Neuroimaging in Lewy body dementia

High pulse wave velocity is associated with enlarged perivascular spaces in dementia with Lewy bodies

Previous studies have demonstrated associations between enlarged perivascular spaces (EPVS) and dementias such as Alzheimer's disease. However, an association between EPVS and dementia with Lewy bodies (DLB) has not yet been clarified. We performed a cross-sectional analysis of our prospective study cohort of 109 participants (16 with DLB). We assessed cognitive function, pulse wave velocity (PWV), and brain magnetic resonance imaging features. The relationships between EPVS and DLB were evaluated using multivariable logistic regression analyses. Compared with the non-dementia group, the DLB group was more likely to have EPVS in the basal ganglia. Compared with participants without EPVS, those with EPVS were older and had cognitive impairment and high PWV. In multivariable analyses, EPVS in the basal ganglia was independently associated with DLB. High PWV was also independently associated with EPVS in both the basal ganglia and centrum semiovale. High PWV may cause cerebrovascular pulsatility, leading to accelerated EPVS in DLB participants.

Differentiating Prodromal Dementia with Lewy Bodies from Prodromal Alzheimer's Disease: A Pragmatic Review for Clinicians

This pragmatic review synthesises the current understanding of prodromal dementia with Lewy bodies (pDLB) and prodromal Alzheimer's disease (pAD), including clinical presentations, neuropsychological profiles, neuropsychiatric symptoms, biomarkers, and indications for disease management. The core clinical features of dementia with Lewy bodies (DLB)-parkinsonism, complex visual hallucinations, cognitive fluctuations, and REM sleep behaviour disorder are common prodromal symptoms. Supportive clinical features of pDLB include severe neuroleptic sensitivity, as well as autonomic and neuropsychiatric symptoms. The neuropsychological profile in mild cognitive impairment attributable to Lewy body pathology (MCI-LB) tends to include impairment in visuospatial skills and executive functioning, distinguishing it from MCI due to AD, which typically presents with impairment in memory. pDLB may present with cognitive impairment, psychiatric symptoms, and/or recurrent episodes of delirium, indicating that it is not necessarily synonymous with MCI-LB. Imaging, fluid and other biomarkers may play a crucial role in differentiating pDLB from pAD. The current MCI-LB criteria recognise low dopamine transporter uptake using positron emission tomography or single photon emission computed tomography (SPECT), loss of REM atonia on polysomnography, and sympathetic cardiac denervation using meta-iodobenzylguanidine SPECT as indicative biomarkers with slowing of dominant frequency on EEG among others as supportive biomarkers. This review also highlights the emergence of fluid and skin-based biomarkers. There is little research evidence for the treatment of pDLB, but pharmacological and non-pharmacological treatments for DLB may be discussed with patients. Non-pharmacological interventions such as diet, exercise, and cognitive stimulation may provide benefit, while evaluation and management of contributing factors like medications and sleep disturbances are vital. There is a need to expand research across diverse patient populations to address existing disparities in clinical trial participation. In conclusion, an early and accurate diagnosis of pDLB or pAD presents an opportunity for tailored interventions, improved healthcare outcomes, and enhanced quality of life for patients and care partners.

Bidirectional two-sample Mendelian randomization analyses support causal relationships between structural and diffusion imaging-derived phenotypes and the risk of major neurodegenerative diseases

Previous observational investigations suggest that structural and diffusion imaging-derived phenotypes (IDPs) are associated with major neurodegenerative diseases; however, whether these associations are causal remains largely uncertain. Herein we conducted bidirectional two-sample Mendelian randomization analyses to infer the causal relationships between structural and diffusion IDPs and major neurodegenerative diseases using common genetic variants-single nucleotide polymorphism (SNPs) as instrumental variables. Summary statistics of genome-wide association study (GWAS) for structural and diffusion IDPs were obtained from 33,224 individuals in the UK Biobank cohort. Summary statistics of GWAS for seven major neurodegenerative diseases were obtained from the largest GWAS for each disease to date. The forward MR analyses identified significant or suggestively statistical causal effects of genetically predicted three structural IDPs on Alzheimer's disease (AD), frontotemporal dementia (FTD), and multiple sclerosis. For example, the reduction in the surface area of the left superior temporal gyrus was associated with a higher risk of AD. The reverse MR analyses identified significantly or suggestively statistical causal effects of genetically predicted AD, Lewy body dementia (LBD), and FTD on nine structural and diffusion IDPs. For example, LBD was associated with increased mean diffusivity in the right superior longitudinal fasciculus and AD was associated with decreased gray matter volume in the right ventral striatum. Our findings might contribute to shedding light on the prediction and therapeutic intervention for the major neurodegenerative diseases at the neuroimaging level.

Differences in Retinal and Choroidal Microvasculature and Structure in Dementia With Lewy Bodies Compared With Normal Cognition

Purpose: To evaluate the retinal and choroidal microvasculature and structure in individuals with dementia with Lewy bodies (DLB) compared with controls with normal cognition using optical coherence tomography (OCT) and OCT angiography (OCTA). Methods: An institutional review board-approved cross-sectional comparison of patients with DLB and cognitively normal controls was performed. The Cirrus HD-OCT 5000 with AngioPlex (Carl Zeiss Meditec) was used to obtain OCT and OCTA images. Results: Thirty-four eyes of 18 patients with DLB and 85 eyes of 48 cognitively normal patients were analyzed. The average capillary perfusion density (CPD) was higher in the DLB group than in the control group (P = .005). The average capillary flux index (CFI) and ganglion cell inner-plexiform layer (GC-IPL) thickness were lower in the DLB group than in the control group (P = .016 and P = .040, respectively). Conclusions: Patients with DLB had an increased peripapillary CPD, decreased peripapillary CFI, and attenuated GC-IPL thickness compared with those with normal cognition.

