Pathological basis for dementia in elderly patients with idiopathic Parkinson's disease.

We have examined the pathological basis for dementia in elderly patients with Lewy-type Parkinson's disease (PD). 37 (66.1%) of 56 examined cases (mean age of 77.9 years) had evidence of dementia. According to the distribution pattern of Lewy bodies and senile changes, as well as abiotrophic changes of the nucleus basalis of Meynert, nucleus paranigralis and locus ceruleus, demented PD could be subdivided into three groups: (1) demented PD without cerebral alzheimerization (21.6%, 8 cases); (2) demented PD with cerebral alzheimerization (64.9%, 24 cases), and (3) demented PD with combined senile-vascular changes (13.5%). Based on neuropathological findings, damage not to a single, but to multiple neuronal networks including the innominatocortical cholinergic, ceruleocortical noradrenergic as well as mesocortical dopaminergic systems could play a role in the development of dementia in PD. We also discussed the nosological situation of 'diffuse Lewy body disease', regarding it as one distinct disease entity.