Update of the MDS research criteria for prodromal Parkinson's disease

Biofluid Markers and Tissue Biopsies Analyses for the Prodromal and Earliest Phase of Parkinson's Disease

The recent development of new methods to detect misfolded α-synuclein (αSyn) aggregates in biofluids and tissue biopsies in the earliest Parkinson's disease (PD) phases is dramatically challenging the biological definition of PD. The αSyn seed amplification methods in cerebrospinal fluid (CSF) showed high sensitivity and specificity for early diagnosis of PD and Lewy bodies disorders. Several studies in isolated REM sleep behavior disorders and other at-risk populations also demonstrated a high prevalence of CSF αSyn positivity and its potential value in predicting the phenoconversion to clinically manifested diseases. Growing evidence exists for αSyn aggregates in olfactory mucosa, skin, and other tissues in subjects with PD or at-risk subjects. DOPA decarboxylase and numerous other candidates have been additionally proposed for either diagnostic or prognostic purposes in earliest PD phases. The newly described αSyn detection in blood, through its quantification in neuronally-derived exosome vesicles, represents a technical challenge that could open a new scenario for the biological diagnosis of PD. Despite this growing evidence in the field, most of method of αSyn detection and markers still need to be validated in ongoing longitudinal studies through an accurate assessment of different prodromal disease subtypes and scenarios before being definitively implemented in clinical settings.

Biofluid Detection of Pathological α-Synuclein in the Prodromal Phase of Synucleinopathies

Synucleinopathies are disorders characterized by the aggregation and deposition of pathological α-synuclein conformers. The underlying neurodegenerative processes begin years or decades before the onset of cardinal motor symptoms. This prodromal phase may manifest with various signs or symptoms. However, there are no current standardized laboratory tests to ascertain the progression and conversion of prodromal conditions such as mild cognitive impairment, isolated REM sleep behavior disorder or pure autonomic failure. The aim of this systematic review was to evaluate the diagnostic possibilities using human biofluids as source material to detect pathological α-synuclein in the prodromal phase of synucleinopathies. Our review identified eight eligible studies, that investigated pathological α-synuclein conformers using cerebrospinal fluid from patients with prodromal signs of synulceinopathies to differentiate this patient group from non-synucleinopathies, while only one study investigated this aspect using blood as medium. While previous studies clearly demonstrated a high diagnostic performance of α-synuclein seed amplification assays for differentiating synucleinopathies with Lewy bodies from healthy controls, only few analyses were performed focussing on individuals with prodromal disease. Nevertheless, results for the early detection of α-synuclein seeds using α-synuclein seed amplification assays were promising and may be of particular relevance for future clinical trials and clinical practice.

Louis EK, Noyce AJ. Ethical Considerations for Identifying Individuals in the Prodromal/Early Phase of Parkinson's Disease: A Narrative Review

The ability to identify individuals in the prodromal phase of Parkinson's disease has improved in recent years, raising the question of whether and how those affected should be informed about the risk of future disease. Several studies investigated prognostic counselling for individuals with isolated REM sleep behavior disorder and have shown that most patients want to receive information about prognosis, but autonomy and individual preferences must be respected. However, there are still many unanswered questions about risk disclosure or early diagnosis of PD, including the impact on personal circumstances, cultural preferences and specific challenges associated with different profiles of prodromal symptoms, genetic testing or biomarker assessments. This narrative review aims to summarize the current literature on prognostic counselling and risk disclosure in PD, as well as highlight future perspectives that may emerge with the development of new biomarkers and their anticipated impact on the definition of PD.

Deciphering a Prodrome: Looking for a Disease in a Haystack

In many chronic diseases, the underlying biological processes begin long before the condition is clinically recognized and diagnosed. After biologic onset of the disease an early, often nonspecific, set of symptoms, or prodrome, may develop before more characteristic symptoms of the disease present. For instance, in Parkinson disease (PD), some of the earliest manifestations, such as smell or taste dysfunction, may occur 2 decades before typical symptoms, such as tremor, appear.1 Generally, the combination of long prodromal phases and nonspecific symptoms hampers early recognition of disease. Recognizing the prodromal phase of a disease in an individual has 2 potential benefits. First, accurate identification of etiologic factors for disease depends on ensuring that the putative exposure preceded biologic onset of the disease and that the identified symptoms are not related to a delay in diagnosis. Therefore, recognition of a prodromal phase may enhance the ability to identify etiologic factors. Second, accurate prediction that an individual is in the prodromal phase of the disease offers the tantalizing possibility that intervention in this phase could prevent or delay evolution of more typical clinical manifestations.2.

Identification of potential immune-related hub genes in Parkinson's disease based on machine learning and development and validation of a diagnostic classification model

BACKGROUND

Parkinson's disease is the second most common neurodegenerative disease in the world. However, current diagnostic methods are still limited, and available treatments can only mitigate the symptoms of the disease, not reverse it at the root. The immune function has been identified as playing a role in PD, but the exact mechanism is unknown. This study aimed to search for potential immune-related hub genes in Parkinson's disease, find relevant immune infiltration patterns, and develop a categorical diagnostic model.

METHODS

We downloaded the GSE8397 dataset from the GEO database, which contains gene expression microarray data for 15 healthy human SN samples and 24 PD patient SN samples. Screening for PD-related DEGs using WGCNA and differential expression analysis. These PD-related DEGs were analyzed for GO and KEGG enrichment. Subsequently, hub genes (dld, dlk1, iars and ttd19) were screened by LASSO and mSVM-RFE machine learning algorithms. We used the ssGSEA algorithm to calculate and evaluate the differences in nigrostriatal immune cell types in the GSE8397 dataset. The association between dld, dlk1, iars and ttc19 and 28 immune cells was investigated. Using the GSEA and GSVA algorithms, we analyzed the biological functions associated with immune-related hub genes. Establishment of a ceRNA regulatory network for immune-related hub genes. Finally, a logistic regression model was used to develop a PD classification diagnostic model, and the accuracy of the model was verified in three independent data sets. The three independent datasets are GES49036 (containing 8 healthy human nigrostriatal tissue samples and 15 PD patient nigrostriatal tissue samples), GSE20292 (containing 18 healthy human nigrostriatal tissue samples and 11 PD patient nigrostriatal tissue samples) and GSE7621 (containing 9 healthy human nigrostriatal tissue samples and 16 PD patient nigrostriatal tissue samples).

RESULTS

Ultimately, we screened for four immune-related Parkinson's disease hub genes. Among them, the AUC values of dlk1, dld and ttc19 in GSE8397 and three other independent external datasets were all greater than 0.7, indicating that these three genes have a certain level of accuracy. The iars gene had an AUC value greater than 0.7 in GES8397 and one independent external data while the AUC values in the other two independent external data sets ranged between 0.5 and 0.7. These results suggest that iars also has some research value. We successfully constructed a categorical diagnostic model based on these four immune-related Parkinson's disease hub genes, and the AUC values of the joint diagnostic model were greater than 0.9 in both GSE8397 and three independent external datasets. These results indicate that the categorical diagnostic model has a good ability to distinguish between healthy individuals and Parkinson's disease patients. In addition, ceRNA networks reveal complex regulatory relationships based on immune-related hub genes.

CONCLUSION

In this study, four immune-related PD hub genes (dld, dlk1, iars and ttd19) were obtained. A reliable diagnostic model for PD classification was developed. This study provides algorithmic-level support to explore the immune-related mechanisms of PD and the prediction of immune-related drug targets.

Trajectories of healthy aging and their association with prodromal parkinson disease: The HELIAD study

Background: The aim of the present study was to investigate the association of prodromal PD (pPD) with trajectories of healthy aging, according to its latest definition by the WHO.Methods: In a sample of 1,226 older adults (704 women), PD diagnosis was reached through standard clinical research procedures. Probability of pPD was calculated according to the International Parkinson and Movement Disorder Society's research criteria for PD-free participants. A healthy aging metric was introduced using an item response theory approach (IRT) based on information from validated questionnaires assessing functionality. Four trajectories of healthy aging were created based on whether the healthy aging status of participants was above or below the median at baseline and follow up: High-High, High-Low, Low-High and Low-Low.Results: 34.3% belonged to the High-High group, 15.7% to the High-Low, 18.6% to the Low-High and 31.4% to the Low-Low group. Participants with possible/probable pPD were 78% less likely to belong in High-High trajectory of healthy aging as compared to those without pPD (OR = 0.22, 95%CI 0.06-0.79, p-value = 0,02).Conclusion: Our findings suggest an inverse association of pPD probability with healthy aging among older adults; Further research is needed to investigate the clinical implications of this association.

