Adverse Childhood Experiences (ACEs)

Adverse childhood experiences (ACEs) are traumatic events or unstable conditions experienced before age 18 — including violence, abuse, neglect, and household dysfunction (substance use, mental illness, incarceration, separation, domestic violence). ACEs are common and have measurable, lasting effects on physical, mental, and behavioral health throughout adulthood. The original CDC-Kaiser ACE Study, published in 1998 by Felitti and Anda, identified a striking dose-response pattern: the more categories of childhood adversity a person reports, the higher their adult risk for depression, anxiety, substance use, heart disease, and early mortality.

This page is the conditions-hub on ACEs as a clinical and public-health concept — what they are, how they reshape the developing brain, the mental and physical health outcomes they predict, how they transmit across generations, and the trauma-informed therapies that help adults heal. For child-focused, parent-facing guidance on what trauma looks like at every age, see childhood trauma.

~64%

Source: Centers for Disease Control and Prevention (CDC)

Definition and Types of ACEs

The original ACE Study tracked ten specific categories of childhood adversity drawn from three domains: abuse, neglect, and household dysfunction. Each "yes" to a category counts as one point, regardless of frequency — a person who experienced repeated physical abuse over a decade and a person who experienced it once both score one point in that category. The resulting score (0 to 10) is a blunt instrument by design, intended to capture cumulative load rather than fine-grained severity.

Newer frameworks have expanded the ten-item list to capture adversities the 1998 study did not name: community violence, bullying, racism and discrimination, food and housing insecurity, the death of a parent or sibling, foster-care placement, and exposure to natural disasters or war. Researchers refer to these as expanded ACEs, and the Philadelphia ACE Study and the Centre for Youth Wellness ACE-Q are two widely used instruments that include them. The conceptual point is the same: cumulative early adversity matters more than any single event.

Quick facts and stats

• ~64% of U.S. adults report at least one ACE; about 17% report four or more (CDC Behavioral Risk Factor Surveillance System).
• ~3 in 4 U.S. high school students report at least one ACE; 1 in 5 report four or more (CDC Youth Risk Behavior Surveillance).
• ACEs cluster: people who experience one category are substantially more likely to experience others, which is why cumulative score matters.
• Rates are higher among women, American Indian/Alaska Native, multiracial, and LGBQ+ youth in U.S. epidemiology.
• The CDC estimates that preventing ACEs could reduce adult depression by up to 44%, suicide attempts by up to 89%, and heavy drinking by up to 24%.

How ACEs Affect Brain Development and Stress Response

ACEs do their damage through a biological pathway that the National Scientific Council on the Developing Child named toxic stress — the prolonged activation of the body's stress response in the absence of a buffering relationship with a stable caregiver. Brief, manageable stress is normal and even strengthening (positive stress). Sustained but supported stress — illness, loss, a hard move — is what developmental psychologists call tolerable stress. Toxic stress is the third category: chronic, unbuffered, and developmentally costly.

Inside the developing brain, toxic stress produces measurable changes:

• Hyperactive amygdala — the threat-detection system becomes faster and louder, scanning ordinary environments for danger.
• Underdeveloped prefrontal cortex — the regions responsible for planning, impulse control, and emotion regulation grow more slowly under chronic cortisol exposure.
• Smaller hippocampus — the structure central to memory and contextualizing fear shows volumetric reductions in adults with high ACE scores.
• Dysregulated HPA axis — the hypothalamic-pituitary-adrenal stress system loses its normal rhythm, often producing flattened cortisol curves and impaired recovery from stressors.
• Inflammatory dysregulation — chronic stress shifts the immune system toward a low-grade inflammatory state that, over decades, contributes to cardiovascular and metabolic disease.

These are not abstract findings. They explain why adults with high ACE scores often describe feeling "on alert" without knowing why, why their emotional reactions feel disproportionate to the trigger, and why ordinary stressors — a work conflict, a partner being late — can land like an emergency. The body learned, early, that the world is dangerous and that nobody is coming. Therapy is, in part, the slow work of teaching the nervous system a different forecast.

Signs and Symptoms of ACEs in Adults and Children

ACEs are not themselves a set of symptoms — they are experiences. But the cumulative effects show up in recognizable patterns. In children, the signs cluster around dysregulation; in adults, they often persist as the architecture of how someone moves through the world.

