Up to 80% of Parkinson\'s disease patients develop dementia, but time to dementia varies widely from motor symptom onset. Dementia with Lewy bodies presents with clinical features similar to Parkinson\'s disease dementia, but cognitive impairment precedes or coincides with motor onset. It remains controversial whether dementia with Lewy bodies and Parkinson\'s disease dementia are distinct conditions or represent part of a disease spectrum. The biological mechanisms underlying disease heterogeneity, in particular the development of dementia, remain poorly understood, but will likely be the key to understanding disease pathways and, ultimately, therapy development. Previous genome-wide association studies in Parkinson\'s disease and dementia with Lewy bodies/Parkinson\'s disease dementia have identified risk loci differentiating patients from controls. We collated data for 7804 patients of European ancestry from Tracking Parkinson\'s, The Oxford Discovery Cohort, and Accelerating Medicine Partnership-Parkinson\'s Disease Initiative. We conducted a discrete phenotype genome-wide association study comparing Lewy body diseases with and without dementia to decode disease heterogeneity by investigating the genetic drivers of dementia in Lewy body diseases. We found that risk allele rs429358 tagging APOEe4 increases the odds of developing dementia, and that rs7668531 near the MMRN1 and SNCA-AS1 genes and an intronic variant rs17442721 tagging LRRK2 G2019S on chromosome 12 are protective against dementia. These results should be validated in autopsy-confirmed cases in future studies.

Transcription factor EB (TFEB) is a master regulator of genes involved in the maintenance of autophagic and lysosomal homeostasis, processes which have been implicated in the pathogenesis of GBA-related and sporadic Parkinson\'s disease (PD), and dementia with Lewy bodies (DLB). TFEB activation results in its translocation from the cytosol to the nucleus. Here, we investigated TFEB subcellular localization and its relation to intracellular alpha-synuclein (aSyn) accumulation in post-mortem human brain of individuals with either incidental Lewy body disease (iLBD), GBA-related PD/DLB (GBA-PD/DLB) or sporadic PD/DLB (sPD/DLB), compared to control subjects. We analyzed nigral dopaminergic neurons using high-resolution confocal and stimulated emission depletion (STED) microscopy and semi-quantitatively scored the TFEB subcellular localization patterns. We observed reduced nuclear TFEB immunoreactivity in PD/DLB patients compared to controls, both in sporadic and GBA-related cases, as well as in iLBD cases. Nuclear depletion of TFEB was more pronounced in neurons with Ser129-phosphorylated (pSer129) aSyn accumulation in all groups. Importantly, we observed previously-unidentified TFEB-immunopositive perinuclear clusters in human dopaminergic neurons, which localized at the Golgi apparatus. These TFEB clusters were more frequently observed and more severe in iLBD, sPD/DLB and GBA-PD/DLB compared to controls, particularly in pSer129 aSyn-positive neurons, but also in neurons lacking detectable aSyn accumulation. In aSyn-negative cells, cytoplasmic TFEB clusters were more frequently observed in GBA-PD/DLB and iLBD patients, and correlated with reduced GBA enzymatic activity as well as increased Braak LB stage. Altered TFEB distribution was accompanied by a reduction in overall mRNA expression levels of selected TFEB-regulated genes, indicating a possible early dysfunction of lysosomal regulation. Overall, we observed cytoplasmic TFEB retention and accumulation at the Golgi in cells without apparent pSer129 aSyn accumulation in iLBD and PD/DLB patients. This suggests potential TFEB impairment at the early stages of cellular disease and underscores TFEB as a promising therapeutic target for synucleinopathies.

Up to 80% of Parkinson\'s disease patients develop dementia, but time to dementia varies widely from motor symptom onset. Dementia with Lewy bodies presents with clinical features similar to Parkinson\'s disease dementia, but cognitive impairment precedes or coincides with motor onset. It remains controversial whether dementia with Lewy bodies and Parkinson\'s disease dementia are distinct conditions or represent part of a disease spectrum. The biological mechanisms underlying disease heterogeneity, in particular the development of dementia, remain poorly understood, but will likely be key to understanding disease pathways and ultimately therapy development. Previous genome-wide association studies in Parkinson\'s disease and dementia with Lewy bodies/Parkinson\'s disease dementia have identified risk loci differentiating patients from controls. We collated data for 7,804 patients of European ancestry from Tracking Parkinson\'s (PRoBaND), The Oxford Discovery Cohort, and AMP-PD. We conducted a discrete phenotype genome-wide association studies comparing Lewy body diseases with and without dementia to decode disease heterogeneity by investigating the genetic drivers of dementia in Lewy body diseases. We found that risk alleles rs429358 tagging APOEe4 and rs7668531 near the MMRN1 and SNCA-AS1 genes, increase the odds of developing dementia and that an intronic variant rs17442721 tagging LRRK2 G2019S, on chromosome 12 is protective against dementia. These results should be validated in autopsy confirmed cases in future studies.