Staging Parkinson's disease according to the MNCD classification correlates with caregiver burden

BACKGROUND AND OBJECTIVE

Recently, we demonstrated that staging Parkinson's disease (PD) with a novel simple classification called MNCD, based on four axes (motor, non-motor, cognition, and dependency) and five stages, correlated with disease severity and patients' quality of life. Here, we analyzed the correlation of MNCD staging with PD caregiver's status.

PATIENTS AND METHODS

Data from the baseline visit of PD patients and their principal caregiver recruited from 35 centers in Spain from the COPPADIS cohort from January 2016 to November 2017 were used to apply the MNCD total score (from 0 to 12) and MNCD stages (from 1 to 5) in this cross-sectional analysis. Caregivers completed the Zarit Caregiver Burden Inventory (ZCBI), Caregiver Strain Index (CSI), Beck Depression Inventory-II (BDI-II), PQ-10, and EUROHIS-QOL 8-item index (EUROHIS-QOL8).

RESULTS

Two hundred and twenty-four PD patients (63 ± 9.6 years old; 61.2% males) and their caregivers (58.5 ± 12.1 years old; 67.9% females) were included. The frequency of MNCD stages was 1, 7.6%; 2, 58.9%; 3, 31.3%; and 4-5, 2.2%. A more advanced MNCD stage was associated with a higher score on the ZCBI (p < .0001) and CSI (p < .0001), and a lower score on the PQ-10 (p = .001), but no significant differences were observed in the BDI-II (p = .310) and EUROHIS-QOL8 (p = .133). Moderate correlations were observed between the MNCD total score and the ZCBI (r = .496; p < .0001), CSI (r = .433; p < .0001), and BDI-II (r = .306; p < .0001) in caregivers.

CONCLUSION

Staging PD according to the MNCD classification is correlated with caregivers' strain and burden.

Clinical subtypes in patients with isolated REM sleep behaviour disorder

Patients with Parkinson's disease (PD) show a broad heterogeneity in clinical presentation, and subtypes may already arise in prodromal disease stages. Isolated REM sleep behaviour disorder (iRBD) is the most specific marker of prodromal PD, but data on clinical subtyping of patients with iRBD remain scarce. Therefore, this study aimed to identify iRBD subtypes. We conducted comprehensive clinical assessments in 66 patients with polysomnography-proven iRBD, including motor and non-motor evaluations, and applied a two-step cluster analysis. Besides, we compared iRBD clusters to matched healthy controls and related the resulting cluster solution to cortical and subcortical grey matter volumes by voxel-based morphometry analysis. We identified two distinct subtypes of patients based on olfactory function, dominant electroencephalography frequency, amount of REM sleep without atonia, depressive symptoms, disease duration, and motor functions. One iRBD cluster (Cluster I, late onset-aggressive) was characterised by higher non-motor symptom burden despite shorter disease duration than the more benign subtype (Cluster II, early onset-benign). Motor functions were comparable between the clusters. Patients from Cluster I were significantly older at iRBD onset and exhibited a widespread reduction of cortical grey matter volume compared to patients from Cluster II. In conclusion, our findings suggest the existence of clinical subtypes already in the prodromal stage of PD. Future longitudinal studies are warranted that replicate these findings and investigate the risk of the more aggressive phenotype for earlier phenoconversion and dementia development.

Impact of diabetes and glycated hemoglobin level on the clinical manifestations of Parkinson's disease

BACKGROUND

The coexistence of diabetes mellitus (DM) has been suggested to accelerate the progression of Parkinson's disease (PD) and make the phenotype more severe. In this study, we investigated whether DM or glycated hemoglobin (HbA1c) levels affect the differences in motor and nonmotor symptoms.

METHODS

We conducted a cross-sectional study including 140 consecutive Japanese patients with PD for whom medical history and serum HbA1c records were available. The PD patients with a DM diagnosis were classified into the diabetes-complicated group (PD-DM) and the nondiabetes-complicated group (PD-no DM). Next, patients were classified based on a median HbA1c value of 5.7, and clinical parameters were compared. The correlations between HbA1c levels and other clinical variables were analyzed.

RESULTS

Of 140 patients, 23 patients (16%) had DM. Compared to PD-no DM patients, PD-DM patients showed lower MMSE scores. Compared to the lower HbA1c group, the higher HbA1c group showed a higher MDS-UPDRS part III score and a lower metaiodobenzylguanidine (MIBG) scintigraphy heart-to-mediastinum (H/M) ratio. HbA1c levels were positively correlated with age and the MDS-UPDRS part III score and negatively correlated with the MMSE score and H/M ratio on cardiac MIBG scintigraphy. Binary logistic regression analysis, which included age, sex, disease duration, and MMSE and MDS-UPDRS part III scores as independent variables, revealed that a lower MMSE score was an independent contributor to PD-DM and PD with high HbA1c levels.

CONCLUSIONS

DM complications and high HbA1c levels may affect cognitive function in patients with PD.

Applications of Machine Learning to Diagnosis of Parkinson's Disease

BACKGROUND

Accurate diagnosis of Parkinson's disease (PD) is challenging due to its diverse manifestations. Machine learning (ML) algorithms can improve diagnostic precision, but their generalizability across medical centers in China is underexplored.

OBJECTIVE

To assess the accuracy of an ML algorithm for PD diagnosis, trained and tested on data from different medical centers in China.

METHODS

A total of 1656 participants were included, with 1028 from Beijing (training set) and 628 from Fuzhou (external validation set). Models were trained using the least absolute shrinkage and selection operator-logistic regression (LASSO-LR), decision tree (DT), random forest (RF), eXtreme gradient boosting (XGboost), support vector machine (SVM), and k-nearest neighbor (KNN) techniques. Hyperparameters were optimized using five-fold cross-validation and grid search techniques. Model performance was evaluated using the area under the curve (AUC) of the receiver operating characteristic (ROC) curve, accuracy, sensitivity (recall), specificity, precision, and F1 score. Variable importance was assessed for all models.

RESULTS

SVM demonstrated the best differentiation between healthy controls (HCs) and PD patients (AUC: 0.928, 95% CI: 0.908-0.947; accuracy: 0.844, 95% CI: 0.814-0.871; sensitivity: 0.826, 95% CI: 0.786-0.866; specificity: 0.861, 95% CI: 0.820-0.898; precision: 0.849, 95% CI: 0.807-0.891; F1 score: 0.837, 95% CI: 0.803-0.868) in the validation set. Constipation, olfactory decline, and daytime somnolence significantly influenced predictability.

CONCLUSION

We identified multiple pivotal variables and SVM as a precise and clinician-friendly ML algorithm for prediction of PD in Chinese patients.

Interaction of an α-synuclein epitope with HLA-DRB1∗15:01 triggers enteric features in mice reminiscent of prodromal Parkinson's disease

Enteric symptoms are hallmarks of prodromal Parkinson's disease (PD) that appear decades before the onset of motor symptoms and diagnosis. PD patients possess circulating T cells that recognize specific α-synuclein (α-syn)-derived epitopes. One epitope, α-syn32-46, binds with strong affinity to the HLA-DRB1∗15:01 allele implicated in autoimmune diseases. We report that α-syn32-46 immunization in a mouse expressing human HLA-DRB1∗15:01 triggers intestinal inflammation, leading to loss of enteric neurons, damaged enteric dopaminergic neurons, constipation, and weight loss. α-Syn32-46 immunization activates innate and adaptive immune gene signatures in the gut and induces changes in the CD4+ TH1/TH17 transcriptome that resemble tissue-resident memory (TRM) cells found in mucosal barriers during inflammation. Depletion of CD4+, but not CD8+, T cells partially rescues enteric neurodegeneration. Therefore, interaction of α-syn32-46 and HLA-DRB1∗15:0 is critical for gut inflammation and CD4+ T cell-mediated loss of enteric neurons in humanized mice, suggesting mechanisms that may underlie prodromal enteric PD.

