Modifiable risk and protective factors in disease development, progression and clinical subtypes of Parkinson's disease: What do prospective studies suggest?

Smoking-diseases correlation database: comprehensive analysis of the correlation between smoking and 422 diseases based on NHANES 2013-2018

Background

Smoking is a risk factor for a wide range of diseases. Previous research has confirmed over 30 Smoking-Associated Diseases in diverse systems. There is limited research exploring the correlation among multiple diseases, with an absence of comprehensive investigations. Few studies concentrate on diseases exhibiting a negative correlation with smoking, wherein smokers demonstrate a lower prevalence.

Objective

This study aimed to detect the correlation between smoking and other diseases using data from National Health and Nutrition Examination Surveys (NHANES) and construct a Smoking-Diseases Correlation Database (SDCD). The second aim is to obtain an extensive screening test for diseases that may be linked to smoking.

Methods

39,126 subjects' data from the NHANES 2013-2018 dataset were extracted. The baseline information, difference in blood routine and blood chemistry indicators between smokers and non-smokers, and diseases' correlation with smoking in four different models were analyzed by R. The data and statistics were aggregated into an online SDCD.

Results

Our study reported 46 Smoking-Associated Diseases (SAD), including 29 Smoking Positively Associated Diseases (SPAD) and 17 Smoking Negatively Associated Diseases (SNAD). The SDCD of 422 diseases was constructed and can be accessed at https://chatgptmodel.shinyapps.io/sdcd/.

Conclusion

Our findings revealed 46 SADs including 29 SPADs and 17 SNADs. We aggregated the statistics and developed online SDCD, advancing our understanding of the correlation between smoking and diseases.

Association of dietary selenium intake and all-cause mortality of Parkinson's disease and its interaction with blood cadmium level: a retrospective cohort study

BACKGROUND

Parkinson's disease (PD) is a slowly progressive neurodegenerating disease that may eventually lead to disabling condition and pose a threat to the health of aging populations. This study aimed to explore the association of two potential risk factors, selenium and cadmium, with the prognosis of Parkinson's disease as well as their interaction effect.

METHODS

Data were obtained from the National Health and Nutrition Examination Survey (NHANES) 2005-2006 to 2015-2016 and National Death Index (NDI). Participants were classified as Parkinson's patients by self-reported anti-Parkinson medications usage. Cox regression models and restricted cubic spline models were applied to evaluate the association between PD mortality and selenium intake level as well as blood cadmium level. Subgroup analysis was also conducted to explore the interaction between them.

RESULTS

A total of 184 individuals were included. In full adjusted cox regression model (adjusted for age, gender, race, hypertension, pesticide exposure, smoking status and caffeine intake), compared with participants with low selenium intake, those with normal selenium intake level were significantly associated with less risk of death (95%CI: 0.18-0.76, P = 0.005) while no significant association was found between low selenium intake group and high selenium group (95%CI: 0.16-1.20, P = 0.112). Restricted cubic spline model indicated a nonlinear relationship between selenium intake and PD mortality (P for nonlinearity = 0.050). The association between PD mortality and blood cadmium level was not significant (95%CI: 0.19-5.57, P = 0.112). However, the interaction term of selenium intake and blood cadmium showed significance in the cox model (P for interaction = 0.048). Subgroup analysis showed that the significant protective effect of selenium intake existed in populations with high blood cadmium but not in populations with low blood cadmium.

CONCLUSION

Moderate increase of selenium intake had a protective effect on PD mortality especially in high blood cadmium populations.

