Non motor symptoms (NMS) represent a significant burden in Parkinson's disease (PD) with numerous studies highlighting the importance of NMS both in "pre-motor" phase of PD as well as throughout the course of disease. In part this has led the international Parkinson and Movement Disorder Society (IPMDS) task force to attempt a re-definition of PD incorporating NMS and not base the diagnosis solely on motor symptoms. While motor subtypes within PD have been recognized and researched, recent clinical and neurobiological research suggests the existence of discrete non motor subtypes in PD, particularly in untreated (drug naïve) and early PD patients. Several independent observers have reported specific "clusters of NMS dominant PD" using a data driven approach in early and untreated PD patients while others have reported on the burden of NMS in untreated PD and specific NMS dominant phenotypes in untreated or treated PD using observational case series based data. In this review we report on specific NMS dominant phenotypes of PD as described in the literature using clinical observational studies and address pathophysiological concepts. A proposal for several NMS subtypes are reported combining clinical reports with, where possible, evidence base supporting probable biomarkers.

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.