Post-Traumatic Stress Disorder and Risk of Degenerative Synucleinopathies: Systematic Review and Meta-Analysis

OBJECTIVE

A systematic review was conducted to answer whether adult-onset post-traumatic stress disorder (PTSD) is associated with increased risk of Parkinson's disease (PD) and related synucleinopathies.

DESIGN

A systematic search of Medline (Ovid), Embase (Elsevier), PsycInfo (Ovid), Cochrane Library (Wiley), and Web of Science (Clarivate) was performed using MeSH headings and equivalent terms for PTSD, PD, DLB, and related disorders.

SETTING

No restrictions.

PARTICIPANTS

Eligible articles were published in peer-reviewed journals, sampled adult human populations, and treated PTSD and degenerative synucleinopathies as exposures and outcomes, respectively.

MEASUREMENTS

Extracted data included diagnostic methods, sample characteristics, matching procedures, covariates, and effect estimates. Bias assessment was performed with the Newcastle-Ottawa scale. Hazard ratios were pooled using the random effects model, and the Hartung-Knapp adjustment was applied due to the small number of studies.

RESULTS

A total of six articles comprising seven unique samples (total n = 1,747,378) met eligibility criteria. The risk of PD was reported in three retrospective cohort studies and one case-control study. Risk of DLB was reported in one retrospective cohort, one case-control, and one prospective cohort study. No studies addressed potential relationships with multiple system atrophy or pure autonomic failure. Meta-analysis of hazard ratios from four retrospective cohort studies supported the hypothesis that incident PTSD was associated with PD and DLB risk (pooled HR 1.88, 95% C.I. 1.08-3.24; p = 0.035).

CONCLUSIONS

The sparse literature to-date supports further investigations on the association of mid- to late-life PTSD with Parkinson's and related neurodegenerative disorders.

Sexual dysfunction among patients with Parkinson's disease: A systematic review and meta-analysis

BACKGROUND

Previous studies have reported a higher prevalence of sexual dysfunction (SD) in patients with Parkinson's disease (PD). In the current study, we aimed to conduct a systematic review and meta-analysis to investigate the role of PD as a potential risk factor for SD in both genders.

METHODS

We performed a comprehensive search on PubMed, Embase, Scopus, and Web of Science. All observational studies comparing the prevalence of SD in PD with the general population were included.

RESULTS

After screening 22 studies were included in our qualitative and statistical analysis. We included 13 studies that reported odds ratio (OR) and found a significant association between PD and SD (pooled OR = 3.5, 95% CI = 2.19-5.58). Five studies included only male patients and reported an OR of 3.34 (95% CI = 1.34-8.35; heterogeneity I2 = 81%, Tau2 = 0.79, p < 0.00), while seven studies included both sexes and reported an OR of 3.55 (95% CI = 1.89-6.66; heterogeneity I2 = 78%, Tau2 = 0.53, p < 0.00).

CONCLUSION

In conclusion, our study suggests a strong association between PD and SD in both men and women. Our analysis of 22 observational studies reveals that the prevalence of sexual dysfunction is significantly higher in patients with PD compared to the general population. These findings highlight the importance of addressing SD as part of the comprehensive management of patients with PD.

Computerized analysis of hypomimia and hypokinetic dysarthria for improved diagnosis of Parkinson's disease

Background and Objective

An aging society requires easy-to-use approaches for diagnosis and monitoring of neurodegenerative disorders, such as Parkinson's disease (PD), so that clinicians can effectively adjust a treatment policy and improve patients' quality of life. Current methods of PD diagnosis and monitoring usually require the patients to come to a hospital, where they undergo several neurological and neuropsychological examinations. These examinations are usually time-consuming, expensive, and performed just a few times per year. Hence, this study explores the possibility of fusing computerized analysis of hypomimia and hypokinetic dysarthria (two motor symptoms manifested in the majority of PD patients) with the goal of proposing a new methodology of PD diagnosis that could be easily integrated into mHealth systems.

Methods

We enrolled 73 PD patients and 46 age- and gender-matched healthy controls, who performed several speech/voice tasks while recorded by a microphone and a camera. Acoustic signals were parametrized in the fields of phonation, articulation and prosody. Video recordings of a face were analyzed in terms of facial landmarks movement. Both modalities were consequently modeled by the XGBoost algorithm.

Results

The acoustic analysis enabled diagnosis of PD with 77% balanced accuracy, while in the case of the facial analysis, we observed 81% balanced accuracy. The fusion of both modalities increased the balanced accuracy to 83% (88% sensitivity and 78% specificity). The most informative speech exercise in the multimodality system turned out to be a tongue twister. Additionally, we identified muscle movements that are characteristic of hypomimia.

Conclusions

The introduced methodology, which is based on the myriad of speech exercises likewise audio and video modality, allows for the detection of PD with an accuracy of up to 83%. The speech exercise - tongue twisters occurred to be the most valuable from the clinical point of view. Additionally, the clinical interpretation of the created models is illustrated. The presented computer-supported methodology could serve as an extra tool for neurologists in PD detection and the proposed potential solution of mHealth will facilitate the patient's and doctor's life.

Familial α-synucleinopathy spectrum features in patients with psychiatric REM sleep behaviour disorder

BACKGROUND

Rapid eye movement (REM) sleep behaviour disorder (RBD) is one of the earliest and most specific prodromes of the α-synucleinopathies including Parkinson's disease (PD). It remains uncertain whether RBD occurring in the context of psychiatric disorders (psy-RBD), although very common, is merely a benign epiphenomenon of antidepressant treatment, or whether it harbours an underlying α-synucleinopathy. We hypothesised that patients with psy-RBD demonstrate a familial predisposition to an α-synucleinopathy.

METHODS

In this case-control-family study, a combination of family history and family study method was used to measure the α-synucleinopathy spectrum features, which included RBD, neurodegenerative prodromal markers and clinical diagnoses of neurodegenerative disorders. We compared the risk of α-synucleinopathy spectrum features in the first-degree relatives (FDRs) of patients with psy-RBD, psychiatric controls and healthy controls.

RESULTS

There was an increase of α-synucleinopathy spectrum features in the psy-RBD-FDRs, including possible and provisional RBD (adjusted HR (aHR)=2.02 and 6.05, respectively), definite RBD (adjusted OR=11.53) and REM-related phasic electromyographic activities, prodromal markers including depression (aHR=4.74) and probable subtle parkinsonism, risk of prodromal PD and clinical diagnosis of PD/dementia (aHR=5.50), as compared with healthy-control-FDRs. When compared with psychiatric-control-FDRs, psy-RBD-FDRs consistently presented with a higher risk for the diagnosis and electromyographic features of RBD, diagnosis of PD/dementia (aHR=3.91) and risk of prodromal PD. In contrast, psychiatric controls only presented with a familial aggregation of depression.

CONCLUSION

Patients with psy-RBD are familially predisposed to α-synucleinopathy. The occurrence of RBD with major depression may signify a subtype of major depressive disorders with underlying α-synucleinopathy neurodegeneration.

TRIAL REGISTRATION NUMBER

NCT03595475.

Relevance of tissue-resident memory CD8 T cells in the onset of Parkinson's disease and examination of its possible etiologies: infectious or autoimmune?

Tissue-resident memory CD8 T cells are responsible for local immune surveillance in different tissues, including the brain. They constitute the first line of defense against pathogens and cancer cells and play a role in autoimmunity. A recently published study demonstrated that CD8 T cells with markers of residency containing distinct granzymes and interferon-γ infiltrate the parenchyma of the substantia nigra and contact dopaminergic neurons in an early premotor stage of Parkinson's disease. This infiltration precedes α-synuclein aggregation and neuronal loss in the substantia nigra, suggesting a relevant role for CD8 T cells in the onset of the disease. To date, the nature of the antigen that initiates the adaptive immune response remains unknown. This review will discuss the role of tissue-resident memory CD8 T cells in brain immune homeostasis and in the onset of Parkinson's disease and other neurological diseases. We also discuss how aging and genetic factors can affect the CD8 T cell immune response and how animal models can be misleading when studying human-related immune response. Finally, we speculate about a possible infectious or autoimmune origin of Parkinson's disease.

