Differences in cognitive profiles between Lewy body and Parkinson's disease dementia

Visual dysfunction in dementia with Lewy bodies

PURPOSE OF REVIEW

To review the literature on visual dysfunction in dementia with Lewy bodies (DLB), including its mechanisms and clinical implications.

RECENT FINDINGS

Recent studies have explored novel aspects of visual dysfunction in DLB, including visual texture agnosia, mental rotation of 3-dimensional drawn objects, and reading fragmented letters. Recent studies have shown parietal and occipital hypoperfusion correlating with impaired visuoconstruction performance. While visual dysfunction in clinically manifest DLB is well recognized, recent work has focused on prodromal or mild cognitive impairment (MCI) due to Lewy body pathology with mixed results. Advances in retinal imaging have recently led to the identification of abnormalities such as parafoveal thinning in DLB. Patients with DLB experience impairment in color perception, form and object identification, space and motion perception, visuoconstruction tasks, and illusions in association with visual cortex and network dysfunction. These symptoms are associated with visual hallucinations, driving impairment, falls, and other negative outcomes.

Exploring the Regulatory Landscape of Dementia: Insights from Non-Coding RNAs

Dementia, a multifaceted neurological syndrome characterized by cognitive decline, poses significant challenges to daily functioning. The main causes of dementia, including Alzheimer's disease (AD), frontotemporal dementia (FTD), Lewy body dementia (LBD), and vascular dementia (VD), have different symptoms and etiologies. Genetic regulators, specifically non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are known to play important roles in dementia pathogenesis. MiRNAs, small non-coding RNAs, regulate gene expression by binding to the 3' untranslated regions of target messenger RNAs (mRNAs), while lncRNAs and circRNAs act as molecular sponges for miRNAs, thereby regulating gene expression. The emerging concept of competing endogenous RNA (ceRNA) interactions, involving lncRNAs and circRNAs as competitors for miRNA binding, has gained attention as potential biomarkers and therapeutic targets in dementia-related disorders. This review explores the regulatory roles of ncRNAs, particularly miRNAs, and the intricate dynamics of ceRNA interactions, providing insights into dementia pathogenesis and potential therapeutic avenues.

Alterations of Cortical Structure and Neurophysiology in Parkinson's Disease Are Aligned with Neurochemical Systems

OBJECTIVE

Parkinson's disease (PD) affects the structural integrity and neurophysiological signaling of the cortex. These alterations are related to the motor and cognitive symptoms of the disease. How these changes are related to the neurochemical systems of the cortex is unknown.

METHODS

We used T1-weighted magnetic resonance imaging (MRI) and magnetoencephalography (MEG) to measure cortical thickness and task-free neurophysiological activity in patients with idiopathic PD (nMEG = 79, nMRI = 65) and matched healthy controls (nMEG = 65, nMRI = 37). Using linear mixed-effects models, we examined the topographical alignment of cortical structural and neurophysiological alterations in PD with cortical atlases of 19 neurotransmitter receptor and transporter densities.

RESULTS

We found that neurophysiological alterations in PD occur primarily in brain regions rich in acetylcholinergic, serotonergic, and glutamatergic systems, with protective implications for cognitive and psychiatric symptoms. In contrast, cortical thinning occurs preferentially in regions rich in noradrenergic systems, and the strength of this alignment relates to motor deficits.

INTERPRETATION

This study shows that the spatial organization of neurophysiological and structural alterations in PD is relevant for nonmotor and motor impairments. The data also advance the identification of the neurochemical systems implicated. The approach uses novel nested atlas modeling methodology that is transferrable to research in other neurological and neuropsychiatric diseases and syndromes. ANN NEUROL 2024;95:802-816.

