How childhood trauma changes your adult biology

Few things have as lasting an impact on adult health as what happened to us in childhood. Dr. Nadine Burke Harris, a pediatrician trained at Stanford and Harvard, has spent years studying how adverse early experiences translate into biological responses that can last decades. Her work has redefined what trauma means and, more importantly, what we can do about it.

What trauma actually is

Trauma is not the event itself but the body's biological response to it. This distinction changes everything. It does not matter whether you remember what happened; if your nervous system registered it as an overwhelming threat, it keeps responding accordingly. Infants and young children are especially vulnerable: even without conscious memories, their stress systems get wired from those early experiences.

Adverse childhood experiences (ACEs)

In 1998, the CDC and Kaiser Permanente published the ACE study with more than 17,500 participants. The ten categories analyzed included:

• Physical, emotional, or sexual abuse
• Physical or emotional neglect
• Growing up with a parent who had a mental illness, substance dependence, or a history of incarceration
• Parental separation or divorce
• Intimate partner violence in the household

The findings were stark: two-thirds of participants had experienced at least one ACE, and one in six had experienced four or more. People with four or more ACEs were 4.5 times more likely to experience depression, 2.5 times more likely to develop heart disease, and faced higher risk of autoimmune disease, asthma, and cancer. Only half of that risk was explained by health-damaging behaviors; the rest was a direct consequence of an overactive stress response.

How chronic stress affects the body

When we perceive a threat, the amygdala triggers the release of adrenaline and cortisol. The heart speeds up, blood rushes to large muscles, and the prefrontal cortex, responsible for judgment and self-control, shuts down. This fight, flight, or freeze mechanism is brilliant for surviving real danger but devastating when activated repeatedly without resolution.

A stress response kept on constant alert raises inflammation and weakens the immune system. This explains the link between ACEs and chronic diseases that seem unrelated to childhood. Behaviorally, it shows up as emotional reactivity, procrastination, difficulty concentrating, and recurring physical symptoms without apparent cause.

Buffering: how to rebalance the seesaw

Dr. Burke Harris introduces the concept of buffering to describe the interventions that help the nervous system regulate itself. It works like a seesaw: stress weighs on one side and regulatory practices weigh on the other.

The younger you were when you experienced adversity, the greater the imbalance: you need far more buffering to restore equilibrium. This explains why some people feel they have moved on, yet keep experiencing symptoms they cannot understand.

The seven evidence-based interventions Dr. Burke Harris included in the Surgeon General's report are:

1. Restorative sleep
2. Regular physical exercise
3. Adequate nutrition
4. Mindfulness and meditation
5. Active mental health support
6. Safe and stable relationships
7. Time in nature

Corrective experiences and neuroplasticity

Altered biology can adapt. Corrective experiences, those in which you receive what you were once denied, modify epigenetic markers and change how DNA is expressed. Studies with rats showed that the level of maternal care received altered stress reactivity and epigenetic markers even in subsequent generations, regardless of biological origin.

EMDR (eye movement desensitization and reprocessing) is one of the most evidence-backed therapies for creating these corrective experiences. Through bilateral stimulation, the brain can reprocess traumatic memories and generate new emotional responses to them.

Where to start

Dr. Burke Harris proposes the principle of "I'm here": showing up for yourself, consistently. This can begin with something as concrete as a 20-minute daily walk, a few minutes of conscious breathing in the morning, or writing in a journal.

Identifying one trusted person with whom you can be authentically vulnerable, even just one, is equally powerful. And if the stress response is significantly affecting your daily life, seeking specialized therapeutic support is not a luxury; it is part of the buffering process your nervous system needs.

Trauma is not a destination. Understanding its biology is the first step toward no longer living at its mercy.