A mindfulness- and relaxation-based nature intervention improves mood in depressed patients in psychosomatic rehabilitation: Results from the GREENCARE non-randomized controlled clinical trial.

Introduction: Guided contact with nature has positive effects on well-being. Little is known about the effectiveness of adding nature-based interventions to inpatient treatment for depression. Therefore, we evaluated a mindfulness- and relaxation-based nature intervention for depressed patients in psychosomatic rehabilitation treatment. Method: Psychosomatic rehabilitation inpatients with depression were allocated to either a Greencare mindfulness- and relaxation-based nature intervention (n = 116) or to treatment as usual plus waitlist control group (TAU + WL) (n = 111) in two centres. All patients received questionnaires on admission (T1) and discharge (T2). Greencare patients received follow-up questionnaires three months after the intervention (T3). Main outcome was mood, assessed by the Positive and Negative Affect Schedule (PANAS). Secondary outcomes were depression, mindfulness, state self-compassion, and contact with nature. Data were analysed as intent-to-treat using mixed models for repeated measures, adjusted for propensity score and centre. Patients' ratings of the effectiveness of the sessions and their well-being, and situational aspects of each session, were recorded. Results: We found significant interactions of time*group for PANAS, showing greater positive affect (Cohen's d at T2 = 0.48) and lower negative affect (Cohen's d at T2 = 0.52) in the Greencare group compared to the TAU + WL group at T2. At follow-up (T3), the effects in the Greencare group decreased, but remained significant compared to T1. Significant results for self-compassion and non-significant effects for depression and mindfulness were found. The groups did not differ in the amount of contact with nature. Sensitivity analyses revealed more favourable follow-up effects for patients with higher levels of depression. Patients reported high ratings of effectiveness and well-being for each session, and these ratings were not related to the weather conditions. No adverse events were reported. Discussion: Depressed inpatients benefitted from a Greencare mindfulness- and relaxation-based nature intervention by improving positive and negative affect. The effects were slightly reduced after three months, but less in patients with higher levels of depression on admission. Results show that the intervention is feasible and effective even for patients with higher symptom burden. Trial registration: German Clinical Trials Register (trial registration number: DRKS00023369, universal trial registration number: U1111-1260-7305).