Combined 18F-FDG PET-CT markers in dementia with Lewy bodies

INTRODUCTION

18F-Fluoro-deoxyglucose-positron emission tomography (FDG-PET) is a supportive biomarker in dementia with Lewy bodies (DLB) diagnosis and its advanced analysis methods, including radiomics and machine learning (ML), were developed recently. The aim of this study was to evaluate the FDG-PET diagnostic performance in predicting a DLB versus Alzheimer's disease (AD) diagnosis.

METHODS

FDG-PET scans were visually and semi-quantitatively analyzed in 61 patients. Radiomics and ML analyses were performed, building five ML models: (1) clinical features; (2) visual and semi-quantitative PET features; (3) radiomic features; (4) all PET features; and (5) overall features.

RESULTS

At follow-up, 34 patients had DLB and 27 had AD. At visual analysis, DLB PET signs were significantly more frequent in DLB, having the highest diagnostic accuracy (86.9%). At semi-quantitative analysis, the right precuneus, superior parietal, lateral occipital, and primary visual cortices showed significantly reduced uptake in DLB. The ML model 2 had the highest diagnostic accuracy (84.3%).

DISCUSSION

FDG-PET is a valuable tool in DLB diagnosis, having visual and semi-quantitative analyses with the highest diagnostic accuracy at ML analyses.

Globular glial tauopathy presenting clinically as atypical parkinsonism with dementia: A clinicopathological case report

•Globular Glial Tauopathy presents as atypical parkinsonism with dementia.•Globular Glial Tauopathy is underrecognized among movement disorders specialists.•Globular Glial Tauopathy type III without preferential language dysfunction or semantic dementia.

A SPECT-based method for dynamic imaging of the glymphatic system in rats

The glymphatic system is a brain-wide waste drainage system that promotes cerebrospinal fluid circulation through the brain to remove waste metabolites. Currently, the most common methods for assessing glymphatic function are ex vivo fluorescence microscopy of brain slices, macroscopic cortical imaging, and MRI. While all these methods have been crucial for expanding our understanding of the glymphatic system, new techniques are required to overcome their specific drawbacks. Here, we evaluate SPECT/CT imaging as a tool to assess glymphatic function in different anesthesia-induced brain states using two radiolabeled tracers, [111In]-DTPA and [99mTc]-NanoScan. Using SPECT, we confirmed the existence of brain state-dependent differences in glymphatic flow and we show brain state-dependent differences of CSF flow kinetics and CSF egress to the lymph nodes. We compare SPECT and MRI for imaging glymphatic flow and find that the two imaging modalities show the same overall pattern of CSF flow, but that SPECT was specific across a greater range of tracer concentrations than MRI. Overall, we find that SPECT imaging is a promising tool for imaging the glymphatic system, and that qualities such as high sensitivity and the variety of available tracers make SPECT imaging a good alternative for glymphatic research.

Aphasic mild cognitive impairment in prodromal dementia with Lewy bodies

Introduction

This study aimed to determine the characteristics of aphasic mild cognitive impairment (aphasic MCI), which is characterized by a progressive and relatively prominent language impairment compared with other cognitive impairments, in the prodromal phase of dementia with Lewy bodies (DLB).

Methods

Of the 26 consecutive patients with aphasic MCI who had been prospectively recruited at our hospital, 8 patients were diagnosed with prodromal DLB and underwent language, neurological, neuropsychological, and neuroimaging (N-isopropyl-p-[123I] iodoamphetamine single-photon emission computed tomography; IMP-SPECT) testing. Three of these patients also underwent cholinesterase inhibitor therapy with donepezil.

Results

In our aphasic MCI cohort, the clinical diagnosis of probable prodromal DLB accounted for more than 30% of cases; therefore, the presence of language impairment in prodromal DLB was not very uncommon. Five patients were diagnosed with progressive anomic aphasia and three with logopenic progressive aphasia. Anomic aphasia was characterized by apparent anomia but relatively preserved repetition and comprehension ability and logopenic progressive aphasia by anomia, phonemic paraphasia, and impaired repetition. IMP-SPECT revealed hypoperfusion of the temporal and parietal lobes in the left hemisphere in all but one patient. All patients who underwent cholinesterase inhibitor therapy with donepezil showed improvement in general cognitive function, including language function.

Discussion

The clinical and imaging features of aphasic MCI in prodromal DLB are similar to those observed in Alzheimer's disease. Progressive fluent aphasia, such as progressive anomic aphasia and logopenic progressive aphasia, is one of the clinical presentations in prodromal state of DLB. Our findings provide further insight into the clinical spectrum of prodromal DLB and may contribute to the development of medication for progressive aphasia caused by cholinergic insufficiency.

Oral environment and cerebral blood flow in patients with neurodegenerative dementia: comparison of Alzheimer type dementia and dementia with Lewy bodies

BACKGROUND

The number of patients with dementia is increasing worldwide. Modifying risk factors may significantly reduce the prevalence and cost of dementia. The number of remaining teeth, occlusal force, denture use, and periodontal disease status are associated with the risk of developing dementia. The oral environment may be a risk factor for dementia. This study aimed to investigate the association between the oral environment and cerebral blood flow in patients with mild cognitive impairment and dementia (either Alzheimer type dementia (ATD) or dementia with Lewy bodies (DLB)). We aimed to identify differences in the oral environment according to the underlying neurodegenerative disease.

METHODS

The participants were 25 patients with ATD and 25 patients with DLB who visited the Department of Dementia and Geriatric Medicine, Kanagawa Dental University Hospital. Patients were diagnosed with ATD and DLB by well-trained specialists certified by the Japanese Dementia Society and categorised as Level 3 or 4 by the Functional Assessment Staging of Alzheimer Disease scale. The correlation between oral environment (number of teeth, periodontal tissue, and oral function) and cerebral blood flow in each brain area calculated by single photon emission computed tomography was examined.

