Depression is a common mental disorder among adolescents, with increased rates during the COVID-19 pandemic. Despite its high burden, few young people seek professional help due to, among other things, low mental health literacy and fear of stigma. Since most adolescents often seek health information online and use social media daily, the "ich bin alles" (English: "I am everything"; www.ich-bin-alles.de) project was launched to provide accessible, age-appropriate information about depression via a website and social media channels (e.g., Instagram). This study aims to understand how participants perceive and evaluate the social media channel "ich bin alles" (English: "I am everything"; https://www.instagram.com/ich.bin.alles/).

Depression is one of the most common mental disorders worldwide, with a prevalence of approx. 7.5% in youth. In connection with the COVID-19 pandemic, a meta-analysis found an increase in clinically relevant depressive symptoms to 25.2% in children and adolescents. At the same time, adolescents who experience mental health crises are reluctant to seek help and only 12% of adolescents with clinically relevant depressive symptoms seek professional treatment. The main barriers for young people to seek professional help include low knowledge of mental disorders/low mental health literacy and social factors such as the fear of stigmatization. Mental health literacy (MHL) is defined as "knowledge of how to prevent mental disorders, recognition of when a disorder is developing, knowledge of help-seeking options and treatment available, knowledge of effective self-help strategies for milder problems, and first aid skills to support others who are affected by mental health problems". It has been found that increased depression literacy can reduce depressive symptoms in adults and improve help-seeking for depression. Stigma in the context of mental health is a multidimensional concept that encompasses several domains. For many people living with mental illness, stigma is a significant contributor to a wide range of negative outcomes, including delayed help-seeking, hopelessness, diminished self-esteem, reduced quality of life and poorer clinical outcomes. Many of these negative effects have also been found in young people with mental health problems. Therefore, improving MHL and reducing the stigmatization of mental illness are two important starting points that can serve as targets for interventions. Improved MHL goes hand in hand with better knowledge about seeking help and less stigmatization of mental illness.

The vast majority of adolescents in western countries, such as the United States and Germany, have access to digital devices, such as smartphones. 97% of young people in the United States (13-17 years) state that they use social media and 45% say that they are online almost all the time. Along with this, young people are more likely to ask health questions, including mental health questions, online than through other channels. However, to date, few digital psychoeducational interventions for depression in adolescents have been developed and evaluated. In order to meet this need for action in a contemporary manner that attracts youth, the web-based project "ich bin alles" (English: "I am everything"; www.ich-bin-alles.de) was launched in September 2021 with an associated social media presence. The "ich bin alles" project provides comprehensive evidence-based and age-appropriate information on depression and mental health in youth via social media (such as Instagram). This strategy of providing information via social media is to be scientifically evaluated in this study.

The aim of this qualitative study is to evaluate the spontaneous thoughts and feelings that young people express while viewing "ich bin alles" Instagram content and to understand how the participants perceive and evaluate it. This will be investigated using the "Thinking Aloud Protocol"- method in 10-20 healthy adolescents and adolescents with current or remitted depression aged 13-18 years. The results of the study can help to gain insight into the perception and acceptance of the content.

Inclusion Criteria:

• Ownership of an Instagram account
• Regular use of Instagram
• in group of adolescents with a current or remitted depression: ICD-10 diagnoses F32.0; F32.1; F32.2, F33.0, F33.1, F.33.2 based on "Diagnostisches Interview bei psychischen Störungen im Kindes- und Jugendalter (Diagnostic Interview for Mental Disorders in Childhood and Adolescence)"

Exclusion Criteria:

• Insufficient knowledge of German
• Following the "ich bin alles" (English: "I am everything") social media channels before participating in the study
• Knowing the "ich bin alles" (English: "I am everything") website before participating in the study
• in group of healthy adolescents: no ICD-10 diagnoses based on "Diagnostisches Interview bei psychischen Störungen im Kindes- und Jugendalter (Diagnostic Interview for Mental Disorders in Childhood and Adolescence)"

10-20 healthy adolescents and adolescents with current or remitted depression aged 13-18 years

The study population will also be further described using the following questionnaires:

1. Depression Literacy - Assessed with an adapted version of the German version of the Adolescent Depression Knowledge Questionnaire and the Depression Literacy Scale German (Time Frame: Start of appointment, before the Thinking Aloud Protocol)
2. Stigma - Assessed with the German version of the Self Stigma of Depression Scale and an adapted Version of the Peer mental health stigmatization scale (Time Frame: Start of appointment, before the Thinking Aloud Protocol)
3. Mental Health - Assessed with the Depression Screener for Teenagers and the Perceived Stress Scale (Time Frame: Start of appointment, before the Thinking Aloud Protocol)

Consider briefly explaining why IPD will not or might not be shared. The data collected in this study include sensitive details about participants, such as various sociodemographic characteristics and information about mental health status. Publicly sharing the raw dataset could risk revealing individual identities, thereby violating ethical standards related to participant confidentiality. As a result, the raw data will not be publicly released. However, detailed descriptions of the methodology, materials used, and sample characteristics will be provided within the article and supplementary materials. The intervention is also publicly accessible in German on the "ich bin alles" - Instagram channel. Aggregated data and additional supporting materials may be shared upon request (contact: sara.kaubisch@med.uni-muenchen.de).