Evaluation Study of Medical-Social Collaboration Model for Middle-aged and Older Adults With Depressive Symptoms

The goal of this clinical trial is to learn if a medical-social collaboration model works to reduce depressive symptoms in middle-aged and older adults with depressive symptoms who are waiting for their first psychiatric appointment. Secondary outcomes of the study include reduced anxiety symptoms, reduced loneliness, reduced rumination, reduced self-criticism, improved self-reassurance, improved resilience, improved self-efficacy, improved health-related quality of life, as well as improved quality-adjusted life years, and reduced healthcare service utilisation. Researchers will compare a medical-social collaboration model to a self-management booklet. Participants will: * Receive CBT-based stepped-care interventions through the medical-social collaboration model or a self-management booklet. * Complete a survey about their mental health and service use every three months until their