Neuropsychological evaluation of phenoconversion risk in REM sleep behaviour disorder: A scoping review

The objective of this study was to assess the role of cognitive evaluation in the prediction of phenoconversion in polysomnography-confirmed idiopathic or isolated rapid eye movement sleep behaviour disorder, through a scoping review focussing on a longitudinal comprehensive neuropsychological assessment of patients with idiopathic REM sleep behaviour disorder. A literature search (2006-2022) yielded 1034 records, and 20 were selected for analysis. The sample included 899 patients from eight different cohorts and five countries. We extracted data on clinical evolution, mild cognitive impairment diagnosis, neuropsychological tests used, and classification of cognitive domains. Tests, cognitive domains, and mild cognitive impairment definitions were heterogeneous across the studies, precluding a meta-analysis. Ten studies (50%) evaluated the presence of mild cognitive impairment; 14 studies (70%) grouped neuropsychological tests into between three (6 studies, 21.4%) and seven (1 study, 7.1%) cognitive domains. The most frequently used tests were semantic fluency, Stroop colour word test, trail making test A and B, digit span, Rey auditory verbal learning test, and Rey-Osterrieth figure. All except digit span showed a role in predicting phenoconversion. The authors did not consistently assign tests to specific cognitive domains. In conclusion, we discuss methodological differences between the studies and highlight the need for a standardised framework for neuropsychological data acquisition and presentation, based on a multilevel approach covering test selection, domain assignment, and mild cognitive impairment diagnostic criteria.

Normative Data for the Judgment of Line Orientation Test (Long and Short Forms) in the Quebec-French Population Aged between 50 and 89 Years

The Judgment of Line Orientation (JLO) Test of Benton assesses visuospatial processing without requiring motor skills. The test is frequently used in geriatric or brain-injured populations. As with other cognitive tests, performance on the JLO test may vary according to age, level of education, sex, and cultural background of individuals. The present study aimed to establish normative data for a short (15 items) and a long (30 items) form of the JLO. The sample for the short and long forms comprised 198 and 260 individuals, respectively, aged 50-89 years. All participants were French-speaking people from the province of Quebec, Canada. Using regression-based norming, the effects of age, years of formal education, and sex on JLO performance were estimated. The normative adjustment of the JLO short and long forms considered the weight of each predictor on test performance. Results indicated that JLO performance was positively associated with years of formal education and male sex, whereas it was negatively associated with age. Accordingly, normative data were generated using Z-scores and adjusted scaled scores derived from the regression equations. To conclude, the present norms will ease the detection of visuospatial impairment in French-Quebec middle-aged and older adults.

Morphological characteristics differentiate dementia with Lewy bodies from Parkinson disease with and without dementia

Dementia with Lewy bodies (DLB) and Parkinson disease (PD) with and without dementia are entities of a spectrum of Lewy body diseases. About 26.3% of all PD patients develop dementia increasing up to 83%. Parkinson disease-dementia (PDD) and DLB share many clinical and morphological features that separate them from non-demented PD (PDND). Clinically distinguished by the temporal sequence of motor and cognitive symptoms, the pathology of PDD and DLB includes variable combinations of Lewy body (LB) and Alzheimer (AD) lesions, both being more severe in DLB, but much less frequent and less severe in PDND. The objective of this study was to investigate the morphological differences between these three groups. 290 patients with pathologically confirmed PD were reviewed. 190 of them had clinical dementia; 110 met the neuropathological criteria of PDD and 80 of DLB. The major demographic and clinical data were obtained from medical records. Neuropathology included semiquantitative assessment of LB and AD pathologies including cerebral amyloid angiopathy (CAA). PDD patients were significantly older than PDND and DLB ones (83.9 vs 77.9 years, p < 0.05); the age of DLB patients was between them (80.0 years), while the disease duration was shortest in DLB. Brain weight was lowest in DLB, which showed higher Braak LB scores (mean 5.2 vs 4.2) and highest Braak tau stages (mean 5.2 vs 4.4 and 2.3, respectively). Thal Aβ phases were also highest in DLB (mean 4.1 vs 3.0 and 1.8, respectively). Major findings were frequency and degree of CAA, being highest in DLB (95% vs 50% and 24%, with scores 2.9 vs 0.7 and 0.3, respectively), whereas other small vessel lesions showed no significant differences. Striatal Aβ deposits also differentiated DLB from the other groups. This and other studies of larger cohorts of PD patients indicate that the association of CAA and cortical tau-but less-LB pathologies are associated with more severe cognitive decline and worse prognosis that distinguish DLB from PDD and PDND. The particular impact of both CAA and tau pathology supports the concept of a pathogenic continuum ranging from PDND to DLB + AD within the spectrum of age-related synucleinopathies.

