This study aims to evaluate and compare the degree of alcohol reduction between high-risk drinkers who use a motivational interviewing-based conversational agent (chatbot) application for four weeks and those in the control group who do not use the application, in order to verify its clinical effectiveness.

"This study is a randomized controlled trial (RCT) employing a waitlist control design to examine the effectiveness of a motivational interviewing-based conversational mobile application for high-risk drinkers.

After obtaining voluntary written consent, participants will complete a screening process that includes a clinical interview (MINI, DSM) and demographic data collection. Those who meet all inclusion criteria and none of the exclusion criteria will be randomly assigned in a 1:1 ratio to either the intervention group (n = 110) or the control group (n = 110).

For the intervention group, the total study period is 16 weeks and consists of three visits (week 0, 4, and 16). The control group will participate for 20 weeks and complete four visits (week 0, 4, 16, and 20). The final follow-up assessment for both groups will be conducted via telephone and online.

The intervention group will use the mobile app (chatbot) for 4 weeks beginning on the baseline assessment day (Visit 1). Re-assessments will be conducted at week 4 (Visit 2), marking the end of the intervention period, and again at week 16 (Visit 3), which occurs three months after the intervention.

The control group will not receive any intervention from baseline to week 16 and will complete the same reassessments at week 4 (Visit 2) and week 16 (Visit 3). After the week 16 assessment, the control group will also use the mobile app for 4 weeks and undergo a final evaluation at week 20 (Visit 4), following completion of their intervention period.

This waitlist control design allows for a rigorous comparison of outcomes between the two groups while ensuring that all participants eventually receive access to the intervention, supporting both ethical considerations and improved retention.

Inclusion Criteria:

1. Individuals aged 19 to 59 years who are capable of providing valid written informed consent.
2. Individuals who meet the definition of high-risk drinking (AUDIT score ≥ 8).3.- Individuals who express a desire to reduce their alcohol consumption.
3. Individuals who own and use an Android smartphone (version 8 or higher).
4. Individuals who have no difficulty using mobile applications.
5. Individuals who are able to communicate adequately with the research team.
6. Individuals who fully understand the study procedures and voluntarily agree to participate.

Exclusion Criteria:

1. Individuals who are unable to read or understand the consent form (e.g., illiterate individuals, non-Korean speakers).
2. Individuals with impaired decision-making capacity.
3. Pregnant individuals or those planning to become pregnant during the study period.
4. Individuals who are currently participating in another clinical study.
5. Individuals who are receiving treatment or counseling for alcohol-related problems.
6. Individuals who use two or more mobile phones.
7. Individuals who are expected to change their mobile phone or SIM card, or who plan to travel 8. abroad during the intervention period.
8. Any individual deemed inappropriate for study participation at the discretion of the investigator.