[Abstract]Objective: To explore the longitudinal patterns and influencing factors of depression and cognitive impairment in patients with Parkinson's disease (PD), examine the bidirectional predictive relationship between the two, preliminarily analyze the modifying effects of medication on depression and cognitive impairment, and provide clues for in-depth understanding of the comorbidity mechanism and clinical intervention for depression and cognitive impairment in PD. Methods: A total of 86 de novo drug-na?ve patients with idiopathic PD were enrolled and assessed for motor and non-motor symptoms at initial consultation (baseline) and follow-up, including the Unified Parkinson's Disease Rating Scale part III for motor symptoms, Hamilton Depression Rating Scale for depressive symptoms, and Montreal Cognitive Assessment for cognitive function. Results: During follow-up, patients' motor symptoms significantly deteriorated, while depressive symptoms exhibited dynamic conversion characteristics. Motor symptoms and other non-motor symptoms (anxiety, sleep disturbances) demonstrated statistically significant differences across groups stratified by varying degrees of depression severity. Patients with mild cognitive impairment primarily exhibited impairments in visuospatial and executive functions and delayed memory. Dopaminergic medication showed no significant effects on depression or cognitive function. Cognitive impairment and depressive symptoms showed synchronous changes and had bidirectional predictive effects. Conclusion: Depressive symptoms in patients with Parkinson's disease exhibit dynamic progression patterns. Non-motor symptoms such as anxiety and sleep disturbances potentially serve as critical indicators for depression screening in PD, Cognitive impairment and depressive symptoms had bidirectional predictive effects. Dopaminergic medication demonstrates no therapeutic efficacy in ameliorating either cognitive or depressive symptoms.