Rethinking the concept of disease modification in an evolving Parkinson's disease treatment landscape.

We are in an era in which increasing numbers of potentially disease-modifying treatments for Parkinson's disease are being tested in clinical development. Current definitions of disease modification have inherent limitations; hence there is a need to establish a clear, unified definition. This unified definition of disease modification should be applicable to both idiopathic and genetic forms of Parkinson's disease. In addition to motor function, it must address important milestones (e.g., cognition, autonomic dysfunction) across all disease stages. This review examines existing definitions and highlights the need for a more holistic approach that integrates the perspectives of patients, healthcare professionals, and researchers.