Neuropathological basis of nonmotor manifestations of Parkinson's disease.

Nonmotor manifestations of Parkinson's disease (PD) can begin well before motor PD begins. It is now clear, from clinical and autopsy studies, that there is significant Lewy-type α-synucleinopathy present outside the nigro-striatal pathway and that this may underlie these nonmotor manifestations. This review discusses neuropathological findings that may underlie nonmotor symptoms that either predate motor findings or occur as the disease progresses.