Early Visuospatial Deficits Predict the Occurrence of Visual Hallucinations in Autopsy-Confirmed Dementia With Lewy Bodies

Abstract

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 to patients with Alzheimer’s 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-VIS; DLB: n=35, AD: n=26) and otherwise were considered mild (Mild-VIS; DLB: n=20, AD: n=29). Results Forty percent of the Severe-VIS DLB group had baseline VH compared to 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 alpha-synuclein pathology rather than AD pathology and may inform treatment plans as well as future research.

The New Qualitative Scoring MMSE Pentagon Test (QSPT) as a Valid Screening Tool between Autopsy-Confirmed Dementia with Lewy Bodies and Alzheimer's Disease

“…The present results are consistent with those of a number of other studies that show deficits in visuospatial, visuoperceptual and construction abilities are greater in patients with DLB than in equally demented patients with AD [6, 16, 38]. They also support the view that tests of visuo-construction abilities might be useful and valid tools for differentiating between the two syndromes.…”

“…Furthermore, this qualitative evaluation of pentagons copy further characterizes the cognitive profile of DLB and might contribute to the differentiation of DLB from AD. Improved ability to identify individuals who are likely to develop the prototypical DLB syndrome has important treatment implications because the development of viable therapeutics is hindered by poor diagnostic sensitivity for DLB in the living population [38]. Thus, identification of valid cognitive screening tools that increase the correspondence between the DLB clinical phenotype in living patients and the presence of Lewy bodies at autopsy is important.…”

Lewy body dementias

“…77 The presence of early, severe visuospatial deficits in patients with suspected dementia with Lewy bodies predicts rapid decline and the development of visual hallucinations, and might identify patients whose clinical syndrome is due to Lewy bodies rather than Alzheimer’s disease pathology. 78 …”

A clinicopathological approach to the diagnosis of dementia

“…The fluctuations in mental status, conceived as a low-grade chronic delirium, may be due to profound cholinergic deficits in addition to neocortical Lewy body pathology 202 . Visuospatial and constructional deficits are frequently seen in early AD, but are also suggestive of Lewy body pathology 203,204 , where they foreshadow more-rapid decline and visual hallucinations 205 . In comparison with AD, however, memory functions are often preserved in the early stages of DLB, although episodic memory deficits are frequently reported with older age, possibly due to mixed Lewy body and AD pathology 24 .…”