Therapist-Guided Versus Self-Guided Forest Immersion: Comparative Efficacy on Short-Term Mental Health and Economic Value

Forest therapy, guided by clinical professionals (psychologists or psychotherapists), is increasingly recognized as a preventive and complementary health practice with evidence-based therapeutic potential; however, the specific contribution of therapist guidance compared to self-guided immersion remains unclear. This retrospective study evaluated the short-term mental health outcomes of therapist-guided (TG) compared to self-guided (SG) forest immersion, based on the validated State-Trait Anxiety Inventory and Profile of Mood States questionnaires. Data were collected from 282 adults participating in eight paired TG-SG sessions conducted at the same forest sites across Italy. The results showed that TG sessions were associated with greater improvements in state anxiety, self-esteem, and total mood disturbance, with statistically significant effects in most cases. Therapist-led guidance also occasionally reduced interindividual variability, suggesting enhanced emotional regulation. An illustrative economic assessment, based on standardized psychometric improvements translated into quality-adjusted life years (QALYs), indicated that the TG sessions yielded approximately 1.7 times the annual per-person economic value of the SG sessions, outweighing the associated therapist-related costs. These findings suggest that TG forest therapy interventions deliver significant and economically quantifiable added value compared to SG experiences, supporting their inclusion in preventive health and mental well-being programs and justifying further longitudinal and cost-effectiveness investigations.