RESULTS

The DLB group showed a significant correlation between masticatory performance and cerebral blood flow in some areas, while no such correlation was observed in the ATD group. Significant correlations were found between periodontal pocket depth and bleeding on probing and cerebral blood flow in some areas in both groups, although the correlation was considerable in the ATD group.

CONCLUSIONS

The results of this study suggest that the association between changes in the oral environment and cerebral blood flow may differ among patients with ATD and DLB, depending on the underlying causative disease.

Blood Biomarkers for the Diagnosis of Neurodegenerative Dementia: A Systematic Review

IMPORTANCE

Accurately diagnosing neurodegenerative dementia is often challenging due to overlapping clinical features. Disease specific biomarkers could enhance diagnostic accuracy. However, CSF analysis procedures and advanced imaging modalities are either invasive or high-priced, and routinely unavailable. Easily accessible disease biomarkers would be of utmost value for accurate differential diagnosis of dementia subtypes.

OBJECTIVE

To assess the diagnostic accuracy of blood-based biomarkers for the differential diagnosis of AD from Frontotemporal Lobar Degeneration (FTLD), or AD from Dementia with Lewy Bodies (DLB).

METHODS

Systematic review. Three databases (PubMed, Scopus, and Web of Science) were searched. Studies assessing blood-based biomarkers levels in AD versus FTLD, or AD versus DLB, and its diagnostic accuracy, were selected. When the same biomarker was assessed in three or more studies, a meta-analysis was performed. QUADAS-2 criteria were used for quality assessment.

RESULTS

Twenty studies were included in this analysis. Collectively, 905 AD patients were compared to 1262 FTLD patients, and 209 AD patients were compared to 246 DLB patients. Regarding biomarkers for AD versus FTLD, excellent discriminative accuracy (AUC >0.9) was found for p-tau181, p-tau217, synaptophysin, synaptopodin, GAP43 and calmodulin. Other biomarkers also demonstrated good accuracy (AUC = 0.8-0.9). For AD versus DLB distinction, only miR-21-5p and miR-451a achieved excellent accuracy (AUC >0.9).

CONCLUSION

Encouraging results were found for several biomarkers, alone or in combination. Prospective longitudinal designs and consensual protocols, comprising larger cohorts and homogeneous testing modalities across centres, are essential to validate the clinical value of blood biomarkers for the precise etiological diagnosis of dementia.

FDG-PET combined with learning vector quantization allows classification of neurodegenerative diseases and reveals the trajectory of idiopathic REM sleep behavior disorder

BACKGROUND AND OBJECTIVES

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with principal component analysis (PCA) has been applied to identify disease-related brain patterns in neurodegenerative disorders such as Parkinson's disease (PD), Dementia with Lewy Bodies (DLB) and Alzheimer's disease (AD). These patterns are used to quantify functional brain changes at the single subject level. This is especially relevant in determining disease progression in idiopathic REM sleep behavior disorder (iRBD), a prodromal stage of PD and DLB. However, the PCA method is limited in discriminating between neurodegenerative conditions. More advanced machine learning algorithms may provide a solution. In this study, we apply Generalized Matrix Learning Vector Quantization (GMLVQ) to FDG-PET scans of healthy controls, and patients with AD, PD and DLB. Scans of iRBD patients, scanned twice with an approximate 4 year interval, were projected into GMLVQ space to visualize their trajectory.

METHODS

We applied a combination of SSM/PCA and GMLVQ as a classifier on FDG-PET data of healthy controls, AD, DLB, and PD patients. We determined the diagnostic performance by performing a ten times repeated ten fold cross validation. We analyzed the validity of the classification system by inspecting the GMLVQ space. First by the projection of the patients into this space. Second by representing the axis, that span this decision space, into a voxel map. Furthermore, we projected a cohort of RBD patients, whom have been scanned twice (approximately 4 years apart), into the same decision space and visualized their trajectories.

RESULTS

The GMLVQ prototypes, relevance diagonal, and decision space voxel maps showed metabolic patterns that agree with previously identified disease-related brain patterns. The GMLVQ decision space showed a plausible quantification of FDG-PET data. Distance traveled by iRBD subjects through GMLVQ space per year (i.e. velocity) was correlated with the change in motor symptoms per year (Spearman's rho =0.62, P=0.004).

CONCLUSION

In this proof-of-concept study, we show that GMLVQ provides a classification of patients with neurodegenerative disorders, and may be useful in future studies investigating speed of progression in prodromal disease stages.

"Occipital Pole" Sign on 18 F-FDG PET for Dementia With Lewy Bodies and Posterior Cortical Atrophy : Evidence From the Treviso Dementia (TREDEM) Registry

ABSTRACT

The 18 F-FDG PET images of dementia with Lewy bodies and posterior cortical atrophy, a visual-cognitive phenotype described in patients with Alzheimer disease, show occipital lobe hypometabolism with relative sparing of the primary visual cortex (PVC) generating the "occipital tunnel" sign proposed by Sawyer and Kuo in 2017, which is viewable on the medial sagittal projection. We believe that the saving of PVC compared with the lateral occipital cortex can be better appreciated by capturing the posterior projection of the PVC in a 3D stereotactic surface projection map, and we propose the name of "occipital pole" sign for this evidence.

The Cognitive Profile of Atypical Parkinsonism: A Meta-Analysis

Atypical Parkinsonism (AP) syndromes are characterized by a wide spectrum of non-motor symptoms including prominent attentional and executive deficits. However, the cognitive profile of AP and its differences and similarities with that of Parkinson's Disease (PD) are still a matter of debate. The present meta-analysis aimed at identifying patterns of cognitive impairment in AP by comparing global cognitive functioning, memory, executive functions, visuospatial abilities, language, non-verbal reasoning, and processing speed test performances of patients with AP relative to healthy controls and patients with PD. All investigated cognitive domains showed a substantial impairment in patients with AP compared to healthy controls. When AP syndromes were considered separately, their cognitive functioning was distributed along a continuum from Multiple Systemic Atrophy at one extreme, with the least impaired cognitive profile (similar to that observed in PD) to Progressive Supranuclear Palsy, with the greatest decline in global cognitive and executive functioning (similar to Corticobasal Syndrome). These findings indicate that widespread cognitive impairment could represent an important clinical indicator to distinguish AP from other movement disorders.

