Diagnostic Criteria for Dementia with Lewy Bodies: Updates and Future Directions

α-Synuclein pathology from the body to the brain: so many seeds so close to the central soil

ABSTRACT

α-Synuclein is a protein that mainly exists in the presynaptic terminals. Abnormal folding and accumulation of α-synuclein are found in several neurodegenerative diseases, including Parkinson's disease. Aggregated and highly phosphorylated α-synuclein constitutes the main component of Lewy bodies in the brain, the pathological hallmark of Parkinson's disease. For decades, much attention has been focused on the accumulation of α-synuclein in the brain parenchyma rather than considering Parkinson's disease as a systemic disease. Recent evidence demonstrates that, at least in some patients, the initial α-synuclein pathology originates in the peripheral organs and spreads to the brain. Injection of α-synuclein preformed fibrils into the gastrointestinal tract triggers the gut-to-brain propagation of α-synuclein pathology. However, whether α-synuclein pathology can occur spontaneously in peripheral organs independent of exogenous α-synuclein preformed fibrils or pathological α-synuclein leakage from the central nervous system remains under investigation. In this review, we aimed to summarize the role of peripheral α-synuclein pathology in the pathogenesis of Parkinson's disease. We also discuss the pathways by which α-synuclein pathology spreads from the body to the brain.

Sympathetic 123I-metaiodobenzylguanidine index for Lewy body disease: probability-based diagnosis and identifying patients exempt from late imaging

OBJECTIVE

We aimed to establish a practical diagnostic index for Lewy body diseases (LBD), such as Parkinson's disease and dementia, with Lewy bodies in outpatient settings and criteria for exempting patients from late imaging.

METHODS

We acquired early and late 123I-metaiodobenzylguanidine (MIBG) images from 108 consecutive patients with suspected LBD and standardized heart-to-mediastinum (H/M) ratios for collimator conditions. Exclusions included young-onset Parkinson's disease (age < 50 years) and genetic transthyretin-type amyloidosis. We developed logistic models incorporating H/M ratios with or without age (n = 92). The sympathetic MIBG index for LBD (SMILe index), categorized LBD likelihood from 0 (lowest) to 1 (highest). Diagnostic accuracy was assessed as the area under the receiver operating characteristic (ROC) curve (AUC). The characteristics of the new index were compared with H/M ratios. The need for late imaging was explored using the SMILe index.

RESULTS

Early or late SMILe indexes using a single H/M ratio variable discriminated LBD from non-LBD. The AUC values for early and late SMILe indexes were 0.880 and 0.894 (p < 0.0001 for both), identical to those for early and late H/M ratios. The sensitivity and the specificity of early SMILe indexes with a 0.5 threshold were 76% and 90%, achieving accuracy of accuracy 86%. Similarly, the late SMILe index demonstrated a sensitivity of 76% and specificity of 87%, with an accuracy of 84%. Early SMILe indexes < 0.3 or > 0.7 (representing 84% patients) indicated a diagnosis without a late MIBG study.

CONCLUSION

The 123I-MIBG-derived SMILe indexes provide likelihood of LBD, and those with a 50% threshold demonstrated optimal diagnostic accuracy for LBD. The index values of either < 0.3 or > 0.7 accurately selected patients who do not need late imaging.

The usefulness of combined analysis using CIScore and VSRAD parameters for differentiating between dementia with Lewy body and Alzheimer's disease

PURPOSE

The Cingulate Island score (CIScore) is useful index for differentiating between dementia with Lewy body (DLB) and Alzheimer's disease (AD) using regional cerebral blood flow (rCBF) SPECT. The Z score standing for medial temporal lobe (MTL) atrophy and the ratio of Z score between dorsal brain stem (DBS) to MTL are useful indices for differentiating between DLB and AD using MRI with VSRAD. The current study investigated the diagnostic ability by the combined use of rCBF SPECT and MRI in the differentiation between AD and DLB.

MATERIALS AND METHODS

In cases with 42 AD and 28 DLB undertaken Tc-99m-ECD SPECT and MRI, we analyzed differential diagnostic ability between AD and DLB among following conditions by single or combined settings. Namely, they were (1) the CIScore as a parameter of rCBF SPECT (DLB ≦ 0.25), (2) Z score value of MTL atrophy (DLB ≦ 2.05), (3) the ratio of Z score of DBS to medial temporal gray matter as a parameter of brain atrophy using VSRAD (DLB ≧ 0.38). Also, we analyzed them both including and omitting the elderly (over 75 years old).

RESULTS

The accuracy of differential diagnosis in this condition was 74% for (1), 69% for (2), and 67% for (3). The accuracy by combination condition was 84% for (1) and (2), 81% for (1) and (3), and 67% for (2) and (3), respectively. The combination method by CIScore and the Z score of MTL showed the best accuracy. When we confined condition to ages younger than 75 years, the accuracy improved to 94% in the combination method.

CONCLUSION

The combined use of CIScore and Z score of MTL was suggested to be useful in the differential diagnosis between DLB and AD particularly in younger than 75 years old.

The clinical diagnosis of Parkinson's disease

After more than 200 years since its initial description, the clinical diagnosis of Parkinson's disease (PD) remains an often-challenging endeavor, with broad implications that are fundamental for clinical management. Despite major developments in understanding it's pathogenesis, pathological landmarks, non-motor features and potential paraclinical clues, the most accepted diagnostic criteria remain solidly based on a combination of clinical signs. Here, we review this process, discussing its history, clinical criteria, differential diagnoses, ancillary diagnostic testing, and the role of non-motor and pre-motor signs and symptoms.

Absolute quantitation of sympathetic nerve activity using [123I] metaiodobenzylguanidine SPECT-CT in neurology

BACKGROUND AND PURPOSE

The ability of [123I]metaiodobenzylguanidine (MIBG) sympathetic nerve imaging with three-dimensional (3D) quantitation to clinically diagnose neurological disorders has not been evaluated. This study compared absolute heart counts calculated as mean standardized uptake values (SUVmean) using conventional planar imaging and assessed the contribution of [123I]MIBG single-photon emission computed tomography (SPECT)-CT to the diagnosis of neurological diseases.

METHODS

Seventy-two patients with neurological diseases were consecutively assessed using early and delayed [123I]MIBG SPECT-CT and planar imaging. Left ventricles were manually segmented in early and delayed SPECT-CT images, then the SUVmean and washout rates (WRs) were calculated. Heart-to-mediastinum ratios (HMRs) and WRs on planar images were conventionally computed. We investigated correlations between planar HMRs and SPECT-CT SUVmeans and between WRs obtained from planar and SPECT-CT images. The cutoff for SPECT-CT WRs defined by linear regression and that of normal planar WRs derived from a database were compared with neurological diagnoses of the patients. We assigned the patients to groups according to clinical diagnoses as controls (n = 6), multiple system atrophy (MSA, n = 7), progressive supranuclear palsy (PSP, n = 17), and Parkinson's disease or dementia with Lewy bodies (PD/DLB, n = 19), then compared SPECT-CT and planar image parameters.

RESULTS

We found significant correlations between SPECT-CT SUVmean and planar HMR on early and delayed images (R2 = 0.69 and 0.82, p < 0.0001) and between SPECT-CT and planar WRs (R2 = 0.79, p < 0.0001). A threshold of 31% for SPECT-CT WR based on linear regression resulted in agreement between planar and SPECT-CT WR in 67 (93.1%) of 72 patients. Compared with controls, early and delayed SUVmean in patients with PSP and MSA tended more towards significance than planar HMR. This trend was similar for SPECT-CT WRs in patients with PSP.

