The associations of residential greenness with cortisol in patients with heart failure

Abstract

Heart failure (HF) is the leading cause of hospitalizations in cardiovascular disease patients, in many countries, including the United States, Europe, and Lithuania. HF patients often have elevated cortisol levels, associated with higher mortality. Urban greenery can improve physical and mental health. We hypothesize that greater residential environment greenness exposure is linked to reduced cortisol levels in symptomatic HF patients. During 2006-2009, in Kaunas, Lithuania, health data was collected from 85 urban patients (a population of ≥ 10,000 inhabitants) who underwent rehabilitation for symptomatic HF. Patients were assessed for general, cardiorespiratory systems parameters, also for blood cortisol levels at baseline and after 6 months. Greenness was assessed using the Normalized Difference Vegetation Index (NDVI) in buffer zones. A multivariate linear regression model was used to evaluate the effect of NDVI on cortisol change after 6 months. A decrease in cortisol by −30.8 mmol/l (SE = 14.7, p = 0.036) was associated with a 0.1 higher level of NDVI at 300 m. NDVI effect was stronger when cortisol test was done after 10 AM and in patients with ejection fraction < 30%. Our results confirm that greenness was related to a decrease in cortisol levels after 6 months in patients with symptomatic HF.