[Parkinson disease with dementia--responsible locus for dementia].

Responsible locus for dementia in Parkinson disease (PD) was investigated. Serial 1,395 autopsy cases were studied for the combined pathology of PD and Alzheimer disease (AD). Following the one-year rule by the first Consensus Guidelines, definite AD pathology was quite rare in PD with dementia (PDD) but common in dementia with Lewy bodies (DLB) . Plaque-dominant senile changes apparently enhanced neocortical Lewy-body pathology in both the conditions. About the hypometabolism in the visual cortex of PDD, a 66-year old man presented with fluctuation in hallucination commensurate with fluctuating hypometabolism. Considering the paucity in pathological changes of the visual cortex, this hypometabolism may represent functional impairment in the fiber connection. Comparative pathological studies with PD and PDD were carried out. Only one case of a 48-year-old woman, who unexpectedly died of heart failure, was free from cognitive decline, and did not show limbic and neocortical involvement. Another case of a 75-year old man with MCI presented with the similar pathology. All other cases showed clinical documentation of cognitive impairment and limbic and neocortical pathological involvement. Thus, the combination of prospective clinical and radiological studies and retrospective pathological studies (dynamic neuropathology) may be essential to investigate a role of the basal-forebrain cholinergic system.