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© 2025 The Author(s). Movement Disorders Clinical Practice published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.Background: Parkinson's disease (PD) is associated with both motor and non-motor symptoms, which collectively impact activities of daily living (ADLs) and contribute to the loss of functional independence. There is a lack of understanding of how non-motor symptoms drive this loss in independence. Objectives: This study aims to firstly implement a milestone-based approach to determine the time-points at which subjects with PD require help with specific tasks, using current gold-standard scales. Secondly, we aimed to explore the influence of motor and non-motor symptoms on the progression of functional dependence in individuals with early-stage PD over a 7-year period. Methods: Using data from 166 PD participants, obtained from the Parkinson's Progression Markers Initiative (PPMI), we determined the time taken to reach the first functional dependence “event” over 7 years of annual visits, using clinician- and patient-reported outcomes, including the Schwab & England ADL scale and the MDS-UPDRS Parts I and II. To determine the effect of non-motor symptoms on functional dependence, linear mixed modelling was employed, adjusting for key motor variables, medication, age, sex and PD duration. Results: Depression, fatigue, and motor impairment emerged as significant influencers of functional dependence, with cardiovascular dysfunction nearing significance. Conclusions: We identified that, over time, both motor and non-motor symptoms contributed to the decline in functional independence, with depression, fatigue and cardiovascular dysfunction playing a particularly prominent role. These findings highlight the importance of a comprehensive, multidisciplinary approach to PD management, addressing both motor and non-motor symptoms to improve long-term outcomes and quality of life. |