Exploring causal relationships between child maltreatment and child internalising and externalising behavioural problems : a bidirectional mendelian randomization study

Abstract

Background: Prior observational studies have shown associations between child maltreatment and behavioural problems in children. However, the causal relationship and directionality between these variables stay unclear, necessitating rigorous methodologies to determine whether caregivers perpetrate maltreatment in response to child misbehaviour or if children develop behavioural problems because of maltreatment. Method: This study employed a bidirectional two-sample Mendelian Randomization (MR) analysis to elucidate the causal relationships between child maltreatment and behavioural problems. We utilized summary data from large-scale genome-wide association studies (GWAS) and GWAS meta-analyses for child maltreatment (185,414 participants), aggressive behaviours (87,485 participants), internalising symptoms (64,561 participants), and diagnosed behavioural and emotional disorders (3029 cases and 215,763 controls). Results: The MR analyses revealed that exposure to child maltreatment significantly increased the risk of developing aggressive behaviour (β = 0.126, SE = 0.052, P = 0.014) and overall childhood behavioural or emotional disorders (β = 0.963, SE = 0.379, P = 0.011), but did not significantly affect internalising symptoms (β = 0.064, SE = 0.054, P = 0.235). In contrast, insufficient evidence was identified on causal effects of various phenotypes of child behavioural problems on the risk of experiencing child maltreatment (all P > 0.05). Conclusions: Our findings provide evidence for a causal effect of child maltreatment on the development of aggressive behaviour and general behavioural or emotional disorders, while suggesting no reverse causation. These results emphasize that child misbehaviour should not be viewed as a justification for maltreatment, but rather as one of its detrimental consequences. The study highlights the urgent need for timely prevention and intervention strategies to address child maltreatment in order to enhance child development and promote behavioural health.