Childhood Trauma and ACEs

What is Childhood Trauma?

While trauma can happen to anyone at any age, childhood trauma can contribute to lifelong effects because of its biological impact on the developing brain and body. Childhood trauma occurs when a person who is under the age of 18 experiences an event, series of events, or situation as extremely frightening, threatening, or harmful to their physical or emotional well-being.

According to the National Childhood Traumatic Stress Network, these experiences "can initiate strong emotions and physical reactions that can persist long after the event. Children may feel terror, helplessness, or fear, as well as physiological reactions such as heart pounding, vomiting, or loss of bowel or bladder control."

What types of experiences might be traumatic for a child?

Any event that a child experiences as frightening, threatening, or dangerous can cause trauma, and so can witnessing an event that threatens the life or physical safety of a loved one or the sudden loss of a loved one. Examples of events that can cause childhood traumatic stress include:

  • Natural disasters or terrorism

  • Violence in the home or community

  • Sudden loss of a loved one

  • Refugee experiences and war

  • Serious accidents or illnesses

  • Physical or emotional abuse

What are symptoms of childhood traumatic stress?

Every experience of childhood trauma is different. One child may react very differently from another child to the same event, and symptoms of traumatic stress can vary in their duration and severity. Reactions also vary by age and developmental level.

Age five and younger

  • Clinging or challenges with attachment

  • Crying or having tantrums

  • Physical discomfort

  • Bedwetting or thumb sucking

  • Increased fearfulness

  • Incorporating traumatic experience into imaginary play

Age six to eleven

  • Problems in school

  • Nightmares or other sleep problems

  • Self-isolating

  • Anger and irritability

  • Difficulty concentrating

  • Physical discomfort

  • Irrational fears

  • Lost interest in fun activities

Age twelve to eighteen

  • Nightmares or other sleep problems

  • Avoidance of reminders of the event

  • Risky behaviors like substance use and unhealthy sexual activity

  • Physical discomfort

  • Self-isolation, anger, and resentment

  • Lost interest in fun activities

Adverse Childhood Experiences

Adverse childhood experiences, or ACEs, are potentially traumatic events or experiences that occur in childhood. They include:

  • Being the victim of violence, abuse, or neglect

  • Witnessing violence in the home or community

  • Having a family member attempt or die from suicide

  • Mental health or substance use disorder in the home

  • Parental divorce of incarceration

  • Community-level adversities

ACEs impact brain development in ways that can lead people to adopt social and emotional coping mechanisms to deal with stressful environments, and some of these coping mechanisms can contribute to the cascade of negative outcomes associated with ACEs.

The CDC and Kaiser ACEs Study

The original research into ACEs was conducted by Kaiser-Permanente in partnership with the U.S. Centers for Disease Control in Prevention from 1995 to 1997. The researchers surveyed over 17,000 adults about their childhood experiences and subsequent health behaviors and outcomes.

Their findings showed that not only are ACEs common experiences (26% of respondents had at least one ACE and 12.5% reported four or more), they also increase the risk of long-term negative outcomes in health, well-being, education, and work.

A child with ACEs has an increased risk of of “injury, sexually transmitted infections, maternal and child health problems, teen pregnancy, involvement in sex trafficking, and a wide range of chronic diseases and leading causes of death such as cancer, diabetes, heart disease, and suicide.” And as the number of ACEs increase, so does a person's risk of experiencing negative outcomes.

ACEs at a Glance

Adverse Childhood Experiences (ACEs) are potentially traumatic events or experiences that occur in childhood. They include:

Being the victim of violence, abuse, or neglect

Witnessing violence in the home or community

Having a family member attempt or die from suicide


Mental illness or substance use disorder in the home

Parental divorce or incarceration

Community-level adversities

The Philadelphia ACEs Study

The CDC and Kaiser research and other early research into ACEs was limited because data was predominantly collected from white middle- and upper-class participants and focused on experiences inside the home. Nearly three out of four respondents was white, and over 75% had at least some college education.

The Philadelphia ACEs Project expanded the scope of this research by looking at not only the original set of individual-level adverse experiences but also the impact of community-level adversities. These additional community-level adverse experiences included witnessing violence in the community, being subjected to racial or ethnic discrimination, feeling unsafe in one's neighborhood, being bullied, and living in foster care.

The demographics of Philadelphians who participated in the survey were substantially different from those of participants in the original ACEs study, and what the researchers found was that in Philadelphia, with about 25% living in poverty, and 70% of respondents had at least one ACE and 40% had four or more. And almost 40% had also experienced four or more of the community-level ACEs.

The ACE Pyramid

The ACE Pyramid shows how the impact of historial trauma, social conditions, and ACEs cascade into higher risks for disrupted neurodevelopment that can lead to social, emotional, and cognitive impairment, adoption of coping mechanisms and health risk behaviors, disability and social problems, and risk of earlier death.

Risk and Protective Factors

Thinking about childhood trauma and ACEs can feel a little hopeless, but it’s also important to remember that experiences of trauma, even childhood trauma, are not determinative of the course a person’s life will take. ACEs are useful for understanding someone’s history and as a gateway to empathy and healing, but they are not a crystal ball.

Boosting protective factors and building resilience in youth and adults can be powerful counterweights to the risks that result from ACEs and other trauma. Practicing trauma-informed care can help develop resilience and strengthens positive coping behaviors to reduce the impact of risk factors on a person's life.

Top Resources on Childhood Trauma and ACEs