Effects of an audio-dominant nonverbal audiovisual intervention on anxiety and depressive symptoms in college students: a three-arm systematically allocated controlled intervention study

Abstract Background Current digital mental health interventions (DMHIs) predominantly rely on textual materials, which may limit their applicability across cultural contexts and among users who prefer nonverbal formats. This study aims to evaluate the preliminary outcomes of a novel, nonverbal, audio-dominant audiovisual intervention for anxiety and depressive symptoms among college students. Methods A total of 334 eligible students were systematically allocated in chronological order according to a repeating A-B-C sequence. The completer analysis included 193 participants: Group A ( n = 58, audio-dominant nonverbal audiovisual intervention), Group B ( n = 57, audiovisual intervention with guided narration), and Group C ( n = 78, waitlist control). Overall, 53 of 111 participants (47.7%) in Group A, 54 of 111 (48.6%) in Group B, and 34 of 112 (30.4%) in Group C were not included in the analysis. Baseline records were available for all 334 allocated participants and could be linked to study group and post-intervention completion status. Post-intervention SAS and SDS outcomes were available for 193 participants but unavailable for 141 participants, and the reasons for non-completion were not recorded. No imputation-based intention-to-treat analysis or missing-outcome sensitivity analysis was performed. Groups A and B received four weeks of 15-minute daily nature-themed materials (Ocean, Forest, Flower Garden, Candlelight) delivered through a WeChat mini-program. Group A received the audio-dominant nonverbal version, whereas Group B received the same materials with guided narration. Pre- and post-intervention changes were assessed using the Self-Rating Anxiety Scale (SAS) as the primary outcome and the Self-Rating Depression Scale (SDS) as the secondary outcome. This outcome hierarchy was established post hoc after data collection rather than prospectively prespecified. Results Analysis of the 193 completers showed significant group-by-time interactions for both SAS and SDS (both p < 0.001). Within-group analyses also showed significant post-intervention reductions in SAS and SDS scores across all three groups (all p < 0.001). Both Group A and Group B showed greater symptom reductions and lower adjusted post-test SAS and SDS scores than the waitlist Group C (all Holm-adjusted p < 0.001). Large within-group pre-post effect sizes were observed in Groups A and B (partial η² range: 0.36–0.40). No statistically significant difference was detected between Groups A and B for either SAS or SDS (both Holm-adjusted p = 0.434). Conclusions A four-week, audio-dominant nonverbal audiovisual intervention was associated with greater reductions in anxiety and depressive symptoms than a waitlist condition among participants included in the completer analysis. No statistically significant difference was detected between the versions with and without guided narration, but this finding does not establish equivalence. The “subtraction design” comparison of versions with and without guided narration supports further investigation of the nonverbal audiovisual intervention as a potential digital mental health support option. Further confirmatory studies are needed to establish its clinical value and to evaluate its proposed cognitive load advantages and cross-cultural generalizability. Trial registration Not prospectively registered.