Early visuospatial deficits predict the occurrence of visual hallucinations in autopsy-confirmed dementia with Lewy bodies.

OBJECTIVES: The current study explored the value of visuospatial findings for predicting the occurrence of visual hallucinations (VH) in a sample of patients with dementia with Lewy bodies (DLB) compared with patients with Alzheimer disease (AD). PARTICIPANTS/MEASUREMENTS: Retrospective analysis of 55 autopsy-confirmed DLB and 55 demographically similar, autopsy-confirmed AD cases determined whether severe initial visuospatial deficits on the WISC-R Block Design subtest predicted the development of VH. Visuospatial deficits were considered severe if Block Design z scores were 2.5 or more standard deviations below the mean of a well-characterized normal control group (severe visuospatial deficits [severe-VIS]; DLB: n = 35, AD: n = 26) and otherwise were considered mild (mild visuospatial deficits [mild-VIS]; DLB: n = 20, AD: n = 29).
RESULTS: Forty percent of the severe-VIS DLB group had baseline VH compared with 0% of mild-VIS DLB patients. Only 8% of the severe-VIS and 3% mild-VIS AD patients had baseline VH. During the follow-up period (mean = 5.0 years), an additional 61% of the severe-VIS but only 11% of the mild-VIS DLB patients developed VH. In that period, 38% of the severe-VIS and 20% of the mild-VIS AD patients developed VH. After considering initial MMSE score and rate of decline, logistic regression analyses found that performance on Block Design significantly predicted the presence of VH in the DLB group but not the AD group.
CONCLUSIONS: The presence of early, severe deficits on neuropsychological tests of visuospatial skill increases the likelihood that patients with suspected DLB will develop the prototypical DLB syndrome. The presence of such deficits may identify those DLB patients whose syndrome is driven by α-synuclein pathology rather than AD pathology and may inform treatment plans as well as future research.