The Association Between Physical Environment and Externalising Problems in Typically Developing and Neurodiverse Children and Young People: A Narrative Review

The physical environment is of critical importance to child development. Understanding how exposure to domains of the physical environment such as greenspace, urbanicity, air pollution or noise affects externalising problems in typical and neurodiverse children is of particular importance given the significant long-term impact of those problems. In this narrative review we investigated the evidence for domains of the physical environment that may ameliorate or contribute to the display of externalising behaviours. We have considered a broad range of study designs that include typically developing and neurodiverse children and young people aged 0-18 years. We used the GRADE system to appraise the evidence. Searches were performed in 8 databases in July 2020 and updated in June 2022. Additional articles were further identified by hand-searching reference lists of included papers. The protocol for the review was preregistered with PROSPERO. Results: We retrieved 7174 studies of which 67 are included in this review. The studies reported on green space, environmental noise and music, air pollution, meteorological effects, spatial density, urban or rural setting, and home elements (e.g., damp/sensory aspects/colour). They all used well validated parent and child reported measures of externalising problems. Most of the studies were rated as having high or probably high risk of bias. Greenspace rurality and interior design had most evidence, although the certainty of the association was low. As expected, noise, air pollution, urbanicity, spatial density, colour and humidity appeared to increase the display of externalising behaviours. There was a dearth of studies on the role of the physical environment in neurodiverse children. The studies were heterogeneous and measured a range of externalising behaviours from symptoms to full syndromes. Greenspace exposure was the most common domain studied but certainty of evidence for the association between environmental exposures and externalising problems in the child or young person was low across all domains. We found a large knowledge gap in the literature concerning neurodiverse children, which suggests that future studies should focus on these children, who are also more likely to experience adverse early life experiences including living in more deprived environments as well as being highly vulnerable to the onset of mental ill health. Such research should also aim to dis-aggregate the mechanisms of action for both environmental influences on the externalising problems the results of which may point to pathways for public health interventions and policy development to address inequities that can be relevant to ill health in neurodiverse young people.