Understanding Childhood Trauma and the Brain

“Our early emotional stories determine the body and brain’s operating system and how well they will be able to guard our optimal physical and emotional health all of our adult lives.”

Many kids who undergo trauma endure victimization and negativity in their surroundings. For a child, enduring abuse is often the only option, especially if it’s inflicted by a trusted person—like a parent, sibling, teacher, or clergy member—which shatters the foundation of trust for a lifetime.

Children facing repeated trauma often show a common pattern of disorders like regulatory issues, attachment problems, hyperactivity, conduct disorders, or a mix of conduct and emotional issues from early childhood through adolescence.

Moreover, many symptoms of disorders in childhood often persist into adulthood. When a young child encounters emotional adversity or stress, the brain releases a hormone that shrinks the developing hippocampus, affecting their ability to process emotions and manage stress throughout life.

This blog will discuss how childhood trauma changes and affects the brain.

How Does Childhood Trauma Affect The Brain?

MRI studies reveal that as childhood trauma scores increase, key brain processing areas like the prefrontal cortex (linked to decision-making), the amygdala (how we process fear), and sensory association cortices and cerebellum (impacting emotion regulation) have smaller cerebral gray matter or brain volume.

Other studies found that the smaller amygdala (a part of the brain) is more active for grown-ups who had a tough childhood. The front parts of their brain work differently, making them super sensitive even to tiny stressors in everyday life.

The Brain & Inflammation

Continuous, early stress that’s unpredictable can start a process of mild swelling in the brain itself. When we’re constantly stressed, the brain reacts by causing a state of neuroinflammation. This kind of inflammation happens because of a brain cell called microglia.

Why Microglia Matters

Our microglial cells make up about one-tenth of our brain cells. Scientists used to think these microglia cells were just there to clean up things we didn’t need, like taking out the trash. But it turns out that microglia also play a crucial role in trimming our brain’s neurons and in brain development.

They play a vital role in the brain’s regular operations, constantly scanning their surroundings, figuring out, “Are things okay here? Or not so great? Are we safe? Or not safe?” They tell us to turn on the lights, get out of there, etc.

Needless to say, microglia don’t like chronic, unpredictable stress. Microglia goes off-kilter in the face of chronic, unpredictable stress. They get pretty agitated and release chemicals that cause inflammation in the brain.

This under-the-radar, ongoing chronic neuroinflammation can cause changes that set the brain’s tone for life. If microglia go off balance, they might cut away neurons—basically, getting rid of the brain cells we need.

When Microglia Kills

In a healthy brain, microglia manage the number of neurons the cerebral cortex requires. However, when microglia are unhappy, they might overly cut away cells in regions crucial for basic executive functions, such as reasoning and impulse control. They are essential in a healthy brain but can start eating away at the brain’s synapses in the face of chronic, unpredictable stress.

When the microglia destroys healthy neurons, it can trigger depression, anxiety disorders, and even more extreme psychopathology, such as schizophrenia and Alzheimer’s disease.

Microglia might also trim a specific set of neurons in the hippocampus that have the unique ability to regenerate. We once believed that we couldn’t create new neurons, but in the last decade, we discovered new neurons are constantly being born in the hippocampus. The growth of these new neurons is crucial for adult mental health, and if something disrupts their growth, it leads to depression.

When Microglia Lives In A Healthy Brain

Scientists recently put healthy microglia back into a mouse brain, and the outcome was remarkable: once the mice brains were filled with microglia, all signs of depression vanished. So much relies on our brain’s microglia being content and undisturbed.

When the hippocampus loses healthy neurons, our emotional well-being will suffer in the long run. Experiencing repeated and unexpected stress in childhood prompts microglia to cut away essential neurons, triggering a state of neuroinflammation that sets the brain’s tone, creating conditions for lasting anxiety and depression.

A Perfect Storm: Childhood Stress, Brain Pruning, and Adolescence

When we’re very young, we have more neurons and connections than we need. As children enter adolescence, they naturally go through a phase of trimming down unnecessary neurons. Some of these connections naturally die off to help us “quiet down” the brain and improve our skills in things that capture our interest.

However, if childhood stress has already removed many neurons and synapses when the natural pruning of adolescence begins—there might be too much trimming happening all at once.

Dan Siegel, MD, a child neuropsychiatrist and clinical professor at UCLA, is a leader in the growing field of interpersonal biology, blending neuroscience and psychology. Siegel explains, “Stress from Adverse Childhood Experiences harms the neurons and neural pathways that connect different parts of the brain.”