Use of antiviral drugs and incidence of Parkinson's disease in Taiwan

Patients infected with herpes zoster might be at risk for Parkinson's disease (PD). However, antiviral drugs may impede viral deoxyribonucleic acid (DNA) synthesis. This study aimed to determine whether the currently observed association between herpes zoster and PD is consistent with previous findings, and whether antiviral drug use is associated with PD. This retrospective cohort study used the Longitudinal Generation Tracking Database. We included patients aged 40 years and above and applied propensity score matching at 1:1 ratio for study comparability. PD risk was evaluated using Cox proportional hazards regression methods. A total of 234,730 people were analyzed. The adjusted hazard ratio (aHR) for PD in patients with herpes zoster was 1.05. Furthermore, the overall incidence of PD was lower in those treated with antiviral drugs than in the untreated ones (3.17 vs. 3.76 per 1,000 person-years); the aHR was 0.84. After stratifying for sex or age, a similar result was observed. In conclusion, herpes zoster may increase the risk of PD, particularly among females, but receiving antiviral treatment reduces the risk by 16%. Therefore, using antiviral drugs may help prevent PD. However, additional research is required to determine the underlying mechanism(s).

Progression subtypes in Parkinson's disease identified by a data-driven multi cohort analysis

The progression of Parkinson's disease (PD) is heterogeneous across patients, affecting counseling and inflating the number of patients needed to test potential neuroprotective treatments. Moreover, disease subtypes might require different therapies. This work uses a data-driven approach to investigate how observed heterogeneity in PD can be explained by the existence of distinct PD progression subtypes. To derive stable PD progression subtypes in an unbiased manner, we analyzed multimodal longitudinal data from three large PD cohorts and performed extensive cross-cohort validation. A latent time joint mixed-effects model (LTJMM) was used to align patients on a common disease timescale. Progression subtypes were identified by variational deep embedding with recurrence (VaDER). In each cohort, we identified a fast-progressing and a slow-progressing subtype, reflected by different patterns of motor and non-motor symptoms progression, survival rates, treatment response, features extracted from DaTSCAN imaging and digital gait assessments, education, and Alzheimer's disease pathology. Progression subtypes could be predicted with ROC-AUC up to 0.79 for individual patients when a one-year observation period was used for model training. Simulations demonstrated that enriching clinical trials with fast-progressing patients based on these predictions can reduce the required cohort size by 43%. Our results show that heterogeneity in PD can be explained by two distinct subtypes of PD progression that are stable across cohorts. These subtypes align with the brain-first vs. body-first concept, which potentially provides a biological explanation for subtype differences. Our predictive models will enable clinical trials with significantly lower sample sizes by enriching fast-progressing patients.

Association between Parkinson disease and selenium levels in the body: A systematic review and meta-analysis

BACKGROUND

Parkinson disease (PD) is a common neurodegenerative disorder, but its pathogenesis is still not entirely understood. While some trace elements, such as selenium, iron, and copper, are considered pivotal in PD onset due to their role in oxidative stress, the association between selenium concentrations and PD susceptibility remains ambiguous.

METHODS

A systematic review and meta-analysis was conducted in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and framed by the Patient, Intervention, Comparison, Outcome paradigm. Data were sourced from 4 prominent electronic databases: PubMed, Embase, Web of Science, and Cochrane Library. Eligible studies must have had a PD case group and a control group, both of which presented data on selenium concentrations. The quality of the studies was assessed using the Newcastle-Ottawa Scale.

RESULTS

Of 1541 initially identified articles, 12 studies comprising a total of 597 PD cases and 733 controls were selected for the meta-analysis. Pronounced heterogeneity was observed among these studies. When assessing blood selenium levels, no significant difference was found between patients with PD and the controls. However, when examining the cerebrospinal fluid, selenium levels in PD patients were significantly elevated compared to controls (standard mean difference = 1.21, 95% CI 0.04-2.39, P < .05). Subgroup analyses, sensitivity analyses, and evaluation of publication bias were performed to ensure data robustness.

CONCLUSIONS

Elevated selenium levels in cerebrospinal fluid may be associated with a higher risk of Parkinson. Further prospective research is required to solidify this potential link and to offer avenues for novel therapeutic interventions or preventive measures.

