The ATICC study (Addiction, Trauma, and Immigration, Prevention and Cross-Cultural Support for Care) investigates the complex relationships between trauma, substance use, migration experiences, and mental health perceptions among vulnerable young adults in Transitional Housing (Foyers de Jeunes Travailleurs) in France. Using a tripartite methodology, the study includes: (1) a cross-sectional survey to identify risk factors, (2) qualitative interviews to explore individual experiences, and (3) a longitudinal intervention using focus groups to assess psychological well-being and attitudes toward care. The findings will contribute to developing culturally adapted prevention and support programs.

The ATICC study (Addiction, Trauma, and Immigration, Prevention and Cross-Cultural Support for Care) is a mixed-methods research project aimed at understanding the interplay between trauma, substance use, migration experiences, and mental health perceptions among vulnerable young adults residing in Transitional Housing for Young Adults (Foyers de Jeunes Travailleurs, FJT) in France. The study will identify key risk factors, assess barriers to healthcare access, and evaluate the effectiveness of group interventions in improving psychological well-being and attitudes toward mental health services.

The study is structured into three complementary research components:

Cross-sectional study: Utilizes standardized questionnaires to assess substance use behaviors, trauma history, mental health status, and barriers to healthcare. The data will be collected at baseline and analyzed using descriptive and multivariate statistical techniques (R software).

Qualitative study: Conducts semi-structured interviews with a subset of participants who engage in substance use. Thematic analysis using NVivo software will be applied to explore individual narratives and subjective experiences related to substance use and mental health perceptions.

Longitudinal interventional study: Implements focus group interventions within transitional housing settings to evaluate their impact on psychological well-being and attitudes toward healthcare. Pre- and post-intervention assessments will be conducted using validated psychological measures.

Data will be analyzed using mixed models and appropriate statistical corrections to assess intervention effectiveness.

Registry procedures and quality factors include a Quality Assurance Plan ensuring data validation, site monitoring, and ethical compliance through adherence to the Committee for the Protection of Persons (CPP) Ile-de-France; Data Checks & Source Data Verification through automated validation rules and cross-checking against medical records; a Data Dictionary defining all variables, including sources, coding systems (e.g., ICD-10, WHO Drug Dictionary, MedDRA), and reference ranges; and Standard Operating Procedures (SOPs) for participant recruitment, data collection, data management, adverse event reporting, and change management to ensure consistency and compliance. The Sample Size Assessment includes at least 300 participants for the cross-sectional study to ensure statistical power, 40 participants for qualitative interviews to achieve data saturation, and 6-8 participants per focus group session, with repeated measures over six months to track changes. The plan for Missing Data incorporates multiple imputation techniques, sensitivity analyses, and data inconsistency reviews. The statistical analysis plan includes descriptive analyses for mean, median, and standard deviations, and inferential analyses using logistic regression for risk factor identification, mixed-effects models for intervention outcomes, and thematic coding for qualitative data analyzed with NVivo software. Ethical considerations and registration details confirm that the study has received ethical approval from the CPP Ile-de-France (November 18, 2024) and is registered with the French National Agency for the Safety of Medicines and Health Products (ANSM) under ID-RCB: 2024-A01534-43, with participant confidentiality maintained through anonymized data storage and GDPR-compliant procedures. This detailed description provides the necessary technical information on the ATICC study, ensuring compliance with clinical trial registration requirements.

Inclusion Criteria:

• Resident in a Housing center, speak and read french, adult participants who are not under guardianship or curatorship, any cultural background.

Exclusion Criteria:

• minors, don't speak and read french, adults under guardianship and curatorship.

The study population consists of young adults aged 16 to 25 years residing in Transitional Housing for Young Adults (Foyers de Jeunes Travailleurs, FJT) affiliated with the Union Régionale pour l'Habitat des Jeunes (URHAJ). These individuals meet specific vulnerability criteria and come from diverse life trajectories, including those aging out of child welfare services (ASE), individuals under judicial protection (PJJ), persons with disabilities, refugees, and single-parent families. Due to their backgrounds, these young adults face significant adversity, which may have profound effects on their mental health and well-being. This population is particularly exposed to psychosocial stressors, making them a relevant demographic for studying the interplay between trauma, substance use, and mental health care access.

We will not share individual participant data (IPD) in order to protect the privacy and confidentiality of our study participants. Our publications will present aggregate findings and summary statistics without revealing any identifiable details.