Depression is a prevalent mental disorder characterized by pervasive low mood, diminished interest or pleasure, and a range of cognitive and physical symptoms. According to the World Health Organization (WHO), depression is a leading cause of disability worldwide, affecting approximately 280 million individuals of all ages. In spite of the widespread occurrence and negative consequences linked to depression, fewer than 30% of individuals with common mental disorders sought assistance from mental health services in the previous year due to reasons such as, high-cost and stigma.

Cognitive behavioral therapy (CBT) is the gold-standard and evidence-based intervention for various mental health disorders, including depression, anxiety, and its effectiveness has been widely proven. With the recent advancement in AI and other relevant technologies, the use of digital CBT has become possible. Indeed, a recent systematic review demonstrated a comparable effectiveness of traditional CBT and digital CBT, after controlling the moderators (e.g., intervention duration, and adherence). While digital CBT has achieved impressive performance, the majority of them utilized web-based or app-based platforms. Therefore, one of the disadvantages of such digital CBT is the lack of interaction between (digital) therapists and clients. Additionally, lower adherence to digital interventions was observed, indicating the need for briefer sessions, such as single-session integrated CBT (SSI-CBT), for digital interventions. SSI-CBT involves a collaborative effort between the therapist and the client, aimed at assisting the client in accomplishing their desired outcome within a single session. It is understood that additional support is accessible if required. A recent study using SSI-CBT demonstrated promising results of its effectiveness in reducing depression and anxiety, which can last for two months. To further generalize the application of digital interventions, a more interactive virtual therapist utilizing a brief CBT-based intervention approach is desired.

This study will evaluate the effectiveness of virtual CBT therapist for reducing depression symptoms, compared to a waitlist control group. Based on previous research, it is expected that a virtual CBT therapist can significantly reduce the depression symptoms at both post-intervention and one-month follow-up.

Inclusion Criteria:

1. Chinese young adult aged 18-40 years
2. Native Cantonese speaker
3. Presence of depressive symptoms, as indicated by a score of 10 or higher on the depression sub-scale of the Depression Anxiety Stress Scale 21 (DASS-21).
4. Able and willing to comply with the requirements of the study protocol

Exclusion Criteria:

1. A current or history of any psychiatric disorder(s) other than depressive disorder and anxiety disorder, such as bipolar disorder, psychotic disorders, and substance use disorder
2. A current or history of any voice, speech, and language disorders
3. A current or history of non-suicidal self-injury or suicidality
4. Incompetent in giving informed consent for participation in the study
5. A current or history of significant motion sickness, active nausea, and vomiting or epilepsy.
6. A current or history of color vision deficiency
7. Subject who is preparing for pregnancy or pregnant