CONCLUSIONS

Absolute heart counts and SUVmean determined using [123I]MIBG SPECT-CT correlated with findings of conventional planar images in patients with neurological diseases. Three-dimensional quantitation with [123I]MIBG SPECT-CT imaging might differentiate patients with PSP and MSA from controls.

Clinicopathological correlation of cerebrospinal fluid alpha-synuclein seed amplification assay in a behavioral neurology autopsy cohort

INTRODUCTION

Lewy body disease (LBD) is a common primary or co-pathology in neurodegenerative syndromes. An alpha-synuclein seed amplification assay (αSyn-SAA) is clinically available, but clinical performance, especially lower sensitivity in amygdala-predominant cases, is not well understood.

METHODS

Antemortem CSF from neuropathology-confirmed LBD cases was tested with αSyn-SAA (N = 56). Diagnostic performance and clinicopathological correlations were examined.

RESULTS

Similar to prior reports, sensitivity was 100% for diffuse and transitional LBD (9/9), and overall specificity was 96.3% (26/27). Sensitivity was lower in amygdala-predominant (6/14, 42.8%) and brainstem-predominant LBD (1/6, 16.7%), but early spread outside these regions (without meeting criteria for higher stage) was more common in αSyn-SAA-positive cases (6/7, 85.7%) than negative (2/13, 15.4%).

DISCUSSION

In this behavioral neurology cohort, αSyn-SAA had excellent diagnostic performance for cortical LBD. In amygdala- and brainstem-predominant cases, sensitivity was lower, but positivity was associated with anatomical spread, suggesting αSyn-SAA detects early LBD progression in these cohorts.

HIGHLIGHTS

A cerebrospinal fluid alpha-synuclein assay detects cortical LBD with high sensitivity/specificity. Positivity in prodromal stages of LBD was associated with early cortical spread. The assay provides precision diagnosis of LBD that could support clinical trials. The assay can also identify LBD co-pathology, which may impact treatment responses.

Altered structural and functional connectivity in Posterior Cortical Atrophy and Dementia with Lewy bodies

Posterior cortical atrophy (PCA) and dementia with Lewy bodies (DLB) show distinct atrophy and overlapping hypometabolism profiles, but it is unknown how disruptions in structural and functional connectivity compare between these disorders and whether breakdowns in connectivity relate to either atrophy or hypometabolism. Thirty amyloid-positive PCA patients, 24 amyloid-negative DLB patients and 30 amyloid-negative cognitively unimpaired (CU) healthy individuals were recruited at Mayo Clinic, Rochester, MN, and underwent a 3T head MRI, including structural MRI, resting state functional MRI (rsfMRI) and diffusion tensor imaging (DTI) sequences, as well as [18F] fluorodeoxyglucose (FDG) PET. We assessed functional connectivity within and between 12 brain networks using rsfMRI and the CONN functional connectivity toolbox and calculated regional DTI metrics using the Johns Hopkins atlas. Multivariate linear-regression models corrected for multiple comparisons and adjusted for age and sex compared DTI metrics and within-network and between-network functional connectivity across groups. Regional gray-matter volumes and FDG-PET standard uptake value ratios (SUVRs) were calculated and analyzed at the voxel-level using SPM12. We used univariate linear-regression models to investigate the relationship between connectivity measures, gray-matter volume, and FDG-PET SUVR. On DTI, PCA showed degeneration in occipito-parietal white matter, posterior thalamic radiations, splenium of the corpus collosum and sagittal stratum compared to DLB and CU, with greater degeneration in the temporal white matter and the fornix compared to CU. We observed no white-matter degeneration in DLB compared to CU. On rsfMRI, reduced within-network connectivity was present in dorsal and ventral default mode networks (DMN) and the dorsal-attention network in PCA compared to DLB and CU, with reduced within-network connectivity in the visual and sensorimotor networks compared to CU. DLB showed reduced connectivity in the cerebellar network compared to CU. Between-network analysis showed increased connectivity in both cerebellar-to-sensorimotor and cerebellar-to-dorsal attention network connectivity in PCA and DLB. PCA showed reduced anterior DMN-to-cerebellar and dorsal attention-to-sensorimotor connectivity, while DLB showed reduced posterior DMN-to-sensorimotor connectivity compared to CU. PCA showed reduced dorsal DMN-to-visual connectivity compared to DLB. The multimodal analysis revealed weak associations between functional connectivity and volume in PCA, and between functional connectivity and metabolism in DLB. These findings suggest that PCA and DLB have unique connectivity alterations, with PCA showing more widespread disruptions in both structural and functional connectivity; yet some overlap was observed with both disorders showing increased connectivity from the cerebellum.

Supercomplex formation of mitochondrial respiratory chain complexes in leukocytes from patients with neurodegenerative diseases

With population aging, cognitive impairments and movement disorders due to neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD) and dementia with Lewy bodies (DLB), are increasingly considered as key social issues. Clinically, it has remained challenging to diagnose them before the onset of symptoms because of difficulty to observe the progressive loss of neurons in the brain. Therefore, with exploratory research into biomarkers, a number of candidates have previously been proposed, such as activities of mitochondrial respiratory chain complexes in blood in AD and PD. In this study, we focused on the formation of mitochondrial respiratory chain supercomplexes (SCs) because the formation of SC itself modulates the activity of each complex. Here we investigated the SC formation in leukocytes from patients with AD, PD and DLB. Our results showed that SCs were well formed in AD and PD compared with controls, while poorly formed in DLB. We highlighted that the disruption of the SC formation correlated with the progression of PD and DLB. Taking our findings together, we propose that pronounced SC formation would already have occurred before the onset of AD, PD and DLB and, with the progression of neurodegeneration, the SC formation would gradually be disrupted.

Identification of Potentially Repurposable Drugs for Lewy Body Dementia Using a Network-Based Approach

The conventional method of one drug being used for one target has not yielded therapeutic solutions for Lewy body dementia (LBD), which is a leading progressive neurological disorder characterized by significant loss of neurons. The age-related disease is marked by memory loss, hallucinations, sleep disorder, mental health deterioration, palsy, and cognitive impairment, all of which have no known effective cure. The present study deploys a network medicine pipeline to repurpose drugs having considerable effect on the genes and proteins related to the diseases of interest. We utilized the novel SAveRUNNER algorithm to quantify the proximity of all drugs obtained from DrugBank with the disease associated gene dataset obtained from Phenopedia and targets in the human interactome. We found that most of the 154 FDA-approved drugs predicted by SAveRUNNER were used to treat nervous system disorders, but some off-label drugs like quinapril and selegiline were interestingly used to treat hypertension and Parkinson's disease (PD), respectively. Additionally, we performed gene set enrichment analysis using Connectivity Map (CMap) and pathway enrichment analysis using EnrichR to validate the efficacy of the drug candidates obtained from the pipeline approach. The investigation enabled us to identify the significant role of the synaptic vesicle pathway in our disease and accordingly finalize 8 suitable antidepressant drugs from the 154 drugs initially predicted by SAveRUNNER. These potential anti-LBD drugs are either selective or non-selective inhibitors of serotonin, dopamine, and norepinephrine transporters. The validated selective serotonin and norepinephrine inhibitors like milnacipran, protriptyline, and venlafaxine are predicted to manage LBD along with the affecting symptomatic issues.

