Visuospatial impairment in dementia with Lewy bodies and Alzheimer's disease: a process analysis approach.

Reports of differential impairments on visual-construction tasks in dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are sometimes controversial, whereas visual-perceptual data are lacking. The existence of different clinical sub-groups of DLB has been hypothesized to explain the discrepancies among the cognitive results. The goal of this study was to compare the visual-perceptual performance of subjects with DLB with predominant psychosis, DLB with predominant parkinsonian features and AD. This is a cross-sectional neuropsychological study with between diagnostic group comparisons. The Benton Judgement Line Orientation (BJLO) test was administered to four DLB patients with predominant psychosis (DLB-psy), four DLB subjects with predominant parkinsonian features (DLB-PD), and 13 patients with AD. An analysis of error types was applied to the results of the BJLO with QO1, QO2, QO3, QO4 (visual attention) errors, as well as VH, IQO, IQOV, and IQOH (visual-spatial perception) errors. A MANOVA showed significant differences between the DLB, and AD groups on the number of VH (F = 6.049, df = 1,19, p = 0.024), IQOH (F = 4.645, df = 1,19, p = 0.044) and QO1 (F = 4.491, df = 1,19, p = 0.047) errors, but no difference on the total score of the BJLO. Another MANOVA and post hoc Student-Newman-Keuls analyses demonstrated that the DLB-psy sub-group made significantly more VH and IQOH errors than AD and the DLB-PD subjects. Subjects with DLB and psychosis have more severe visual-perception (VH errors) impairments than subjects with DLB and predominant parkinsonian features, and AD subjects.