Imaging of sleep disorders in pre-Parkinsonian syndromes

PURPOSE OF REVIEW

Neuroimaging has been advanced in the last years and enabled clinicians to evaluate sleep disorders, especially isolated rapid eye movement sleep disorder (iRBD), which can be seen in alpha-synucleinopathies. iRBD is the best prodromal clinical marker for phenoconversion to these neurodegenerative diseases. This review aims to provide an update on advanced neuroimaging biomarkers in iRBD.

RECENT FINDINGS

Advanced structural MRI techniques, such as diffusion tensor imaging and functional MRI, neuromelanin-sensitive MRI, and scintigraphic neuroimaging such as cholinergic PET, dopamine transporter imaging - single-photon emission computerized tomography, perfusional single-photon emission computerized tomography, and cardiac metaiodobenzylguanidine can provide diagnostic and prognostic imaging biomarkers for iRBD, in isolation and more robustly when combined.

SUMMARY

New advanced neuroimaging can provide imaging biomarkers and aid in the appropriate clinical assessment and future therapeutic trials.

Neural Mechanisms of Motor Dysfunction in Mild Cognitive Impairment and Alzheimer’s Disease: A Systematic Review

Background:

Despite the prevalence of motor symptoms in mild cognitive impairment (MCI) and Alzheimer’s disease (AD), their underlying neural mechanisms have not been thoroughly studied.

Objective:

This review summarizes the neural underpinnings of motor deficits in MCI and AD.

Methods:

We searched PubMed up until August of 2021 and identified 37 articles on neuroimaging of motor function in MCI and AD. Study bias was evaluated based on sample size, availability of control samples, and definition of the study population in terms of diagnosis.

Results:

The majority of studies investigated gait, showing that slower gait was associated with smaller hippocampal volume and prefrontal deactivation. Less prefrontal activation was also observed during cognitive-motor dual tasking, while more activation in cerebellar, cingulate, cuneal, somatosensory, and fusiform brain regions was observed when performing a hand squeezing task. Excessive subcortical white matter lesions in AD were associated with more signs of parkinsonism, poorer performance during a cognitive and motor dual task, and poorer functional mobility. Gait and cognitive dual-tasking was furthermore associated with cortical thickness of temporal lobe regions. Most non-gait motor measures were only reported in one study in relation to neural measures.

Conclusion:

Cross-sectional designs, lack of control groups, mixing amnestic- and non-amnestic MCI, disregard of sex differences, and small sample sizes limited the interpretation of several studies, which needs to be addressed in future research to progress the field.

Recent advances in Lewy body dementia: A comprehensive review

Lewy Body Dementia is the second most frequent neurodegenerative illness proven to cause dementia, after Alzheimer's disease (AD). It is believed to be vastly underdiagnosed, as there is a significant disparity between the number of cases diagnosed clinically and those diagnosed via neuropathology at the time of postmortem autopsy. Strikingly, many of the pharmacologic treatments used to treat behavioral and cognitive symptoms in other forms of dementia exacerbate the symptoms of DLB. Therefore, it is critical to accurately diagnose DLB as these patients require a specific treatment approach. This article focuses on its pathophysiology, risk factors, differentials, and its diverse treatment modalities. In this study, an English language literature search was conducted on Medline, Cochrane, Embase, and Google Scholar till April 2022. The following search strings and Medical Subject Headings (MeSH) terms were used: "Lewy Body Dementia," "Dementia with Lewy bodies," and "Parkinson's Disease Dementia." We explored the literature on Lewy Body Dementia for its epidemiology, pathophysiology, the role of various genes and how they bring about the disease, biomarkers, its differential diagnoses and treatment options.

Spatial covariance analysis of FDG-PET and HMPAO-SPECT for the differential diagnosis of dementia with Lewy bodies and Alzheimer's disease

We investigated diagnostic characteristics of spatial covariance analysis (SCA) of FDG-PET and HMPAO-SPECT scans in the differential diagnosis of dementia with Lewy bodies (DLB) and Alzheimer's disease (AD), in comparison with visual ratings and region of interest (ROI) analysis. Sixty-seven patients (DLB 29, AD 38) had both HMPAO-SPECT and FDG-PET scans. Spatial covariance patterns were used to separate AD and DLB in an initial derivation group (DLB n=15, AD n=19), before being forward applied to an independent group (DLB n=14, AD n=19). Visual ratings were by consensus, with ROI analysis utilising medial occipital/medial temporal uptake ratios. SCA of HMPAO-SPECT performed poorly (AUC 0.59±0.10), whilst SCA of FDG-PET (AUC 0.83±0.07) was significantly better. For FDG-PET, SCA showed similar diagnostic performance to ROI analysis (AUC 0.84±0.08) and visual rating (AUC 0.82±0.08). In contrast to ROI analysis, there was little concordance between SCA and visual ratings of FDG-PET scans. We conclude that SCA of FDG-PET outperforms that of HMPAO-SPECT. SCA of FDG-PET also performed similarly to the other analytical approaches, despite the limitations of a relatively small SCA derivation group. Compared to visual rating, SCA of FDG-PET relies on different sources of group variance to separate DLB from AD.

