Adverse Childhood Experiences, or ACEs, are potentially traumatic events that occur in childhood (0-17 years) such as experiencing violence, abuse, or neglect; witnessing violence in the home; and having a family member attempt or die by suicide. Also included are aspects of the child’s environment that can undermine their sense of safety, stability, and bonding such as growing up in a household with substance misuse, mental health problems, or instability due to parental separation or incarceration of a parent, sibling or other member of the household. Traumatic events in childhood can be emotionally painful or distressing and can have effects that persist for years. Factors such as the nature, frequency and seriousness of the traumatic event, prior history of trauma, and available family and community supports can shape a child’s response to trauma.

A large and growing body of research indicates that toxic stress during childhood can harm the most basic levels of the nervous, endocrine, and immune systems, and that such exposures can even alter the physical structure of DNA (epigenetic effects). Changes to the brain from toxic stress can affect such things as attention, impulsive behavior, decision-making, learning, emotion, and response to stress. Absent factors that can prevent or reduce toxic stress, children growing up under these conditions often struggle to learn and complete schooling. They are at increased risk of becoming involved in crime and violence, using alcohol or drugs, and engaging in other health-risk behaviors (e.g., early initiation of sexual activity; unprotected sex; and suicide attempts). They are susceptible to disease, illness, and mental health challenges over their lifetime. Children growing up with toxic stress may have difficulty forming healthy and stable relationships. They may also have unstable work histories as adults and struggle with finances, family, jobs, and depression throughout life—the effects of which can be passed on to their own children.