Identification of key genes and signaling pathways associated with dementia with Lewy bodies and Parkinson's disease dementia using bioinformatics

Objective

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are collectively known as Lewy body dementia (LBD). Considering the heterogeneous nature of LBD and the different constellations of symptoms with which patients can present, the exact molecular mechanism underlying the differences between these two isoforms is still unknown. Therefore, this study aimed to explore the biomarkers and potential mechanisms that distinguish between PDD and DLB.

Methods

The mRNA expression profile dataset of GSE150696 was acquired from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) between 12 DLB and 12 PDD were identified from Brodmann area 9 of human postmortem brains using GEO2R. A series of bioinformatics methods were applied to identify the potential signaling pathways involved, and a protein–protein interaction (PPI) network was constructed. Weighted gene co-expression network analysis (WGCNA) was used to further investigate the relationship between gene co-expression and different LBD subtypes. Hub genes that are strongly associated with PDD and DLB were obtained from the intersection of DEGs and selected modules by WGCNA.

Results

A total of 1,864 DEGs between PDD and DLB were filtered by the online analysis tool GEO2R. We found that the most significant GO- and KEGG-enriched terms are involved in the establishment of the vesicle localization and pathways of neurodegeneration-multiple diseases. Glycerolipid metabolism and viral myocarditis were enriched in the PDD group. A B-cell receptor signaling pathway and one carbon pool by folate correlated with DLB in the results obtained from the GSEA. We found several clusters of co-expressed genes which we designated by colors in our WGCNA analysis. Furthermore, we identified seven upregulated genes, namely, SNAP25, GRIN2A, GABRG2, GABRA1, GRIA1, SLC17A6, and SYN1, which are significantly correlated with PDD.

Conclusion

The seven hub genes and the signaling pathways we identified may be involved in the heterogeneous pathogenesis of PDD and DLB.

Disease Progression and Longitudinal Clinical Outcomes of Lewy Body Dementia in the NACC Database

INTRODUCTION

As the identification of Lewy body dementia (LBD) is often confirmed postmortem, there is a paucity of evidence on the progression of disease antemortem. This study aimed to comprehensively assess the course of LBD over time across cognitive, functional, and neuropsychiatric outcomes using real-world data.

METHODS

Adults with at least one visit to an Alzheimer's Disease Center with a diagnosis of mild cognitive impairment/dementia (index date), indication of LBD, and at least one follow-up visit were identified in the National Alzheimer's Coordinating Center database (September 2005-June 2020). Participant characteristics, medication use, comorbidities, and changes in outcomes were assessed over a 5-year follow-up period and stratified by disease severity based on the Clinical Dementia Rating (CDR®) Dementia Staging Instrument-Sum of Boxes (CDR-SB) score at index.

RESULTS

A total of 2052 participants with LBD (mean age at index 73.4 years) were included (mild, 219; moderate, 988; severe, 845). Mean annualized increase over 5 years was 0.9 points for CDR-Global Score, 5.6 points for CDR-SB, 10.4 points for the Functional Activities Questionnaire, and 2.0 points for the Neuropsychiatric Inventory-Questionnaire. Disease progression was greater among participants with moderate and severe LBD at index compared with those with mild LBD.

CONCLUSION

Participants with LBD experienced decline across all outcomes over time, and impairment increased with disease severity. Findings highlight the substantial clinical burden associated with LBD and the importance of earlier diagnosis and effective treatment. Further research is needed to understand the predictors of cognitive and functional decline in LBD which may help inform clinical trials.