Fractal dimension of the brain in neurodegenerative disease and dementia: A systematic review

Sensitive and specific antemortem biomarkers of neurodegenerative disease and dementia are crucial to the pursuit of effective treatments, required both to reliably identify disease and to track its progression. Atrophy is the structural magnetic resonance imaging (MRI) hallmark of neurodegeneration. However in most cases it likely indicates a relatively advanced stage of disease less susceptible to treatment as some disease processes begin decades prior to clinical onset. Among emerging metrics that characterise brain shape rather than volume, fractal dimension (FD) quantifies shape complexity. FD has been applied in diverse fields of science to measure subtle changes in elaborate structures. We review its application thus far to structural MRI of the brain in neurodegenerative disease and dementia. We identified studies involving subjects who met criteria for mild cognitive impairment, Alzheimer's Disease, Vascular Dementia, Lewy Body Dementia, Frontotemporal Dementia, Amyotrophic Lateral Sclerosis, Parkinson's Disease, Huntington's Disease, Multiple Systems Atrophy, Spinocerebellar Ataxia and Multiple Sclerosis. The early literature suggests that neurodegenerative disease processes are usually associated with a decline in FD of the brain. The literature includes examples of disease-related change in FD occurring independently of atrophy, which if substantiated would represent a valuable advantage over other structural imaging metrics. However, it is likely to be non-specific and to exhibit complex spatial and temporal patterns. A more harmonious methodological approach across a larger number of studies as well as careful attention to technical factors associated with image processing and FD measurement will help to better elucidate the metric's utility.

Neuroimaging in Glucocerebrosidase-Associated Parkinsonism: A Systematic Review

Background

Mutations in the GBA gene cause Gaucher's disease (GD) and constitute the most frequent genetic risk factor for idiopathic Parkinson's disease (iPD). Nonmanifesting carriers of GBA mutations/variants (GBA‐NMC) constitute a potential PD preclinical population, whereas PD patients carrying some GBA mutations/variants (GBA‐PD) have a higher risk of a more aggressive disease course. Different neuroimaging techniques are emerging as potential biomarkers in PD and have been used to study GBA‐associated parkinsonism.

Objective

The aim is to critically review studies applying neuroimaging to GBA‐associated parkinsonism.

Methods

Literature search was performed using PubMed and EMBASE databases (last search February 7, 2022). Studies reporting neuroimaging findings in GBA‐PD, GD with and without parkinsonism, and GBA‐NMC were included.

Results

Thirty‐five studies were included. In longitudinal studies, GBA‐PD patients show a more aggressive disease than iPD at both structural magnetic resonance imaging and 123‐fluoropropylcarbomethoxyiodophenylnortropane single‐photon emission computed tomography. Fluorodeoxyglucose‐positron emission tomography and brain perfusion studies reported a greater cortical involvement in GBA‐PD compared to iPD. Overall, contrasting evidence is available regarding GBA‐NMC for imaging and clinical findings, although subtle differences have been reported compared with healthy controls with no mutations.

Conclusions

Although results must be interpreted with caution due to limitations of the studies, in line with previous clinical observations, GBA‐PD showed a more aggressive disease progression in neuroimaging longitudinal studies compared to iPD. Cognitive impairment, a “clinical signature” of GBA‐PD, seems to find its neuroimaging correlate in the greater cortical burden displayed by these patients as compared to iPD. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Case Report: Depression × dementia with Lewy bodies in the elderly: The importance of differential diagnosis

BACKGROUND

Dementia is a clinical syndrome which is more common in elderly people. Dementia with Lewy bodies (LBD) is not so rare in elderly people, with cognitive impairment in about 30% over age 65. The clinical picture is characterized by fluctuation in cognitive functions, recurrent, well-formed, detailed visual hallucinations, and Parkinsonism, with rigidity, tremor, bradykinesia, and slurred speech.

CASE PRESENTATION

We present a case report of LBD in a 73-year-old retired teacher, which a initial wrong diagnosis of refractory depression for at least 3 years. We also conduct a review of recent works on theme.

CONCLUSION

LBD diagnosis can be neglected for years, with a legal and clinical issues to patients and their families. Detailed medical research, including differential diagnosis, are very necessary on those cases, specially when they are called refractory. We encourage new research and adequate clinical training to prevent damage.

Practical Application of DaTQUANT with Optimal Threshold for Diagnostic Accuracy of Dopamine Transporter SPECT

Evaluation of Parkinsonian Syndromes (PS) with Ioflupane iodine-123 dopamine transporter single photon emission computed tomography (DaT-SPECT), in conjunction with history and clinical examination, aids in diagnosis. FDA-approved, semi-quantitative software, DaTQUANT^TM (GE Healthcare, Chicago, IL, USA) is available to assist in interpretation. This study aims to evaluate the optimal variables and thresholds of DaTQUANT to yield the optimal diagnostic accuracy. It is a retrospective review with three different patient populations. DaT-SPECT images from all three study groups were evaluated using DaTQUANT^TM software, and both single and multi-variable logistic regression were used to model PS status. The optimal models were chosen via accuracy, sensitivity, and specificity, then evaluated on the other study groups. Among single variable models, the posterior putamen yielded the highest accuracy (84% to 95%), while balancing sensitivity and specificity. Multi-variable models did not substantially improve the accuracy. When the optimal single variable models for each group were used to evaluate the remaining two groups, comparable results were achieved. In typical utilization of DaT-SPECT for differentiation between nigrostriatal degenerative disease (NSDD) and non-NSDD, the posterior putamen was the single variable that yielded the highest accuracy across three different patient populations. The posterior putamen’s recommended thresholds for DaTQUANT are SBR ≤ 1.0, z-score of ≤−1.8 and percent deviation ≤ −0.34.