Comparison of different risk scores for Parkinson disease in a population-based 10-year study

BACKGROUND AND PURPOSE

Different algorithms aiming to identify individuals at risk of Parkinson disease (PD) have been proposed. Comparative studies of these scores and their recent updates in the general elder population are needed.

METHODS

We have previously applied the "basic" PREDICT-PD algorithm, designed for remote screening, and the original and updated Movement Disorder Society (MDS) criteria for prodromal PD to the longitudinal population-based Bruneck study cohort. We have now additionally employed the "enhanced" PREDICT-PD algorithm (which includes motor assessment, olfaction, probable rapid eye movement sleep behaviour disorder status, pesticide exposure, and diabetes as additional factors). Risk scores were calculated based on comprehensive baseline assessments (2005) in 574 subjects aged 55-94 years (290 females), and cases of incident PD were identified at 5-year (n = 11) and 10-year follow-up (n = 9). We analysed the association of the different log-transformed risk scores with incident PD at follow-up (calculated per 1-SD unit change).

RESULTS

The enhanced PREDICT-PD algorithm was associated with incident PD over 10-years of follow-up, yielding higher odds for incident PD (odds ratio [OR] = 4.61, 95% confidence interval [CI] = 2.68-7.93, p < 0.001) compared with the basic PREDICT-PD score (OR = 2.38, 95% CI = 1.49-3.79, p < 0.001). The updated MDS prodromal criteria yielded a numerically higher OR of 7.13 (95% CI = 3.49-14.54, p < 0.001) in comparison with the original criteria as well as the enhanced PREDICT-PD algorithm, with overlapping 95% CIs.

CONCLUSIONS

The enhanced PREDICT-PD algorithm was significantly associated with incident PD. The consistent performance of both the enhanced PREDICT-PD algorithm and the updated MDS prodromal criteria compared to their original versions supports their use in PD risk screening.

Polygenic risk score for Parkinson's disease and olfaction among middle-aged to older women

INTRODUCTION

Olfactory impairment and Parkinson's disease (PD) may share common genetic and environmental risk factors. This study investigates the association of a PD polygenic risk score (PRS) with olfaction, and whether the associations are modified by environmental exposures of PM2.5, NO2, or smoking.

METHODS

This analysis included 3358 women (aged 50-80) from the Sister Study with genetic data and results from the Brief Smell Identification Test (B-SIT) administered in 2018-2019. PD PRS was calculated using 90 single nucleotide polymorphisms. Olfactory impairment was defined with different B-SIT cutoffs, and PD diagnosis was adjudicated via expert review. We report odds ratios (ORs) and 95% confidence intervals (CIs) from multivariable logistic regression.

RESULTS

As expected, PD PRS was strongly associated with the odds of having PD (OR highest vs. lowest quartile = 3.79 (1.64, 8.73)). The highest PRS quartile was also associated with olfactory impairment, with OR ranging from 1.24 (0.98, 1.56) for a B-SIT cutoff of 9 to 1.42 (1.04, 1.92) for a cutoff of 6. For individual B-SIT items, the highest PRS quartile was generally associated with lower odds of correctly identifying the odorant, albeit only statistically significant for pineapple (0.72 (0.56, 0.94), soap (0.76 (0.58, 0.99)) and rose (0.70 (0.54, 0.92)). The association of PD PRS with olfactory impairment was not modified by airborne environmental exposures or smoking.

CONCLUSION

These preliminary data suggest that high PD genetic susceptibility is associated with olfactory impairment in middle-aged and older women.

Nigral-specific increase in ser31 phosphorylation compensates for tyrosine hydroxylase protein and nigrostriatal neuron loss: Implications for delaying parkinsonian signs

Compensatory mechanisms that augment dopamine (DA) signaling are thought to mitigate onset of hypokinesia prior to major loss of tyrosine hydroxylase (TH) in striatum that occurs in Parkinson's disease. However, the identity of such mechanisms remains elusive. In the present study, the rat nigrostriatal pathway was unilaterally-lesioned with 6-hydroxydopamine (6-OHDA) to determine whether differences in DA content, TH protein, TH phosphorylation, or D1 receptor expression in striatum or substantia nigra (SN) aligned with hypokinesia onset and severity at two time points. In striatum, DA and TH loss reached its maximum (>90%) 7 days after lesion induction. However, in SN, no DA loss occurred, despite ∼60% TH loss. Hypokinesia was established at 21 days post-lesion and maintained at 28 days. At this time, DA loss was ∼60% in the SN, but still of lesser magnitude than TH loss. At day 7 and 28, ser31 TH phosphorylation increased only in SN, corresponding to less DA versus TH protein loss. In contrast, ser40 TH phosphorylation was unaffected in either region. Despite DA loss in both regions at day 28, D1 receptor expression increased only in lesioned SN. These results support the concept that augmented components of DA signaling in the SN, through increased ser31 TH phosphorylation and D1 receptor expression, contribute as compensatory mechanisms against progressive nigrostriatal neuron and TH protein loss, and may mitigate hypokinesia severity.

A Review on the Clinical Diagnosis of Multiple System Atrophy

Multiple system atrophy (MSA) is a rare, adult-onset, progressive neurodegenerative disorder with major diagnostic challenges. Aiming for a better diagnostic accuracy particularly at early disease stages, novel Movement Disorder Society criteria for the diagnosis of MSA (MDS MSA criteria) have been recently developed. They introduce a neuropathologically established MSA category and three levels of clinical diagnostic certainty including clinically established MSA, clinically probable MSA, and the research category of possible prodromal MSA. The diagnosis of clinically established and clinically probable MSA is based on the presence of cardiovascular or urological autonomic failure, parkinsonism (poorly L-Dopa-responsive for the diagnosis of clinically established MSA), and cerebellar syndrome. These core clinical features need to be associated with supportive motor and non-motor features (MSA red flags) and absence of any exclusion criteria. Characteristic brain MRI markers are required for a diagnosis of clinically established MSA. A research category of possible prodromal MSA is devised to capture patients manifesting with autonomic failure or REM sleep behavior disorder and only mild motor signs at the earliest disease stage. There is a number of promising laboratory markers for MSA that may help increase the overall clinical diagnostic accuracy. In this review, we will discuss the core and supportive clinical features for a diagnosis of MSA in light of the new MDS MSA criteria, which laboratory tools may assist in the clinical diagnosis and which major differential diagnostic challenges should be borne in mind.

Cryopreserved clinical-grade human embryonic stem cell-derived dopaminergic progenitors function in Parkinson's disease models

AIM

Parkinson's Disease (PD) is a common age-related neurodegenerative disorder with a rising prevalence. Human pluripotent stem cells have emerged as the most promising source of cells for midbrain dopaminergic (mDA) neuron replacement in PD. This study aimed to generate transplantable mDA progenitors for treatment of PD.

MATERIALS AND METHODS

Here, we optimized and fine-tuned a differentiation protocol using a combination of small molecules and growth factors to induce mDA progenitors to comply with good manufacturing practice (GMP) guidelines based on our clinical-grade human embryonic stem cell (hESC) line.

KEY FINDINGS

The resulting mDA progenitors demonstrated robust differentiation and functional properties in vitro. Moreover, cryopreserved mDA progenitors were transplanted into 6-hydroxydopamine-lesioned rats, leading to functional recovery.

SIGNIFICANCE

We demonstrate that our optimized protocol using a clinical hESC line is suitable for generating clinical-grade mDA progenitors and provides the ground work for future translational applications.

Risk and protective factors in Parkinson's disease: a simultaneous and prospective study with classical statistical and novel machine learning models

BACKGROUND

Several environmental/lifestyle factors have been individually investigated in previous Parkinson's disease (PD) studies with controversial results. No study has prospectively and simultaneously investigated potential risk/protective factors of PD using both classical statistical and novel machine learning analyses. The latter may reveal more complex associations and new factors that are undetected by merely linear models. To fill this gap, we simultaneously investigated potential risk/protective factors involved in PD in a large prospective population study using both approaches.

