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How the ACE Study Changed Everything: the relationship between childhood experiences and illnesses

Updated: Feb 23, 2023

In 1995, an American study came out that caused a shockwave in the medical, mental health, and social services fields. The foundation of what the American healthcare system considered the basis of illness was turned on its head. Yet, many adults today have never heard of this study much less understood its massive implications upon their health and quality of life.

If you hope to make 2023 a year of growth, healing, or self-improvement, the most powerful foundation you could lay for your work is knowing your ACE score. Here is why:

Adulthood health is built on the foundation of whatever your brain experienced during childhood. This means that a person’s susceptibility to chronic disease, psychological health, and emotional and behavioral resilience all hinge on whether or not you felt safe as a child.

It turns out that while sticks and stones may in fact break your bones, some words can sabotage the fabric of your DNA and set you up for a lifetime of chronic illness and mental health issues. It doesn't roll off the tongue the same way as the original saying, but it’s more accurate. Let’s unpack the evidence that supports such a bold claim:

The ACE Study was conducted between 1995 and 1997 by Dr. Vincent Felitti with Kaiser Permanente and Robert Anda with the Center for Disease Control. More than 17,000 adults were surveyed about their traumatic childhood experiences in an attempt to discover hidden correlations between early trauma and life-long health and psychological impairments.

The study focused on specific household dysfunctions such as:

  • Emotional and verbal abuse

  • Physical abuse

  • Emotional and physical neglect

  • Sexual abuse

  • Parental incarceration

  • Substance abuse

  • Domestic violence

  • Caregiver mental illness

Each traumatic event was assigned a value to produce a score between 0-10.


The survey data was then correlated with documented long-term health outcomes and self-reports of well-being. The results, which were published in the American Journal of Preventive Medicine, revealed a staggering pattern: there is a powerful relationship between the breadth of exposure to family dysfunction and adversity during childhood and multiple risk factors for several of the leading causes of death in adults. These leading causes include heart disease, auto-immune disease, mental illness, and cancer.

The results of the study indicate that even a score as low as 1 resulted in a 2x increased risk of developing heart disease or cancer. Those with a score of 4 were at least 12x more at risk of attempting or committing suicide than those with a score of 0. Dr. Nadine Burke Harris summarized other staggering statistics in her famous Ted Talk delivered in 2015:

It turns out that the conditions of your childhood environment have a measurable impact on your adult brain development, immune system, hormonal balance, rate of healing, impulse control, emotional regulation, sleep habits, and more. These findings bolster a phrase that is rapidly growing in popularity:

“Genetics loads the gun; environment pulls the trigger.”

The following table breaks down ACE score percentages among men and women:


Genetics alone is not sufficient for activating latent genetic precursors for disease. The environment has now been shown to have a greater impact on mental health and physical health than heredity alone. (source)

The fact that most formative traumas take place before the age of five might project a false sense of irrelevance - ie “that was a long time ago.” Contrary to popular belief, time is not a safety net that passively heals all wounds.

If anything, time is more like a garbage compressor. Repressed traumas may feel like they take up less space the more they are shoved down. In fact, this makes traumas increasingly dense and difficult to tease out from other common stressors.

In other words, unacknowledged trauma informs adult decision-making. Traumas often show up as reactions; not memories. This misunderstanding of the nature of trauma generates cultures of silence, shame, and isolation - all ingredients necessary for the accumulation of potential health hazards.

The ACE study was so groundbreaking that it inspired waves of additional, expanded studies and surveys. In order to gain greater insights to previously unexamined correlations, new surveys were conducted specifically among the veteran population. Results were outlined in this research paper. Their findings indicated that:

“ACE's may be a particularly relevant predictor of health in veteran populations…Veteran populations experience disproportionate burdens of poor self-rated health and limitations in activity due to physical or mental health more often than non-veterans.”

The high rate of PTSD occurrences in military and first-responder careers is often chalked up to the nature of the work itself. The evidence of the ACE study suggests that in many cases, service members and first responders enter the environment with existing and unresolved traumas, which are further aggravated by new traumatic experiences.

Due to outdated but established stigmas surrounding mental health, these men and women are subverted into silence, isolation, shame, and unhealthy coping mechanisms when confronted with their trauma. Not only is mental health given little historical consideration, but attempts made by the individual to address mental health issues can be used against them by means of non-promotion, stunted career growth, and peer rejection.

Until the culture itself improves its systems and standards to accommodate these groundbreaking findings, veterans and first responders will remain a high-risk population for suicidal ideation, substance abuse, domestic violence, divorce, financial hardship, and chronic pain and illness.

The more abstract consequences implied by the ACE study are the qualitative impacts on well-being. If the average veteran or first responder doesn't know how her childhood trauma modified her brain development, she may never think to look there for insights or relief. Unfortunately, it is common for veterans and first responders to seek help only after severe consequences have made their lives feel unbearable. The belief that one must “nut up” and handle the problem logically translates to emotional overwhelm and feelings of hopelessness and isolation. Here is why:

The regions of the brain responsible for logical thinking, long-term decision-making, and personal values is the same region of the brain that is hindered by the overdeveloped fight-or-flight response brought on by trauma (ie: the Hypothalamic pituitary adrenal access or the internal system that governs the flight-or-fight response.)

As long as the person is caught in the body-and-brain cycle of adrenal fatigue and cortisol flooding, he will not have the internal resources available to make necessary shifts in perspective or use creative problem-solving. In civilian populations, talk therapy is a common remedy for such crises.

Due to the continued negative stigma of talk therapy and the often labor-intensive requirements for many veterans and first responders to gain access to affordable mental health resources, these concerns are largely neglected by the individual. The approach of “suffering in silence” becomes the norm, thus further provoking mental turbulence.

Promising breakthroughs are nonetheless taking place today. Alternative therapies have proven to be powerful agents in the healing of veterans, first responders, and their families. While Horses and Heroes is proud to be one of many midwestern options which offer services to these populations, it is only one of many. As more alternative mental health programs break ground and gain traction, it is our hope that these systematic concerns will soon become relics of the past.

If you are curious about learning more or want to explore the ACE study, here are several free resources:

The Original ACE study:

The Adverse Childhood Experiences (ACE) Study. American Journal of Preventative Medicine, 14, 245-258. Finkelhor, D., Shattuck, A., Turner, H., & Hamby, S. (2015).

The original ACE Questionnaire:

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