Circuit imaging biomarkers in preclinical and prodromal Parkinson's disease

Parkinson's disease (PD) commences several years before the onset of motor features. Pathophysiological understanding of the pre-clinical or early prodromal stages of PD are essential for the development of new therapeutic strategies. Two categories of patients are ideal to study the early disease stages. Idiopathic rapid eye movement sleep behavior disorder (iRBD) represents a well-known prodromal stage of PD in which pathology is presumed to have reached the lower brainstem. The majority of patients with iRBD will develop manifest PD within years to decades. Another category encompasses non-manifest mutation carriers, i.e. subjects without symptoms, but with a known mutation or genetic variant which gives an increased risk of developing PD. The speed of progression from preclinical or prodromal to full clinical stages varies among patients and cannot be reliably predicted on the individual level. Clinical trials will require inclusion of patients with a predictable conversion within a limited time window. Biomarkers are necessary that can confirm pre-motor PD status and can provide information regarding lead time and speed of progression. Neuroimaging changes occur early in the disease process and may provide such a biomarker. Studies have focused on radiotracer imaging of the dopaminergic nigrostriatal system, which can be assessed with dopamine transporter (DAT) single photon emission computed tomography (SPECT). Loss of DAT binding represents an effect of irreversible structural damage to the nigrostriatal system. This marker can be used to monitor disease progression and identify individuals at specific risk for phenoconversion. However, it is known that changes in neuronal activity precede structural changes. Functional neuro-imaging techniques, such as ¹⁸F-2-fluoro-2-deoxy-D-glucose Positron Emission Tomography (¹⁸F-FDG PET) and functional magnetic resonance imaging (fMRI), can be used to model the effects of disease on brain networks when combined with advanced analytical methods. Because these changes occur early in the disease process, functional imaging studies are of particular interest in prodromal PD diagnosis. In addition, fMRI and ¹⁸F-FDG PET may be able to predict a specific future phenotype in prodromal cohorts, which is not possible with DAT SPECT. The goal of the current review is to discuss the network-level brain changes in pre-motor PD.

Cerebrovascular disease, neurodegeneration, and clinical phenotype in dementia with Lewy bodies

We investigated whether cerebrovascular disease contributes to neurodegeneration and clinical phenotype in dementia with Lewy bodies (DLB). Regional cortical thickness and subcortical gray matter volumes were estimated from structural magnetic resonance imaging (MRI) in 165 DLB patients. Cortical and subcortical infarcts were recorded and white matter hyperintensities (WMHs) were assessed. Subcortical only infarcts were more frequent (13.3%) than cortical only infarcts (3.1%) or both subcortical and cortical infarcts (2.4%). Infarcts, irrespective of type, were associated with WMHs. A higher WMH volume was associated with thinner orbitofrontal, retrosplenial, and posterior cingulate cortices, smaller thalamus and pallidum, and larger caudate volume. A higher WMH volume was associated with the presence of visual hallucinations and lower global cognitive performance, and tended to be associated with the absence of probable rapid eye movement sleep behavior disorder. Presence of infarcts was associated with the absence of parkinsonism. We conclude that cerebrovascular disease is associated with gray matter neurodegeneration in patients with probable DLB, which may have implications for the multifactorial treatment of probable DLB.

Lewy Body Dementias: A Coin with Two Sides?

Lewy body dementias (LBDs) consist of dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), which are clinically similar syndromes that share neuropathological findings with widespread cortical Lewy body deposition, often with a variable degree of concomitant Alzheimer pathology. The objective of this article is to provide an overview of the neuropathological and clinical features, current diagnostic criteria, biomarkers, and management of LBD. Literature research was performed using the PubMed database, and the most pertinent articles were read and are discussed in this paper. The diagnostic criteria for DLB have recently been updated, with the addition of indicative and supportive biomarker information. The time interval of dementia onset relative to parkinsonism remains the major distinction between DLB and PDD, underpinning controversy about whether they are the same illness in a different spectrum of the disease or two separate neurodegenerative disorders. The treatment for LBD is only symptomatic, but the expected progression and prognosis differ between the two entities. Diagnosis in prodromal stages should be of the utmost importance, because implementing early treatment might change the course of the illness if disease-modifying therapies are developed in the future. Thus, the identification of novel biomarkers constitutes an area of active research, with a special focus on α-synuclein markers.

Neuroimaging in Dementia With Lewy Bodies

Dementia with Lewy bodies (DLB) is one of the most common forms of dementia. It can present as neurocognitive decline, visual hallucinations, and concomitant symptoms of rapid eye movement (REM) sleep behavior disorder. Early diagnosis remains one of the cornerstones of managing this form of neurocognitive disorder but, often, making an early and accurate diagnosis can prove to be challenging. For this article, our goal was to review the utility of various neuroimaging modalities in making a swift and accurate diagnosis of DLB. We used PubMed to look for helpful, informative, and peer-reviewed articles. We discussed the role of a plethora of different imaging techniques, ranging from structural imaging like computed tomography (CT) and magnetic resonance imaging (MRI) to molecular imaging (single-photon emission computed tomography, positron emission to- tomography) as a diagnostic tool for DLB. We arrived at the conclusion that these novel neuroimaging modalities have already proven to be very helpful in ruling out differentials and making an early diagnosis of DLB. However, ongoing research is required to increase the diagnostic accuracy, leading to the early identification and treatment of DLB.

Genetic Architecture and Molecular, Imaging and Prodromic Markers in Dementia with Lewy Bodies: State of the Art, Opportunities and Challenges

Dementia with Lewy bodies (DLB) is one of the most common causes of dementia and belongs to the group of α-synucleinopathies. Due to its clinical overlap with other neurodegenerative disorders and its high clinical heterogeneity, the clinical differential diagnosis of DLB from other similar disorders is often difficult and it is frequently underdiagnosed. Moreover, its genetic etiology has been studied only recently due to the unavailability of large cohorts with a certain diagnosis and shows genetic heterogeneity with a rare contribution of pathogenic mutations and relatively common risk factors. The rapid increase in the reported cases of DLB highlights the need for an easy, efficient and accurate diagnosis of the disease in its initial stages in order to halt or delay the progression. The currently used diagnostic methods proposed by the International DLB consortium rely on a list of criteria that comprises both clinical observations and the use of biomarkers. Herein, we summarize the up-to-now reported knowledge on the genetic architecture of DLB and discuss the use of prodromal biomarkers as well as recent promising candidates from alternative body fluids and new imaging techniques.

