BetterMood: A human-like AI counseling service for adolescents and young adults.

Objective: In-person counseling faces limitations in timing and geographical accessibility, often causing adolescents and young adults (AYAs) to miss timely psychological support. With the advent of large language models (LLMs), the mental health care industry has increasingly focused on developing chat counseling services as supplementary tools to reduce these barriers. However, existing services have two primary limitations: tendency toward generic advice and absence of human-like dialogue. To overcome these limitations, this article proposes BetterMood, a human-like AI counseling service specifically for Korean-speaking AYAs. Methods: Our design for BetterMood separately addressed the content and delivery of counseling dialogue. For content, we develop a concern-aware counseling LLM refined through prompt-engineering with a novel prompt derived from collected counseling data. For delivery, we create a human-like AI counselor that employs a chunk-based streaming methodology to enable human-like dialogue. We then conducted a user study with 10 adolescents, 110 young adults, and 8 professional clinicians to assess the feasibility and user experience across four domains: (i) interaction capability, (ii) perceived support, (iii) usability, and (iv) ethical safety. Results: Our user study indicates that BetterMood's interactive capabilities, particularly its ability to suggest appropriate responses, received positive feedback from 90.0% of adolescents, 90.9% of young adults, and 75.0% of professional clinicians. Stratified analysis revealed that outcomes regarding perceived support and usability of the service differed across cohorts and initial screening status. Furthermore, independent evaluations by eight professional clinicians demonstrated moderate agreement for individual ratings but excellent reliability for the aggregated assessment. Conclusion: Positive user experience and high inter-rater reliability among clinicians support BetterMood's potential as an accessible supplementary tool for initial psychological support.