Pathological substrate of dementia in Parkinson's disease-its relation to DLB and DLBD

The pathological background of dementia in Parkinson's disease (PD) has been a matter of controversy. Recent studies have revealed the appearance of many Lewy bodies in the cerebral cortex of PD with dementia (PDD). This pathological change corresponds to the neocortical type, which was originally reported as diffuse Lewy body disease (DLBD), or a transitional type of dementia with Lewy bodies (DLB). Clinical differentiation between DLBD and the transitional type of Lewy body disease (LBD) is sometimes difficult because the symptoms overlap. Therefore, it is appropriate, at least at present, that DLB and PDD are used as clinical diagnoses and that DLBD and the transitional- and brainstem-types of LBD are used as neuropathological diagnoses.