Review of research on adverse childhood experiences identifies significant differences in size of effects

Adverse childhood experiences (ACEs) significantly affect lifelong health and well-being. Despite extensive research on the topic, a wide-reaching understanding of ACEs' multifaceted impacts remains unrealized. In a new study, researchers have synthesized evidence from nearly 100 meta-analyses to provide a comprehensive view of ACEs' effects. They found significant differences in effect sizes depending on studies' approach, suggesting a critical need for a broad range of approaches to understand, prevent, and reduce the effects of ACEs.

The study, by researchers at Sam Houston State University (SHSU), appears in the Journal of Child Psychology and Psychiatry.

"The impacts of ACEs are heterogeneous and influenced by the type of adverse experience and the specific outcomes considered," according to Bitna Kim, professor of criminology and criminal justice at SHSU, who led the study. "Our findings highlight the complexity and varied nature of ACEs' influence on individual development and societal well-being, which has practical implications for public health and welfare."

ACEs encompass a spectrum of potentially traumatic events encountered from birth until age 17 as delineated by the U.S. Centers for Disease Control and Prevention, such as abuse, witnessing violence, and growing up in a family with mental health problems. Their overall prevalence is high, with about two in every five adults globally having experienced at least one ACE.

In the United States, more than 60% of adults have at least one ACE, with almost 17% enduring multiple ACEs. As a result, total annual costs attributable to ACEs in North America is estimated to be $748 billion, underscoring the financial burden on health and economic outcomes.

The field of research on ACEs is evolving rapidly, with hundreds of studies on diverse approaches to conceptualizing ACEs and their effects. In this context, maintaining a clear overview of the evidence has become increasingly challenging.

In this study, researchers used an umbrella synthesis method to integrate findings from 99 meta-analyses involving nearly 600 effect sizes. The study examined ACEs through four prevalent approaches: specificity (which examines the unique effects of individual adversities), lumping (which groups various adversities together), dimensional (which distinguishes between adversities while considering overarching dimensions), and child maltreatment-centric (which views abuse and neglect as interconnected elements).

Researchers assessed the impact of ACEs across six domains: biological system dysregulation, neuropsychological impairments, physical health complications, mental health conditions, social and behavioral challenges, and criminal justice involvement. Among the study's findings:

• Although the overarching effect size of ACEs on various outcomes is small to moderate, the true complexity and variability of their impact unfold only upon examining the interplay between the different approaches of measuring ACE and distinct outcomes.
• Specific approaches to studying ACEs yielded varying levels of impact, with notable differences in effects on mental health, social/behavioral issues, and criminal justice involvement.
• When ACEs were aggregated without distinguishing between different types but considering their cumulative effects, adverse outcomes were significantly exacerbated.
• The child maltreatment-centric approach consistently demonstrated substantial effects across all evaluated domains, including increased criminal justice involvement, more pronounced social and behavioral problems, and a range of mental health challenges.

The study's findings underscore the heterogeneity in ACEs' impacts, influenced by the type of ACE and specific outcomes considered. They also highlight the necessity for comprehensive approaches to understanding, preventing, and reducing the effects of ACEs.

"The insights we gleaned from our review highlight the pressing need for a shift in approach, moving beyond generic intervention models toward more sophisticated, coordinated, and multidisciplinary strategies that acknowledge the multifaceted nature of ACEs and their diverse impacts across different domains," says Meghan Royle, a doctoral student in criminology and criminal justice at SHSU, who co-authored the study.

"This requires a thorough reevaluation of current intervention strategies and policy frameworks to ensure they take into account the specific interactions between different ACEs and their varied developmental impacts."

For example, implementing ACE-informed practices across various settings should be paramount, so that individuals affected by ACEs receive consistent support in such settings as educational institutions, health care facilities, social care settings, and the criminal justice system. Prevention strategies are equally if not more important to alleviate the immediate impacts of ACEs and deter the long-term, complex challenges they present.

Among the study's limitations, the authors point out the difficulty of synthesizing the potential impact of research design on the effect sizes of the relationship between ACE approaches and outcomes. Given the methodological challenges, the authors propose a future ACE umbrella review agenda that addresses, among other foci, protective factors that shield children from the detrimental effects of adversity (e.g., stable and supportive relationships, resilience skills, positive school and community environments).