Latest advances in mechanisms of epileptic activity in Alzheimer's disease and dementia with Lewy Bodies

Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) stand as the prevailing sources of neurodegenerative dementia, impacting over 55 million individuals across the globe. Patients with AD and DLB exhibit a higher prevalence of epileptic activity compared to those with other forms of dementia. Seizures can accompany AD and DLB in early stages, and the associated epileptic activity can contribute to cognitive symptoms and exacerbate cognitive decline. Aberrant neuronal activity in AD and DLB may be caused by several mechanisms that are not yet understood. Hyperexcitability could be a biomarker for early detection of AD or DLB before the onset of dementia. In this review, we compare and contrast mechanisms of network hyperexcitability in AD and DLB. We examine the contributions of genetic risk factors, Ca2+ dysregulation, glutamate, AMPA and NMDA receptors, mTOR, pathological amyloid beta, tau and α-synuclein, altered microglial and astrocytic activity, and impaired inhibitory interneuron function. By gaining a deeper understanding of the molecular mechanisms that cause neuronal hyperexcitability, we might uncover therapeutic approaches to effectively ease symptoms and slow down the advancement of AD and DLB.

The Role of Electroconvulsive Therapy in the Treatment of Catatonia Associated With Lewy Body Dementia: A Case Report

Catatonia is a complex amalgamation of neuropsychiatric symptoms that can manifest in both psychiatric and neurological conditions. The treatment of catatonia related to psychiatric illnesses is well documented as it typically responds to benzodiazepines and electroconvulsive therapy (ECT). However, the treatment of catatonia related to neurological disorders has shown to be more difficult, particularly when associated with Lewy Body Dementia (LBD). Here, we present the case of a 78-year-old woman with LBD, Bipolar I, depressive type, who successfully underwent twelve ECT sessions to treat catatonia refractory to benzodiazepine therapy. The effectiveness of the treatment was measured using the Bush-Françis Catatonia Scale (BFCS) to measure her catatonic symptoms as she progressed through the therapy. This report highlights the importance of considering ECT as a leading therapeutic approach in this particular subset of patients who do not respond adequately to pharmaceutical therapy and medical titrations.

Suspecting Non-Alzheimer's Pathologies and Mixed Pathologies: A Comparative Study Between Brain Metabolism and Tau Images

BACKGROUND

Alzheimer's disease (AD) pathology can be disclosed in vivo using amyloid and tau imaging, unlike non-AD neuropathologies for which no specific markers exist.

OBJECTIVE

We aimed to compare brain hypometabolism and tauopathy to unveil non-AD pathologies.

METHODS

Sixty-one patients presenting cognitive complaints (age 48-90), including 32 with positive AD biomarkers (52%), performed [18F]-Fluorodeoxyglucose (FDG)-PET (brain metabolism) and [18F]-MK-6240-PET (tau). We normalized these images using data from clinically normal individuals (n = 30), resulting in comparable FDG and tau z-scores. We computed between-patients correlations to evaluate regional associations. For each patient, a predominant biomarker (i.e., Hypometabolism > Tauopathy or Hypometabolism≤Tauopathy) was determined in the temporal and frontoparietal lobes. We computed within-patient correlations between tau and metabolism and investigated their associations with demographics, cognition, cardiovascular risk factors (CVRF), CSF biomarkers, and white matter hypointensities (WMH).

RESULTS

We observed negative associations between tau and FDG in 37 of the 68 cortical regions-of-interest (average Pearson's r = -0.25), mainly in the temporal lobe. Thirteen patients (21%) had Hypometabolism > Tauopathy whereas twenty-five patients (41%) had Hypometabolism≤Tauopathy. Tau-predominant patients were more frequently females and had greater amyloid burden. Twenty-three patients (38%) had Hypometabolism≤Tauopathy in the temporal lobe, but Hypometabolism > Tauopathy in the frontoparietal lobe. This group was older and had higher CVRF than Tau-predominant patients. Patients with more negative associations between tau and metabolism were younger, had worse cognition, and greater amyloid and WMH burdens.

CONCLUSIONS

Tau-FDG comparison can help suspect non-AD pathologies in patients presenting cognitive complaints. Stronger Tau-FDG correlations are associated with younger age, worse cognition, and greater amyloid and WMH burdens.

Proteomic comparison between non-purified cerebrospinal fluid and cerebrospinal fluid-derived extracellular vesicles from patients with Alzheimer's, Parkinson's and Lewy body dementia

Dementia is a leading cause of death worldwide, with increasing prevalence as global life expectancy increases. The most common neurodegenerative disorders are Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). With this study, we took an in-depth look at the proteome of the (non-purified) cerebrospinal fluid (CSF) and the CSF-derived extracellular vesicles (EVs) of AD, PD, PD-MCI (Parkinson's disease with mild cognitive impairment), PDD and DLB patients analysed by label-free mass spectrometry. This has led to the discovery of differentially expressed proteins that may be helpful for differential diagnosis. We observed a greater number of differentially expressed proteins in CSF-derived EV samples (N = 276) compared to non-purified CSF (N = 169), with minimal overlap between both datasets. This finding suggests that CSF-derived EV samples may be more suitable for the discovery phase of a biomarker study, due to the removal of more abundant proteins, resulting in a narrower dynamic range. As disease-specific markers, we selected a total of 39 biomarker candidates identified in non-purified CSF, and 37 biomarker candidates across the different diseases under investigation in the CSF-derived EV data. After further exploration and validation of these proteins, they can be used to further differentiate between the included dementias and may offer new avenues for research into more disease-specific pharmacological therapeutics.

Young-onset dementia with Lewy Bodies presenting with apathy and alexithymia

A diagnosis of young-onset dementia can pose a significant challenge for the clinician. We present a young patient with a very unusual presentation of Dementia with Lewy Bodies. The lack of motor symptoms and his marked apathy delayed his diagnosis. His symptoms were thought to be due to depression based on normal structural imaging and the psychiatric nature of his presentation. An extensive work-up was performed. Evidence of a structural neurodegenerative process was provided by the HMPAO-SPECT. Cardiac MIBG confirmed the diagnosis.

Clinical biomarkers for Lewy body diseases

Synucleinopathies are a group of neurodegenerative disorders characterized by pathologic aggregates of neural and glial α-synuclein (α-syn) in the form of Lewy bodies (LBs), Lewy neurites, and cytoplasmic inclusions in both neurons and glia. Two major classes of synucleinopathies are LB disease and multiple system atrophy. LB diseases include Parkinson's disease (PD), PD with dementia, and dementia with LBs. All are increasing in prevalence. Effective diagnostics, disease-modifying therapies, and therapeutic monitoring are urgently needed. Diagnostics capable of differentiating LB diseases are based on signs and symptoms which might overlap. To date, no specific diagnostic test exists despite disease-specific pathologies. Diagnostics are aided by brain imaging and cerebrospinal fluid evaluations, but more accessible biomarkers remain in need. Mechanisms of α-syn evolution to pathologic oligomers and insoluble fibrils can provide one of a spectrum of biomarkers to link complex neural pathways to effective therapies. With these in mind, we review promising biomarkers linked to effective disease-modifying interventions.

