Pathological and clinical comparison of Parkinson’s disease dementia and dementia with Lewy bodies.

Abstract

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are two major neurodegenerative diseases sharing common clinical, pathophysiological and morphologic features. The pathological hallmark of both diseases is the presence of Lewy-bodies (LB). The main constituent of these inclusions is the pathologically aggregated α-synuclein protein. In DLB, LBs are predominantly located in the cortex, whereas in PDD, the subcortical regions are predominantly affected. Furthermore, in DLB, coexisting Alzheimer's disease (AD), pathology with β-amyloid plaques and neurofibrillary tangles are more common. It is still debated whether DLB and PDD are two distinct entities or different phenotypes of the same disease. Clinical diagnosis is based on the temporal sequence of motor and cognitive symptoms. Dementia often precedes parkinsonism in DLB, while in PDD, cognitive decline generally appears after the onset of motor symptoms. Also, fluctuation of cognitive functions and neuroleptic sensitivity is more severe in DLB than PDD. The recent advancements of imaging techniques revealed that cortical damage, cholinergic deficit and concomitant AD pathology are more severe in DLB compared to PDD. The analysis of cerebrospinal fluid biomarkers shows higher oligomeric α-synuclein burden in PDD. Levodopa is less effective in DLB than in PDD and may increase the risk of psychosis. In this review, we comprehensively analyse the pathological, radiological and clinical features of DLB and PDD, highlighting the overlaps and differences. Orv Hetil. 2020; 161(18): 727-737.