” traumatic memories that got stuck in the brain. EMDR helps the brain integrate the memories and make sense of the associated emotions.
  • Neurofeedback: By training the brain to consciously regulate brain wave patterns and alter neural pathways, this technique can reduce hyperarousal and anxiety.
  • Biofeedback: Visual and tactile feedback about the body’s stress response, like heart rate variability, teaches self-regulation skills to calm the nervous system.
  • Yoga and mindfulness meditation: These practices strengthen prefrontal cortex functioning and restore healthy cognitive control over the fear circuitry of the traumatized brain.

Lifestyle Factors for Brain Health

Daily life habits also support the traumatized brain’s recovery. Important factors include:

  • Sleep: Getting regular, high-quality sleep helps normalize cortisol and metabolize stress hormones. Lack of sleep maintains the brain in a hypervigilant state.
  • Exercise: Aerobic exercise and strength training stimulate neurogenesis, support nerve growth factors like BDNF, and reduce inflammation in the brain.
  • Nutrition: An anti-inflammatory diet full of antioxidants protects the brain. Probiotics and omega-3 fatty acids also improve cognitive functioning.
  • Social connection: Warm, caring human relationships build resilience against trauma’s effects. Social bonds stimulate oxytocin and neural growth.
  • Nature time: Spending time outdoors activates the parasympathetic nervous system. Nature has cognitive benefits and helps regulate brain chemicals.

Avoiding Retraumatization

Since the traumatized brain is so sensitized to stress, it is vital to minimize unnecessary stressors in daily life. Providing trauma survivors with accommodations and resources to reduce stress promotes healing. This may involve adaptations at home, school, or work. Establishing a sense of safety, predictability, and community are central to recovery.


Trauma, especially when repeated, sets off a cascade of changes in brain structure and functioning. These changes underlie many of the emotional, cognitive, physical, and behavioral symptoms seen in trauma survivors. The good news is that the brain remains capable of growth and adaptation across the lifespan. Understanding trauma’s impacts points the way toward therapies and lifestyle factors that can restore healthy brain functioning. Recovery is possible, but it requires comprehensive treatment tailored to addressing trauma’s pervasive nervous system disruption. With proper support, the traumatized brain has the inherent wisdom and resilience to heal.