Comparison of Taiwanese and European Calibration Factors for Heart-to-Mediastinum Ratio in Multicenter 123I-mIBG Phantom Studies

Background: Cross-calibration of 123I-labeled meta-iodobenzylguanidine (mIBG) myocardial-derived indices is essential to extrapolate findings from several clinical centers. Here, we conducted a phantom study to generate conversion coefficients for the calibration of heart-to-mediastinum ratios and compare them between Taiwan and Europe. Methods: We used an acrylic phantom dedicated to 123I-mIBG planar imaging to calculate the conversion coefficients of 136 phantom images derived from 36 Taiwanese institutions. A European phantom image database including 191 images from 27 institutions was used. Conversion coefficients were categorized into five collimator types: low-energy (LE) high-resolution (LEHR), LE general-purpose (LEGP), extended LEGP (ELEGP), medium-energy (ME) GP (MEGP), and ME low-penetration (MELP) collimators. Results: The conversion coefficients were 0.53 ± 0.039, 0.59 ± 0.032, 0.79 ± 0.032, 0.96 ± 0.038, and 0.99 ± 0.050 for LEHR, LEGP, ELEGP, MEGP, and MELP collimators, respectively. The Taiwanese and European conversion coefficients for the LEHR, LEGP, and MELP collimators did not significantly differ. The coefficient of variation was slightly higher for the Taiwanese than the European conversion coefficients (3.7%-7.5% vs. 2.3%-5.6%). Conclusions: We calculated conversion coefficients for various types of collimators used in Taiwan using a 123I-mIBG phantom. In general, the Taiwanese and European conversion coefficients were comparable. These findings further corroborated and highlighted the need for 123I-mIBG standardization using the phantom-determined conversion coefficients.

Three-Dimensional Heart Segmentation and Absolute Quantitation of Cardiac 123I-metaiodobenzylguanidine Sympathetic Imaging Using SPECT/CT

Background: A three-dimensional (3D) approach to absolute quantitation of 123I-metaiodobenzylguanidine (MIBG) sympathetic nerve imaging using single-photon emission tomography (SPECT) / computed tomography (CT) is not available. Therefore, we calculated absolute cardiac counts and standardized uptake values (SUVs) from images of 72 consecutive patients with cardiac and neurological diseases using 123I-MIBG SPECT/CT and compared them with conventional planar quantitation. We aimed to develop new methods for 3D heart segmentation and the quantitation of these diseases. Methods: We manually segmented early and late SPECT/CT images of the heart in 3D, then calculated mean (SUVmean) and maximum (SUVmax) SUVs. We analyzed correlations between SUVs and planar heart-to-mediastinum ratios (HMRs), and between washout rates (WRs) derived from the SUVs and planar data. We also categorized WRs as normal or abnormal using linear regression lines determined by the relationship between SPECT/CT and planar WRs, and assessed agreement between them. Results: We calculated SUVmean and SUVmax from all early and late 123I-MIBG SPECT/CT images. Planar HMRs correlated with early and late SUVmean (R2=0.59 and 0.73, respectively) and SUVmax (R2=0.46 and 0.60, respectively; both p<0.0001). The SPECT/CT WRs determined based on SUVmean and SUVmax (R2=0.79 and 0.45, p<0.0001) closely correlated with planar WRs. Agreement of high and low WRs between planar WRs and SPECT/CT WRs calculated using SUVmax and SUVmean reached 88.1% and 94.4% respectively. Conclusions: We found that sympathetic nervous activity could be absolutely quantified in 3D from 123I-MIBG SPECT/CT images. Therefore, we propose a new method for quantifying sympathetic innervation on SPECT/CT images.

Cardiac 123I-Metaiodobenzylguanidine (MIBG) Scintigraphy in Parkinson's Disease: A Comprehensive Review

Cardiac sympathetic denervation, as documented on 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, is relatively sensitive and specific for distinguishing Parkinson's disease (PD) from other neurodegenerative causes of parkinsonism. The present study aims to comprehensively review the literature regarding the use of cardiac MIBG in PD. MIBG is an analog to norepinephrine. They share the same uptake, storage, and release mechanisms. An abnormal result in the cardiac MIBG uptake in individuals with parkinsonism can be an additional criterion for diagnosing PD. However, a normal result of cardiac MIBG in individuals with suspicious parkinsonian syndrome does not exclude the diagnosis of PD. The findings of cardiac MIBG studies contributed to elucidating the pathophysiology of PD. We investigated the sensitivity and specificity of cardiac MIBG scintigraphy in PD. A total of 54 studies with 3114 individuals diagnosed with PD were included. The data were described as means with a Hoehn and Yahr stage of 2.5 and early and delayed registration H/M ratios of 1.70 and 1.51, respectively. The mean cutoff for the early and delayed phases were 1.89 and 1.86. The sensitivity for the early and delayed phases was 0.81 and 0.83, respectively. The specificity for the early and delayed phases were 0.86 and 0.80, respectively.

Autonomic dysfunction in dementia with Lewy bodies: Focusing on cardiovascular and respiratory dysfunction

Dementia with Lewy bodies (DLB) is the second most common cause of dementia after Alzheimer's disease. The disease is characterized by many Lewy bodies appearing in the patient's cerebrum. DLB frequently presents with a variety of autonomic symptoms from the early or prodromal stages of the disease, and these are listed as supportive features in the diagnostic criteria. As several useful assessment methods for evaluating autonomic function in DLB have been reported, this review will focus on cardiovascular and respiratory dysfunction and its assessments. Cardiovascular disorders, such as orthostatic hypotension and abnormal heart rate variability, have been reported in DLB patients. Decreased myocardial uptake by metaiodobenzylguanidine myocardial scintigraphy has been added as an indicative biomarker for DLB in the 2017 revision of the diagnostic criteria. We have reported reduced ventilatory response to hypercapnia, abnormal respiratory rhythm, and high frequency of sleep-disordered breathing as abnormalities of the respiratory regulatory system associated with DLB. Since autonomic dysfunction is highly prevalent in DLB from the early or prodromal phase of the disease and is associated with reduced activities of daily living and quality of life, the evaluation of autonomic dysfunction is also useful in the differential diagnosis of DLB from Alzheimer's disease. There are fewer studies on the respiratory regulatory system than on the cardiovascular system, thus further research is needed to explore its role in DLB.

Beyond Strains: Molecular Diversity in Alpha-Synuclein at the Center of Disease Heterogeneity

Alpha-synucleinopathies (α-synucleinopathies) such as Parkinson's disease (PD), Parkinson's disease dementia (PDD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA) are all characterized by aggregates of alpha-synuclein (α-syn), but display heterogeneous clinical and pathological phenotypes. The mechanism underlying this heterogeneity is thought to be due to diversity in the α-syn strains present across the diseases. α-syn obtained from the post-mortem brain of patients who lived with these conditions is heterogenous, and displays a different protease sensitivity, ultrastructure, cytotoxicity, and seeding potential. The primary aim of this review is to summarize previous studies investigating these concepts, which not only reflect the idea of different syn strains being present, but demonstrate that each property explains a small part of a much larger puzzle. Strains of α-syn appear at the center of the correlation between α-syn properties and the disease phenotype, likely influenced by external factors. There are considerable similarities in the properties of disease-specific α-syn strains, but MSA seems to consistently display more aggressive traits. Elucidating the molecular underpinnings of heterogeneity amongst α-synucleinopathies holds promise for future clinical translation, allowing for the development of personalized medicine approaches tackling the root cause of each α-synucleinopathy.

Toward a new nosology of neurodegenerative diseases

New "omic" technologies are revealing shared and distinct biological pathways within and across neurodegenerative diseases (NDDs), allowing a better understanding of endophenotypes that exceeds the boundaries of the current diagnostic criteria. Moreover, a diagnostic framework is needed that can accommodate the co-pathology and the clinical overlap and heterogeneity of NDDs. Apart from dissecting the reasons for a revolution in how we conceive NDD, this article aims to prompt a change in how we diagnose and classify NDD, drafting a general scheme for a new nosology. As identifying a cause is the key to using the term "disease" properly, we propose using a tridimensional classification based on three axes: (1) etiology or pathogenic mechanism, (2) pathology markers and molecular biomarkers, (3) anatomic-clinical; and three hierarchical levels of etiology: (1) genetic/sporadic (2) cellular pathways and processes, and function of fluidic brain systems, and (3) risk factors.

