An Observational Feasibility Study on the Impact of Green Exposure on Major Depressive Episode Symptomatology and Inflammatory Biomarkers

Gianna Pavarino^1,2Claudio Brasso^1,3*Marina Boido^1,2Anna Carluccio^1,3Francesca Cirulli⁴Giulio Mengozzi^5,6Roberta Schellino^1,2Alessandro Vercelli^1,2Paola Rocca^1,3

• ¹Department of Neuroscience Rita Levi Montalcini, University of Turin, Turin, Piedmont, Italy
• ²Neuroscience institute Cavaleri Ottolenghi (NICO), Turin, Piedmont, Italy
• ³Dipartimento di Neuroscienze e Salute Mentale, Azienda Ospedaliera Universitaria Città della Salute e della Scienza di Torino, Torino, Italy
• ⁴Center of Reference for Behavioral Sciences and Mental Health, National Institute of Health (ISS), Rome, Lazio, Italy
• ⁵Department of Medical Sciences, School of Medicine, University of Turin, Turin, Piedmont, Italy
• ⁶Dipartimento di Medicina di Laboratorio, Azienda Ospedaliera Citta' Della Salute E Della Scienza Di Torino, Torino, Italy

Major depressive and bipolar disorders are prevalent mental health conditions sharing the presence of major depressive episodes (MDEs). While psychopharmacological and psychological therapies are first-line treatments for MDEs, the response is often incomplete. New approaches focused on the human-nature relationship might complement antidepressant treatments, improving response. This observational pilot study aims to assess the feasibility of implementing regular exposure to green environments such as woods, forests, large parks, and gardens for at least forty-five minutes twice a week in a sample of patients experiencing a MDE and needing a modification of the antidepressant therapy. It also has the purpose of detecting changes in symptoms and inflammatory biomarkers at follow-up after six weeks. Fifty-three patients were evaluated at the baseline; thirty-one completed the study. Nineteen (61%) of the completers reported regular exposure to greenery during the study. At follow-up, actively exposed patients showed trends of improvements in depressive symptoms, lower levels of C-reactive protein and interleukin-6, and higher adiponectin concentrations. This result suggests that incorporating green exposure into clinical practice is feasible and potentially useful. However, more rigorous evaluations on larger samples are needed to verify whether exposure to greenery may complement MDEs treatment and favorably impact MDE-associated inflammatory processes.