Effectiveness of Unguided Internet-Based Cognitive Behavioral Therapy for Subthreshold Social Anxiety Disorder in Adolescents and Young Adults: Multicenter Randomized Controlled Trial

Background Social anxiety disorder (SAD) is a common mental disorder in adolescents and young adults. Early intervention and support could help prevent the development of full-blown SAD. Considering that adolescents with social anxiety symptoms do not prefer face-to-face sessions due to their fear of communicating with therapists, internet-based cognitive behavioral therapy (ICBT) was implemented. Objective This study aimed to examine the effectiveness of complete self-help ICBT for subthreshold SAD in high school and college students with no history of mental disorders. Methods A multicenter randomized controlled trial designed to demonstrate the objective was conducted from December 2022 to October 2023. Participants were students enrolled at 6 universities and 1 high school. The intervention was a complete self-help ICBT and consisted of 10 text-based sessions that taught cognitive behavioral therapy techniques for social anxiety in youths and young adults. The comparison was a no-treatment condition (control group), which was randomly assigned in a 1: 1 ratio by a computer program. A total of 2 psychological scales were used to assess the severity of social anxiety, and 1 psychological scale each was used to measure symptoms of depression, general anxiety, and quality of life. Results In total, 77 students were enrolled as study participants. Through the randomization procedure, 38 participants were included in the intervention group, and 39 patients were included in the control group. Results from the analysis of covariance with depression as covariates showed that the participants in the intervention group had significantly reduced symptoms of social anxiety, depression, and general anxiety compared to the control group. The response rate was 61% (19/31) in the intervention group and 24% (9/38) in the control group: odds ratio (OR) 4. 97 (95% CI 1. 61-16. 53; P=. 003) in the Fisher exact test. The recovery rate was 68% (21/31) in the intervention group and 34% (13/38) in the control group: OR 3. 95 (95% CI 1. 32-12. 56; P=. 008). The OR for the remission ratio was 2. 01 (95% CI 0. 64-6. 60; P=. 20) and for the risk of worsening was 0. 23 (95% CI 0. 002-1. 33; P=. 10), but no significant difference was observed. Conclusions The results of this randomized controlled trial show that fully unguided ICBT improves subthreshold SAD in adolescents and young adults. Interpretation of the effectiveness in preventing SAD that meets the diagnostic criteria is limited by sample size and the follow-up period. Future studies should include more extended observations and larger sample sizes in high-risk populations. Trial Registration UMIN-CTR UMIN000050064; https: //center6. umin. ac. jp/cgi-open-bin/ctr/ctrᵥiew. cgi? recptno=R000057035