Magnetic resonance imaging in the diagnosis of progressive supranuclear palsy: A case report and review of literature

Key Clinical Message

Progressive supranuclear palsy (PSP) has many clinical features overlapping with other Parkinson syndromes and differentiation on clinical ground is difficult. This case highlights how a brain MRI can help diagnose PSP in settings with limited resources where histological diagnosis is difficult.

Abstract

Progressive supranuclear palsy (PSP) may be challenging to diagnose due to its widely acknowledged clinical complexity and challenges with diagnosis confirmation, particularly in resource-poor settings where the ability to obtain confirmatory tests is highly complicated, leading to an inaccurate or incomplete diagnosis of PSP. This paper discusses using brain magnetic resonance imaging (MRI) to diagnose PSP, and a review of relevant literature addresses the diagnostic value of MRI in PSP.

Machine learning-based prediction of conversion coefficients for I-123 metaiodobenzylguanidine heart-to-mediastinum ratio

PURPOSE

We developed a method of standardizing the heart-to-mediastinal ratio in 123I-labeled meta-iodobenzylguanidine (MIBG) images using a conversion coefficient derived from a dedicated phantom. This study aimed to create a machine-learning (ML) model to estimate conversion coefficients without using a phantom.

METHODS

210 Monte Carlo (MC) simulations of 123I-MIBG images to obtain conversion coefficients using collimators that differed in terms of hole diameter, septal thickness, and length. Simulated conversion coefficients and collimator parameters were prepared as training datasets, then a gradient-boosting ML was trained to estimate conversion coefficients from collimator parameters. Conversion coefficients derived by ML were compared with those that were MC simulated and experimentally derived from 613 phantom images.

RESULTS

Conversion coefficients were superior when estimated by ML compared with the classical multiple linear regression model (root mean square deviations: 0.021 and 0.059, respectively). The experimental, MC simulated, and ML-estimated conversion coefficients agreed, being, respectively, 0.54, 0.55, and 0.55 for the low-; 0.74, 0.70, and 0.72 for the low-middle; and 0.88, 0.88, and 0.88 for the medium-energy collimators.

CONCLUSIONS

The ML model estimated conversion coefficients without the need for phantom experiments. This means that conversion coefficients were comparable when estimated based on collimator parameters and on experiments.

Significance of clinical symptoms and red flags in early differential diagnosis of Parkinson's disease and atypical Parkinsonian syndromes

The clinical presentation of Parkinson's disease and atypical Parkinsonian syndromes is often heterogeneous. Additional diagnostic procedures including brain imaging and biomarker analyses can help to appreciate the various syndromes, but a precise clinical evaluation and differentiation is always necessary. To better assess the relevance of distinct clinical symptoms that arose within 1 year of disease manifestation and evaluate their indicative potential for an atypical Parkinsonian syndrome, we conducted a modified Delphi panel with seven movement disorder specialists. Five different topics with several clinical symptom items were discussed and consensus criteria were tested. This resulted in distinct symptom patterns for each atypical Parkinsonian syndrome showing the multitude of clinical involvement in each neurodegenerative disease. Strongly discriminating clinical signs were few and levels of indication were variable. A prospective validation of the assessments made is needed. This demonstrates that both clinical evaluation and elaborate additional diagnostic procedures are needed to achieve a high diagnostic standard.

Electroencephalography in young onset dementia

BACKGROUND

Young onset dementia (YOD) is a major diagnostic and management problem.

METHODS

We set out to explore if electroencephalography (EEG) might be useful in the diagnosis of young onset Alzheimer's disease (YOAD) and young onset frontotemporal dementia (YOFTD). The ARTEMIS project is a 25-year prospective study of YOD based in Perth, Western Australia. 231 participants were included: YOAD: n = 103, YOFTD: n = 28, controls: n = 100. EEGs were performed prospectively, with 30-minute recording time for each subject, without knowledge of diagnosis or other diagnostic data.

RESULTS

80.9% of patients with YOD had abnormal EEGs (P < 0.00001). Slow wave changes were more frequent in YOAD that YOFTD (P < 0.00001), but no difference in the frequency of epileptiform activity (P = 0.32), with 38.8% of YOAD and 28.6% of YOFTD patients having epileptiform activity. Slow wave changes were more generalized in YOAD (P = 0.001). Slow wave changes and epileptiform activity were not sensitive to the diagnosis of YOD, but highly specific (97-99%). The absence of slow wave changes and epileptiform activity had a 100% negative predictive value and likelihood radio 0.14 and 0.62 respectively, meaning that those without slow wave changes or epileptiform activity had low probability of having YOD. No relationship was established between EEG findings and the patient's presenting problem. Eleven patients with YOAD developed seizures during the study, and only one with YOFTD.

CONCLUSIONS

The EEG is highly specific for the diagnosis of YOD with the absence of slow wave changes and epileptiform phenomena making the diagnosis unlikely, with 100% negative predictive value and with low probability for the dementia diagnosis.

Early- and late-onset of isolated rapid eye movement sleep behavior disorder: A retrospective cohort study

OBJECTIVE

Age at onset of neurodegenerative disease has significant implications in differentiating disease profiles. We aimed to determine whether age at onset could identify clinical and neurodegenerative profiles in patients with isolated/idiopathic rapid eye movement sleep behavior disorder (iRBD) - a prodromal stage of α-synucleinopathies.

METHODS

In this retrospective cohort study, the time of the first episode of dream-enactment behaviors that the patient/bed-partners recalled at the time of the patient's first visit to sleep clinic was collected. The distribution of age at onset was examined and patients were dichotomized into early- and late-onset groups based on the intersection point of underlying two Gaussian distributions of onset age.

RESULTS

A total of 241 patients were included. The intersection of underlying two Gaussian models of onset age was 64.6 years, yielding 168 early- (median onset age: 58.0 years, range: 38.0-64.0) and 73 late-onset patients (median onset age: 70.0 years, range: 65.0-82.0). Among them, 154 of early- and 68 late-onset patients were followed-up. Late-onset patients had milder RBD symptoms, but worse sleep, cognition, olfactory and motor functions, and a higher risk of phenoconversion (adjusted hazard ratio (aHR) = 2.2, 95% confidence interval (CI) = 1.2-3.9), especially to probable dementia with Lewy bodies (DLB) (aHR = 8.9, 95% CI = 3.0-26.2), than early-onset patients.

CONCLUSIONS

Late-onset iRBD was associated with a higher level of neurodegenerative markers and a quicker phenoconversion, especially to probable DLB. Age at onset of iRBD could help identify clinical features and predict prognosis of iRBD.

Neurofilament light chain is increased in the parahippocampal cortex and associates with pathological hallmarks in Parkinson's disease dementia

BACKGROUND

Increased neurofilament levels in biofluids are commonly used as a proxy for neurodegeneration in several neurodegenerative disorders. In this study, we aimed to investigate the distribution of neurofilaments in the cerebral cortex of Parkinson's disease (PD), PD with dementia (PDD) and dementia with Lewy bodies (DLB) donors, and its association with pathology load and MRI measures of atrophy and diffusivity.

METHODS

Using a within-subject post-mortem MRI-pathology approach, we included 9 PD, 12 PDD/DLB and 18 age-matched control donors. Cortical thickness and mean diffusivity (MD) metrics were extracted respectively from 3DT1 and DTI at 3T in-situ MRI. After autopsy, pathological hallmarks (pSer129-αSyn, p-tau and amyloid-β load) together with neurofilament light-chain (NfL) and phosphorylated-neurofilament medium- and heavy-chain (p-NfM/H) immunoreactivity were quantified in seven cortical regions, and studied in detail with confocal-laser scanning microscopy. The correlations between MRI and pathological measures were studied using linear mixed models.

