The last two decades have seen a huge research focus on understanding the experience and impact of adverse childhood experiences (ACEs). ACEs include experiences such as child maltreatment, domestic violence, having a parent with a mental illness or in prison, parental substance misuse, and parental separation. This increase in research interest was largely aided by the development of the ACE questionnaire by Felitti & colleagues (1998), which will be familiar to most people working in ACEs research and possibly also to those who have had training in trauma-informed practice.

It is well established that experiencing ACEs has negative impacts on health outcomes across the life course (see previous blog).

Whilst there have been previous meta-analyses of the prevalence of ACEs, these have focused on specific populations and contexts (Merrick et al, 2018; Liu et al, 2021) and there has not been an attempt to establish a global prevalence within the general population.

Madigan et al. (2023) therefore sought to estimate a global prevalence of ACEs by pooling all available information from published studies and to identify groups of the population who are most at risk of experiencing ACEs.

Methods

Three databases (Medline, Embase & PsycINFO) were searched for the terms “ACEs” and “Adverse childhood experience”.

Studies were included if they:

• Used the ACE Questionnaire capturing between 6 and 12 ACEs
• Reported prevalence of ACEs in an adult population sample
• Were published in English

Authors used a quality assessment tool to establish the quality of studies and performed a single multicategory meta-analysis to pull together all the study findings and estimate a summary prevalence of ACEs across all studies. The authors estimated the prevalence of people having experienced 0, 1, 2, 3 or 4+ ACEs. They also pulled together evidence from the studies to find out which groups of people were most at risk of having experienced ACEs.

Results

11,920 studies were identified via database searches. 4,656 studies were full-text screened for inclusion. 206 studies met the full inclusion criteria, of which 208 ACEs prevalence proportions were taken, resulting in data from a total of 546,458 adults being included in analysis.

Study characteristics and demographics

The majority of studies reported data from North America (83.5%). 9.7% of studies were from Europe, 2.9% Asia, 1.9% Australia & New Zealand, 1% South Africa, 0.5% Africa and 0.5% the Caribbean.

The average age of samples was 33.9±11.7 years. The average proportion of women in samples was 35%. The studies included many ethnic groups, including White (58%), Black (26%), Latinx (18%), Asian (13%), Native American (12%), mixed (8%), and other (11%).

Global prevalence of ACEs

Through the meta-analysis of the 208 proportions, the authors reported that an estimated:

• 40% of people had experienced no ACEs at all (39.9%, 95% CI 29.8 to 49.2)
• 22% had experienced one ACE (22.4%, 95% CI 14.1 to 30.6)
• 13% had experienced two ACEs (13.0%, 95% CI 6.5 to 29.8)
• 9% had experienced three ACEs (8.7%, 95% CI: 3.4 to 14.5)
• 16% had experienced 4 or more ACEs (16.1%, 95% CI: 8.9 to 23.5)

This means that 60% of people around the world are estimated to have experienced at least one form of childhood adversity, based on existing available international evidence.

Who is most at risk of reporting ACEs?

Results of the ratio of prevalence proportions analysis focussed on the difference of prevalence within those experiencing 4+ ACEs and those with 0 ACEs.

People who had experienced 4+ ACEs were more likely to come from low-income households (compared to middle- or high-income). They were also more likely to come from a minoritised ethnic group, be homeless, have a history of mental health conditions or substance misuse or addictions.

However, people with no ACEs were less likely to come from low-income households, be unhoused, have a history of mental health problems and substance abuse or addiction.

There was also some evidence that fewer people with no ACEs had a history of offending. There was also a higher prevalence of no ACEs amongst men and in European samples (compared to North America).

Finally, there was evidence to suggest that the prevalence of 0 and 4+ ACEs differed slightly by age and study quality.

Conclusions

This study suggests that ACEs are common, with 6 in 10 adults reporting having experienced one or more ACE and 1 in 6 reporting four or more ACEs. The authors concluded that whilst data suggests that ACEs are common, there are sizeable differences across the population, particularly for those who are in some ethnic minority groups, those of low income and those with a history of mental health issues or addiction. As such, they describe how ACEs should be considered a “key public health priority”. The authors also call for future research to focus on disparities in ACEs, recognising that some groups have higher risk of ACEs and their effects.

