Clinical and Cognitive Phenotype of Mild Cognitive Impairment Evolving to Dementia with Lewy Bodies

Abstract

Objective: The aim of this study was to determine which characteristics could better distinguish dementia with Lewy bodies (DLB) from Alzheimer's disease (AD) at the mild cognitive impairment (MCI) stage, with particular emphasis on visual space and object perception abilities. Methods: Fifty-threepatients with mild cognitive deficits that were eventually diagnosed with probable DLB (MCI-DLB: n = 25) and AD (MCI-AD: n = 28) at a 3-year follow-up were retrospectively studied. At the first visit, the patients underwent cognitive assessment including the Qualitative Scoring Mini Mental State Examination Pentagon Test and the Visual Object and Space Perception Battery. The Neuropsychiatric Inventory Questionnaire, Unified Parkinson's Disease Rating Scale (UPDRS) and questionnaires for cognitive fluctuations and sleep disorders were also administered. Results: The best clinical predictor of DLB was the presence of soft extrapyramidal signs (mean UPDRS score: 4.04 ± 5.9) detected in 72% of patients, followed by REM sleep behavior disorder (60%) and fluctuations (60%). Wrong performances in the pentagon's number of angles were obtained in 44% of DLB and 3.7% of AD patients and correlated with speed of visual attention. Executive functions, visual attention and visuospatial abilities were worse in DLB, while verbal episodic memory impairment was greater in AD. Deficits in the visual-perceptual domain were present in both MCI-DLB and AD. Conclusions: Poor performance in the pentagon's number of angles is specific of DLB and correlates with speed of visual attention. The dorsal visual stream seems specifically more impaired in MCI-DLB with respect to the ventral visual stream, the latter being involved in both DLB and AD. These cognitive features, associated with subtle extrapyramidal signs, should alert clinicians to a diagnostic hypothesis of DLB.

How does dementia with Lewy bodies start? prodromal cognitive changes in REM sleep behavior disorder

“…In MCI‐DLB cases, there is a high risk of subtle features of parkinsonism, hallucinations, and cognitive fluctuations . Moreover, impaired attentional abilities, executive functioning, and visuospatial abilities are common in MCI‐DLB . Furthermore, a recent study found impaired verbal memory in 20% of MCI‐DLB cases .…”

Research criteria for the diagnosis of prodromal dementia with Lewy bodies

“…5 Spontaneous parkinsonism often develops within the predementia stage but is not present in all patients. 3,6 RBD is a parasomnia that typically occurs years, and even decades, before the onset of dementia or parkinsonism and may presage any of the α-synucleinopathies. 4,7,e4 In patients with mild cognitive deficits who later develop dementia, both parkinsonism and RBD strongly predict a later transition to DLB rather than to AD or other dementia types.…”

“…4,7,e4 In patients with mild cognitive deficits who later develop dementia, both parkinsonism and RBD strongly predict a later transition to DLB rather than to AD or other dementia types. 6,8 Delirium can occur during the predementia stage of DLB 9 as can fluctuations of cognition and arousal 3 that may give rise to a diagnosis of delirium. Visual hallucinations (VHs) either spontaneous or provoked by illness or medication are more likely to occur compared with normal controls or prodromal AD.…”

Prodromal Dementia With Lewy Bodies: Clinical Characterization and Predictors of Progression

“…4 Some cross-sectional studies suggest that the cognitive profile of MCI-LB differs from MCI-AD, with less pronounced memory impairment, 8 but lower performance in attention, 3,9 executive, 8,10 and visuospatial functions. 10,11 Other studies in MCI-LB found prominent neuropsychiatric symptoms (NPS), with frequent anxiety, apathy, and sleep disturbances. 3,8 Only a few longitudinal studies on MCI-LB have been described.…”