The science of ACEs: What brain and body research can teach us

Many people have heard of Adverse Childhood Experiences (ACEs) but may not realise just how much early adversity can shape the brain, body, and overall health. Thanks to decades of research, we now know that childhood trauma isn’t “just in your head.” It leaves real, measurable imprints on the nervous system, the brain, and even long-term physical health.

The good news? Science also shows that healing and recovery is possible. Our brains and bodies are remarkably resilient, and with the right support, they can rewire, recover, and thrive.

What Are ACEs?

Adverse Childhood Experiences (ACEs) are potentially traumatic events that happen before age 18. These may include:

• Abuse (emotional, physical, or sexual)
• Neglect (emotional or physical)
• Growing up in a household with addiction, domestic violence, or mental illness
• Separation from a parent through divorce, incarceration, or death

The original ACE Study, conducted in the 1990s by the CDC and Kaiser Permanente, revealed a clear connection: the more ACEs a person experienced, the higher their risk for mental health struggles, chronic illnesses, and difficulties in adulthood.

How Adverse Childhood Experiences Affect the Brain

Childhood trauma often occurs during critical periods of brain development. Research shows that ACEs can impact:

• The amygdala (the alarm system): Becomes overactive, making it harder to feel safe and calm.
• The hippocampus (memory and learning): Stress hormones can shrink this area, affecting memory and focus.
• The prefrontal cortex (decision-making and regulation): Development may be slowed, making it harder to manage impulses and emotions.

This doesn’t mean the brain is damaged. It means the brain adapted to survive in a stressful environment. Later in life, those same adaptations can feel like obstacles.

The Body’s Stress Response to ACEs

The body reacts to ACEs through the stress response system (the “fight, flight, or freeze” response). When a child faces ongoing adversity:

• The stress response gets “stuck on,” flooding the body with cortisol and adrenaline.
• The immune system and cardiovascular system stay on high alert, increasing risk of conditions like heart disease, diabetes, and chronic pain.
• Sleep, digestion, and hormone regulation may all be disrupted.

This is why ACEs are linked not only to emotional challenges but also to physical health issues.

The Role of Resilience and Healing

Here’s the hopeful part: the brain and body can change. This concept is called neuroplasticity, which refers to the ability of the brain to form new pathways and heal over time.

Research shows that resilience factors, such as:

• Stable, supportive relationships
• Therapy and trauma-informed care
• Mind-body practices like mindfulness, yoga, or breathwork
• Healthy lifestyle choices such as sleep, nutrition, and exercise

…can help reduce the long-term effects of ACEs and promote healing.

How Therapy Helps with ACEs

Therapy provides a safe place to:

• Process difficult experiences at your own pace
• Learn calming strategies to regulate the nervous system
• Reframe old survival patterns that no longer serve you
• Build healthier relationships rooted in trust and connection

Healing is not about erasing the past. It’s about giving your brain and body new ways to feel safe, connected, and resilient.