Mild parkinsonian signs: the interface between aging and Parkinson’s disease

Mild Parkinsonian Signs (MPS) describe a spectrum that exists between the expected motor decline of normal aging and a more serious motor deterioration resulting from Parkinson’s disease (PD) and neurodegeneration. Although MPS are a feature of the prodromal stage of PD, their formal definition is unclear and still relies somewhat on conventional clinical criteria for PD. This review will summarise the early motor features of PD and methods of assessment, from conventional clinical scales to advances in quantitative measures. Finally, the boundaries of motor decline as part of normal aging and pathological neurodegeneration will be discussed.