This three-phase study first assesses the prevalence of anxiety and depressive symptoms among adolescents, then evaluates the effectiveness of a randomized controlled nature-based therapy intervention. The final phase explores emotional, behavioral, and psychosocial changes through qualitative interviews with parents of adolescents in the intervention group. The study aims to provide evidence for nature-based therapies as effective complementary interventions for adolescent mental health.

This study aims to determine the prevalence of anxiety and depressive symptoms among adolescents, evaluate the effectiveness of a structured nature-based therapy (NBT) intervention, and explore psychosocial changes observed in adolescents through parental perspectives. Adolescence represents a critical developmental period marked by intense biological, emotional, and cognitive transitions that increase vulnerability to internalizing disorders such as anxiety and depression. When not addressed early, these symptoms may persist into adulthood and result in long-term psychological impairment.

The research is conducted using a three-phase mixed-methods design. In the first phase, a large-scale screening is implemented to assess the prevalence of anxiety and depressive symptoms within the adolescent population using standardized psychological assessment tools. This stage aims to identify individuals at elevated risk and determine eligibility for the intervention phase.

The second phase consists of a randomized controlled trial in which eligible participants are randomly assigned to either an experimental group receiving the nature-based therapy program or a control group receiving standard follow-up without therapeutic intervention. The nature-based therapy program is delivered in natural outdoor environments and incorporates experiential activities, group-based therapeutic exercises, emotional regulation practices, mindfulness-oriented techniques, and reflective components. The intervention is designed to enhance psychological well-being, reduce stress, improve emotional coping skills, strengthen social interaction, and promote adaptive functioning. Anxiety and depression levels are assessed at baseline, post-intervention, and follow-up to evaluate treatment effectiveness.

The third phase involves qualitative semi-structured interviews conducted with parents of adolescents who participated in the intervention group. These interviews aim to explore observed emotional, behavioral, social, and relational changes in adolescents following the therapy process. This qualitative component provides an in-depth understanding of therapeutic outcomes and supports the quantitative findings through parental observations.

Primary outcome measures include changes in anxiety and depressive symptom severity, while secondary outcomes focus on improvements in emotional regulation, psychosocial functioning, and overall psychological well-being. It is hypothesized that adolescents participating in the nature-based therapy program will demonstrate significant symptom reduction and enhanced psychosocial outcomes compared to the control group.

This study seeks to contribute robust empirical evidence regarding the clinical effectiveness of nature-based therapeutic interventions for adolescent mental health and to support their integration as accessible, holistic, and developmentally appropriate treatment approaches within mental health services.

Inclusion Criteria:

• Adolescents within the defined age range of the study
• Not having a psychiatric diagnosis
• Not receiving psychological or psychiatric support
• Not having a physical disability that would limit participation in therapy sessions
• Having obtained parental consent to participate in the study

Exclusion Criteria:

• Presence of severe psychiatric disorders requiring immediate clinical intervention (e.g., psychosis, severe suicidal risk)
• Ongoing intensive psychological or psychiatric treatment during the study period
• Physical or medical conditions limiting participation in outdoor activities
• Cognitive impairments preventing comprehension of intervention activities

Individual participant data will not be shared to protect participant confidentiality and in accordance with ethical research guidelines and informed consent agreements.