Mental health

ACEs Explained: What Adverse Childhood Experiences Are

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ACEs, or adverse childhood experiences, are potentially traumatic events before age 18: abuse, neglect, and household dysfunction such as violence, substance use, or mental illness. They are common, and decades of research link higher counts to greater risk of health and behavioral challenges over time, though they are not destiny for any one person.

Last updated: July 2026History

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What ACEs are

ACEs — adverse childhood experiences — are potentially traumatic events that occur during childhood (roughly birth through age 17). The term comes from a large 1998 study by the CDC and Kaiser Permanente, which surveyed more than 17,000 adults about their childhoods and then followed their health 1. Researchers grouped these experiences into broad categories: abuse (physical, emotional, or sexual), neglect (physical or emotional), and household dysfunction (such as living with someone who has a substance use problem or mental illness, witnessing violence against a parent, parental separation or divorce, or having a household member who is incarcerated) 2.

How common are ACEs?

ACEs are far more common than many people assume. According to the CDC, about 64% of adults report at least one ACE, and roughly 1 in 5 adults report four or more 2. Experiencing one ACE makes it more likely a person experienced others, because adversities often cluster within a household. Their commonness is part of why they are treated as a public-health issue rather than a rare personal misfortune 3.

Why ACEs matter for health

The original study found a graded, dose-response relationship: as the number of ACEs rises, so does the risk of many of the leading causes of poor health in adulthood, including heart disease, depression, and substance use 1. Later research with the same large cohort confirmed this pattern across many outcomes and connected cumulative childhood stress to changes in how the brain and stress-response systems develop 4. A large meta-analysis pulling together studies beyond the original group reached the same conclusion: people with four or more ACEs face notably higher risk of harms like depression and problematic substance use 5. Importantly, this is about probability across populations, not certainty for any one person.

Are ACEs destiny?

A high ACE score describes elevated risk — not an outcome that is fixed. Research on positive childhood experiences found that adults who reported many supportive, connected experiences in childhood had substantially lower odds of adult depression and poor mental health, even among those who also had high ACE levels 6. Safe, stable, and nurturing relationships are among the most consistently protective factors, and they can be built at any age 7. Understanding your history is a starting point for choosing supports, not a label to carry.

When childhood adversity is worth discussing with a clinician

A behavioral-health clinician can turn awareness of ACEs into something useful. They can use validated screening tools (such as the PHQ-9 for depression or trauma-focused questionnaires) to clarify what's affecting you now, and help rule out medical contributors to symptoms like fatigue or low mood. When indicated, they can offer evidence-based treatments — trauma-focused cognitive behavioral therapy (CBT) is well-supported, and medication is an option for conditions like depression or anxiety. Because childhood adversity can shape stress and relationships in adulthood 4, a clinician also helps you build the protective, supportive connections that research shows buffer these effects 7.

Common questions

No. ACEs raise the likelihood of certain health challenges across large groups of people, but they do not determine any individual's future. Many people with high ACE counts are healthy, especially when they have supportive relationships and access to care 6.

The most studied categories are abuse (physical, emotional, sexual), neglect (physical, emotional), and household dysfunction such as exposure to violence, a household member's substance use or mental illness, parental separation, or incarceration of a household member 2.

Yes. Safe, stable, nurturing relationships and positive experiences are protective, and evidence-based therapies can help. The CDC describes prevention and mitigation strategies built around these supportive relationships and environments 7.

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When to reach out

  • —Memories or reminders of past events that feel overwhelming or intrusive
  • —Persistent low mood, hopelessness, or loss of interest lasting more than two weeks
  • —Using alcohol or other substances to cope
  • —Difficulty functioning at work, school, or in relationships

If you are thinking about harming yourself, call or text 988 (Suicide & Crisis Lifeline) or text HOME to 741741.

This article is general education, not a diagnosis or medical advice; talk with a qualified clinician about your situation.

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References

  1. 1.Felitti VJ, Anda RF, Nordenberg D, Williamson DF, Spitz AM, Edwards V, Koss MP, Marks JS (1998). Relationship of Childhood Abuse and Household Dysfunction to Many of the Leading Causes of Death in Adults: The Adverse Childhood Experiences (ACE) Study. American Journal of Preventive Medicine, 14(4):245-258. doi:10.1016/S0749-3797(98)00017-8 ✓The original CDC-Kaiser ACE Study established a graded dose-response between cumulative childhood adversity and adult leading causes of death and risk behaviors.
  2. 2.Centers for Disease Control and Prevention (CDC) (2026). About Adverse Childhood Experiences. CDC, National Center for Injury Prevention and Control. link ✓CDC overview defining ACE categories and prevalence (about 1 in 5 adults reporting 4+ ACEs).
  3. 3.Centers for Disease Control and Prevention (CDC) (2019). Adverse Childhood Experiences (ACEs) — Vital Signs. CDC Vital Signs. link ✓CDC Vital Signs framing ACEs as a preventable public-health issue.
  4. 4.Anda RF, Felitti VJ, Bremner JD, Walker JD, Whitfield C, Perry BD, Dube SR, Giles WH (2006). The Enduring Effects of Abuse and Related Adverse Experiences in Childhood: A Convergence of Evidence from Neurobiology and Epidemiology. European Archives of Psychiatry and Clinical Neuroscience, 256(3):174-186. doi:10.1007/s00406-005-0624-4 ✓Confirms ACE dose-response across many outcomes and links cumulative childhood stress to altered neurodevelopment and stress-response systems.
  5. 5.Hughes K, Bellis MA, Hardcastle KA, Sethi D, Butchart A, Mikton C, Jones L, Dunne MP (2017). The Effect of Multiple Adverse Childhood Experiences on Health: A Systematic Review and Meta-Analysis. The Lancet Public Health, 2(8):e356-e366. doi:10.1016/S2468-2667(17)30118-4 ✓Meta-analysis showing 4+ ACEs strongly elevate risk of adult harms like depression and problematic substance use.
  6. 6.Christina Bethell, Jennifer Jones, Narangerel Gombojav, Jeff Linkenbach, Robert Sege (2019). Positive Childhood Experiences and Adult Mental and Relational Health in a Statewide Sample: Associations Across Adverse Childhood Experiences Levels. JAMA Pediatrics. doi:10.1001/jamapediatrics.2019.3007 ✓Adults with many positive childhood experiences had much lower odds of adult depression even at high ACE levels.
  7. 7.Centers for Disease Control and Prevention (CDC) (2024). Preventing Adverse Childhood Experiences. CDC, National Center for Injury Prevention and Control. link ✓CDC prevention guidance: safe, stable, nurturing relationships and environments prevent and mitigate ACEs.

7 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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