Lewy body diseases (LBD) are pathologically defined as the accumulation of Lewy bodies composed of an aggregation of α-synuclein (αSyn). In LBD, not only the sole aggregation of αSyn but also the co-aggregation of amyloidogenic proteins, such as amyloid-β (Aβ) and tau, has been reported. In this review, the pathophysiology of co-aggregation of αSyn, Aβ, and tau protein and the advancement in imaging and fluid biomarkers that can detect αSyn and co-occurring Aβ and/or tau pathologies are discussed. Additionally, the αSyn-targeted disease-modifying therapies in clinical trials are summarized.

UNASSIGNED: Idiopathic normal pressure hydrocephalus (iNPH) is the leading reversible cause of cognitive impairment and gait disturbance that has similar clinical manifestations and accompanies to major neurodegenerative disorders in older adults. We aimed to investigate whether cerebrospinal fluid (CSF) biomarker for Alzheimer\'s disease (AD) may be useful in the differential diagnosis of iNPH.
UNASSIGNED: Amyloid-beta (Aß) 42 and 40, total tau (t-tau), phosphorylated tau (p-tau) were measured via ELISA in 192 consecutive CSF samples of patients with iNPH (n=80), AD (n=48), frontotemporal dementia (FTD) (n=34), Lewy body diseases (LBDs) (n=30) consisting of Parkinson\'s disease dementia and dementia with Lewy bodies.
UNASSIGNED: The mean age of the study population was 75.6±7.7 years, and 54.2% were female. CSF Aβ42 levels were significantly higher, and p-tau and t-tau levels were lower in iNPH patients than in those with AD and LBDs patients. Additionally, iNPH patients had significantly higher levels of t-tau than those with FTD. Age and sex-adjusted multi-nominal regression analysis revealed that the odds of having AD relative to iNPH decreased by 37% when the Aβ42 level increased by one standard deviation (SD), and the odds of having LBDs relative to iNPH decreased by 47%. The odds of having LBDs relative to iNPH increased 76% when the p-tau level increased 1SD. It is 2.5 times more likely for a patient to have LBD relative to NPH and 2.1 times more likely to have AD relative to iNPH when the t-tau value increased 1SD.
UNASSIGNED: Our results suggest that levels of CSF Aβ42, p-tau, and t-tau, in particularly decreased t-tau, are of potential value in differentiating iNPH from LBDs and also confirm previous studies reporting t-tau level is lower and Aβ42 level is higher in iNPH than in AD.

OBJECTIVE: Real-time quaking-induced conversion (RT-QuIC) is a novel in vitro acellular seed amplification analysis and has been widely used to detect prion diseases. Due to the similar mechanism of abnormal aggregation of α-synuclein, RT-QuIC has great potential for diagnosing Lewy body diseases. This meta-analysis was performed to evaluate the diagnostic accuracy of RT-QuIC for Lewy body diseases.
METHODS: This study followed the PRISMA statement. We searched six databases for relevant studies published until February 20, 2022. Meta-analysis was conducted using RevMan 5.3, Stata 17.0, and Meta-Disc 1.4. Subgroup analyses were performed to explore sources of heterogeneity.
RESULTS: A total of 16 studies were included in this study. The pooled sensitivity and specificity were 0.91 (95%CI: 0.85-0.94) and 0.95 (95%CI: 0.90-0.97), respectively. The pooled positive and negative likelihood ratios were 17.16 (95% CI: 9.16-32.14) and 0.10 (95% CI: 0.06-0.17), respectively. The pooled diagnostic odds rate and area under the summary receiver operating characteristic curve were 171.16 (95% CI: 66.64-439.62) and 0.97 (95% CI: 0.96-0.99), respectively.
CONCLUSIONS: This study was the first meta-analysis on RT-QuIC for Lewy body diseases. RT-QuIC is a reliable and accurate method to diagnose Lewy body diseases.

The emergence of cognitive impairment and dementia in people with Lewy body spectrum disorders (LBS) significantly impacts the quality of life of the individual and their care partner. Coping well with the condition may depend, in part, on the degree of psychological resilience or capacity to \'bounce back\' from adversity. We explored resilience in people with Parkinson\'s disease mild cognitive disorder or dementia, or dementia with Lewy bodies, and their care partners, and its relation to outcomes related to their mental well-being and quality of life. This exploratory, cross-sectional study recruited 76 participant-dyads. Resilience, quality of life, depression, anxiety, and relationship satisfaction were evaluated in both members of the dyad. In care partners, care burden and stress were also assessed. Over 70% of both care partners and recipients reported high levels of resilience. Lower resilience in both members of the dyad was associated with higher anxiety and lower quality of life. Additionally, lower resilience in care partners was associated with lower well-being, relationship satisfaction, and higher burden and stress. Resilience in persons with LBS and their care partners is important to consider when assessing mental health, relationship, and care burden outcomes, acting as a focus of intervention to support positive outcomes.

