Systematic review finds causal association between childhood maltreatment and mental health problems

A review of 34 quasi-experimental studies has revealed a small causal relationship between childhood maltreatment and mental health issues. The findings, published in the American Journal of Psychiatry, suggest that genetic and environmental risk factors may account for a substantial portion of the mental health risk associated with maltreatment.

Psychology research has consistently shown that exposure to maltreatment during childhood is a risk factor for a range of mental health disorders. However, it is difficult to determine the causality in this relationship — does childhood maltreatment cause mental health problems?

It seems plausible that exposure to abuse during childhood can lead to the development of mental health issues. But mental health problems among maltreated individuals could also be the result of co-occurring risk factors like low socioeconomic status or being a victim of bullying. Alternatively, these issues could stem from genetic factors like family history of mental illness.

To investigate causality between maltreatment and mental health, study author Jessie R. Baldwin and her team conducted a systematic review of existing quasi-experimental studies. These studies are designed to examine causality without using randomization and include twin studies, sibling studies, fixed effects studies, and natural experiments.

“There have been hundreds of studies showing that child maltreatment is associated with mental health problems, but it wasn’t clear whether these associations reflect causal relationships or not,” explained Baldwin, a senior research fellow at University College London. “This is because child maltreatment co-occurs with other risk factors for mental illness, like poverty and family history of mental illness – and it’s not clear whether the observed associations are driven by maltreatment or those other risk factors.

Free daily newsletter

“Randomized control trials (RCT) are typically used in research to establish cause and effect, but it’s clearly not ethical to randomly assign a child to experience maltreatment and then examine their mental health outcomes. Instead, quasi-experimental methods can be used in observational studies to better disentangle the effects of maltreatment from other risk factors. Therefore, we decided to summarize all of the quasi-experimental evidence on the effects of child maltreatment on mental health.”

The review included 34 quasi-experimental studies involving a total of 56,646 participants. Each study included measures of childhood maltreatment, which included any of these experiences: physical, sexual, or emotional abuse, physical or emotional neglect, institutional deprivation, or harsh physical discipline. Each study also included associations with mental health outcomes, which included general psychopathology as well as symptoms of internalizing, externalizing, neurodevelopmental, or thought disorders.

Using a multilevel random-effects meta-analysis, the researchers found a small relationship between childhood maltreatment and mental health problems. Further analysis revealed that this relationship was consistent across different study designs, whether it be a twin study, sibling study, fixed-effects study, or a natural experiment.

The link between maltreatment and mental health issues was also consistent whether maltreatment was assessed prospectively or retrospectively — suggesting that recall bias was not a leading factor — and whether a study used a cross-sectional or a longitudinal design — suggesting no reverse causation. The association also remained more or less similar across a wide variety of mental health outcomes and types of childhood maltreatment.

The overall findings lend support to the notion that childhood maltreatment contributes to mental health problems. “Our findings suggest that child maltreatment has small causal effects on a range of mental health problems,” Baldwin told PsyPost. “Although small, these effects of maltreatment could have far-reaching consequences, given that mental health problems predict poor later outcomes (e.g., difficulties at work, poor physical health, and early mortality).

The researchers noted that the effect size for the association between maltreatment and mental health was substantially reduced after quasi-experimental adjustment. This suggests that a considerable portion of the relationship is influenced by pre-existing risk factors which may include environmental and genetic factors.

“We also found that part of the overall association between child maltreatment and mental health problems is explained by other psychiatric vulnerabilities, such as environmental risk factors and genetic predisposition,” Baldwin explained. “Therefore, to reduce risk of mental health problems in children exposed to maltreatment, clinicians should address other risk factors as well as the maltreatment experience.”

Baldwin and her colleagues offer recommendations for clinical practice based on their study findings. “Regarding clinical practice, to minimize risk of psychopathology in individuals exposed to maltreatment, interventions should adopt a holistic approach that addresses both the maltreatment experience (e.g., via trauma-focused cognitive-behavioral therapy) and wider risk factors for mental illness,” they wrote in their paper.

The authors acknowledged several limitations of their research, including that each individual study comes with its own risk of bias and some studies did not fully account for potential confounding variables.

“It will be important to understand the causal effects of child maltreatment on other outcomes, such as physical health problems,” Baldwin noted.

The study, “Childhood Maltreatment and Mental Health Problems: A Systematic Review and Meta-Analysis of Quasi-Experimental Studies”, was authored by Jessie R. Baldwin, Biyao Wang, Lucy Karwatowska, Tabea Schoeler, Anna Tsaligopoulou, Marcus R. Munafò, and Jean-Baptiste Pingault.