Clinical milestones in Parkinson's disease: Past, present, and future

•Disease milestones represent clinically relevant measures of disease progression. •A score of 3 or more on Hoehn and Yahr scale is the most common motor milestone. •Clinical milestones have expanded to include motor and non-motor manifestations, and functionality. •Milestones should be periodically assessed in the care of every affected individual. •Milestones could inform on disease-modifying interventions.