The Association of Childhood Maltreatment and Mental Health Problems: Partly Causal and Partly Due to Other Factors.

Abstract

Back to table of contents Previous article Next article EditorialsFull AccessThe Association of Childhood Maltreatment and Mental Health Problems: Partly Causal and Partly Due to Other FactorsMeike Bartels, Ph.D., and Christel M. Middeldorp, M.D., Ph.D.Meike BartelsSearch for more papers by this author, Ph.D., and Christel M. MiddeldorpSearch for more papers by this author, M.D., Ph.D.Published Online:1 Feb 2023https://doi.org/10.1176/appi.ajp.20220969AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail Accumulating evidence supports the observed association between childhood maltreatment and mental health. Review studies and meta-analyses consistently report associations between different forms of childhood maltreatment and various forms of mental problems (1–7). The next question is whether this association is causal. This knowledge is crucial to inform prevention and intervention strategies. While it seems likely that mental health problems are directly caused by childhood maltreatment, other (environmental) risk factors and genetic effects can also play a role. For example, both socioeconomic disadvantage (8, 9) and genetic predisposition—for example, in the form of higher polygenic risk scores for mental disorders (10–12)—have been reported to explain part of the association between childhood maltreatment and mental health.A study in this issue by Baldwin et al. (13) concludes that preventing childhood maltreatment could help to prevent psychopathology, but that it is also important to focus on other factors that also partly explain the association. This conclusion is based on their systematic review and meta-analysis of quasi-experimental studies examining the relationship between childhood maltreatment and mental health problems. The focus on quasi-experimental designs enabled the disentanglement of causal effects from effects from other environmental and genetic factors.In their review, the authors included four broad categories of quasi-experimental designs: 1) family-based designs, which capitalize on varying genetic and environmental relationships between family members; 2) panel data designs with longitudinal within-individual change in exposure data; 3) natural experiments, studying effects of social or political processes, such as large-scale institutional neglect; and 4) propensity score methods, mimicking randomized experiments based on preexisting differences between exposed and nonexposed individuals.While these approaches have been used in individual studies, they have not been combined and systematically evaluated before. Baldwin and colleagues’ systematic review and meta-analysis allowed them to examine whether studies across the various quasi-experimental methods, which all have different assumptions and sources of bias, had similar results, thereby strengthening causal inference.The systematic search produced 34 studies with available data. These studies were based on 29 distinct cohorts comprising 54,646 participants. Before adjusting for other factors, the Cohen’s d value expressing the effect size of the association between childhood maltreatment and mental health problems was 0.56 (95% CI=0.41, 0.71). There was still a consistent association after quasi-experimental adjustment (Cohen’s d=0.31, 95% CI=0.24, 0.37). These results indicate a small causal contribution of childhood maltreatment to mental health problems. Importantly, they also show that the meta-analytic association between childhood maltreatment and mental health for quasi-experimental studies was 45% smaller than when the association was based on unadjusted analyses. This suggests that a large part of the overall relationship between childhood maltreatment and mental health is due to other (familial) environmental and genetic effects, thus providing strong evidence that approaches that do not consider this mix of factors can lead to a misinterpretation of the associations. Overestimation (and underestimation) of true casual effects could lead consequently to misguided and wasteful prevention and intervention programs.To strengthen clinical research and clinical application of their results, the authors tested whether their reported association between childhood maltreatment and mental health was moderated by, among other factors, type of mental health outcome, type of maltreatment subtype, and measurement characteristics. The three key findings of these moderator analyses are that 1) maltreatment affects a broad range of mental health outcomes, 2) all subtypes of maltreatment were associated with mental health problems, but emotional abuse and institutional neglect showed the strongest effect, and 3) effect sizes were similar for prospectively and retrospectively assessed childhood maltreatment.Both from a research and a clinical perspective, these findings have important implications. As indicated by the authors, the finding that childhood maltreatment causally influences a broad range of mental health outcomes could inform studies on comorbidity and underlying (biological) factors, altered brain structure and functioning, or, for example, broader emotion regulation. Furthermore, emotional abuse seems more strongly associated with mental health problems than other forms of abuse. Given that this finding is based