UNIPDES - An internet-based transdiagnostic intervention for college students' psychological symptoms: Evaluation of its development, usability and effectiveness: Study protocol.

University students often face significant mental health challenges, including depression, anxiety, and difficulties in adjustment, which can be exaggerated by the demands of independent living and increased life responsibilities. These challenges are often compounded by barriers to seeking help, such as stigma and limited access to university resources, which can further deteriorate students' well-being. This protocol was created to assist college students in overcoming these obstacles and to assess, in comparison to a control group, the impact of a guided and unguided online intervention platform based on transdiagnostic CBT (UNIPDES) on depression, anxiety, and adjustment levels. The calculated sample size for the study will include 330 students, and the participants will be selected from five different universities located in Türkiye. Participants will be randomly assigned to either guided, unguided, or control groups. Guided and unguided group participants will receive six weeks of intervention, and the waitlist control group will receive the unguided version of the program after twelve weeks of randomization. Assessments will take place at baseline, post-test (8 weeks post-baseline) and follow-up (12 weeks post-baseline). A Mixed ANOVA will be employed to analyze the data, with Group (Guided, Unguided, Control) as the between-subjects factor and Time (Baseline, Post-Test, Follow-Up) as the within-subjects factor, as well as to assess the interaction effect between Group and Time on the primary outcomes-changes in depression, anxiety, and adjustment levels. Additionally, students' reasons for dropout will be assessed qualitatively. The results from this study can build evidence for the effectiveness of transdiagnostic guided and unguided internet-based intervention for treating depression, anxiety, and adjustment problems of students. UNIPDES can provide a flexible, easy-to-access, and cost-effective treatment for the problems that students commonly face. Trial registration is registered at ClinicalTrials.gov Protocol Registration and Results System (Trial number: NCT06245200).