Memory Outcome in Prodromal and Mild Dementia with Lewy Bodies and Alzheimer's Disease: A Longitudinal Study

BACKGROUND

Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are likely to induce memory impairments from the prodromal stage but, to our knowledge, no longitudinal study of these patients' memory profile has been conducted to date.

OBJECTIVE

The aim of our study was to describe the characteristics and the evolution of the long-term memory profile of patients with prodromal and mild DLB and AD.

METHODS

We collected verbal (RL/RI-16) and visual (DMS48) memory scores from 91 DLB patients, 28 AD patients, 15 patients with both conditions (DLB/AD), and 18 healthy control subjects at their inclusion visit and at 12, 24, and 48 months.

RESULTS

On the RL/RI-16, DLB patients performed better than AD patients in terms of total recall (p < 0.001), delayed total recall (p < 0.001), recognition (p = 0.031), and loss of information over time (p = 0.023). On the DMS48, differences between these two groups were not significant (p > 0.05). Longitudinally, the memory performance of DLB patients was stable over 48 months, unlike that of AD patients.

CONCLUSION

Four indicators were relevant to distinguish between DLB and AD patients in terms of memory performance: DLB patients benefitted greatly from semantic cueing, their recognition and consolidation abilities were well-preserved, and both their verbal and visual memory performance remained remarkably stable over four years. However, no performance differences between DLB and AD patients were found regarding visual memory, either qualitatively (memory profile) or quantitatively (severity of impairment), indicating the lesser relevance of this test in distinguishing between these two diseases.

An adaptive measure of visuospatial impairment in Dementia with Lewy Bodies

Background

Dementia with Lewy bodies (DLB) is a common cause of dementia with poor prognosis and high hospitalization rates. DLB is frequently misdiagnosed, with clinical features that overlap significantly with other diseases including Parkinson's disease (PD). Clinical instruments that discriminate and track the progression of cognitive impairment in DLB are needed.

Objectives

The current study was designed to assess the utility of a mental rotation (MR) task for assessing visuospatial impairments in early DLB.

Methods

Accuracy of 22 DLB patients, 22 PD patients and 22 age‐matched healthy controls in the MR task were compared at comparing shapes with 0°, 45° and 90° rotations.

Results

Healthy controls and PD patients performed at similar levels while the DLB group were significantly impaired. Further, impairment in the visuospatial and executive function measures correlated with MR poor outcomes.

Conclusion

These findings support the MR task as an objective measure of visuospatial impairment with the ability to adjust difficulty to suit impairments in a DLB population. This would be a useful tool within clinical trials.

Dissecting the Interplay Between Time of Dementia and Cognitive Profiles in Lewy Body Dementias

BACKGROUND

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are differentiated by the time of onset of cognitive and motor symptoms ('1-year rule'). We explored the neuropsychological continuum of DLB and PDD subjects with different timing of dementia onset.

OBJECTIVE

Our aim was to compare the neuropsychological profile of DLB and PDD patients with different timing of dementia onset.

METHODS

Neuropsychological findings at the diagnosis of dementia of 66 PDD and 42 DLB patients were retrospectively compared. Patients with PDD were divided into three tertile subgroups according to the time interval between the onset of parkinsonism and dementia (N = 24, 2-4 years; N = 17, 5-7 years; N = 25 ≥8 years, respectively).

RESULTS

DLB patients performed worse on the Stroop and semantic fluency tests than PDD, even in comparison to PD with early dementia onset. No significant differences among PDD subgroups were reported.

CONCLUSION

Executive and semantic language tests could differentiate DLB and PD patients with earlier development of dementia relative to parkinsonism.

