Research on the Pre-Motor Symptoms of Parkinson's Disease: Clinical and Etiological Implications

Environ Health Perspect. 2013 Aug 9. [Epub ahead of print]

Chen H, Burton EA, Ross GW, Huang X, Savica R, Abbott RD, Ascherio A, Caviness JN, Gao X, Gray KA, Hong JS, Kamel F, Jennings D, Kirshner A, Lawler C, Liu R, Miller GW, Nussbaum R, Peddada SD, Comstock Rick A, Ritz B, Siderowf AD, Tanner CM, Tröster AI, Zhang J.

Source

National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA.

Abstract

BACKGROUND:

The etiology and natural history of Parkinson's disease (PD) are not well understood. Some non-motor symptoms such as hyposmia, rapid eye movement sleep behavior disorder, and constipation may develop during the prodromal stage of PD and precede PD diagnosis by years.

OBJECTIVES:

To discuss the promise and pitfalls of research on pre-motor symptoms of PD and to develop priorities and strategies to understand their clinical and etiological implications.

METHODS:

This review was based on a workshop held on June 7-8, 2012 at the National Institute of Environmental Health Sciences.

DISCUSSION:

Research on pre-motor symptoms of PD may offer an excellent opportunity to characterize higher-risk populations and to better understand PD etiology. Such research may lead to evaluation of novel etiological hypotheses such as the possibility that environmental toxicants or viruses may initiate PD pathogenesis in the gastrointestinal tract or olfactory bulb. At present, our understanding of pre-motor symptoms of PD is in its infancy and faces many obstacles. These symptoms are often not specific to PD and have low positive predictive value for early PD diagnosis. Further, the pathological bases and biological mechanisms of these pre-motor symptoms and their relevance to PD pathogenesis are poorly understood.

CONCLUSION:

This is an emerging research area with important data gaps to be filled. Future research is needed to understand the prevalence of multiple pre-motor symptoms and their etiological relevance to PD. Animal experiments and mechanistic studies will help understand the biology of these non-motor symptoms and test novel etiological hypothesis.