In children and adolescents

• Hypervigilance and easy startle; trouble sleeping; nightmares
• Emotional dysregulation — large reactions to small triggers, long recovery times
• Difficulty trusting caregivers, teachers, or peers; intense attachment or avoidance patterns
• Concentration and attention problems often misdiagnosed as ADHD
• Regression (loss of recently acquired skills like potty training, speech, or independence)
• Somatic complaints — headaches, stomachaches — without medical explanation
• School avoidance, behavior problems, or sudden academic decline
• In adolescents: substance use, self-harm, disordered eating, risky sex, running away

In adults

• Hypervigilance, exaggerated startle response, persistent sense that something is wrong
• Emotional dysregulation — emotions arrive faster, peak higher, and recover more slowly
• Difficulty trusting others; insecure attachment patterns (anxious, avoidant, fearful-avoidant)
• Chronic shame, self-blame, and a pervasive sense of being defective or unlovable
• Dissociation under stress — feeling unreal, foggy, or detached from the body
• Sleep disruption — insomnia, nightmares, or non-restorative sleep
• Chronic pain, gastrointestinal problems, autoimmune flares, and other stress-linked physical conditions
• Difficulty identifying or naming emotions (alexithymia)
• Patterns of substance use, food, sex, or work that function to regulate emotion
• Repeated entry into relationships that recapitulate childhood dynamics

A high ACE score does not mean a person has every symptom in this list; many adults have a few, manage them, and live well. The reason to learn the pattern is not to pathologize ordinary distress — it is to recognize that some of what feels like "just how I am" may be the long shadow of toxic stress, and therefore changeable.

ACE vs. Single Trauma Event

A common point of confusion is how ACEs differ from a single traumatic event. Both can produce trauma symptoms; the differences are in cumulative dose, developmental timing, and treatment implications.

The clinical implication is that ACEs more often produce a complex trauma picture — the kind described in the ICD-11's complex PTSD diagnosis — which calls for phased treatment rather than direct exposure-based work alone. This is why a thoughtful trauma therapist will not push adults with high ACE scores straight into processing the worst memory; they will first build the regulation and safety skills that make processing tolerable.

ACEs and Mental Health: Depression, Anxiety, PTSD

The CDC-Kaiser ACE Study's most influential finding was the dose-response relationship: each additional ACE category increases the likelihood of nearly every adverse adult outcome, and the relationship is monotonic — there is no safe threshold. Compared to people with zero ACEs, people with four or more have substantially elevated risk for the conditions below.

Top mental and physical health outcomes tied to ACEs

1. Depression — 4+ ACEs roughly 4–5x the lifetime risk of major depressive disorder.
2. Anxiety — Significantly elevated risk of generalized anxiety, panic disorder, and social anxiety in adulthood.
3. PTSD and complex PTSD — ACEs are among the strongest predictors of adult PTSD, and the cumulative pattern more often produces complex PTSD than the discrete-event PTSD seen after a single traumatic incident.
4. Substance use disorders — 4+ ACEs raise the risk of alcohol use disorder ~7x and injection drug use ~10x; the original ACE Study was launched, in part, from this finding.
5. Suicidality — 4+ ACEs are associated with a roughly 12-fold increase in lifetime suicide attempts.
6. Cardiovascular and metabolic disease — Adults with 4+ ACEs have ~2x the risk of heart disease, stroke, and type 2 diabetes; the pathway runs through chronic inflammation, HPA dysregulation, and ACE-mediated health behaviors.

Which ACE types predict which outcomes?

The ACE score is cumulative, but the specific adversities a person experienced also matter for the conditions they are likely to develop. A few patterns are well-documented:

• Household substance abuse is one of the strongest predictors of adult substance use disorder, both through learned coping and through the chronic stress and unpredictability that household addiction produces.
• Sexual abuse is uniquely strongly linked to adult PTSD, dissociative disorders, and complex trauma presentations.
• Emotional neglect is one of the most overlooked ACEs and is a particularly strong predictor of adult depression, chronic shame, alexithymia, and difficulty receiving care in relationships.
• Domestic violence in the home raises the risk of adult anxiety disorders, hypervigilance, and re-entry into violent adult relationships.
• Parental mental illness doubles the risk of adult mood and anxiety disorders even when the child is not directly mistreated, partly through inherited vulnerability and partly through the caregiving disruptions that come with untreated illness.

This is why the ACE score alone is not enough to plan treatment. A trauma-informed assessment looks at the kinds of adversity, the developmental ages at which they occurred, the protective factors that were also present, and the symptom picture today — not only at the total score.

Trauma-Informed Therapy and Healing from ACEs

The CDC's framing is heavily preventive — for good reason at the population level. But the therapeutic question for an adult reader is different: what now? The evidence is that ACEs are treatable in adulthood, and several therapy modalities have substantial evidence for healing from their effects. Most adult ACE work fits a three-phase model (originally proposed by Judith Herman): safety and stabilization first, then trauma processing, then integration and reconnection.