only on three quasi-experimental studies and several non-quasi-experimental studies, however, it warrants further study. The finding that effect sizes are similar for prospectively and retrospectively assessed childhood maltreatment opens new avenues for research, where retrospectively assessed childhood maltreatment can be added to running (longitudinal) quasi-experimental study designs, such as the long-running twin-family studies around the world. This also opens avenues for immediate action to diversify childhood psychiatric research. This is essential since all studies that are included in the systematic review are based on European ancestry populations, which makes generalization to or clinical use of the results for other populations impossible.The sharp reduction (45%) in effect size based on the quasi-experimental designs used in this study in comparison to the effect based on unadjusted studies indicates that a multitude of environmental adversities and genetic predisposition play a substantial role in the association between childhood maltreatment and mental health. The results of the study are in line with reviews that focused on genetically informed studies exploring parental risk factors for psychopathology (14, 15). The results also indicate that the conventional multiple regression approaches overestimate the (causal) effects. This is also illustrated, for example, for the well-established association between maternal perinatal anxiety and depression with mental disorders later in childhood, where maternal pre- and postnatal anxiety were no longer associated with child internalizing or externalizing problems after adjusting for maternal depression and familial confounding (16). Given that this trend is seen for multiple associations, it is essential to obtain valid values for the magnitude of (causal) effects. This can be achieved by adopting rigorous quasi-experimental methods to identify other potential mechanisms underlying an observed association. Family-based designs, for example, can identify whether other familial factors explain part of the association, and panel data designs with longitudinal data can indicate whether the outcome for an individual changes when the exposure changes. Triangulation, that is, investigating the underlying mechanisms of an association with different methods, is of major importance to ensure the validity of the results across methods. Extending these methods with genomic data even further enables disentangling the role of various genetic and environmental risk and protective factors to improve our understanding of the impact of parents on children and vice versa (17).It has become evident that the model-based hypothesis-testing science that dominated the last century should be accompanied, or preceded, by exploratory data-driven systematic triangulation approaches to generate innovative (often hidden and unexpected) hypotheses. Warrier et al. (18), for example, performed a genome-wide association study of childhood maltreatment and explored the causality of the association with mental disorders by applying Mendelian randomization, another advanced method to explore causality. The results of these analyses suggested a unidirectional causal role of childhood maltreatment in depression. In addition, they found a causal effect of childhood maltreatment on schizophrenia and ADHD, but that effect also went the other way around—that is, schizophrenia and ADHD were also associated with an increased risk for childhood maltreatment.As Baldwin et al. mention in their discussion, clinicians should be aware that the occurrence of childhood maltreatment is likely to be an indicator of the presence of other risk factors for mental disorders. So, in addition to trying to diminish the harmful effects of childhood maltreatment, it is also important to address these other risk factors—for example, the presence of mental disorders such as ADHD. In families with many adversities and chaos, it may seem as if treating the child’s mental disorders will not be effective. The Baldwin et al. study as well as the study by Warrier et al. suggest, however, that optimal treatment of these mental disorders could play a role in improving the outcomes for these vulnerable children. Research should further focus on identifying the other factors that explain the association between childhood maltreatment and mental disorders. In the meantime, addressing concurrent parental mental health problems and improving social disadvantage, if possible, seem sensible ways to further decrease the risk of ongoing mental health problems, as there is evidence that these are related to mental health problems too (15, 19, 20).Overall, the Baldwin et al. study shows that even if it seems highly likely that an association is causal, it is still utterly important to carefully explore whether, and to what extent, that is indeed the case. While childhood maltreatment has been found to have a small causal effect on mental disorders, in addition to efforts to prevent childhood maltreatment, more interventions are needed to optimize outcomes for these children.Department of Biological Psychology, Vrije Universiteit Amsterdam (Bartels); Amsterdam Public Health Research Institute, Amsterdam University Medical Centers, Amsterdam (Bartels); Child Health Research Centre, University of Queensland, Brisbane, Australia (Middeldorp); Child and