METHODS

Participants in the Moli-sani study were enrolled between 2005 and 2010 and followed up until December 2018. Incident PD cases were identified by individual-level record linkage to regional hospital discharge forms, the Italian death registry, and the regional prescription register. Exposure to potential risk/protective factors was assessed at baseline. Multivariable Cox Proportional Hazards (PH) regression models and survival random forests (SRF) were built to identify the most influential factors.

RESULTS

We identified 213 incident PD cases out of 23,901 subjects. Cox PH models revealed that age, sex, dysthyroidism and diabetes were associated with an increased risk of PD. Both hyper and hypothyroidism were independently associated with PD risk. SRF showed that age was the most influential factor in PD risk, followed by coffee intake, daily physical activity, and hypertension.

CONCLUSION

This study sheds light on the role of dysthyroidism, diabetes and hypertension in PD onset, characterized to date by an uncertain relationship with PD, and also confirms the relevance of most factors (age, sex, coffee intake, daily physical activity) reportedly shown be associated with PD. Further methodological developments in SRF models will allow to untangle the nature of the potential non-linear relationships identified.

Exploring depression in Parkinson's disease: an Italian Delphi Consensus on phenomenology, diagnosis, and management

BACKGROUND

Depression is a prodromic and a frequent non-motor symptom of Parkinson's disease, associated to reduced quality of life and poor outcomes. The diagnosis of depression in parkinsonian patients represents a challenge due to the overlapping of symptoms typical of the two conditions.

METHODS

A Delphi panel survey was performed to reach a consensus amongst different Italian specialists on four main topics: the neuropathological correlates of depression, main clinical aspects, diagnosis, and management of depression in Parkinson's disease.

RESULTS AND CONCLUSION

Experts have recognized that depression is an established risk factor of PD and that its anatomic substrate is related to the neuropathological abnormalities typical of the disease. Multimodal and SSRI antidepressant have been confirmed as a valid therapeutic option in the treatment of depression in PD. Tolerability, safety profile, and potential efficacy on broad spectrum of symptoms of depression including cognitive symptoms and anhedonia should be considered when selecting an antidepressant and the choice should be tailored on the patients' characteristics.

The pharmacological management of the behavioral aspects of Parkinson's disease: an update

INTRODUCTION

Behavioural symptoms are common manifestations of Parkinson's disease and include depression, anxiety, impulse control disorders, hallucinations, psychosis, and cognitive dysfunction. They remain inadequately addressed in many patients despite their relevance for quality of life and disability. This applies also to impulse control disorders where the most common approach in recent literature is to refrain from using dopamine agonists without consideration about their potential benefit on motor complications.

AREAS COVERED

We conducted a narrative review searching for articles on behavioral symptoms in Parkinson disease and selected those which included involved neurotransmitters such as dopamine, noradrenaline, serotonin, acetylcholine. We specifically focused our search on open-label and randomized double-blind studies and biomarkers which could best characterize these clinical manifestations.

EXPERT OPINION

Management of Parkinson disease behavioural manifestations lacks clear guidelines and standardized protocols beside general suggestions of dose adjustments in dopamine replacement therapy and use of antidepressants or antipsychotic drugs with little consideration of patients' age, sex, comorbidities, and motor status. We suggest a pragmatic approach which includes education of affected patients and caring people, dealing with complex cases by experienced multidisciplinary teams, use of cognitive behavioural therapy, and psychological counselling to complement drug treatment.

Evaluating cognitive impairment in the early stages of Parkinson's disease using the Cambridge brain sciences-cognitive platform

BACKGROUND

Non-motor symptoms (NMS) such as cognitive impairment are among common presentations in patients with Parkinson's disease (PD). In parallel with motor symptoms, these impediments can affect PD patients' quality of life. However, cognitive impairment has received less attention in early PD. On the other hand, the relationship between olfactory symptoms and cognitive impairment is unclear in early PD. Considering the importance of accurate and timely assessment of cognitive function in PD patients using readily available/validated tests, this study has employed the Cambridge Brain Sciences-Cognitive Platform (CBS-CP) as a computer-based tool to assess cognitive presentations in early PD patients.

METHODS

Thirty-four eligible males and females were assigned to PD and healthy controls (HCs). The cognitive performance was assessed using CBS-CP and Mini-Mental State Examination (MMSE), and olfactory function was measured through the standardized olfactory Quick Smell test (QST).

RESULTS

PD patients had poorer performance in all CBS-CP tasks, including short-term memory, attention, and reasoning domains than HCs. Meanwhile, the verbal domain task scores showed no significant difference between groups. PD MMSE results were in the normal range (mean=26.96), although there was a significant difference between the PD and HCs groups (P = 0.000). Our results revealed no correlation between cognitive impairment and olfactory function in PD patients.

CONCLUSION

Given the widely studied features of CBS-CP and its reliability across published evidence, CBS-CP appears to be a suitable measurement to evaluate cognitive impairment in early PD with normal MMSE scores. It seems cognitive and olfactory impairments are independent in early PD.

DATA AVAILABILITY STATEMENT

The datasets generated during the current study are available from the corresponding author upon reasonable request.

Diet quality and prodromal Parkinson's disease probability in isolated REM sleep behavior disorder

INTRODUCTION

It is reported that a diet that lowers oxidative stress reduces the prodromal Parkinson's disease (pPD) probability as well as the risk of Parkinson's disease (PD). In this study, we evaluated whether the diet quality of patients with isolated rapid eye movement (REM) sleep behavior disorder (iRBD) were associated with the pPD probability score, PD risk markers, or prodromal markers.

METHODS

Polysomnography (PSG)-confirmed iRBD patients from the Neurology Department at Seoul National University Hospital were enrolled. We calculated the pPD probability using the "Web-based Medical Calculator for Prodromal Risk in Parkinsonism" Diet quality was assessed using the Recommended Food Score (RFS).

RESULTS

We enrolled 101 patients with iRBD. The mean RFS score of patients with iRBD was 28.23 ± 9.29, which did not differ from the general population. Among patients with iRBD, the probability of pPD did not differ between the high and low RFS groups. In patients aged <70 years, although total RFS was not correlated with pPD probability (p = 0.529, Spearman rank correlation), legume consumption was negatively correlated with pPD probability (p = 0.032): furthermore, legume consumption was significantly higher in patients with fewer prodromal markers (p = 0.016).

CONCLUSION

Diet quality assessed by RFS did not differ between the general population and patients with iRBD in Korea. Further studies are needed to confirm these protective effects of legume consumption on iRBD, which may have strong implications for the prevention and management of PD.

Imaging Markers in Genetic Forms of Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disorder characterized by motor symptoms such as bradykinesia, rigidity, and resting tremor. While the majority of PD cases are sporadic, approximately 15-20% of cases have a genetic component. Advances in neuroimaging techniques have provided valuable insights into the pathophysiology of PD, including the different genetic forms of the disease. This literature review aims to summarize the current state of knowledge regarding neuroimaging findings in genetic PD, focusing on the most prevalent known genetic forms: mutations in the GBA1, LRRK2, and Parkin genes. In this review, we will highlight the contributions of various neuroimaging modalities, including positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI), in elucidating the underlying pathophysiological mechanisms and potentially identifying candidate biomarkers for genetic forms of PD.

Subjective Cognitive Decline in Women with Features Suggestive of Prodromal Parkinson's Disease

BACKGROUND

Cognitive deficits can be present in the prodromal phase of Parkinson's disease (PD). Subjective cognitive decline (SCD) may contribute to identifying individuals with prodromal PD.

OBJECTIVE

The objective of this study was to examine whether SCD is more likely to be present in women with features suggestive of prodromal PD compared with women without these features.

METHODS

The study population comprised 12,427 women from the Nurses' Health Study selected to investigate prodromal PD. Prodromal and risk markers of PD were assessed via self-administered questionnaires. We evaluated the association of hyposmia, constipation, and probable rapid eye movement sleep behavior disorder, three major features of prodromal PD, with SCD, adjusting for age, education, body mass index, physical activity, smoking, alcohol, caffeine intake, and depression. We also explored whether SCD was associated with the probability of prodromal PD and conducted additional analyses using data from neurocognitive tests.

