Lumping and splitting the Parkinson Plus syndromes: dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and cortical-basal ganglionic degeneration.

The atypical parkinsonian or Parkinson Plus syndromes are often difficult to differentiate from Parkinson's disease and each other. In this article, the clinicopathological characteristics of dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and cortical-basal ganglionic degeneration are discussed. These disorders, although clinically distinct, may have more similarities than previously thought, based on modern immunocytochemical techniques and new genetic findings. These intriguing interconnections at a basic molecular level have provided the scientific rationale for lumping these diseases into two groups, the synucleinopathies and the tauopathies.