Investigating the causal relationship between maltreatment and cognition in children: A systematic review

Abstract Background Cognitive impairment (i.e. lower IQ/cognitive development) in individuals who have experienced childhood maltreatment is well documented in the literature. It is not yet clear whether maltreatment itself causes cognitive impairment, or whether reduced cognitive functioning pre-dates maltreatment exposure and places children at risk of maltreatment. Objective This systematic review critically evaluated the evidence for a causal association between child maltreatment and impaired cognition in children under 12 years. Methods Following PRISMA guidelines, databases were searched and articles extracted according to inclusion criteria. Quality rating of articles was conducted independently by two reviewers and the evidence for a causal association was evaluated using guidelines based on the Hill criteria for causation in epidemiological and public health research. Results 31 articles were included in the review, with results that suggested lower IQ/cognitive development in maltreated children compared to controls, and a dose-response relationship between timing and duration of maltreatment and impaired cognition. Assessment of causality indicated strong evidence for a causal association between maltreatment and reduced overall cognitive performance in institutionalised children. Findings were less robust for non-institutionalised samples. Evidence regarding specific cognitive functions was mixed. Conclusions Extreme maltreatment may lead to reduced cognitive functioning in children under 12 years. More research is required to determine the impact of the nature and timing of maltreatment, as well as additional heritable and social factors, on specific profiles of cognition in this population.