In my last post, I referred to John Bowlby’s work on attachment as being (in my opinion) the most influential theorist in mental health history. Now let’s talk about the single most impactful research study that completely changed how we treat trauma.
As a trauma and PTSD specialist, the ACE study (1995-1997) laid the groundwork for pretty much everything that I do.
What the ACE Study Actually Looked At
Back in the 1980s a researcher-physician, Dr. Vincent Felitti, noticed that patients with a history of childhood sexual abuse were more likely to drop out of Kaiser Permanente’s obesity clinic. Those who did lose significant weight were more likely to regain it.
In the 1990s, Kaiser Permanente, in collaboration with the Centers for Disease Control (CDC) researchers, took his observations a step farther. They weren’t trying to study trauma. They were trying to understand why certain health problems, like obesity and serious or chronic illnesses, kept showing up in patients who, on paper, “should” have been healthy.
17,337 adults were given a physical and surveyed about ten categories of personal and household adversity before age 18:
Abuse & Neglect (Personal Experiences)
- Physical Abuse: Being hit, kicked, or slapped.
- Emotional/Verbal Abuse: Swearing at, insulting, or threatening.
- Sexual Abuse: Unwanted sexual contact.
- Physical Neglect: Lacking food, clothing, or protection.
- Emotional Neglect: Feeling unloved or unsupported.
Household Dysfunction (Environmental Experiences)
- Domestic Violence: Witnessing a mother or caregiver being treated violently.
- Household Substance Abuse: Living with a problem drinker or drug user.
- Household Mental Illness: Living with a relative with serious mental health issues.
- Incarcerated Household Member: A family member going to prison.
- Parental Separation or Divorce: The breakup of the home.
What they found shocked the medical world.
With one point given for each category, the higher your ACE score, the higher your risk for serious and chronic medical and mental health conditions. If a person has an ACE Score of 4 or more, their risk of the following conditions increases:
4+ ACEs:
- Nicotine use: 2x
- Morbid Obesity (BMI ≥ 35): 2x
- Heart Disease: 2x
- Stroke: 2x
- Cancer: 2x
- Diabetes: 2x
- Sexually Transmitted Disease: 3x
- Chronic Lung Disease: 4x
- Depression: 5x
- Alcoholism: 7x
- Intravenous Drug Use: 10x
- Suicide Attempt: 12x
The study also found that 57% of men and 80% of women with a score of six or more had 20+ years shorter life expectancy.
This was the first time a large-scale study said, essentially:
“Your childhood experiences show up in your adult body.”
For many people, that sentence alone is life-changing. *
How the ACE Study Changed Everything
Before the ACE Study, trauma was often treated like a character flaw. People were told they were “too sensitive,” “overreacting,” or just plain “crazy.”
The conclusion of the ACE Study blew that idea apart:
These associations are important because it is now clear that the leading causes of morbidity and mortality in the United States are related to health behaviors and lifestyle factors… Insofar as abuse and other potentially damaging childhood experiences contribute to the development of these risk factors, then these childhood exposures should be recognized as the basic causes of morbidity and mortality in adult life.
With at least five of the top ten leading causes of death on this list, the ACE Study forced the medical field to confront what therapists had been seeing for decades:
- Trauma is a public health issue, not a personal failure.
- Symptoms are adaptations to adversity, not weaknesses.
- The body keeps score whether we want it to or not.
- Childhood environments shape adult physical and mental health.
It validated what so many people had lived without language for.
It helped destigmatize mental health treatment.
It helped lead the way for health insurance companies to cover mental healthcare.
It changed the entire landscape of mental healthcare.
What the ACE Study doesn’t tell us
While the ACE Study was groundbreaking, it wasn’t complete.
It didn’t capture the kinds of trauma that don’t look dramatic on paper but leave lasting imprints on the brain and body.
The ACE Study measured categories of adversity. It didn’t measure content or context.
It didn’t ask whether sexual abuse was by a parent or a cousin seen twice a year.
It didn’t ask whether the person with a substance use problem was a parent or a sibling.
It didn’t ask whether foster care happened because of abuse, neglect, or imprisonment.
And most importantly, it also didn’t ask the age at which the adverse events occurred.
As we’ve discussed in my previous posts — age matters. A toddler, a six‑year‑old, and a sixteen‑year‑old experience the same event in profoundly different ways.
Two people can have the same ACE score and completely different outcomes.
People can have low ACE scores and still carry deep, invisible wounds.
Because context matters.
The relational environment is where the nervous system is shaped. When a child grows up in a home where their body has to stay on high alert — scanning, bracing, adapting — that chronic activation eventually takes a toll. The body can only run at a twelve out of ten for so long before it starts to fall apart.
The ACE Study opened the door, but it didn’t tell the whole story. It sparked decades of additional research into how trauma shapes the brain and body. One of the most influential voices in that next wave was Bessel van der Kolk, whose work helped translate the science of trauma into something people could finally understand. If you want a deeper look at how trauma lives in the nervous system and the body, his book The Body Keeps the Score is an excellent resource.
What ACE Scores mean in real life
Now, before you go Googling the ACE questionnaire (⟵ here it is, by the way) to find out your score, know this: Your ACE score is a screening tool, not a diagnostic assessment. Only a mental health professional can administer the proper diagnostic assessments needed to make a diagnosis.
The ACE Study tells us about risk, not destiny. It gives us a starting point to understand — not a personal judgment.
A high ACE score doesn’t mean you’re doomed, and a low ACE score doesn’t mean you escaped unscathed.
Your ACE score does not measure how traumatic your childhood was, or how it has affected you. It just validates that what happened to you matters.
Why ACEs Still Matter in Therapy Today
ACEs help us understand:
- Why certain patterns show up
- Why the body reacts the way it does
- Why some people struggle with regulation, trust, or boundaries
- Why certain symptoms make perfect sense in context
When my clients learn about ACEs, something shifts.
The story helps patterns make sense.
Shame loosens.
Self‑compassion grows.
Blame and guilt go back to the people who caused the harm.
The noise quiets.
Healing begins.