During adolescent pruning, changes occur in the integrated circuitry among the hippocampus (important for memory), corpus callosum (linking left and right brain hemispheres), and prefrontal cortex, significantly impacting decision-making, self-regulation, attention, emotional regulation, thoughts, and behavior.

According to Siegel, these circuits are influenced by adversity and genetic vulnerability during preadolescence. Then puberty arrives, adolescent pruning trims down the already insufficient number of integrated fibers, making a child susceptible to mood dysregulation.

An Example of How Childhood Stress, Brain Pruning, and Adolescence Plays Out

Imagine, let’s say, all kids start with 5,000 neurons (only for an example). Now, consider two six-year-old girls, Samantha and Jill. Samantha experiences early adversity, while Jill doesn’t. Due to chronic, unpredictable stress, Samantha’s neurons are gradually trimmed away. By the time Samantha turns thirteen, with a lot of stress-related pruning, she’s left with 2,800 neurons.

She’s still doing fine; 2,800 neurons (in our hypothetical scenario) are sufficient because kids initially have more than they require. Then, Samantha and Jill both experience the adolescent phase of neuronal pruning. Like all kids, let’s assume that each loses another hypothetical 1,000 neurons during adolescence.

Samantha, raised in early chronic unpredictable stress, has a significantly different brain than Jill. The gap between Samantha’s brain and Jill’s trauma-free brain becomes pronounced. Jill, who had a relatively adversity-free upbringing, still has his 4,000 neurons—plenty to lead a healthy and happy life. Meanwhile, Samantha is left with only 1,800 neurons.

And that makes a significant difference. Samantha barely has enough for basic brain function, let alone enough to maintain a healthy state. For children who have already experienced pruning due to early stress, Siegel clarifies, “When typical adolescent pruning happens, what’s left is insufficient to maintain our moods in balance. If stress levels are high, this pruning process may be even more intense, leading to a further reduction in the number and effectiveness of at-risk circuits.”

What Are The Long-Term Effects Of Trauma In Children?

A child who encountered Adverse Childhood Experiences is more prone to developing depression, bipolar disorder, eating disorders, anxiety disorders, or impaired executive function and decision-making—issues that can often lead to substance abuse.

This could explain why, statistically, many young people exhibit initial signs of depression or bipolar disorders during high school and college—even those who appeared perfectly fine just a year or two earlier. It also sheds light on why, according to the National Institute of Mental Health (NIMH), depression affects eighteen million Americans.

The World Health Organization has identified depression as the “leading cause of disability worldwide,” surpassing the combined impact of cancer, HIV/AIDS, and cardiovascular and respiratory diseases. This observation may also shed light on other brain-related health conditions.

For example, a recent study examining brain scans of individuals with chronic fatigue syndrome, or CFS—myalgic encephalomyelitis, or ME—reveals heightened inflammation in specific brain areas, including the hippocampus and amygdala.

The more a patient reports experiencing symptoms of chronic fatigue syndrome (CFS), the more visible the brain inflammation appears to be. This could contribute to the understanding of why individuals who have experienced Adverse Childhood Experiences are six times more likely to develop chronic fatigue in the first place.

What Are The Four Areas That Childhood Trauma Affects Most?

Affective and Physiological Dysregulation

Affected Areas: Control, Appropriate Response to Environment

Result: The child shows impaired developmental competencies in arousal regulation, with at least two of the following:

Difficulty modulating, tolerating, or recovering from extreme emotional states (e.g., fear, anger, shame), leading to prolonged tantrums or immobilization
Disturbances in regulating bodily functions (e.g., persistent issues in sleeping, eating, and elimination; heightened or reduced reactions to touch and sounds; disorganization during routine transitions)
Reduced awareness or dissociation from sensations, emotions, and bodily states
Impaired ability to articulate emotions or bodily states

Attentional and Behavioral Dysregulation

Affected Areas: Presence, Attention, Understanding of Environment, Behavioral Norms

Result: The child demonstrates impaired developmental competencies in sustained attention, learning, or stress coping with at least three of the following:

Preoccupation with threat or difficulty perceiving threat, including misinterpreting safety and danger cues.
Impaired ability for self-protection, involving extreme risk-taking or thrill-seeking.
Maladaptive attempts at self-soothing.
Habitual (intentional or automatic) or reactive self-harm.
Inability to initiate or sustain goal-directed behavior.