RESULTS

Compared to controls, p-NfM/H immunoreactivity was increased in all cortical regions in PD and PDD/DLB, whereas NfL immunoreactivity was increased in the parahippocampal and entorhinal cortex in PDD/DLB. NfL-positive neurons showed degenerative morphological features and axonal fragmentation. The increased p-NfM/H correlated with p-tau load, and NfL correlated with pSer129-αSyn but more strongly with p-tau load in PDD/DLB. Lastly, neurofilament immunoreactivity correlated with cortical thinning in PD and with increased cortical MD in PDD/DLB.

CONCLUSIONS

Taken together, increased neurofilament immunoreactivity suggests underlying axonal injury and neurofilament accumulation in morphologically altered neurons with increased pathological burden. Importantly, we demonstrate that such neurofilament markers at least partly explain MRI measures that are associated with the neurodegenerative process.

Costs During the Last Five Years of Life for Patients with Clinical and Pathological Confirmed Diagnosis of Lewy Body Dementia and Alzheimer's Disease

BACKGROUND

Little is known regarding healthcare expenditures for patients with dementia with Lewy bodies (DLB) during the end of life.

OBJECTIVE

This study estimated Medicare expenditures during the last 5 years of life in a decedent sample of patients who were clinically diagnosed with Alzheimer's disease (AD) or DLB and had autopsy confirmed diagnosis.

METHODS

The study included 58 participants clinically diagnosed with mild dementia at study entry (AD: n = 44, DLB: n = 14) and also had autopsy-confirmed diagnoses of pure AD (n = 32), mixed AD+Lewy body (LB) (n = 5), or pure LB (n = 11). Total Medicare expenditures were compared by clinical and pathology confirmed diagnosis, adjusting for sex, age at death, and patient's cognition, function, comorbidities, and psychiatric and extrapyramidal symptoms.

RESULTS

When pathology diagnoses were not considered, predicted annualized total Medicare expenditures during the last 5 years of life were similar between clinically diagnosed AD ($7,465±1,098) and DLB ($7,783±1,803). When clinical diagnoses were not considered, predicted expenditures were substantially higher in patients with pathology confirmed mixed AD+LB ($12,005±2,455) than either pure AD ($6,173±941) or pure LB ($4,629±1,968) cases. Considering clinical and pathology diagnosis together, expenditures for patients with clinical DLB and pathology mixed AD+LB ($23,592±3,679) dwarfed other groups.

CONCLUSION

Medicare expenditures during the last 5 years of life were substantially higher in patients with mixed AD+LB pathology compared to those with pure-AD and pure-LB pathologies, particularly in those clinically diagnosed with DLB. Results highlight the importance of having both clinical and pathology diagnoses in examining healthcare costs.

Progressive Olfactory Impairment and Cardiac Sympathetic Denervation in REM Sleep Behavior Disorder

Background:

Isolated rapid eye movement sleep behavior disorder (iRBD) is prodromal for Parkinson’s disease (PD) and dementia with Lewy bodies (DLB).

Objective:

We investigated the use of cardiac [¹²³I]meta-iodo-benzyl-guanidine scintigraphy ([¹²³I]MIBG) and olfactory testing— in comparison to [¹²³I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane single photon emission computed tomography ([¹²³I]FP-CIT-SPECT)— for identifying iRBD patients as prodromal phenotype of PD/DLB.

Methods:

37 RBD subjects underwent cardiac [¹²³I]MIBG and brain [¹²³I]FP-CIT-SPECT at baseline. Olfactory (Sniffin’ Sticks), cognitive and motor functions were tested annually for ∼4 years.

Results:

29/37 (78.4%) subjects had a pathological [¹²³I]MIBG, of whom 86.2% (25/29) presented at least a moderate hyposmia at baseline (threshold/discrimination/identification-(TDI-)score ≤25). 20/37 (54.1%) subjects had a pathological [¹²³I]FP-CIT-SPECT, always combined with a pathological [¹²³I]MIBG. In subjects with pathological [¹²³I]MIBG, olfactory function worsened (mainly due to threshold and discrimination subscores) from baseline to follow-up (p = 0.005). Olfaction was more impaired in subjects with pathological [¹²³I]MIBG compared to those with normal [¹²³I]MIBG at baseline (p = 0.001) and follow-up (p < 0.001). UPDRS-III scores increased in subjects with both pathological [¹²³I]MIBG and [¹²³I]FP-CIT-SPECT. In this group, seven subjects phenoconverted to PD, all— except for one— presented with at least moderate hyposmia at baseline.

Conclusion:

A combination of the biomarkers “pathological [¹²³I]MIBG” and “hyposmia” likely identifies iRBD patients in an early prodromal stage of PD/DLB, i.e., before nigrostriatal degeneration is visualized. One-third of the subjects with pathological [¹²³I]MIBG had a normal [¹²³I]FP-CIT-SPECT. Noteworthy, in iRBD subjects with pathological [¹²³I]MIBG, olfactory impairment is progressive independent of the [¹²³I]FP-CIT-SPECT status.

Diagnostic Performance for Differential Diagnosis of Atypical Parkinsonian Syndromes from Parkinson’s Disease Using Quantitative Indices of 18F-FP-CIT PET/CT

We are aimed to evaluate the diagnostic performances of quantitative indices obtained from dual-phase ¹⁸F-FP-CIT PET/CT for differential diagnosis of atypical parkinsonian syndromes (APS) from Parkinson’s disease (PD). We analyzed 172 subjects, including 105 non-Parkinsonism, 26 PD, 8 PSP, 1 CBD, 8 MSA-P, 9 MSA-C, and 15 DLB retrospectively. Two sequential PET/CT scans were acquired at 5 min and 3 h. We compared subregional binding potentials, putamen-to-caudate nucleus ratio of the binding potential, asymmetry index, and degree of washout. To differentiate APS, all BPs in both early and late phases (except late BPbrainstem) and all factors of the percent change except for putamen in APS significantly differed from PD. When a cut-off for early BPcerebellum was set as 0.79, the sensitivity, specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy for differentiating APS 73.2%, 91.7%, 93.8%, 66.7%, and 80.0%. The early BPcerebellum showed significantly greater SP and PPV than the late quantitative indices. Combined criteria regarding both early and late indices exhibited only greater NPV. The quantitative indices showed high diagnostic performances in differentiating APS from PD. Our findings provide the dual-phase ¹⁸F-FP-CIT PET/CT would be useful for differentiating APS from PD.

The promise of amplification assays for accurate early detection of α-synucleinopathies: A review

Lewy body dementia encompasses the common neurodegenerative disorders Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). Lewy Body disease (LBD) is characterized by abnormal aggregates of α-synuclein (α-syn) in the brain which form Lewy bodies. LBD is commonly misdiagnosed/underdiagnosed, especially in early stages. There remains a great need for reliable biomarkers to assist with LBD diagnosis. Amplification techniques such as real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA) represent an important advance for biomarker detection. Amplification assays detect the ability of pathogenic protein to induce conformational change in normal protein; α-syn has been shown to propagate in a prion-like manner, making it a candidate for such analysis. In this review, we describe the diagnostic potential of amplification techniques for differentiating α-synucleinopathies from other neurodegenerative disorders such as Alzheimer's disease (AD), frontotemporal dementia (FTD), progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), and atypical parkinsonism, as well as α-synucleinopathies from each other. Recent studies report accurate detection of α-syn seeding activity in human tissues such as cerebrospinal fluid (CSF), submandibular gland (SMG), and posterior cervical skin. Adaptation to clinical settings may present challenges. However, the high accuracy of recent results, combined with the success of amplification assay diagnostics in clinical practice for Creutzfeldt-Jakob disease, suggest high promise for eventual clinical application.