Phase 1 — Safety, stabilization, and regulation skills

Before any direct trauma processing, the nervous system needs to develop reliable tools for noticing dysregulation, slowing it, and recovering. This is the phase where most damage from poorly sequenced trauma therapy happens — pushing into the worst memories without these skills often makes things worse. Typical Phase 1 work includes:

• Psychoeducation about the nervous system, the window of tolerance, and how toxic stress shapes adult reactions
• Grounding, breathing, and orienting techniques that anchor attention in present-moment safety
• Skills training drawn from DBT (mindfulness, distress tolerance, emotion regulation) and from somatic approaches
• Sleep, exercise, nutrition, and substance-use stabilization where needed
• Building a present-day support network — friends, family, recovery groups — that did not exist in childhood

Phase 2 — Trauma processing

Once the person can stay regulated through difficult material, trauma-focused modalities help the brain re-encode early experiences so they no longer hijack present-day life. Several have strong evidence bases for ACE-related adult trauma:

• Trauma-focused cognitive behavioral therapy (TF-CBT) — Originally developed for children but adapted for adults; combines cognitive restructuring, graduated trauma narrative work, and skills training. Strong evidence base for childhood trauma sequelae.
• EMDR (Eye Movement Desensitization and Reprocessing) — Uses bilateral stimulation while bringing trauma memories to mind; well-suited to discrete and cumulative trauma alike, and often a good fit when verbal processing alone is overwhelming.
• Somatic therapy — Approaches like Somatic Experiencing and Sensorimotor Psychotherapy work directly with the body's stored stress responses, helping the nervous system complete what it could not in childhood. See body-based trauma therapies compared.
• Internal Family Systems (IFS) — Works with the "parts" of the self that formed in childhood (protectors, exiles, the wounded child) and helps the adult Self relate to them with compassion. Particularly useful for shame, self-criticism, and the parts-based experience common after early relational trauma. See IFS for trauma.
• Attachment-focused therapy — For people whose primary ACE story is relational (neglect, inconsistent caregiving, disrupted attachment), modalities like emotionally focused therapy and attachment-based therapy directly repair the relational template. See EFT for trauma and attachment and healing insecure attachment.

A comparison of these options for trauma broadly is in our guide on the best therapy for trauma. For adult complex trauma specifically, see best therapy for complex PTSD and complex PTSD treatment.

Phase 3 — Integration and reconnection

The final phase is rebuilding the adult life that the trauma constricted: relationships, identity, work, meaning, and the capacity to receive care without flinching. This is often the longest phase and the most overlooked. Practical work includes:

• Building secure adult relationships and learning to repair, not just rupture
• Recovering goals, hobbies, and identity dimensions that were suppressed in childhood
• Parenting (or relating to children) without recreating the patterns that hurt
• Connecting to community, purpose, and the meaning-making that trauma often interrupts

Choosing a therapist

Not every "trauma therapist" is trained in phased, complex-trauma work. The difference between trauma-informed and trauma-focused matters: trauma-informed care is a baseline orientation any clinician should have; trauma-focused care is specific training in a modality (TF-CBT, EMDR, somatic, IFS) that processes trauma directly. For ACEs specifically, look for clinicians with training in complex trauma — meaning they understand sequencing, attachment ruptures, and developmental impact, not just discrete-event PTSD. Our guides on how to find a trauma therapist and questions to ask a trauma therapist walk through the practical search.

Building Resilience and Recovery from Childhood Trauma

A finding nearly as important as the dose-response curve is its corollary: protective factors buffer ACEs. The CDC and the Center on the Developing Child at Harvard converge on a short list of factors that, when present in childhood or rebuilt in adulthood, substantially attenuate ACE effects on adult health. The single most powerful is at least one stable, supportive relationship with a caring adult during the years the adversity occurred. Even one is enough to bend the curve.

In adulthood, the resilience factors are similar in spirit, even when the developmental window has closed:

• At least one secure, reliable adult relationship — a partner, friend, mentor, therapist, or community member who is consistent and attuned
• A sense of agency — the experienced felt-sense that one's actions affect outcomes; a direct counter to the helplessness that toxic stress installs
• Regulation skills — learnable in any therapy worth its name; the somatic, breathing, and cognitive tools that bring the nervous system back to baseline
• Meaning and purpose — work, creativity, faith, parenting, activism, community — something that anchors identity beyond the trauma
• Care for the body — sleep, exercise, nutrition, and treatment of physical comorbidities, all of which are biological partners to psychological healing
• A connection to one's own story — the capacity to look at what happened, name it, and integrate it without being controlled by it

Resilience is not the absence of suffering. It is the developed capacity to bend, recover, and stay connected through suffering — and it can be built in adulthood, even after decades of dysregulation.

