Association between childhood green space, genetic liability, and the incidence of schizophrenia

Childhood exposure to green space and genetic liability are both independently and additively associated with schizophrenia in adulthoodDecades of extensive scientific research have been devoted to gaining a better understanding of schizophrenia, yet the underlying causes of this serious mental disorder are poorly understood. This study investigated the association between childhood green space, genetic liability, and the incidence of schizophrenia. While previous research found an association between childhood exposure to green space and a lower risk of developing schizophrenia later in life, this is the first study to examine if this association is mediated by genetic liability or whether the two risk factors work in conjunction with each other.

To investigate possible gene–environment associations with the risk of schizophrenia, researchers combined an estimate of childhood exposure to residential-level green space with genetic liability estimates for a large Danish population. The researchers used information from the Danish registers of health, residential address, and socioeconomic status to adjust risk estimates for established confounders (parents’ socioeconomic status and family history of mental illness). Estimates of green space exposure were based on satellite images within 210 meter × 210 meter square regions centered at each individual’s residence from birth until the 10th birthday.

An analysis of the data indicated that childhood green space and genetic liability for schizophrenia appear to be unrelated. Additionally, each of these factors (childhood green space and genetic liability) were independently associated with risk of schizophrenia in dose–response relationships. Childhood green space is associated with lower risk for schizophrenia; high genetic liability is associated with higher risk. The study found no evidence of an interaction between green space and genetic liability for schizophrenia. In other words, a gene–environment interaction does not increase the risk of schizophrenia beyond each risk factor separately.

This research adds support to the understanding that growing up surrounded by more green space is associated with a lower risk of developing schizophrenia later in life. Increasing childhood exposure to green space could thus be a protective environmental factor for schizophrenia.