Relative preservation of MMSE scores in autopsy-proven dementia with Lewy bodies - PubMed (original) (raw)

Relative preservation of MMSE scores in autopsy-proven dementia with Lewy bodies

P T Nelson et al. Neurology. 2009.

Abstract

Background: Recent studies raised questions about the severity of cognitive impairment associated with dementia with Lewy bodies (DLB). However, there have been few analyses of large, multicenter data registries for clinical-pathologic correlation.

Methods: We evaluated data from the National Alzheimer's Coordinating Center registry (n = 5,813 cases meeting initial inclusion criteria) and the University of Kentucky Alzheimer's Disease Center autopsy series (n = 527) to compare quantitatively the severity of cognitive impairment associated with DLB pathology vs Alzheimer disease (AD) and AD+DLB pathologies.

Results: Mini-Mental State Examination (MMSE) scores showed that persons with pure DLB had cognitive impairment of relatively moderate severity (final MMSE score 15.6 +/- 8.7) compared to patients with pure AD and AD+DLB (final MMSE score 10.7 +/- 8.6 and 10.6 +/- 8.6). Persons with pure DLB pathology from both data sets had more years of formal education and were more likely to be male. Differences in final MMSE scores were significant (p < 0.01) between pure DLB and both AD+DLB and pure AD even after correction for education level, gender, and MMSE-death interval. Even in cases with extensive neocortical LBs, the degree of cognitive impairment was most strongly related to the amount of concomitant AD-type neurofibrillary pathology.

Conclusions: Dementia with Lewy bodies can constitute a debilitating disease with associated psychiatric, motoric, and autonomic dysfunction. However, neocortical Lewy bodies are not a substrate for severe global cognitive impairment as assessed by the Mini-Mental State Examination. Instead, neocortical Lewy bodies appear to constitute or reflect an additive disease process, requiring Alzheimer disease or other concomitant brain diseases to induce severe global cognitive deterioration.

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Figures

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Figure 1 Evaluation of average final antemortem MMSE scores for patients with and without appreciable neocortical LBs present according to Braak neurofibrillary stages on neuropathology reports Note that the presence of neocortical Lewy bodies (LBs) is associated with a relatively modest decrease in final Mini-Mental State Examination (MMSE) scores at some Braak stages. The University of Kentucky Alzheimer's Disease Center (UK ADC) data are shown separately from the National Alzheimer's Coordinating Center (NACC) Registry data because each study group has unique characteristics. For these figures, only cases with autopsies from 1999 to 2008 were used to ensure most up-to-date pathologic techniques. Statistically, the mean final MMSE scores were not different in Braak stage VI patients in the presence vs absence of neocortical LBs (using NACC Registry, UK ADC, or combining data). Error bars = standard deviation. MMSE scores vary by Alzheimer disease–type Braak staging and presence or absence of neocortical LBs.

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Figure 2 Cognitive impairment is seen in some but not all patients with pure dementia with Lewy bodies confirmed at autopsy The rate of cognitive impairment for 9 individuals with pure dementia with Lewy bodies from the University of Kentucky Alzheimer's Disease Center database with 3 or more serial Mini-Mental State Examination (MMSE) scores. The abscissa refers to years before death.

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Figure 3 Rate of cognitive deterioration in patients with autopsy-confirmed pure DLB, pure AD, or AD+DLB Analysis of last 4 Mini-Mental State Examination (MMSE) scores before death of persons from the University of Kentucky Alzheimer's Disease Center autopsy series with pathologically confirmed pure dementia with Lewy bodies (DLB; n = 9), pure Alzheimer disease (AD; n = 107), or AD+DLB (n = 27) was performed to determine how the average intercept and slope varied among the 3 neuropathologic diagnostic groups after adjusting for years of education. With the caveat that it is a small group, the pure DLB group had higher MMSE scores 4 visits before death compared to the other groups and declined less perceptibly than the AD+DLB group (see text for details).

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