Group-based IMPROVE Therapy for Problematic Internet Use in University Students

Assessed using the Internet Addiction Test (IAT). Scores range from 20 to 100, with higher scores indicating greater severity. The primary endpoint is the change from baseline to post-intervention

Assessing the maintenance of intervention effects using the Internet Addiction Test (IAT) scores during the follow-up phase.

Participant satisfaction and acceptability will be assessed at postintervention using an adapted eight-item questionnaire based on the Client Satisfaction Questionnaire, supplemented by study-specific closed-ended items assessing overall programme quality, perceived helpfulness, needs fulfilment, willingness to recommend or participate again, satisfaction with therapist guidance, the helpfulness of individual sessions and intervention components, session length, programme duration, between-session practice burden, and group atmosphere. Item-level response distributions will be summarized descriptively.

Assessed using the Smartphone Addiction Scale-Short Version (SAS-SV). Scores range from 10 to 60, with higher scores indicating higher risk of smartphone addiction.

Assessed using the Assessment of Criteria for Specific Internet-use Disorders (ACSID-11). Frequency scores of four core ICD-11 diagnostic features (impaired control, increasing priority, continuation despite negative consequences, and functional impairment) will be evaluated. Scores range from 0 to 33, with higher scores indicating more severe addiction.

Self-reported daily usage hours. Prior to trial implementation, objective smartphone use time was removed from the secondary outcomes due to limited comparability across smartphone brands and operating systems.

Assessed using a modified Questionnaire on Smoking Urges-Brief (QSU-Brief) adapted for internet use. Scores range from 10 to 70, with higher scores indicating more severe craving.

Assessed using the adapted Brief Negative Consequence Scale (BNCS). Evaluates negative consequences across six domains (occupational, academic, interpersonal, etc.) on a 4-point scale. Scores range from 0 to 18, with higher scores suggesting more functional impairment.

Assessed using the Patient Health Questionnaire-9 (PHQ-9). Scores range from 0 to 27, with higher scores indicating more severe depression.

Assessed using the Generalized Anxiety Disorder-7 (GAD-7). Scores range from 0 to 21, with higher scores indicating more severe anxiety.

Assessed using the Insomnia Severity Index (ISI). Scores range from 0 to 28, with higher scores indicating more severe insomnia.

Assessed using the Adult ADHD Self-Report Scale (ASRS-v1.1) Symptom Checklist to screen for attention-deficit/hyperactivity disorder symptoms.The total score ranges from 0 to 72. Higher scores indicate greater ADHD symptom severity.

Assessed using the WHO-Five Well-Being Index. A 5-item measure of current mental well-being. Each item is scored from 0 to 5. The raw total score ranges from 0 to 25. Higher scores indicate better mental well-being.

Assessed using a single-item Quality of Life Visual Analog Scale (0-100), where 100 represents the best imaginable quality of life.

Assessed using the International Physical Activity Questionnaire - Short Form (IPAQ-SF). Measures frequency and duration of physical activity. Physical activity is expressed as metabolic equivalent task minutes per week (MET-minutes/week), derived from walking, moderate-intensity, and vigorous-intensity activities. Higher values indicate greater levels of physical activity. There is no fixed upper limit.

Assessed using the Chinese Adolescents Maladaptive Cognitions Scale (CAMCS). Measures dimensions such as social comfort, distraction, and self-realization. The total score ranges from 0 to 48. Higher scores indicate greater levels of maladaptive cognitions.

Assessed using the Difficulties in Emotion Regulation Scale (DERS-16).The total score ranges from 16 to 80. Higher scores indicate greater problems with emotion regulation.

Assessed using the General Self-Efficacy Scale (GSES). Measures perceived ability to cope with challenges. Items are rated on a 4-point Likert scale (1-4). The total score ranges from 10 to 40. Higher scores indicate greater perceived self-efficacy.

Assessed using the Anhedonia Scale for Adolescents-Chinese version (ASA-C) to evaluate reward processing and motivation. The total score ranges from 0 to 42. Higher scores indicate worse anhedonia.

Assessed using the Perceived Stress Scale (PSS-10). Measures the degree to which life situations are appraised as stressful. Total scores range from 0 to 40, with higher scores suggesting higher perceived stress.

Assessed using the Mind Wandering Questionnaire (MWQ). Measures the frequency of task-unrelated thoughts. Scores range from 5 to 30, with higher scores indicating more frequent mind wandering.

Assessed using the 10-item Connor-Davidson Resilience Scale (CD-RISC). Measures stress coping ability. Scores range from 0 to 40, with higher scores suggesting better resilience.

Gamers were additionally assessed with IGDS9-SF. Measure the severity of IGD, the only internet-related behavioral addictions that get recognized in DSM-5 and ICD-11. Scores range from 9 to 45, with higher scores suggesting more severe internet gaming disorder.

Assessed by a single-item Visual Analogue Scale (VAS, 0-100) for current craving intensity. Higher scores indicate more severe craving.

For gamers, The Chinese version of Revised Internet Gaming Cognition Scale (C-RIGCS) were also assessed. Scores range from 0 to 60, with higher scores suggesting more severe maladaptive cognitions related to gaming.

Clinical remission is defined as an Internet Addiction Test total score below 50. Between-group comparisons will be conducted through the 3-month follow-up assessment (T4). Outcomes at T5 and T6 will be evaluated descriptively because participants in the enhanced waitlist control group will be offered the IMPROVE intervention after T4.

Structural and functional MRI data will be acquired in a voluntary substudy for exploratory, hypothesis-generating analyses. Imaging-derived metrics (e.g., regional brain measures, task-related activation, or connectivity indices) will be determined based on prespecified analytic plans developed prior to data analysis. Analyses will be restricted to consenting participants assigned to the IMPROVE intervention group and will examine within-participant changes in neuroimaging measures from T0 to T2 and their associations with clinical improvement.

Peripheral blood samples will be collected for future exploratory analyses of stress-related and inflammatory biomarkers. Analyses will be restricted to consenting participants assigned to the IMPROVE intervention group and will examine within-participant changes in peripheral biological measures from T0 to T2 and their associations with clinical improvement.