Overview of the Complex Figure Test and Its Clinical Application in Neuropsychiatric Disorders, Including Copying and Recall

The Rey–Osterrieth Complex Figure (ROCF) test is a commonly used neuropsychological assessment tool. It is widely used to assess the visuo-constructional ability and visual memory of neuropsychiatric disorders, including copying and recall tests. By drawing the complex figure, the functional decline of a patient in multiple cognitive dimensions can be assessed, including attention and concentration, fine-motor coordination, visuospatial perception, non-verbal memory, planning and organization, and spatial orientation. This review first describes the different versions and scoring methods of ROCF. It then reviews the application of ROCF in the assessment of visuo-constructional ability in patients with dementia, other brain diseases, and psychiatric disorders. Finally, based on the scoring method of the digital system, future research hopes to develop a new digital ROCF scoring method combined with machine learning algorithms to standardize clinical practice and explore the characteristic neuropsychological structure information of different disorders.

The contribution of beta-amyloid to dementia in Lewy body diseases: a 1-year follow-up study

Dementia in Lewy Body Diseases (Parkinson’s disease and dementia with Lewy Bodies) affects progression of disabilities, quality of life and well-being. Understanding its pathogenetic mechanisms is critical to properly implement disease-modifying strategies. It has been hypothesized that synuclein- and amyloid-pathology act synergistically aggravating cognitive decline in elderly patients but their precise contribution to dementia is debated. In this study, we aimed at exploring if presence of amyloid deposits influences clinical, cognitive and neuroanatomical correlates of mental decline in a cohort of 40 Parkinson’s disease patients with normal cognition (n = 5), mild cognitive impairment (n = 22), and dementia (n = 13) as well as in Dementia with Lewy Bodies (n = 10). Patients underwent simultaneous 3 T PET/MRI with [¹⁸F]-flutemetamol and were assessed with an extensive baseline motor and neuropsychological examination, which allowed level II diagnosis of mild cognitive impairment and dementia. The role of amyloid positivity on each cognitive domain, and on the rate of conversion to dementia at 1-year follow-up was explored. A Kaplan Meier and the Log Rank (Mantel–Cox) test were used to assess the pairwise differences in time-to-develop dementia in Parkinson’s disease patients with and without significant amyloidosis. Furthermore, the presence of an Alzheimer’s dementia-like morphological pattern was evaluated using visual and automated assessment of T₁-weighted and T₂-weighted MRI images. We observed similar percentage of amyloid deposits in Parkinson’s disease dementia and dementia with Lewy Bodies cohorts (50% in each group) with an overall prevalence of 34% of significant amyloid depositions in Lewy Body Diseases. PET amyloid positivity was associated with worse global cognition (Montreal Cognitive Assessment and Mini Mental State Examination), executive and language difficulties. At 12-month follow-up, amyloid positive Parkinson’s disease patients were more likely to have become demented than those without amyloidosis. Moreover, there was no difference in the presence of an Alzheimer’s disease-like atrophy pattern and in vascular load (at Fazekas scale) between Lewy Body Diseases with and without significant amyloid deposits. Our findings suggest that in Lewy Body Diseases, amyloid deposition enhances cognitive deficits, particularly attention-executive and language dysfunctions. However, the large number of patients without significant amyloid deposits among our cognitively impaired patients indicates that synuclein pathology itself plays a critical role in the development of dementia in Lewy Body Diseases.

Impact of social and mobility restrictions in Parkinson's disease during COVID-19 lockdown

BACKGROUND

The consequences of strict COVID-19 mobility restrictions on motor/non-motor features in Parkinson's disease (PD) have not been systematically studied but worse mobility and quality of life have been reported. To elucidate this question, 12 mild to moderate PD patients were assessed in March 2020 before and after two months of isolation as part of a clinical study that had to be interrupted due to the pandemic and the implementation of COVID19 mobility restrictions.