Self and Relational Deregulation

Affected Areas: Healthy Attachment, Healthy Self-Image, Appropriate Social Behavior

Result: The child displays impaired developmental competencies in personal identity and relationship involvement, with at least three of the following:

Intense preoccupation with the safety of caregivers or loved ones or difficulty tolerating reunion after separation
Persistent negative self-perception, including self-loathing, helplessness, worthlessness, ineffectiveness, or defectiveness
Extreme and persistent distrust, defiance, or lack of reciprocal behavior in close relationships
Reactive physical or verbal aggression toward peers, caregivers, or other adults
Inappropriate (excessive or promiscuous) attempts to achieve intimate contact, including sexual or physical intimacy or excessive reliance on peers or adults for safety and reassurance.
Impaired capacity to regulate empathic arousal, as indicated by a lack of empathy or intolerance of others’ distress or excessive responsiveness to others’ distress

Functional Impairment

Affected Area: Achievement of Age-Appropriate Objectives and Behaviors

Result: The disturbance causes clinically significant distress or impairment in at least two of the following areas:

Scholastic: Under-performance, non-attendance, disciplinary problems, drop-out, failure to complete degree/credential(s), conflict with school personnel, learning disabilities, or intellectual impairment not accounted for by neurological or other factors
Familial: Conflict, avoidance/passivity, running away, detachment and surrogate replacements, attempts to physically or emotionally hurt family members, non-fulfillment of responsibilities within the family
Peer Group: Isolation, deviant affiliations, persistent physical or emotional conflict, avoidance/passivity, involvement in violence or unsafe acts, age-inappropriate affiliations or style of interaction
Legal: Arrests/recidivism, detention, convictions, incarceration, violation of probation or other court orders, increasingly severe offenses, crimes against other persons, disregard or contempt for the law or conventional moral standards
Health: Physical illness or problems not fully accounted for, physical injury or degeneration involving the digestive, neurological, sexual, immune, cardiopulmonary, proprioceptive, or sensory systems, severe headache (including migraine), or chronic pain or fatigue

A Generation Of Walking Wounded

It’s challenging to determine the number of adults who have undergone Adverse Childhood Experiences and are, each day, unknowingly navigating a state of low-grade neuroinflammation. They function despite the “reset tone” in their brains, managing general low mood, depression, and anxiety.

This reduced “set point of well-being,” this overall emotional distress, remarkably predicts our likelihood as adults to experience mood fluctuations, anxiety, sadness, and fear. It means reacting to life without resilience rather than truly embracing and living life to the fullest. It’s like the classic cat chasing its tail scenario.

Life’s epigenetic changes lead to an increase in inflammatory chemicals. Chronic unpredictable stress disrupts microglia. Microglia eliminate neurons. Neurons perish, and synapses struggle to connect. Microglia multiply, inducing a state of neuroinflammation. Vital gray matter regions of the brain experience a loss of volume and tone. White matter, the myelin in the brain enabling synapses to connect between neurons, diminishes.

This reduction in brain tone hampers thought processes, increasing the likelihood of negative thoughts, fears, reactivity, and worries over time.

An overly alert and fearful brain triggers more negative reactions and thoughts, generating additional inflammatory hormones and chemicals. This, in turn, results in further microglial dysfunction, pruning, and chronic inflammation in the brain. The cycle perpetuates.

Symptoms of Severe Childhood Trauma

Neuroinflammation is an uncontrolled process fueling chronic overreactivity. Situations that most people would quickly overcome can plunge someone with low-level inflammation into a tailspin.

Individuals experiencing chronic neuroinflammation may struggle to think rationally about their surroundings—interpreting situations more negatively and finding it challenging to discern whether the current circumstances are positive or negative.

The reactive brain and heightened stress sensitivity developed in childhood accompany us throughout life, influencing our mental and physical well-being, often leading to persistent negative feelings.

Chronic neuroinflammation increases the likelihood of persistent irritability, making us easily annoyed and negatively impacting our relationships as we perceive hurt where none is intended. Our chances for a healthy, stable, and satisfying life shrink and continue to shrink as we get older.

This Is Depressing… Is There Anything We Can Do About It?

Researchers have discovered ways to intervene in the biological embedding of childhood adversity, offering hope for reversing the damage caused by early stress, regardless of the family environment we grew up in.

The remarkable aspect of epigenetics is its reversibility, and the brain’s plasticity allows us to overcome early negative changes. We can rehabilitate the brain through various methods, restoring its ability to respond normally to pleasure and pain. The brain can heal itself, regardless of our early experiences.

We can heal the scars from our early experiences and rediscover our true selves!

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Understanding Childhood Trauma and the Brain: Unraveling the Impact