Green Exposure, Depression, and Inflammatory Biomarkers: A Prospective Study

Major depressive disorder and bipolar disorders are prevalent mental health conditions that significantly impact quality of life and life expectancy. These mood disorders involve major depressive episodes (MDE), which pose a substantial burden for patients and their families. While psychopharmacological therapies are a first-line treatment for MDE, the response is often incomplete. New approaches focused on the human-nature relationship may potentially complement antidepressant treatments, thus reducing psychopharmacological needs. This study aims to evaluate whether green exposure affects depressive symptoms and inflammatory biomarker levels in patients with MDE. This prospective study examined the association between exposure to green environments such as woods, forests, large parks, and gardens for at least 45 minutes twice a week, depressive symptoms, and inflammatory biomarkers in 31 patients with an ongoing MDE. The findings suggest that exposure to greenness, together with the modification of antidepressant therapy, is associated with improved depressive symptoms, lower levels of inflammatory biomarker interleukin-6, and higher concentrations of adiponectin after six weeks of treatment. These results suggest that exposure to green environments may have a favorable impact both on mental health and on inflammatory processes, and thus represent a complementary therapeutic strategy. Such information could be relevant to clinicians and urban planners.