RESULTS

Women experiencing the three examined nonmotor features had the worst mean SCD score and the highest odds of poor subjective cognition (odds ratio [OR] = 1.78; 95% confidence interval [CI], 1.29-2.47). This association persisted when women with objective cognitive deficits were excluded from analyses. SCD was also more common in women with a probability of prodromal PD ≥0.80, particularly among those aged younger than 75 years (OR of poor subjective cognition = 6.57 [95% CI, 2.43-17.77]). These observations were consistent with the results from analyses using neurocognitive tests, where a worse global cognitive performance was observed among women with three features.

CONCLUSIONS

Our study suggests that self-perceived cognitive decline can be present during the prodromal phase of PD. © 2023 International Parkinson and Movement Disorder Society.

Wearable movement-tracking data identify Parkinson's disease years before clinical diagnosis

Parkinson's disease is a progressive neurodegenerative movement disorder with a long latent phase and currently no disease-modifying treatments. Reliable predictive biomarkers that could transform efforts to develop neuroprotective treatments remain to be identified. Using UK Biobank, we investigated the predictive value of accelerometry in identifying prodromal Parkinson's disease in the general population and compared this digital biomarker with models based on genetics, lifestyle, blood biochemistry or prodromal symptoms data. Machine learning models trained using accelerometry data achieved better test performance in distinguishing both clinically diagnosed Parkinson's disease (n = 153) (area under precision recall curve (AUPRC) 0.14 ± 0.04) and prodromal Parkinson's disease (n = 113) up to 7 years pre-diagnosis (AUPRC 0.07 ± 0.03) from the general population (n = 33,009) compared with all other modalities tested (genetics: AUPRC = 0.01 ± 0.00, P = 2.2 × 10-3; lifestyle: AUPRC = 0.03 ± 0.04, P = 2.5 × 10-3; blood biochemistry: AUPRC = 0.01 ± 0.00, P = 4.1 × 10-3; prodromal signs: AUPRC = 0.01 ± 0.00, P = 3.6 × 10-3). Accelerometry is a potentially important, low-cost screening tool for determining people at risk of developing Parkinson's disease and identifying participants for clinical trials of neuroprotective treatments.

The Role of Helicobacter pylori and Small Intestinal Bacterial Overgrowth in Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder whose etiology remains largely unexplained. Several studies have aimed to describe a causative effect in the interactions between the gastrointestinal tract and the brain, for both PD pathogenesis and disease course. However, the results have been controversial. Helicobacter pylori and small intestinal bacterial overgrowth (SIBO) are theorized to be agents capable of triggering chronic proinflammatory changes with a possible neurotoxic effect, as well as a cause of erratic L-dopa response in PD patients. This review evaluates the individual and possibly synergistic influence of H. pylori and SIBO on PD, to provide an opportunity to consider prospective therapeutic approaches.

REM Sleep Behavior Disorder and Other REM Parasomnias

OBJECTIVE

This article reviews rapid eye movement (REM) sleep behavior disorder (RBD) and other REM sleep parasomnias, particularly recurrent isolated sleep paralysis and nightmare disorder.

LATEST DEVELOPMENTS

People with RBD have dream enactment behaviors that can be distressing and cause injuries to themselves or a bed partner. Diagnosis of RBD still requires video polysomnography but new evaluative techniques are emerging. Automatic scoring of REM sleep without atonia, the polysomnographic RBD feature, has led to clearer diagnostic cutoff values. Isolated RBD is strongly linked with neurodegenerative disorders, particularly α-synucleinopathies, with a median latency to neurodegenerative disease diagnosis of 8 years. Mounting imaging, electrophysiologic, and pathologic evidence supports neurodegenerative changes in patients with isolated RBD. Safety precautions should be reviewed with patients to reduce the risk of injury. Clonazepam and melatonin are first-line agents for RBD symptoms, and rivastigmine appears to be beneficial for RBD in people with mild cognitive impairment. For nightmare disorder, image rehearsal therapy is effective and can be delivered through online platforms.

ESSENTIAL POINTS

While RBD symptoms can often be managed, patients with isolated RBD should be monitored for signs and symptoms of impending neurodegenerative disease. Individuals who wish to know about the associated risk should be counseled accordingly to allow planning and involvement in research if they choose. Exercise may have some neuroprotective effects, although no treatment has been shown to modify the neurodegenerative risk.

An Overview of Gastrointestinal Dysfunction in Parkinsonian Syndromes

Gastrointestinal (GI) dysfunction is a common nonmotor symptom in Parkinson's disease (PD) as well as other parkinsonian syndromes and may precede the onset of motor symptoms by decades. Involvement of all segments of the GI tract can lead to altered responses to medications and worsened quality of life for patients. While some GI symptoms occur in isolation, others overlap. Therefore, understanding the changes in different segments of the GI tract and how they relate to altered responses to PD treatment can guide both diagnostic and pharmacological interventions. Gut microbiota plays a critical role in immune activity and modulation of the enteric and central nervous systems. Understanding this bidirectional relationship helps to elucidate the pathogenesis of neurodegeneration. This review will describe the current understanding of how GI dysfunction develops in parkinsonian syndromes, common symptoms in PD and related disorders, and available treatments.

Cytokine and chemokine map of peripheral specific immune cell subsets in Parkinson's disease

Peripheral immune cells play a vital role in the development of Parkinson's disease (PD). However, their cytokine and chemokine secretion functions remain unclear. Therefore, we aimed to explore the cytokine and chemokine secretion functions of specific immune cell subtypes in drug-naïve patients with PD at different ages of onset. We included 10 early-onset and 10 late-onset patients with PD and age-matched healthy controls (HCs). We used mass cytometry to select specific immune cell subsets and evaluate intracellular cytokine and chemokine expression. Statistical tests included t-tests, analysis of variance, bivariate correlation analysis, and linear regression analysis. Compared with HCs, patients with PD exhibited significantly decreased intracellular pro-inflammatory cytokines and chemokines in selected clusters (e.g., tumor necrosis factor (TNF)-α, interleukin (IL)-8, IL-1β, and CC-chemokine ligand (CCL)17). Specific cytokines and cell clusters were associated with clinical symptoms. TNF-α played an important role in cognitive impairment. Intracellular TNF-α levels in the naïve CD8⁺ T-cell cluster C16 (CD57^- naïve CD8⁺ T) and natural killer (NK) cell cluster C32 (CD57^- CD28^- NK) were negatively correlated with Montreal Cognitive Assessment scores. The C16 cluster affected cognitive function and motor symptoms. Increased TNF-α and decreased interferon-γ expression in C16 correlated with increased Unified Parkinson's Disease Rating Scale III scores in patients with PD. In summary, we developed a more detailed cytokine and chemokine map of peripheral specific CD8⁺ T cell and NK cell subsets, which revealed disrupted secretory function in patients with PD and provided unique clues for further mechanistic exploration.

Depressive symptoms in Parkinson's disease are insufficiently but more often treated than in other chronic conditions

Depressive symptoms in Parkinson's disease (PD) are multifactorial and are partly linked to the underlying dopaminergic deficit. However, at least a subset of PD patients may exhibit an unspecific depressive reaction to chronic illness. Here, we compared the prevalence and severity of depressive symptoms in PD patients and disease controls (DC). PD patients reported depressive symptoms at similar frequencies as DC but were on antidepressants, especially Mirtazapine, more frequently. Still, in both groups, a high proportion of patients with clinically significant depressive symptoms was not receiving medication. Diagnosis and treatment of depressive symptoms both in PD and DC should be improved.

Two distinct trajectories of clinical and neurodegeneration events in Parkinson's disease

Increasing evidence suggests that Parkinson's disease (PD) exhibits disparate spatial and temporal patterns of progression. Here we used a machine-learning technique-Subtype and Stage Inference (SuStaIn) - to uncover PD subtypes with distinct trajectories of clinical and neurodegeneration events. We enrolled 228 PD patients and 119 healthy controls with comprehensive assessments of olfactory, autonomic, cognitive, sleep, and emotional function. The integrity of substantia nigra (SN), locus coeruleus (LC), amygdala, hippocampus, entorhinal cortex, and basal forebrain were assessed using diffusion and neuromelanin-sensitive MRI. SuStaIn model with above clinical and neuroimaging variables as input was conducted to identify PD subtypes. An independent dataset consisting of 153 PD patients and 67 healthy controls was utilized to validate our findings. We identified two distinct PD subtypes: subtype 1 with rapid eye movement sleep behavior disorder (RBD), autonomic dysfunction, and degeneration of the SN and LC as early manifestations, and cognitive impairment and limbic degeneration as advanced manifestations, while subtype 2 with hyposmia, cognitive impairment, and limbic degeneration as early manifestations, followed later by RBD and degeneration of the LC in advanced disease. Similar subtypes were shown in the validation dataset. Moreover, we found that subtype 1 had weaker levodopa response, more GBA mutations, and poorer prognosis than subtype 2. These findings provide new insights into the underlying disease biology and might be useful for personalized treatment for patients based on their subtype.