Strengths and limitations

This systematic review and meta-analysis benefits from the use of consistent measurement of adversity and rigorous review/screening protocol. The authors should be merited on their consideration of inequalities in ACEs, by considering a broad range of social and demographic groups and looking at which groups were most at risk.

However, limitations of the study must also be considered, some of which the authors have mentioned themselves:

• Considering that over 80% of studies included in this meta-analysis were from North American populations, the “global” population represented in these results hugely underrepresents large portions of the world which are represented in the meta-analysis by a single study. This is further compounded by only considering publications in English.
• Additionally, this over representation of the US should be taken into account when considering the results of moderation analyses, especially the moderating effect of racial-ethnic groups given the particular cultural context of North America. Also, great care should be taken in the interpretation of these results as it would not be appropriate to infer someone’s likelihood of experiencing ACEs based solely on their ethnicity.
• The study relies on data from retrospective report of ACEs, which are known to differ from objective and/or prospective measures of adversity (Baldwin et al, 2019). It would be interesting to consider and compare the present study to one which only considered prospective or objective reports of ACEs and where disparities lie.

Implications for practice

This meta-analysis provides good evidence that ACEs are common in the general population, but they are not experienced equally. Awareness of such inequalities in the experience of ACEs has important implications for practice and policy. Those who have experienced ACEs may be more at risk of negative outcomes (e.g., substance use and addiction) and a history of ACEs is much more likely when working with these groups of people (e.g. unhoused people). Therefore, services (such as health) that are likely to encounter these groups may consider the implementation of trauma-informed care and/or relational approaches. However, implications of this work must be considered within the context of the limitations mentioned in the section above, especially given the cultural context of the current study which is over-represented by North American samples.

For researchers, this meta-analysis demonstrates where evidence on ACE prevalence is under-represented – in all populations outside of North America and Europe. Particularly, there are very few studies from low- and middle-income countries, where disparities and risk factors may differ. In addition, the authors discuss how future studies should consider the prevalence of ACEs amongst the LGBTQ+ community, as there was insufficient evidence for this to be included in the moderation analysis of this research.

Statement of interests

Both authors of this blog are active in ACEs research, but have no other conflicts of interest to declare relevant to this blog.

Links

Primary paper

Madigan, S., Deneault, A.-A., Racine, N., Park, J., Thiemann, R., Zhu, J., Dimitropoulos, G., Williamson, T., Fearon, P., Cénat, J.M., McDonald, S., Devereux, C. and Neville, R.D. (2023), Adverse childhood experiences: a meta-analysis of prevalence and moderators among half a million adults in 206 studies. World Psychiatry, 22: 463-471. https://doi.org/10.1002/wps.21122

Other references

Felitti VJ, Anda RF, Nordenberg D, et al. Relationship of childhood abuse and household dysfunction to many of the leading causes of death in adults: The adverse childhood experiences (ACE) study. American Journal of Preventive Medicine. 1998;14(4):245-258. doi:10.1016/S0749-3797(98)00017-8

Merrick MT, Ford DC, Ports KA, Guinn AS. Prevalence of Adverse Childhood Experiences From the 2011-2014 Behavioral Risk Factor Surveillance System in 23 States. JAMA Pediatrics. 2018;172(11):1038-1044. doi:10.1001/jamapediatrics.2018.2537

Liu M, Luong L, Lachaud J, Edalati H, Reeves A, Hwang SW. Adverse childhood experiences and related outcomes among adults experiencing homelessness: a systematic review and meta-analysis. The Lancet Public Health. 2021;6(11):e836-e847. doi:10.1016/S2468-2667(21)00189-4

Baldwin JR, Reuben A, Newbury JB, Danese A. Agreement Between Prospective and Retrospective Measures of Childhood Maltreatment: A Systematic Review and Meta-analysis. JAMA Psychiatry. 2019;76(6):584-593. doi:10.1001/jamapsychiatry.2019.0097

Photo credits

• Photo by Ramin Talebi on Unsplash
• Photo by Ben White on Unsplash
• Photo by Charlein Gracia on Unsplash
• Photo by Rob Curran on Unsplash
• Photo by Nik Shuliahin 💛💙 on Unsplash
• Photo by Robert Collins on Unsplash