METHODS

Twelve patients were systematically evaluated before and after the lockdown period as part of a larger cohort that previously underwent thermal water rehabilitation. Clinical outcomes were the Body Mass index, the Mini-Balance Evaluation Systems Test, the MDS-Unified Parkinson's Disease Rating Scale part III, the 6 Minute Walking Test and the New Freezing of Gait Questionnaire. Global cognition was evaluated with the Montreal Cognitive Assessment scale. The impact of COVID-19 restrictions on quality of life and functional independence was evaluated with The Parkinson's disease Quality of life (PDQ-39), the Activities of Daily Living (ADL) and Instrumental Activities of Daily Living questionnaires (IADL) and the Parkinson's disease cognitive functional rating scales (PD-CFRS).

RESULTS

After two months of isolation the Mini-BESTest score worsened (p=0.005), and four patients reported one or more falls during the lockdown. BMI increased (p=0.031) while the remaining clinical variables including quality of life did not change.

CONCLUSION

We observed moderate worsening at Mini-BESTest, greater risk of falls and increased body weight as consequence of prolonged immobility. We believe negative effects were partially softened since patients were in contact with our multidisciplinary team during the lockdown and had previously received training to respond to the needs of this emergency isolation. These findings highligh the importnace of patient-centered interventions in PD management.

Significance of cerebral amyloid angiopathy and other co-morbidities in Lewy body diseases

Lewy body dementia (LBD) and Parkinson's disease-dementia (PDD) are two major neurocognitive disorders with Lewy bodies (LB) of unknown etiology. There is considerable clinical and pathological overlap between these two conditions that are clinically distinguished based on the duration of Parkinsonism prior to development of dementia. Their morphology is characterized by a variable combination of LB and Alzheimer's disease (AD) pathologies. Cerebral amyloid angiopathy (CAA), very common in aged persons and particularly in AD, is increasingly recognized for its association with both pathologies and dementia. To investigate neuropathological differences between LB diseases with and without dementia, 110 PDD and 60 LBD cases were compared with 60 Parkinson's disease (PD) cases without dementia (PDND). The major demographic and neuropathological data were assessed retrospectively. PDD patients were significantly older than PDND ones (83.9 vs 77.8 years; p < 0.05); the age of LB patients was in between both groups (mean 80.2 years), while the duration of disease was LBD < PDD < PDND (mean 6.7 vs 12.5 and 14.3 years). LBD patients had higher neuritic Braak stages (mean 5.1 vs 4.5 and 4.0, respectively), LB scores (mean 5.3 vs 4.2 and 4.0, respectively), and Thal amyloid phases (mean 4.1 vs 3.0 and 2.3, respectively) than the two other groups. CAA was more common in LBD than in the PDD and PDND groups (93 vs 50 and 21.7%, respectively). Its severity was significantly greater in LBD than in PDD and PDND (p < 0.01), involving mainly the occipital lobes. Moreover, striatal Aβ deposition highly differentiated LBD brains from PDD. Braak neurofibrillary tangle (NFT) stages, CAA, and less Thal Aβ phases were positively correlated with LB pathology (p < 0.05), which was significantly higher in LBD than in PDD < PDND. Survival analysis showed worse prognosis in LBD than in PDD (and PDND), which was linked to both increased Braak tau stages and more severe CAA. These and other recent studies imply the association of CAA-and both tau and LB pathologies-with cognitive decline and more rapid disease progression that distinguishes LBD from PDD (and PDND).

Evaluating a novel behavioral paradigm for visual hallucinations in Dementia with Lewy bodies

The aim of this study was to evaluate the utility of the Bistable Percept Paradigm (BPP), a computerised behavioural task that has previously been utilised for the assessment of visual hallucinations in Parkinson's Disease, in a Dementia with Lewy bodies (DLB) cohort. Dementia with Lewy bodies patients demonstrated poorer performance than healthy controls (HC) on the BPP with significantly more misperceptions and a greater failure to detect bistable percepts correctly compared to HC. Further, the number of misperceptions was also correlated with the severity of hallucinations. The findings from this study demonstrate that the BPP is a viable tool to measure misperceptions in DLB patients.