Exercise knowledge, barriers and motivators among LRRK2 G2019S mutation carriers

INTRODUCTION

People with a Gly2019Ser mutation in the leucine-rich repeat kinase 2 (LRRK2 G2019S) are at increased risk of developing Parkinson's disease (PD). Recent evidence suggests that exercise may delay or prevent the development of clinically overt symptoms of PD in people at risk of PD. We determined whether LRRK2 G2019S mutation carriers with and without manifest PD are aware of the relationship between exercise and PD and how they differ in awareness, barriers and motivators to exercise.

METHODS

We deployed a survey among 4422 LRRK2 G2019S mutation carriers. In total, 505 (11.4%) of them completed the survey, of whom 105 had self-reported manifest PD.

RESULTS

Ninety-two percent of the LRRK2 G2019S mutation carriers with manifest PD and 63% of those with non-manifest PD were aware of the relationship between exercise and PD. Lack of motivation was the top barrier for those without manifest PD, while having an injury/disability was the most common barrier for those with manifest PD. Improvement of body functioning was the top motivator for both.

CONCLUSION

The fact that many at-risk individuals are not aware of the importance of exercise and would exercise more with fewer barriers creates opportunities for trials using exercise as a possible prevention strategy for PD.

Peripheral blood inflammatory cytokines in prodromal and overt α-synucleinopathies: a review of current evidence

While the pathomechanisms of α-synucleinopathies are not completely understood, accumulating evidence suggests a role of neuroinflammation in the development and progression of the diseases. In addition, emerging data provide insights into the potential role of central neuroinflammation in prodromal α-synucleinopathies. Given the considerable bidirectional crosstalk between peripheral and central inflammation, peripheral blood inflammatory cytokines may be a useful tool to understand immune responses in association with α-synucleinopathies. Indeed, the accessibility and practicality of using blood samples have facilitated multiple investigations evaluating peripheral blood inflammatory cytokines in overt α-synucleinopathies, whereas the associations between these biomarkers and prodromal α-synucleinopathies remain unclear. In this review, we provide an overview of the current evidence available for the role of peripheral blood inflammatory cytokines in prodromal and overt α-synucleinopathies.

Predictive value of abbreviated olfactory tests in prodromal Parkinson disease

There is disagreement in the literature whether olfaction may show specific impairments in Parkinson Disease (PD) and if olfactory tests comprised of selected odors could be more specific for diagnosis. We sought to validate previously proposed subsets of the University of Pennsylvania Smell Identification Test (UPSIT) odors for predicting conversion to PD in an independent, prodromal cohort. Conversion to PD was assessed in 229 participants in the Parkinson At Risk Study who completed baseline olfactory testing with the UPSIT and up to 12 years of clinical and imaging evaluations. No commercially available or proposed subset performed better than the full 40-item UPSIT. The proposed "PD-specific" subsets also did not perform better than expected by chance. We did not find evidence for selective olfactory impairment in Parkinson disease. Shorter odor identification tests, including commercially available 10-12 item tests, may have utility for ease of use and cost, but not for superior predictive value.

Uric acid and neurological disease: a narrative review

Hyperuricemia often accompanies hypertension, diabetes, dyslipidemia, metabolic syndrome, and chronic renal disease; it is also closely related to cardiovascular disease. Moreover, several epidemiological studies have linked hyperuricemia and ischemic stroke. However, uric acid may also have neuroprotective effects because of its antioxidant properties. An association between low uric acid levels and neurodegenerative diseases has been suggested, which may be attributed to diminished neuroprotective effects as a result of reduced uric acid. This review will focus on the relationship between uric acid and various neurological diseases including stroke, neuroimmune diseases, and neurodegenerative diseases. When considering both the risk and pathogenesis of neurological diseases, it is important to consider the conflicting dual nature of uric acid as both a vascular risk factor and a neuroprotective factor. This dual nature of uric acid is important because it may help to elucidate the biological role of uric acid in various neurological diseases and provide new insights into the etiology and treatment of these diseases.

Sleeping Beauty transposon system for GDNF overexpression of entrapped stem cells in fibrin hydrogel in a rat model of Parkinson's disease

There is currently no causal treatment available for Parkinson's disease (PD). However, the use of glial cell line-derived neurotrophic factor (GDNF) to provide regenerative effects for neurons is promising. Such approaches require translational delivery systems that are functional in diseased tissue. To do so, we used a non-viral Sleeping Beauty (SB) transposon system to overexpress GDNF in adipose tissue-derived mesenchymal stromal cells (adMSCs). Entrapment of cells in fibrin hydrogel was used to boost potential neurorestorative effects. Functional GDNF-adMSCs were able to secrete 1066.8 ± 169.4 ng GDNF/120,000 cells in vitro. The GDNF-adMSCs were detectable for up to 1 month after transplantation in a mild 6-hydroxydopamine (6-OHDA) hemiparkinson male rat model. Entrapment of GDNF-adMSCs enabled GDNF secretion in surrounding tissue in a more concentrated manner, also tending to prolong GDNF secretion relatively. GDNF-adMSCs entrapped in hydrogel also led to positive immunomodulatory effects via an 83% reduction of regional IL-1β levels compared to the non-entrapped GDNF-adMSC group after 1 month. Furthermore, GDNF-adMSC-treated groups showed higher recovery of tyrosine hydroxylase (TH)-expressing cells, indicating a neuroprotective function, although this was not strong enough to show significant improvement in motor performance. Our findings establish a promising GDNF treatment system in a PD model. Entrapment of GDNF-adMSCs mediated positive immunomodulatory effects. Although the durability of the hydrogel needs to be extended to unlock its full potential for motor improvements, the neuroprotective effects of GDNF were evident and safe. Further motor behavioral tests and other disease models are necessary to evaluate this treatment option adequately.

Dermal Real-Time Quaking-Induced Conversion Is a Sensitive Marker to Confirm Isolated Rapid Eye Movement Sleep Behavior Disorder as an Early α-Synucleinopathy

BACKGROUND

Skin biopsy is a potential tool for the premortem confirmation of an α-synucleinopathy.

OBJECTIVE

The aim was to assess the aggregation assay real-time quaking-induced conversion (RT-QuIC) of skin biopsy lysates to confirm isolated rapid eye movement sleep behavior disorder (iRBD) as an α-synucleinopathy.

METHODS

Skin biopsies of patients with iRBD, Parkinson's disease (PD), and controls were analyzed using RT-QuIC and immunohistochemical detection of phospho-α-synuclein.

RESULTS

α-Synuclein aggregation was detected in 97.4% of iRBD patients (78.4% of iRBD biopsies), 87.2% of PD patients (70% of PD biopsies), and 13% of controls (7.9% of control biopsies), with a higher seeding activity in iRBD compared to PD. RT-QuIC was more sensitive but less specific than immunohistochemistry.

CONCLUSIONS

Dermal RT-QuIC is a sensitive method to detect α-synuclein aggregation in iRBD, and high seeding activity may indicate a strong involvement of dermal nerve fibers in these patients. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Disruption of locus coeruleus-related functional networks in Parkinson's disease

Locus coeruleus (LC) is severely affected in Parkinson's Disease (PD). However, alterations in LC-related resting-state networks (RSNs) in PD remain unclear. We used resting-state functional MRI to investigate the alterations in functional connectivity (FC) of LC-related RSNs and the associations between RSNs changes and clinical features in idiopathic rapid eye movement sleep behavior disorder (iRBD) and PD patients with (PD^RBD+) and without RBD (PD^RBD-). There was a similarly disrupted FC pattern of LC-related RSNs in iRBD and PD^RBD+ patients, whereas LC-related RSNs were less damaged in PD^RBD- patients than that in patients with iRBD and PD^RBD+. The FC of LC-related RSNs correlated with cognition and duration in iRBD, depression in PD^RBD-, and cognition and severity of RBD in patients with PD^RBD+. Our findings demonstrate that LC-related RSNs are significantly disrupted in the prodromal stage of α-synucleinopathies and proposed body-first PD (PD^RBD+), but are less affected in brain-first PD (PD^RBD-).