Youth Mental Health Service, Children’s Health Queensland Hospital and Health Service, Brisbane, Australia (Middeldorp).Send correspondence to Prof. Middeldorp ([email protected]).The authors report no financial relationships with commercial interests.REFERENCES1. Nelson J, Klumparendt A, Doebler P, et al.: Childhood maltreatment and characteristics of adult depression: meta-analysis. Br J Psychiatry 2017; 210:96–104Crossref, Medline, Google Scholar2. Li M, D’Arcy C, Meng X: Maltreatment in childhood substantially increases the risk of adult depression and anxiety in prospective cohort studies: systematic review, meta-analysis, and proportional attributable fractions. Psychol Med 2016; 46:717–730Crossref, Medline, Google Scholar3. Varese F, Smeets F, Drukker M, et al.: Childhood adversities increase the risk of psychosis: a meta-analysis of patient-control, prospective, and cross-sectional cohort studies. Schizophr Bull 2012; 38:661–671Crossref, Medline, Google Scholar4. Angelakis I, Gillespie EL, Panagioti M: Childhood maltreatment and adult suicidality: a comprehensive systematic review with meta-analysis. Psychol Med 2019; 49:1057–1078Crossref, Medline, Google Scholar5. Liu RT, Scopelliti KM, Pittman SK, et al.: Childhood maltreatment and non-suicidal self-injury: a systematic review and meta-analysis. Lancet Psychiatry 2018; 5:51–64Crossref, Medline, Google Scholar6. Langevin R, Marshall C, Wallace A, et al.: Disentangling the associations between attention deficit hyperactivity disorder and child sexual abuse: a systematic review. Trauma Violence Abuse (Online ahead of print, July 9, 2021)Google Scholar7. Maniglio R: Significance, nature, and direction of the association between child sexual abuse and conduct disorder: a systematic review. Trauma Violence Abuse 2015; 16:241–257Crossref, Medline, Google Scholar8. Sidebotham P, Golding J: Child maltreatment in the “children of the nineties” a longitudinal study of parental risk factors. Child Abuse Negl 2001; 25:1177–1200Crossref, Medline, Google Scholar9. Wang D, Jiang Q, Yang Z, et al.: The longitudinal influences of adverse childhood experiences and positive childhood experiences at family, school, and neighborhood on adolescent depression and anxiety. J Affect Disord 2021; 292:542–551Crossref, Medline, Google Scholar10. Sallis HM, Croft J, Havdahl A, et al.: Genetic liability to schizophrenia is associated with exposure to traumatic events in childhood. Psychol Med 2021; 51:1814–1821Crossref, Medline, Google Scholar11. Ratanatharathorn A, Koenen KC, Chibnik LB, et al.: Polygenic risk for autism, attention-deficit hyperactivity disorder, schizophrenia, major depressive disorder, and neuroticism is associated with the experience of childhood abuse. Mol Psychiatry 2021; 26:1696–1705Crossref, Medline, Google Scholar12. Marchi M, Elkrief L, Alkema A, et al.: Childhood maltreatment mediates the effect of the genetic background on psychosis risk in young adults. Transl Psychiatry 2022; 12:219Crossref, Medline, Google Scholar13. Baldwin JR, Wang B, Karwatowska L, et al.: Childhood maltreatment and mental health problems: a systematic review and meta-analysis of quasi-experimental studies. Am J Psychiatry 2023; 180:117–126 Abstract, Google Scholar14. Ahmadzadeh YI, Schoeler T, Han M, et al.: Systematic review and meta-analysis of genetically informed research: associations between parent anxiety and offspring internalizing problems. J Am Acad Child Adolesc Psychiatry 2021; 60:823–840Crossref, Medline, Google Scholar15. Jami ES, Hammerschlag AR, Bartels M, et al.: Parental characteristics and offspring mental health and related outcomes: a systematic review of genetically informative literature. Transl Psychiatry 2021; 11:197Crossref, Medline, Google Scholar16. Gjerde LC, Eilertsen EM, Eley TC, et al.: Maternal perinatal and concurrent anxiety and mental health problems in early childhood: a sibling‐comparison study. Child Dev 2020; 91:456–470Crossref, Medline, Google Scholar17. McAdams TA, Cheesman R, Ahmadzadeh YI: Annual research review: towards a deeper understanding of nature and nurture: combining family‐based quasi‐experimental methods with genomic data. J Child Psychol Psychiatry (Online ahead of print, November 15, 2022)Google Scholar18. Warrier V, Kwong ASF, Luo M, et al.: Gene-environment correlations and causal effects of childhood maltreatment on physical and mental health: a genetically informed approach. Lancet Psychiatry 2021; 8:373–386Crossref, Medline, Google Scholar19. Eilertsen EM, Jami ES, McAdams TA, et al.: Direct and indirect effects of maternal, paternal, and offspring genotypes: Trio-GCTA. Behav Genet 2021; 51:154–161Crossref, Medline, Google Scholar20. Eilertsen EM, Cheesman R, Ayorech Z, et al.: On the importance of parenting in externalizing disorders: an evaluation of indirect genetic effects in families. J Child Psychol Psychiatry 2022; 63:1186–1195Crossref, Medline, Google Scholar FiguresReferencesCited byDetailsCited byRace-Related Disparities in Childhood Adversity, Trauma, and Stress-Related PsychopathologyNed H. Kalin, M.D.1 February 2023 | American Journal of Psychiatry, Vol. 180, No. 2 Volume 180Issue 2 February 01, 2023Pages 105-107 Metrics KeywordsEnvironmental Risk FactorsGenetics/GenomicsViolence/AggressionChild/Adolescent PsychiatryPDF download History Accepted 28 November 2022 Published online 1 February 2023 Published in print 1 February 2023