This study investigated the possible link between exposure to surrounding greenness during childhood and adolescence and the risk of depression. The study also investigated whether other factors, such as population density, might influence this possible link.
Data from over 11,000 adolescents were used in this study. Their mothers – all nurses -- enrolled them in the Growing Up Today Study (GUTS) when they were between the ages of 9 and 14. In 1999, questionnaires, which included measures of depression, were sent to all the children enrolled in GUTS. After that, follow-up questionnaires were sent annually or biennially. The data provided by the study participants covered a period of up to 17 years. The satellite-based Normalized Difference Vegetation Index (NDVI) was used to estimate childhood exposure to surrounding greenness.
Participants who lived in homes with higher NDVI readings during childhood and adolescence were less likely to report depressive symptoms in adolescence and young adulthood than participants who lived in homes with lower NDVI readings. This suggests that surrounding greenness may have provided some protection against depressive symptoms. The association between surrounding greenness and a lower risk of depressive symptoms seemed to be stronger in adolescence than in early adulthood and in areas of high population density. The same pattern was found for persistent depressive symptoms.
These findings are consistent with other research indicating a possible protective association between greenness and the risk of depression and other mental health concerns. Earlier research, however, related more to adults than to children or adolescents. Additionally, earlier research tended to focus on relatively homogeneous regions versus areas with different population densities. This research adds to the literature by focusing on surrounding greenness during childhood and adolescence and by considering population density as an influencing factor in the association between greenness and mental health. This study, along with previous research, indicates that nature can serve as an antidote to some of the stress-related conditions of an urban environment. This may be especially true for people living in high-density population areas.
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