Structural imaging in dementia with Lewy bodies: the potential of multivariate data analysis

Structural imaging has a limited role in current diagnostic criteria for dementia with Lewy bodies (DLB), possibly since overt brain atrophy is uncommon in this disorder. Multivariate data analysis is promising in this context due to its superiority to detect subtle brain changes. This systematic review reports multivariate studies of structural imaging data in DLB. Preliminary evidence shows the capacity of structural imaging in discriminating DLB patients from Alzheimer's disease patients and healthy controls. Ongoing global initiatives will change statistical possibilities in DLB. Multivariate data analysis in DLB is an emerging field, and its use is encouraged.

Tau pathology associates with in vivo cortical thinning in Lewy body disorders

OBJECTIVES

To investigate the impact of Alzheimer's disease (AD) co-pathology on an in vivo structural measure of neurodegeneration in Lewy body disorders (LBD).

METHODS

We studied 72 LBD patients (Parkinson disease (PD) = 2, PD-MCI = 25, PD with dementia = 10, dementia with Lewy bodies = 35) with either CSF analysis or neuropathological examination and structural MRI during life. The cohort was divided into those harboring significant AD co-pathology, either at autopsy (intermediate/high AD neuropathologic change) or with CSF signature indicating AD co-pathology (t-tau/Aβ1-42  > 0.3) (LBD+AD, N = 19), and those without AD co-pathology (LBD-AD, N = 53). We also included a reference group of 25 patients with CSF biomarker-confirmed amnestic AD. We investigated differences in MRI cortical thickness estimates between groups, and in the 21 autopsied LBD patients (LBD-AD = 14, LBD+AD = 7), directly tested the association between antemortem MRI and post-mortem burdens of tau, Aβ, and alpha-synuclein using digital histopathology in five representative neocortical regions.

RESULTS

The LBD+AD group was characterized by cortical thinning in anterior/medial and lateral temporal regions (P < 0.05 FWE-corrected) relative to LBD-AD. In LBD+AD, cortical thinning was most pronounced in temporal neocortex, whereas the AD reference group showed atrophy that equally encompassed temporal, parietal and frontal neocortex. In autopsied LBD, we found an inverse correlation with cortical thickness and post-mortem tau pathology, while cortical thickness was not significantly associated with Aβ or alpha-synuclein pathology.

INTERPRETATION

LBD+AD is characterized by temporal neocortical thinning on MRI, and cortical thinning directly correlated with post-mortem histopathologic burden of tau, suggesting that tau pathology influences the pattern of neurodegeneration in LBD.

Positron Emission Tomography (PET) and Neuroimaging in the Personalized Approach to Neurodegenerative Causes of Dementia

Generally, dementia should be considered an acquired syndrome, with multiple possible causes, rather than a specific disease in itself. The leading causes of dementia are neurodegenerative and non-neurodegenerative alterations. Nevertheless, the neurodegenerative group of diseases that lead to cognitive impairment and dementia includes multiple possibilities or mixed pathologies with personalized treatment management for each cause, even if Alzheimer's disease is the most common pathology. Therefore, an accurate differential diagnosis is mandatory in order to select the most appropriate therapy approach. The role of personalized assessment in the treatment of dementia is rapidly growing. Neuroimaging is an essential tool for differential diagnosis of multiple causes of dementia and allows a personalized diagnostic and therapeutic protocol based on risk factors that may improve treatment management, especially in early diagnosis during the prodromal stage. The utility of structural and functional imaging could be increased by standardization of acquisition and analysis methods and by the development of algorithms for automated assessment. The aim of this review is to focus on the most commonly used tracers for differential diagnosis in the dementia field. Particularly, we aim to explore ¹⁸F Fluorodeoxyglucose (FDG) and amyloid positron emission tomography (PET) imaging in Alzheimer's disease and in other neurodegenerative causes of dementia.

Role of Fluid Biomarkers and PET Imaging in Early Diagnosis and its Clinical Implication in the Management of Alzheimer's Disease

Clinical diagnosis of Alzheimer's disease (AD) is based on symptoms; however, the challenge is to diagnose AD at the preclinical stage with the application of biomarkers and initiate early treatment (still not widely available). Currently, cerebrospinal fluid (CSF) amyloid-β 42 (Aβ42) and tau are used in the clinical diagnosis of AD; nevertheless, blood biomarkers (Aβ42 and tau) are less predictive. Amyloid-positron emission tomography (PET) imaging is an advancement in technology that uses approved radioactive diagnostic agents (florbetapir, flutemetamol, or florbetaben) to estimate Aβ neuritic plaque density in adults with cognitive impairment evaluated for AD and other causes of cognitive decline. There is no cure for AD to date-the disease progression cannot be stopped or reversed; approved pharmacological agents (donepezil, galantamine, and rivastigmine; memantine) provide symptomatic treatment. However, the disease-modifying therapies are promising; aducanumab and CAD106 are in phase III trials for the early stages of AD. In conclusion, core CSF biomarkers reflect pathophysiology of AD in the early and late stages; the application of approved radiotracers have potential in amyloid-PET brain imaging to detect early AD.

Pay attention to the basal ganglia: a volumetric study in early dementia with Lewy bodies

BACKGROUND

Cortical and subcortical cognitive impairments are usually found in dementia with Lewy bodies (DLB). Roughly, they comprise visuo-constructive/executive function and attention/processing speed impairments, whereas memory would remain relatively spared. In this study, we focused on the neuro-anatomical substrates of attention and processing speed, which is still poorly understood. For the purpose of the study, we examined the correlations between behavioral scores measuring the speed of processing and the degree of cerebral atrophy in patients with prodromal to moderate DLB.

