Kristine Engemann Jensen1,2, Carsten Pedersen2,3,4, Constantinos Tsirogiannis5, Preben Bo Mortensen2,3,4, Jens-Christian Svenning1; 1Section for Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University, Denmark, 2Centre for Integrated Register-based Research, CIRRAU, Aarhus University, Fuglsangs Alle 4, 8210 Aarhus V, Denmark, 3National Centre for Register-based Research, Aarhus BSS, Department of Economics and Business Economics, Aarhus University, Fuglsangs Alle 4, 8210 Aarhus V, Denmark, 4The Lundbeck Foundation Iniative for Integrative Psychiatric Research, iPSYCH, Aarhus University, Fuglsangs Alle 4, 8210 Aarhus V, Denmark, 5Center for Massive Data Algorithmics, MADALGO, Aarhus University, Department of Computer Science, Aarhus University, The IT-park, Åbogade 34, DK-8200 Aarhus N, Denmark
Background Less green space in urbanized areas, where schizophrenia risk is high, could point to green space as an important factor. Green space is hypothesized to positively influence mental health and could mediate schizophrenia risk through noise and particle pollution removal, stress relief or other unknown mechanisms. However, the effect of green space on schizophrenia risk has not been disentangled from that of urbanization and it is unclear if different measures of green space associate differently with risk. Methods We used satellite data from the Landsat program to quantify green space for Denmark in 30×30m resolution for the years 1985-2013. The effect of quantity and heterogeneity of green space and urbanization at place of residence on schizophrenia risk was estimated using cox regression from a longitudinal population-based sample of the Danish population (943027 persons). Schizophrenia risk was controlled for age, sex, parental education, salary, and employment status. Results Living at the lowest amount of green space was associated with a 1.52-fold increased risk of developing schizophrenia compared to persons living at the highest level of green space. The strongest protective association was observed during the earliest childhood years and closest to place of residence. Conclusion Green space decreases schizophrenia risk independent of urbanization - consequently pointing to green space as a new environmental risk factor for schizophrenia. This study supports findings from other studies highlighting the natural environment as an important factor for human health, and points to a new methodological framework that combines epidemiological studies with big data approaches.
