Fig. 1

Schematic of preclinical, prodromal and clinical stages in PD. The y-axis shows the percentage of dopaminergic neurons in the substantia nigra. The exact course of dopaminergic attrition is unknown and is provided here schematically. The x-axis depicts the number of years before (left) and after (right) diagnosis. The exact duration of the preclinical and prodromal stages is unknown. The order of prodromal symptoms may vary between patients and are mentioned here in random order. The disease course depicted in this schematic only applies to patients with the so-called ‘body-first’ subtype of Parkinson’s disease