Clinical Trajectories at the End of Life in Dementia Patients With Alzheimer Disease and Lewy Body Neuropathologic Changes

BACKGROUND AND OBJECTIVES

Evaluating and understanding the heterogeneity in dementia course has important implications for clinical practice, healthcare decision-making, and research. However, inconsistent findings have been reported with regard to the disease courses of the two most common dementias, Alzheimer's disease (AD) and Dementia with Lewy bodies (DLB). Using autopsy-confirmed diagnoses, we aimed to examine the disease trajectories in the years before death among dementia patients with pure AD, pure DLB, or mixed (AD and DLB) pathologies.

METHODS

The current retrospective longitudinal study included 62 participants with autopsy-confirmed diagnoses of pure AD (n=34), mixed AD and DLB (AD+DLB, n = 17), or pure DLB (n=11) from the Predictors 2 Cohort Study, a prospective, clinic-based, cohort of dementia patients. Generalized estimating equation models, with time zero at death, were used to examine the trajectory of cognition (Folstein Mini-Mental State Examination, MMSE), function (Activities of Daily Living, ADL), and dependence scale among patients with different autopsy-confirmed diagnosis (pure AD, AD+DLB, and pure DLB). The models were adjusted for age, sex, education, and baseline features including extrapyramidal signs, MMSE, ADL, and dependence scale.

RESULTS

The participants on average received 9.4±4.6 assessments at 6-month intervals during a mean 5.4±2.9 years of follow-up time. The three groups were similar in both cognition and function status at baseline. Cognition and function were highly correlated among AD+DLB patients but not in pure AD or pure DLB patients at baseline. Patients of the three groups all declined in both cognition and function but had different trajectories of decline. More specifically, the pure DLB patients experienced approximately double the rate of both cognitive decline and functional decline than the pure AD patients, and the mixed pathology group showed double the rate of functional decline as compared to pure AD patients.

DISCUSSION

In this longitudinal study, we found that among patients with dementia, those with Lewy body pathology experienced faster cognitive and functional decline than those with pure AD pathology.

Autonomic symptoms are predictive of dementia with Lewy bodies

INTRODUCTION

Autonomic symptoms are common in patients with dementia with Lewy bodies (DLB). Although autonomic dysfunction is considered as one of the primary early markers in patients with DLB, there are few studies that examine the timing of the onset of autonomic symptoms in these patients. The purpose of the current study was to evaluate the time of onset of autonomic symptoms in patients with DLB using a questionnaire.

METHODS

Autonomic symptoms were evaluated in patients with DLB using the Scales for Outcomes in Parkinson's disease - autonomic (SCOPA-Aut) questionnaire. Time of the onset of autonomic symptoms of patients with DLB was also assessed relative to that of memory loss.

RESULTS

A total of 106 patients with DLB were included. The most frequent symptom of dysautonomia in patients with DLB was constipation (60.4%), followed by orthostatic dizziness (33%), urinary frequency (30.2%), and daytime hyperhidrosis (22.6%). The gastrointestinal system was the most prominent system of autonomic dysfunction in patients with DLB. Orthostatic dizziness, daytime hyperhidrosis, and constipation all preceded the onset of memory loss by 0.2 ± 4.9, 3.3 ± 8.6, and 3.7 ± 9.2 years, respectively, while urinary incontinence occurred 1.7 ± 1.5 years following the onset of memory loss.

CONCLUSION

Many autonomic symptoms precede the onset of memory loss in patients with DLB, especially constipation and daytime hyperhidrosis. These symptoms can facilitate an early diagnosis of patients with DLB.

Convolutional neural network-based automatic heart segmentation and quantitation in 123I-metaiodobenzylguanidine SPECT imaging

Background

Since three-dimensional segmentation of cardiac region in ¹²³I-metaiodobenzylguanidine (MIBG) study has not been established, this study aimed to achieve organ segmentation using a convolutional neural network (CNN) with ¹²³I-MIBG single photon emission computed tomography (SPECT) imaging, to calculate heart counts and washout rates (WR) automatically and to compare with conventional quantitation based on planar imaging.

Methods

We assessed 48 patients (aged 68.4 ± 11.7 years) with heart and neurological diseases, including chronic heart failure, dementia with Lewy bodies, and Parkinson's disease. All patients were assessed by early and late ¹²³I-MIBG planar and SPECT imaging. The CNN was initially trained to individually segment the lungs and liver on early and late SPECT images. The segmentation masks were aligned, and then, the CNN was trained to directly segment the heart, and all models were evaluated using fourfold cross-validation. The CNN-based average heart counts and WR were calculated and compared with those determined using planar parameters. The CNN-based SPECT and conventional planar heart counts were corrected by physical time decay, injected dose of ¹²³I-MIBG, and body weight. We also divided WR into normal and abnormal groups from linear regression lines determined by the relationship between planar WR and CNN-based WR and then analyzed agreement between them.

Results

The CNN segmented the cardiac region in patients with normal and reduced uptake. The CNN-based SPECT heart counts significantly correlated with conventional planar heart counts with and without background correction and a planar heart-to-mediastinum ratio (R² = 0.862, 0.827, and 0.729, p < 0.0001, respectively). The CNN-based and planar WRs also correlated with and without background correction and WR based on heart-to-mediastinum ratios of R² = 0.584, 0.568 and 0.507, respectively (p < 0.0001). Contingency table findings of high and low WR (cutoffs: 34% and 30% for planar and SPECT studies, respectively) showed 87.2% agreement between CNN-based and planar methods.

Conclusions

The CNN could create segmentation from SPECT images, and average heart counts and WR were reliably calculated three-dimensionally, which might be a novel approach to quantifying SPECT images of innervation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00847-x.

A Systematic Review and Comparison of Neurocognitive Features of Late-Life Attention-Deficit/Hyperactivity Disorder and Dementia With Lewy Bodies

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) in adulthood and dementia with Lewy bodies (DLB) share many cognitive and noncognitive similarities. The overlapping features between both disorders complicate differential diagnosis. The aim of the current systematic review was to compare patterns of neuropsychological profiles in older adults with ADHD and DLB.

METHOD

Of the 1989 ADHD-related articles and 1332 DLB-related articles screened, 3 ADHD and 25 DLB articles were retained for qualitative synthesis and review.

RESULTS

A synthesis of individual study findings revealed isolated working memory deficits for late-life ADHD, and performance deficits in areas of attention, memory, language, and visuoperceptual abilities for DLB. Results were limited by small samples and absence of data in some cognitive domains.

CONCLUSION

These initial findings support potentially unique neurocognitive profiles for ADHD in later life and DLB that would enable practitioners to differentially diagnose and appropriately treat older adults presenting with these phenotypically similar disorders.

Advances in computerized MRI‐based biomarkers in Alzheimer’s disease

The use of neuroimaging examinations is crucial in Alzheimer’s disease (AD), in both research and clinical settings. Over the years, magnetic resonance imaging (MRI)–based computer‐aided diagnosis has been shown to be helpful for early screening and predicting cognitive decline. Meanwhile, an increasing number of studies have adopted machine learning for the classification of AD, with promising results. In this review article, we focus on computerized MRI‐based biomarkers of AD by reviewing representative studies that used computerized techniques to identify AD patients and predict cognitive progression. We categorized these studies based on the following applications: (1) identifying AD from normal control; (2) identifying AD from other dementia types, including vascular dementia, dementia with Lewy bodies, and frontotemporal dementia; and (3) predicting conversion from NC to mild cognitive impairment (MCI) and from MCI to AD. This systematic review could act as a state‐of‐the‐art overview of this emerging field as well as a basis for designing future studies.

