Intellectual, Mnemonic, and Frontal Functions in Dementia with Lewy Bodies: A Comparison with Early and Advanced Parkinson’s Disease

Abstract

Both Parkinson's disease (PD) and dementia with Lewy bodies (DLB) share a common neuropathological marker, the presence of Lewy bodies in brain stem and basal forebrain nuclei. DLB, in addition, is associated with Lewy bodies in the neocortex, and, in it's more common form, with Alzheimer-type pathological markers, particularly amyloid plaques. Published neuropsychological studies have focused on the differential profiles of DLB and Alzheimer's disease (AD). However, it is presently unclear whether DLB should be classified as a variant of AD or PD. In the present study we compare a healthy age-matched control group with three groups of patients, one with DLB, and two with PD. One of the PD groups was early in the course (PD-E) and the second, more advanced group (PD-A), was matched on severity of cognitive impairment with the DLB group. The results show that DLB was associated with a different pattern of neuropsychological impairment than the PD-A group, particularly in tests believed to be mediated by prefrontal cortical regions.

Neuropsychological Characteristics of Dementia with Lewy Bodies and Parkinson’s Disease with Dementia: Differentiation, Early Detection, and Implications for “Mild Cognitive Impairment” and Biomarkers

“…Interpretation of the finding of more marked attentional and frontal/executive function impairments in DLB than PDD (Gnanalingham et al 1997) is difficult because the DLB group's greater overall cognitive impairment confounds interpretation of the attentional findings. However, similar findings were reported in a study (Downes et al 1998) that matched DLB and PDD groups for age, education, estimated premorbid IQ, and overall severity of cognitive impairment (MMSE score). DLB demonstrated more severe impairments than PDD on tasks involving attention and working memory (WAIS-R Arithmetic, Stroop), and verbal fluency (letter, category, and alternating fluency).…”

Systematic Review and Meta-Analysis Show that Dementia with Lewy Bodies Is a Visual-Perceptual and Attentional-Executive Dementia

“…More studies used clinical (n = 15) than pathological (n = 6) diagnostic criteria, with only one using pathological DLB(c) criteria. The age of subjects averaged around the mid-70s did not distinguish between groups, with the exception of the study performed by Downes et al [34] who had significantly younger groups.…”

“…Secondly, relative to controls, DLB patients in PD patient comparisons are less variable (SD ratio 0.8-1.8 vs. 2.5-3.8) and less severely affected ( CI 1.5-1.8 vs. 2.2-2.5) than are those in AD patient comparisons, perhaps reflecting the younger age of the groups of Downes et al [34].…”

“…Lewy body pathology in DLB is concentrated in frontal, cingulate, and inferior temporal cortex and in medial temporal structures [34]; areas classically related to attentional, executive, and visual object recognition performance. However, temporal and medial temporal structures are also significantly affected in AD in which visual-perceptual impairments are less severe.…”

“…2 Walker et al [13] reported only variability; therefores included in the variability but not in the effect size analyses. 3 Downes et al [34] used two PD comparison groups: early and late.…”