The Role of Physical Environmental Characteristics and Intellectual Disability in Conduct Problem Trajectories Across Childhood: A Population-Based Cohort Study

Background: The paucity of research investigating the role of the physical environment in the developmental progression of conduct problems and the potential moderating effects of intellectual disability (ID) is surprising, given the clinical relevance of elucidating environmental determinants of disruptive behaviours. Aims: To use data from a large UK cohort study to assess associations between physical environmental exposures, ID, and conduct problem trajectories. Method: The sample included 8,168 Millennium Cohort Study children (1.9% with ID). Multilevel growth curve modelling was used to examine the role of physical environment characteristics in the developmental trajectories of conduct problems after adjustments for ID status. Results: Exposure to external environmental domains was not associated with differences in child conduct problems across development. Alternatively, internal aspects of the household environment: spatial density (b = 0.40, p<.001) and damp problems (b = 0.14, p<.001) were both significantly associated with increased trajectories. Various individual and familial covariates were positively associated with conduct problems over time, including: presence of ID (b = 0.96, p<.001), autism spectrum disorder (b = 1.18, p<.001), male sex (b = 0.26, p<.001), poverty (b = 0.19, p<.001), maternal depression (b = 0.65, p<.001), and non-nuclear family structure (b = 0.35, p<.001). Positive ID status appeared to moderate the effects of internal household spatial density, reporting a non-linear negative association with spatial density and conduct problems across development (b = -1.08, p<.01). Conclusions: Our findings highlight the potential harmful consequences of poor internal residential conditions on child development of disruptive behaviours.