Mechanisms of Neurodegeneration in Various Forms of Parkinsonism-Similarities and Differences

Parkinson’s disease (PD), dementia with Lewy body (DLB), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD) and multiple system atrophy (MSA) belong to a group of neurodegenerative diseases called parkinsonian syndromes. They share several clinical, neuropathological and genetic features. Neurodegenerative diseases are characterized by the progressive dysfunction of specific populations of neurons, determining clinical presentation. Neuronal loss is associated with extra- and intracellular accumulation of misfolded proteins. The parkinsonian diseases affect distinct areas of the brain. PD and MSA belong to a group of synucleinopathies that are characterized by the presence of fibrillary aggregates of α-synuclein protein in the cytoplasm of selected populations of neurons and glial cells. PSP is a tauopathy associated with the pathological aggregation of the microtubule associated tau protein. Although PD is common in the world’s aging population and has been extensively studied, the exact mechanisms of the neurodegeneration are still not fully understood. Growing evidence indicates that parkinsonian disorders to some extent share a genetic background, with two key components identified so far: the microtubule associated tau protein gene (MAPT) and the α-synuclein gene (SNCA). The main pathways of parkinsonian neurodegeneration described in the literature are the protein and mitochondrial pathways. The factors that lead to neurodegeneration are primarily environmental toxins, inflammatory factors, oxidative stress and traumatic brain injury.

Impaired meningeal lymphatic drainage in patients with idiopathic Parkinson's disease

Animal studies implicate meningeal lymphatic dysfunction in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease (PD). However, there is no direct evidence in humans to support this role^1-5. In this study, we used dynamic contrast-enhanced magnetic resonance imaging to assess meningeal lymphatic flow in cognitively normal controls and patients with idiopathic PD (iPD) or atypical Parkinsonian (AP) disorders. We found that patients with iPD exhibited significantly reduced flow through the meningeal lymphatic vessels (mLVs) along the superior sagittal sinus and sigmoid sinus, as well as a notable delay in deep cervical lymph node perfusion, compared to patients with AP. There was no significant difference in the size (cross-sectional area) of mLVs in patients with iPD or AP versus controls. In mice injected with α-synuclein (α-syn) preformed fibrils, we showed that the emergence of α-syn pathology was followed by delayed meningeal lymphatic drainage, loss of tight junctions among meningeal lymphatic endothelial cells and increased inflammation of the meninges. Finally, blocking flow through the mLVs in mice treated with α-syn preformed fibrils increased α-syn pathology and exacerbated motor and memory deficits. These results suggest that meningeal lymphatic drainage dysfunction aggravates α-syn pathology and contributes to the progression of PD.

Dementia with Lewy bodies in first-generation immigrants in a European memory clinic

We wanted to explore possible differences in disease presentation, frequency, and age of onset of dementia with Lewy bodies (DLB) between first-generation immigrants (FGI) and patients born in Belgium (PBIB). We conducted a retrospective study on all patients of our Memory Clinic between June 1, 2010 and January 31, 2020. A synucleinopathy was diagnosed in 150 of 2702 patients (5.5%): 91 received a diagnosis of DLB (3.4%). FGI were two times more likely to receive a diagnosis of DLB, due to a higher prevalence in North-Africans and Latin-Americans. Visual hallucinations were less frequent in North-Africans than in other immigrants. FGI were younger than PBIB and reported more often parasomnia. Our data suggest a higher risk for DLB in certain immigrant groups. Especially for North-African patients, a genetic factor can be suspected, namely mutations in Leucine-rich repeat kinase 2 (LRRK2). Memory clinics with a high rate of FGI may provide interesting data and insights into the prevalence of DLB, genetic and environmental differences.

Delusion and Delirium in Neurodegenerative Disorders: An Overlooked Relationship?

Delusions are part of the neuropsychiatric symptoms that patients suffering from neurodegenerative conditions frequently develop at some point of the disease course and are associated with an increased risk of cognitive and functional decline. Delirium is a syndrome characterized by acute onset of deficits in attention, awareness, and cognition that fluctuate in severity over a short time period. Delusions and delirium are frequently observed in the context of neurodegeneration, and their presence can easily mislead clinicians toward a misdiagnosis of psychiatric disorder further delaying the proper treatment. Risk factors for developing delusion and delirium in neurodegenerative conditions have been investigated separately while the possible interplay between these two conditions has not been explored so far. With this study, we aim to achieve a more comprehensive picture of the relationship between delusions and delirium in neurodegeneration by analyzing prevalence and subtypes of delusions in different neurodegenerative disorders; providing an overview of clinical tools to assess delusions in neurodegenerative patients and how delusions are covered by delirium assessment tools and discussing the possible common pathophysiology mechanisms between delusion and delirium in neurodegenerative patients. A more extensive characterization of the relationship between delusions and delirium may help to understand whether delusions may constitute a risk factor for delirium and may ameliorate the management of both conditions in patients with neurodegenerative disorders.

Calibrated scintigraphic imaging procedures improve quantitative assessment of the cardiac sympathetic nerve activity

The ¹²³I-labeled meta-iodobenzylguanidine (MIBG) is an analogue of noradrenaline that can evaluate cardiac sympathetic activity in scintigraphy. Quantitative analysis of ¹²³I-MIBG images has been verified in patients with heart failure and neurodegenerative diseases. However, quantitative results differ due to variations in scintigraphic imaging procedures. Here, we created and assessed the clinical feasibility of a calibration method for ¹²³I-MIBG imaging. The characteristics of scintigraphic imaging systems were determined using an acrylic calibration phantom to generate a multicenter phantom imaging database. Calibration factors corresponding to the scintigraphic imaging procedures were calculated from the database and applied to a clinical study. The results of this study showed that the calibrated analysis eliminated inter-institutional differences among normal individuals. In summary, our standardization methodology for ¹²³I-MIBG scintigraphy could provide the basis for improved diagnostic precision and better outcomes for patients.

The development of new method to differentiate between Dementia with Lewy bodies and Alzheimer's disease by cerebral perfusion SPECT-comparison to CIScore

PURPOSE

The Cingulate Island Sign score (CIScore) by rCBF SPECT is used in the differentiation between Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) but has some false-positive AD cases. To resolve the problem, we developed new differential diagnosing method incorporating occipital lobe and para-hippocampal rCBF.

MATERIALS AND METHODS

In 27 DLB and 31 AD cases undertaken Tc-99 m-ECD SPECT, we evaluated the mean Z score in the bilateral superior, middle, inferior occipital gyri, cuneus, amygdala, hippocampus, and para-hippocampus. One criterion of DLB was defined as the case with CIScore lower than 0.27. The other criteria were the cases of following either or both two conditions were satisfied. (1) The number of occipital gyri with mean Z score higher than 1 is three or more. (2) The number of hippocampal regions with mean Z score higher than 1 is one or less. We compared the differential diagnostic ability among these four criterions.

RESULTS

The diagnostic accuracy by CIscore was 69% and that of the occipital gyri analysis 84%, para-hippocampal regions analysis 76% and combined occipital gyri and para-hippocampal regions analysis 93%.

CONCLUSION

The new method by combined rCBF analysis of occipital gyri and para-hippocampal regions showed best diagnostic ability in differentiating DLB from AD.