BACKGROUND: Cognitive diseases with Lewy bodies occur in two forms: dementia with Lewy bodies (DLB) and Parkinsonian dementia (PD), which follows the evolution of Parkinson disease. There is currently no curative treatment for these cognitive diseases with Lewy bodies. Therapeutic trials in DLB are rare, due to the fact that the disease has only recently been described and the first international diagnostic criteria have only recently been published (1996).
METHODS: This article proposes a synthesis of the therapeutic trials carried out into DLB in the last five years, including PD patients, using the Clinicaltrials.gov and Pubmed.gov databases.
RESULTS: We identified 35 therapeutic trials on ClinicalTrials.gov and 14 on PubMed. In line with our temporal criteria, 21 trials were analysed. Of the 11 completed trials with reported results, two drugs showed positive results: two trials with zonisamide (phases 2 and 3) showed improvements in Parkinsonian syndrome and one trial with neflamapimod (phase 2) showed improvements in cognition and walking.
CONCLUSIONS: In recent years, there has been an increase in therapeutic research into DLB, which is consistent with the prevalence of this disease - approximately 200,000 patients in France. Compared to other cognitive neurodegenerative diseases, therapeutic research is largely insufficient, although the proportion of positive trials is significant. Effective treatment to modify the course of the disease would have significant consequences for patients and their relatives.

BACKGROUND: Using two static scans for 123I-meta-iodobenzyl-guanidine (123I-MIBG) myocardial scintigraphy ignores the dynamic response from vesicular trapping in nerve terminals. Moreover, the long pause between scans is impractical for patients with Lewy body diseases (LBDs). Here, we optimized indices that capture norepinephrine kinetics, tested their diagnostic performance, and determined the differences in 123I-MIBG performance among disease groups.
METHODS: We developed a new 30-min protocol for 123I-MIBG dynamic planar imaging for suspected LBD patients. Pharmacokinetic modelling of time-activity curves (TACs) was used to calculate three new indices: unidirectional uptake of 123I-MIBG to vesicular trapping (iUp), rate of myocardial 123I-MIBG loss (iLoss), and non-specific fractional distribution of 123I-MIBG in the interstitial space. We compared the performance of the new and existing indices with regard to discrimination of patients with or without LBDs. Subgroup analysis was performed to examine differences in 123I-MIBG turnover between patients in a dementia with Lewy bodies (DLB) group and two Parkinson\'s disease (PD) groups, one with and the other without REM sleep behaviour disorder (RBD).
RESULTS: iLoss was highly discriminative, particularly for patients with low myocardial 123I-MIBG trapping, and the new indices outperformed existing ones. ROC analysis revealed that the AUC of iLoss (0.903) was significantly higher than that of early HMR (0.863), while comparable to that of delayed HMR (0.892). The RBD-positive PD group and the DLB group had higher turnover rates than the RBD-negative PD group, indicating a potential association between prognosis and iLoss.
CONCLUSIONS: 123I-MIBG turnover can be quantified in 30 min using a three-parameter model based on 123I-MIBG TACs. The discriminatory performance of the new model-based indices might help explain the neurotoxicity or neurodegeneration that occurs in LBD patients.

BACKGROUND: Recent reports indicate that Parkinson\'s disease (PD) involves specific functional abnormalities in residual neurons-decreased vesicular sequestration of cytoplasmic catecholamines via the vesicular monoamine transporter (VMAT) and decreased aldehyde dehydrogenase (ALDH) activity. This double hit builds up the autotoxic metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL), the focus of the catecholaldehyde hypothesis for the pathogenesis of PD. An animal model is needed that reproduces this abnormal catecholamine neurochemical pattern.
METHODS: Adult rats received subcutaneous vehicle or rotenone (2 mg/kg/day via a minipump) for 10 days. Locomotor activity was recorded and striatal tissue sampled for catechol contents and catechol ratios that indicate the above abnormalities.
RESULTS: Compared to vehicle, rotenone reduced locomotor activity (p=0.002), decreased tissue dopamine concentrations (p=0.00001), reduced indices of vesicular sequestration (3,4-dihydroxyphenylacetic acid (DOPAC)/dopamine) and ALDH activity (DOPAC/DOPAL) (p=0.0025, p=0.036), and increased DOPAL levels (p=0.04).
CONCLUSIONS: The rat rotenone model involves functional abnormalities in catecholaminergic neurons that replicate the pattern found in PD putamen. These include a vesicular storage defect, decreased ALDH activity, and DOPAL buildup. The rat rotenone model provides a suitable in vivo platform for studying the catecholaldehyde hypothesis.