METHODS

Ninety-three prodromal to moderate DLB patients (mean MMSE = 25.5) were selected to participate in the study as well as 28 healthy elderly subjects (mean MMSE = 28.9), matched in terms of age and educational level. The Trail Making Test A (TMTA) and the Digit Symbol Substitution Test (DSST) were used to assess attention and processing speed. Behavioral performances were compared between patients and healthy control subjects. Three-dimensional MRI images were acquired for all participants, and correlational analyses were performed in the patient group using voxel-based morphometry (VBM).

RESULTS

The behavioral results on both the TMTA (p = .026) and the DSST (p < .001) showed significantly impaired performances in patients in comparison with control subjects. In addition, correlational analyses using VBM revealed for the TMTA negative correlations in the caudate nucleus (left cluster peak significant at .05 FWE corrected), the putamen, the left thalamus, and the subthalamic nuclei (p < .05 FDR corrected). Some positive correlations associated with the DSST were found in the right inferior frontal gyrus, the left thalamus, and the left cerebellum (p < .001 uncorrected).

CONCLUSIONS

The behavioral results are in line with the literature on the DLB cognitive profile and confirm the existence of attention and processing speed impairment. Interestingly, VBM analysis revealed the involvement of the basal ganglia, in particular, the left caudate nucleus, which is part of the attention cerebral network, suggesting an important role of this structure for attentional processing speed. This also suggests the clinical implication of damage in this region relatively early in the course of the disease.

Synthesis and Biological Evaluation of Novel Selenyl and Sulfur-l-Dopa Derivatives as Potential Anti-Parkinson's Disease Agents

Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons at level of substantia nigra pars compacta. To date, there is no cure for this pathology, except for some drugs able to alleviate the symptoms of PD. In this paper we report the synthesis and biological evaluation of novel sulfur- and selenyl-l-Dopa (LD) derivatives (SP1-6) obtained through the amide junction between the amino group of LD and carboxylic moiety of sulfur- and selenyl-organic compounds, which are commercially available. Biological activity was evaluated on human undifferentiated and retinoic acid/phorbol myristyl acetate (RA/PMA)-differentiated SY-SH5Y neuroblastoma cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Antioxidant activity against oxidative stress was measured using nitroblue tetrazolium (NBT) and 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA) assays. Finally, physico-chemical characterization and plasma stability studies of SP1-6 were also performed. Biological data revealed that SP6 has a significant protective action against the neurotoxic action of 6-hydroxydopamine (6-OHDA) and H₂O₂ in a RA/PMA-differentiated SY-SH5Y neuroblastoma cell line that proved to be an effective antioxidant and protective compound. SP6, endowed with a lipophilic nature, low molecular weight, and plasma stability, can easily cross biological membranes via passive diffusion such as through the blood-brain barrier. SP6 has great potential for developing novel pharmacological approach for neurodegenerative diseases, such as PD. Further studies will help define its exact antioxidant mechanism and determine whether the neuroprotective action is mediated or modulated by glutathione peroxidase (GPx).

Neuropathology and pathogenesis of extrapyramidal movement disorders: a critical update-I. Hypokinetic-rigid movement disorders

Extrapyramidal movement disorders include hypokinetic rigid and hyperkinetic or mixed forms, most of them originating from dysfunction of the basal ganglia (BG) and their information circuits. The functional anatomy of the BG, the cortico-BG-thalamocortical, and BG-cerebellar circuit connections are briefly reviewed. Pathophysiologic classification of extrapyramidal movement disorder mechanisms distinguish (1) parkinsonian syndromes, (2) chorea and related syndromes, (3) dystonias, (4) myoclonic syndromes, (5) ballism, (6) tics, and (7) tremor syndromes. Recent genetic and molecular-biologic classifications distinguish (1) synucleinopathies (Parkinson's disease, dementia with Lewy bodies, Parkinson's disease-dementia, and multiple system atrophy); (2) tauopathies (progressive supranuclear palsy, corticobasal degeneration, FTLD-17; Guamian Parkinson-dementia; Pick's disease, and others); (3) polyglutamine disorders (Huntington's disease and related disorders); (4) pantothenate kinase-associated neurodegeneration; (5) Wilson's disease; and (6) other hereditary neurodegenerations without hitherto detected genetic or specific markers. The diversity of phenotypes is related to the deposition of pathologic proteins in distinct cell populations, causing neurodegeneration due to genetic and environmental factors, but there is frequent overlap between various disorders. Their etiopathogenesis is still poorly understood, but is suggested to result from an interaction between genetic and environmental factors. Multiple etiologies and noxious factors (protein mishandling, mitochondrial dysfunction, oxidative stress, excitotoxicity, energy failure, and chronic neuroinflammation) are more likely than a single factor. Current clinical consensus criteria have increased the diagnostic accuracy of most neurodegenerative movement disorders, but for their definite diagnosis, histopathological confirmation is required. We present a timely overview of the neuropathology and pathogenesis of the major extrapyramidal movement disorders in two parts, the first one dedicated to hypokinetic-rigid forms and the second to hyperkinetic disorders.

Molecular Imaging of Dementia With Lewy Bodies

Dementia with Lewy bodies (DLB) is the second most common cause of neurodegenerative dementia. The core clinical features of DLB include fluctuating cognition, visual hallucinations, rapid eye movement sleep behavior disorder, and parkinsonism. Molecular imaging is a powerful tool to assess the brain function in vivo. In this chapter, we reviewed the positron emission tomography, single-photon emission computed tomography, and [¹²³I]-metaiodobenzylguanidine scintigraphy studies evaluating the pathological processes underlying DLB, including altered brain metabolism and neurotransmitter pathways, abnormal protein aggregation, and neuroinflammation. These techniques can aid in the differential diagnosis of DLB (versus Alzheimer's disease and related dementia) and in the monitoring disease progression and treatment efficacy of disease-modifying drugs. Furthermore, we explored the limitations of current imaging biomarkers and future directions, particularly focusing on the vital need for tracers that have high affinity for alpha-synuclein.