Combining skin and olfactory α-synuclein seed amplification assays (SAA)-towards biomarker-driven phenotyping in synucleinopathies

Seed amplification assays (SAA) are becoming commonly used in synucleinopathies to detect α-synuclein aggregates. Studies in Parkinson's disease (PD) and isolated REM-sleep behavior disorder (iRBD) have shown a considerably lower sensitivity in the olfactory epithelium than in CSF or skin. To get an insight into α-synuclein (α-syn) distribution within the nervous system and reasons for low sensitivity, we compared SAA assessment of nasal brushings and skin biopsies in PD (n = 27) and iRBD patients (n = 18) and unaffected controls (n = 30). α-syn misfolding was overall found less commonly in the olfactory epithelium than in the skin, which could be partially explained by the nasal brushing matrix exerting an inhibitory effect on aggregation. Importantly, the α-syn distribution was not uniform: there was a higher deposition of misfolded α-syn across all sampled tissues in the iRBD cohort compared to PD (supporting the notion of RBD as a marker of a more malignant subtype of synucleinopathy) and in a subgroup of PD patients, misfolded α-syn was detectable only in the olfactory epithelium, suggestive of the recently proposed brain-first PD subtype. Assaying α-syn of diverse origins, such as olfactory (part of the central nervous system) and skin (peripheral nervous system), could increase diagnostic accuracy and allow better stratification of patients.

Longitudinal evolution of cortical thickness signature reflecting Lewy body dementia in isolated REM sleep behavior disorder: a prospective cohort study

BACKGROUND

The isolated rapid-eye-movement sleep behavior disorder (iRBD) is a prodromal condition of Lewy body disease including Parkinson's disease and dementia with Lewy bodies (DLB). We aim to investigate the longitudinal evolution of DLB-related cortical thickness signature in a prospective iRBD cohort and evaluate the possible predictive value of the cortical signature index in predicting dementia-first phenoconversion in individuals with iRBD.

METHODS

We enrolled 22 DLB patients, 44 healthy controls, and 50 video polysomnography-proven iRBD patients. Participants underwent 3-T magnetic resonance imaging (MRI) and clinical/neuropsychological evaluations. We characterized DLB-related whole-brain cortical thickness spatial covariance pattern (DLB-pattern) using scaled subprofile model of principal components analysis that best differentiated DLB patients from age-matched controls. We analyzed clinical and neuropsychological correlates of the DLB-pattern expression scores and the mean values of the whole-brain cortical thickness in DLB and iRBD patients. With repeated MRI data during the follow-up in our prospective iRBD cohort, we investigated the longitudinal evolution of the cortical thickness signature toward Lewy body dementia. Finally, we analyzed the potential predictive value of cortical thickness signature as a biomarker of phenoconversion in iRBD cohort.

RESULTS

The DLB-pattern was characterized by thinning of the temporal, orbitofrontal, and insular cortices and relative preservation of the precentral and inferior parietal cortices. The DLB-pattern expression scores correlated with attentional and frontal executive dysfunction (Trail Making Test-A and B: R = - 0.55, P = 0.024 and R = - 0.56, P = 0.036, respectively) as well as visuospatial impairment (Rey-figure copy test: R = - 0.54, P = 0.0047). The longitudinal trajectory of DLB-pattern revealed an increasing pattern above the cut-off in the dementia-first phenoconverters (Pearson's correlation, R = 0.74, P = 6.8 × 10^-4) but no significant change in parkinsonism-first phenoconverters (R = 0.0063, P = 0.98). The mean value of the whole-brain cortical thickness predicted phenoconversion in iRBD patients with hazard ratio of 9.33 [1.16-74.12]. The increase in DLB-pattern expression score discriminated dementia-first from parkinsonism-first phenoconversions with 88.2% accuracy.

CONCLUSION

Cortical thickness signature can effectively reflect the longitudinal evolution of Lewy body dementia in the iRBD population. Replication studies would further validate the utility of this imaging marker in iRBD.

Cognitive heterogeneity in Parkinson's disease: A mechanistic view

Cognitive impairment occurs in most individuals with Parkinson's disease (PD), exacting a high toll on patients, their caregivers, and the healthcare system. In this review, we begin by summarizing the current clinical landscape surrounding cognition in PD. We then discuss how cognitive impairment and dementia may develop in PD based on the spread of the pathological protein alpha-synuclein (aSyn) from neurons in brainstem regions to those in the cortical regions of the brain responsible for higher cognitive functions, as first proposed in the Braak hypothesis. We appraise the Braak hypothesis from molecular (conformations of aSyn), cell biological (cell-to-cell spread of pathological aSyn), and organ-level (region-to-region spread of aSyn pathology at the whole brain level) viewpoints. Finally, we argue that individual host factors may be the most poorly understood aspect of this pathological process, accounting for substantial heterogeneity in the pattern and pace of cognitive decline in PD.

Early detection of Parkinson's disease through enriching the electronic health record using a biomedical knowledge graph

Introduction

Early diagnosis of Parkinson's disease (PD) is important to identify treatments to slow neurodegeneration. People who develop PD often have symptoms before the disease manifests and may be coded as diagnoses in the electronic health record (EHR).

Methods

To predict PD diagnosis, we embedded EHR data of patients onto a biomedical knowledge graph called Scalable Precision medicine Open Knowledge Engine (SPOKE) and created patient embedding vectors. We trained and validated a classifier using these vectors from 3,004 PD patients, restricting records to 1, 3, and 5 years before diagnosis, and 457,197 non-PD group.

Results

The classifier predicted PD diagnosis with moderate accuracy (AUC = 0.77 ± 0.06, 0.74 ± 0.05, 0.72 ± 0.05 at 1, 3, and 5 years) and performed better than other benchmark methods. Nodes in the SPOKE graph, among cases, revealed novel associations, while SPOKE patient vectors revealed the basis for individual risk classification.

Discussion

The proposed method was able to explain the clinical predictions using the knowledge graph, thereby making the predictions clinically interpretable. Through enriching EHR data with biomedical associations, SPOKE may be a cost-efficient and personalized way to predict PD diagnosis years before its occurrence.

Defining the Riddle in Order to Solve It: There Is More Than One "Parkinson's Disease"

BACKGROUND

More than 200 years after James Parkinsondescribed a clinical syndrome based on his astute observations, Parkinson's disease (PD) has evolved into a complex entity, akin to the heterogeneity of other complex human syndromes of the central nervous system such as dementia, motor neuron disease, multiple sclerosis, and epilepsy. Clinicians, pathologists, and basic science researchers evolved arrange of concepts andcriteria for the clinical, genetic, mechanistic, and neuropathological characterization of what, in their best judgment, constitutes PD. However, these specialists have generated and used criteria that are not necessarily aligned between their different operational definitions, which may hinder progress in solving the riddle of the distinct forms of PD and ultimately how to treat them.

OBJECTIVE

This task force has identified current in consistencies between the definitions of PD and its diverse variants in different domains: clinical criteria, neuropathological classification, genetic subtyping, biomarker signatures, and mechanisms of disease. This initial effort for "defining the riddle" will lay the foundation for future attempts to better define the range of PD and its variants, as has been done and implemented for other heterogeneous neurological syndromes, such as stroke and peripheral neuropathy. We strongly advocate for a more systematic and evidence-based integration of our diverse disciplines by looking at well-defined variants of the syndrome of PD.

CONCLUSION

Accuracy in defining endophenotypes of "typical PD" across these different but interrelated disciplines will enable better definition of variants and their stratification in therapeutic trials, a prerequisite for breakthroughs in the era of precision medicine. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.