Abstract
BACKGROUND: Autism spectrum disorder (ASD) is a neurobiological disorder with not clearly explained pathogenetic mechanisms. Toxicological and epidemiological studies have suggested that environmental factors may be involved in both the onset and progression. Although greenness and exposure to green spaces are considered possible protective factors, with an inverse relationship between exposure and disease risk, their role in nervous system diseases is still relatively unexplored. This study aimed to investigate the association between greenness exposure and ASD risk. METHODS: We carried out a case-control study. Recruitment was carried out at the Child Neuropsychiatry Outpatient Clinics of the Policlinico “G. Rodolico - S. Marco” Hospital, Catania (Italy). Greennes exposure data were assessed by satellite data from the Copernicus Global Land Service, a component of the Land Monitoring Core Service. These data are used to calculate the Normalized Difference Vegetation Index (NDVI) as a proxy for green space exposure. Data analysis was performed using restricted cubic spline and logistic regression models using the central quintile as the reference category, adjusting for age and sex. RESULTS: We recruited 61 cases diagnosed from 2010 to 2016 and 93 controls. The study highlighted a non-linear trend in risk both when analyzing exposure relative to the year 2000 [ORs 1.00 (95% CI 0.29-3.40); OR 1.46 (95% CI 0.42-5.05); OR 0.92 (95% CI 0.27-3.10); OR 0.94 (95% CI 0.28-3.22)], and in the following years up to 2016. CONCLUSIONS: Exposure to green space can have beneficial effects due to lower air pollution, reduced stress and increased physical activity and social interaction. Furthermore, it should be noted that not only the availability of green space, but also the actual accessibility to such area should be considered as a relevant methodological issue to be considered when evaluating the relationship between greennes and nervous system disorders. KEY MESSAGES: • The results highlight possible protective effects of greenness on neurodevelopment. • These results seem to confirm a role of the environmental context in the risk of ASD.