The prevalence of adverse childhood experiences in 102 countries

With research showing at least 60 per cent of people have experienced adverse childhood experiences (ACEs) – which can include abuse, neglect, or living with someone with mental illness or substance-use challenges – a new University of Calgary-led study highlights the global scale, and health and well-being implications, of the problem.

The meta-analysis, published in The Lancet Public Health, was led by Dr. Sheri Madigan, PhD, a professor of psychology in the Faculty of Arts, together with researchers from UCalgary’s Determinants of Child Development Lab and scholars at Cambridge University, University College Dublin, and Stellenbosch University in South Africa. 

Madigan was recently named a Tier 1 Canada Research Chair in Child Mental Health and Wellbeing, recognizing her leadership and impact in the field. We spoke with her about the study, its global significance and what these findings could mean for policy and practice.

Q: What are ACEs and why do they matter to public health?

A: ACEs stand for adverse childhood experiences, which refer to potentially traumatic experiences that occur prior to the age of 18. ACEs include 10 types of adversities, such as emotional and physical abuse, neglect, witnessing violence in the home, having a parent who is incarcerated, or growing up with a family member experiencing mental illness or substance use problems.

From a public-health perspective, ACEs matter for two major reasons: They are very common, and they can have long-term consequences for health and well-being. In previous research our team published in World Psychiatry and JAMA Pediatrics, we found that about 60 per cent of individuals worldwide have reported experiencing at least one ACE and one in six reported exposure to four or more ACEs.

What makes ACEs particularly important is that their effects often extend well beyond childhood. Higher exposure to ACEs is associated with increased risk for mental health problems, chronic physical conditions and poorer overall well-being in adulthood. 

Q: What motivated you to take on a study that draws from more than 1,000 other studies and data from two and a half million adults across 102 countries?

A: As a clinical psychologist, I’ve long been interested in how early life experiences connect to mental health and well-being across the lifespan. The history of ACEs research is interesting. It started with physicians, in 1998, trying to figure out why some patients recovered from procedures such as gastric bypass surgery and some did not. This work raised larger questions about how early adversity might be related to a host of adult outcomes, and the research quickly spread across disciplines, including psychology, psychiatry, education, social work and public health. 

Over time, the field generated thousands of individual studies across countries and disciplines, like puzzle pieces scattered around. 

What struck us, though, was that, even with over 25 years of research into ACEs, we still lacked a clear global picture of how common these experiences are. Much of the research has been country or region specific, making it difficult to compare findings or fully grasp the global scale of the problem. 

Our goal was to bring those puzzle pieces together to see the larger global picture. 

Q: In the findings, what stood out most to you?

A: For me, what’s most striking is that behind every statistic is a child’s experience. This study really highlights, sadly, just how common these experiences are and how deeply they affect people’s lives. 

One finding that stood out was the high prevalence of emotional abuse and emotional neglect. About one in four people reported experiencing these forms of adversity in childhood. I think that’s particularly important because emotional abuse and neglect are often less visible, and sometimes less openly discussed, than other types of adversity.

These include things like receiving constant criticism or belittling, lacking parental warmth or affection, or growing up with an emotionally unavailable caregiver. These patterns can become part of a child’s everyday experience and often are ignored or not identified as a problem at the time. 

There is also, I think, a misconception that emotional distress or harsh words don’t impact children as much as physical harm. But decades of research tell us otherwise. Emotional abuse and neglect can be some of the most powerful predictors of long-term challenges. For many people, it’s only later in adulthood that they begin to recognize how these more “hidden hurts” have shaped their lives. 

Q: What do disparities, such as income level, geography, social identity and sexuality tell us about the role of structural and societal factors and childhood adversity?

A: Childhood adversity doesn't occur in a vacuum. Higher rates of ACEs among people experiencing socioeconomic disadvantage or marginalization point to the role inequities like poverty, limited access to resources and social exclusion can play in influencing children's environments.

If families are facing economic stress, they may have housing instability or have less access to things like mental health supports, health care and social services. Over time, that strain can affect the family unit and increase the risk of a child experiencing adversity. 

We also see patterns change depending on country or region. When we see patterns in ACEs, we’re also seeing patterns in inequality.

Q: Your findings suggest that ACEs are not just individual or family issues, but systemic ones. What does this mean for prevention or policy here in Canada? 

A: I'm not a policy specialist, but what our findings suggest is that preventing ACEs requires action at multiple levels. Not only do you have to provide support for children and their families, but you need to create an environment where the adversity will be less likely in the first place. 

In the Canadian context, this means continuing to invest in policies and programs that make it easier for families to alleviate stress in their lives. These could include affordable housing, readily accessible mental health care, and even community and park spaces where families can connect, recharge and gather support. 

For example, the introduction of subsidized child care in Canada helped alleviate economic stress for many families. These kinds of policies can lead to a more supportive environment for children, thus minimizing the potential for ACEs. 

Prevention is really about two things happening together: reducing risk at a system level while ensuring families have meaningful support available when they need it most. 

Q: As far as future work goes, what opportunities do you see coming out of this study?

A: One challenge in ACEs research is that findings are often buried in academic journals and difficult for policymakers, clinicians and communities to easily use. We wanted to help bridge that gap between researchers and real-world action. 

Q: Your paper, “Prevalence of adverse childhood experience items: a systematic review and meta-analyses," is in The Lancet Public Health. What does this recognition mean for the work you’re doing, and the potential impact of this study?

A: Publishing this work in The Lancet Public Health, which has such a broad international audience, is a meaningful opportunity to elevate the conversation around childhood adversity as a global public health issue. Our hope is that the findings will reach policymakers, practitioners and researchers around the world who can translate this evidence into action. 

This is such an honour for us as a group; each co-author has made great contributions towards the project. Ultimately, our goal was not just to document the prevalence of ACEs, but to help prevent it.

In collaboration with Dr. Tyler Williamson at the Centre for Health Informatics (in the Cumming School of Medicine), along with a multidisciplinary data visualisation and web design team, we launched ACEsHub.org. The platform offers easy access to information about ACEs, as well as making the data collected openly available. 

We are excited to have an interactive data visualization tool related to the information presented in The Lancet Public Health paper. Users can explore the prevalence of ACEs across countries and regions, and across participant-demographics factors, which we hope will help policymakers, researchers and organizations better understand the scale of ACEs in their own contexts.

In many ways, we see it as a kind of global map of ACEs, one that can help guide prevention efforts, policy decisions and supports for children and families. 

Ultimately, our hope is that better access to data leads to better decisions, and better outcomes for children and families around the world.