New concepts in the pathogenesis and presentation of Parkinson's disease.

Parkinson's disease (PD) was first described by James Parkinson in 1817. He noted the complex nature of this condition and that non-motor symptoms (NMS) underpinned the classic motor symptoms of PD. The concept of what PD is has therefore undergone substantial changes and it is now recognised that PD is a combined motor and non-motor syndrome and NMS are present during the prodromal phase of PD, starting up to 20 years before the first clinical motor signs emerge. PD may originate from pathology in the gut, olfactory bulb and lower brainstem rather than in the substantia nigra. Complex phenotypes of PD may exist where clinical NMS overshadow motor features. Therapy needs to be adjusted based on motor and non-motor loads, ideally using validated tools. Recently, a multimodal biomarker battery in PD has emerged and might play an important role in the future.