Intergenerational Transmission and Breaking the Cycle

One of the most consequential aspects of ACEs is that they often pass across generations. Parents who were not parented well frequently struggle to parent in ways they wish they could — not from lack of love, but because they are working without an internalized model of attunement, repair, and emotional safety. The mechanisms are several and overlapping:

• Modeled behavior. Children learn from how they were treated. Adults who experienced harsh discipline often default to it under stress, even when they swore they wouldn't.
• Unprocessed dysregulation. A parent whose own nervous system was wired by toxic stress has less capacity to stay regulated during a child's meltdown, which means the child more often co-regulates with a dysregulated adult.
• Disrupted attachment patterns. Insecure attachment is partially heritable (genetic vulnerability) and partially learned (the parent reproduces the relational template they were given). See attachment styles and therapy and healing insecure attachment.
• Material context. ACEs are correlated with poverty, housing instability, and parental untreated mental illness or substance use, all of which often persist across generations unless interrupted.

The hopeful corollary: cycles can be broken. The research on earned secure attachment shows that adults who do the work of making coherent sense of their own childhoods — typically in therapy — go on to parent their own children with substantially more security, even if their childhood was disrupted. Therapy that addresses ACEs is therefore not only for the adult who shows up; it is also, often, the most consequential thing a parent can do for the next generation.

Practical components of cycle-breaking work include:

• Naming and grieving what was missed in one's own childhood, in therapy
• Learning the regulation skills that were not modeled
• Repairing ruptures with children when they happen (the repair, not the absence of rupture, is what builds security)
• Building a parenting support network — co-parents, extended family, therapists, parenting groups — that did not exist for the previous generation
• Treating co-occurring conditions (depression, anxiety, substance use) that compound the difficulty of attuned parenting

ACEs Across Subgroups and Equity

The original ACE Study sample was drawn from a largely white, middle-class HMO population, and subsequent epidemiology has shown that ACEs are not distributed equally across the U.S. population. Higher rates have been documented among:

• Women — Particularly for sexual abuse and emotional abuse categories.
• American Indian/Alaska Native, multiracial, and Black populations — Reflecting both elevated household-level adversity and the role of structural factors (poverty, discrimination, community violence) that the original 10 ACEs do not capture.
• LGBQ+ youth — Elevated rates of family rejection, bullying, and household conflict.
• Children in foster care, in immigrant families, and in low-income households — All of whom face structural adversities not coded in the original 10 categories.

The expanded ACE frameworks (Philadelphia ACE Survey, CYW ACE-Q) include items like community violence, racism, food insecurity, and unsafe neighborhoods specifically to capture these structural exposures. Treatment that ignores structural context — and assumes the same intervention works equally for everyone — misses an important part of the picture.

How to Use Your ACE Score

A common worry is that a high ACE score is a permanent verdict. It is not. The score is a piece of information about cumulative early stress exposure; it is not a diagnosis, a prediction, or a destiny. Useful ways to read your own score:

• As context, not conclusion. A high score helps explain why ordinary stressors land hard, why certain relationships feel familiar, why your body holds tension. It is one input into self-understanding, not the whole story.
• As an entry point to care. A high score is a reason to seek a trauma-informed clinician — not because you are broken, but because the right framework helps the work go faster. Bring the score to the first appointment as a starting point for conversation.
• As an invitation, not an indictment. A high score is not a verdict about who you are or who you can become. The research on resilience and earned secure attachment is unambiguous: change is possible at any age, and many people with high ACE scores live deeply connected, regulated adult lives.

For a broader entry point on what a trauma therapist's first sessions look like, see find a trauma therapist and questions to ask a trauma therapist.

When to Seek Help

Consider reaching out to a trauma-informed clinician if you recognize yourself in several of the following:

• You scored 4 or more on the ACE quiz and want to understand what that means for you
• Ordinary stressors land disproportionately hard; small triggers produce large, slow-to-recover reactions
• You notice patterns in your relationships that feel familiar from childhood — and not in a good way
• You have struggled with depression, anxiety, PTSD, addiction, or chronic somatic symptoms that have not fully responded to standard care
• You feel chronically empty, foggy, or disconnected from your body or your life
• You are parenting (or about to parent) and want to do work that breaks the cycle
• You are noticing dissociation, hypervigilance, or sleep disturbance that has been with you for years
• You have a sense that "something happened" that you have never fully named — and you are ready to begin

You do not need to remember every detail of your childhood, or to know whether what happened "counts," to deserve help. A skilled trauma therapist meets you where you are.

Frequently Asked Questions

ACEs are common — and the effects are treatable

A trauma-informed clinician with training in complex trauma can help you understand your ACE history, build regulation skills, and process what your nervous system has been carrying. Healing is possible at any age.

Find a trauma therapist