Restless legs syndrome and Parkinson's disease: is there an etiologic link?

The etiologic link between restless legs syndrome (RLS) and Parkinson's disease (PD) has been debated. Since dopaminergic dysfunction and response to dopaminergic agents are consistent features in RLS and PD, some authors have suggested that these two diseases may share common pathophysiology. However, presently there is not enough evidence to suggest that the actual pathophysiologic mechanism in both diseases is identical. The nigrostriatal dopaminergic system is primarily involved in PD and it is possible that the extrastriatal dopaminergic system may be variably involved in those PD patients with RLS symptoms. Further clinical, imaging, pharmacologic, and genetic studies will be needed to address the many unanswered questions related to the link between RLS and PD.