There are many unanswered questions about Parkinson disease (PD), but as a result of advances in genetics, proteomics, metabolomics, epigenetics, imaging, and other novel techniques, remarkable progress is being made. In this Viewpoint, we will highlight aspects of future research aimed at addressing the following critical questions.
There is growing recognition that PD is not a single clinical-pathological entity but that there are PD subtypes, possibly caused by different pathogenic mechanisms.1 Furthermore, psychiatric symptoms and cognitive impairment are increasingly recognized as major contributors to disability, and other nonmotor features, such as dysautonomia, hyposmia, and rapid eye movement sleep behavior disorder, may precede motor symptoms by several years or even decades. The traditional view that PD is defined pathologically is increasingly challenged as many genetic forms of PD phenotypes do not show the typical selective deposition of α-synuclein and the presence of Lewy bodies (LBs). Furthermore, α-synuclein pathology can be found in the brains of individuals without any symptoms of PD, the so-called incidental LB disease.
Jankovic J, Sherer T. The Future of Research in Parkinson Disease. JAMA Neurol. 2014;71(11):1351-1352. doi:10.1001/jamaneurol.2014.1717