The mild cognitive impairment stage of dementia with Lewy bodies and Parkinson disease: a comparison of cognitive profiles.

Background: Recent studies have demonstrated that structural and pathologic changes are more severe in patients with dementia with Lewy bodies (DLB) than in those with Parkinson disease with dementia (PDD). We investigated neuropsychological characteristics of patients with mild cognitive impairment (MCI) stage of DLB (DLB-MCI) and PD (PD-MCI) based on the hypothesis that the pathologic differences between DLB and PDD can influence cognitive profiles in the MCI stage of these diseases.
Methods: Baseline demographic characteristics and neuropsychological data obtained from patients with DLB-MCI (n=20) and PD-MCI (n=46) were compared.
Results: The patients with DLB-MCI showed poorer cognitive performance in the Stroop, Go-No-Go, and semantic fluency tests compared with those with PD-MCI. In addition, patients with DLB-MCI had lower scores on visual and verbal memory performance and in the visuospatial domain compared with PD-MCI patients.
Conclusions: Our results demonstrate that patients with DLB-MCI have more severe cognitive impairment in frontal executive, memory, and visuospatial functions than those with PD-MCI. These data suggest that differences in pathologic substrates between PDD and DLB may begin in the MCI stage of the 2 diseases and may lead to differences in cognitive profiles.