Opportunities and Pitfalls of REM Sleep Behavior Disorder and Olfactory Dysfunction as Early Markers in Parkinson's Disease

During its pre-motor stage, Parkinson's disease (PD) presents itself with a multitude of non-motor symptoms with different degrees of specificity and sensitivity. The most important among them are REM sleep behavior disorder (RBD) and olfactory dysfunction. RBD is a parasomnia characterized by the loss of REM sleep muscle atonia and dream-enacting behaviors. Olfactory dysfunction in individuals with prodromal PD is usually described as hyposmia (reduced sense of smell) or anosmia (complete loss of olfactory function). These symptoms can precede the full expression of motor symptoms by decades. A close comprehension of these symptoms and the underlying mechanisms may enable early screening as well as interventions to improve patients' quality of life. Therefore, these symptoms have unmatched potential for identifying PD patients in prodromal stages, not only allowing early diagnosis but potentially opening a window for early, possibly disease-modifying intervention. However, they come with certain challenges. This review addresses some of the key opportunities and pitfalls of both RBD and olfactory dysfunction as early markers of PD.

Exercise as medicine in Parkinson's disease

Parkinson's disease (PD) is an incurable and progressive neurological disorder leading to deleterious motor and non-motor consequences. Presently, no pharmacological agents can prevent PD evolution or progression, while pharmacological symptomatic treatments have limited effects in certain domains and cause side effects. Identification of interventions that prevent, slow, halt or mitigate the disease is therefore pivotal. Exercise is safe and represents a cornerstone in PD rehabilitation, but exercise may have even more fundamental benefits that could change clinical practice. In PD, the existing knowledge base supports exercise as (1) a protective lifestyle factor preventing the disease (ie, primary prevention), (2) a potential disease-modifying therapy (ie, secondary prevention) and (3) an effective symptomatic treatment (ie, tertiary prevention). Based on current evidence, a paradigm shift is proposed, stating that exercise should be individually prescribed as medicine to persons with PD at an early disease stage, alongside conventional medical treatment.

Prevention of Parkinson's Disease: From Risk Factors to Early Interventions

Parkinson's disease (PD) is a debilitating neurological disorder characterized by progressively worsening motor dysfunction. Currently, available therapies merely alleviate symptoms, and there are no cures. Consequently, some researchers have now shifted their attention to identifying the modifiable risk factors of PD, with the intention of possibly implementing early interventions to prevent the development of PD. Four primary risk factors for PD are discussed including environmental factors (pesticides and heavy metals), lifestyle (physical activity and dietary intake), drug abuse, and individual comorbidities. Additionally, clinical biomarkers, neuroimaging, biochemical biomarkers, and genetic biomarkers could also help to detect prodromal PD. This review compiled available evidence that illustrates the relationship between modifiable risk factors, biomarkers, and PD. In summary, we raise the distinct possibility of preventing PD via early interventions of the modifiable risk factors and early diagnosis.

The meaning and impact on well-being of bespoke dancing sessions for those living with Parkinson's

PURPOSE

This paper presents qualitative research findings from the evaluation of a Parkinson's Dance well-being venture in the UK.

METHODS

Qualitative data was gathered to see how bespoke dancing sessions helped people with Parkinson's (PwP) to manage their conditions and improve their lives and prospects. Principles of a participatory approach were incorporated and methods included semi-structured interviewing, researchers participant observation and an elicitation-based activity. Nineteen PwP, six carers, four dance artists and seven helpers participated in the study.

RESULTS

Participating in Parkinson's Dance sessions meant that PwP could experience the possibilities to dance, develop a "can do" attitude, experience fun, enjoyment, social connection, exercise, movement to music, improvement and/or maintenance of their balance, suppleness, coordination and confidence with movement, symptoms being pushed back and ability to learn new things.

CONCLUSIONS

Our findings add to the evidence-base about the benefits of dance for people experiencing Parkinson's and through novel application of the Life-world based well-being framework of K. T. Galvin and Todres (2011) we propose a theoretical basis for Parkinson's Dance as a resource for well-being. There is scope to consider application of the well-being framework to other arts activities and as the basis of an arts and well-being evaluation tool.

Do oral antidiabetic medications alter the risk of Parkinson's disease? An updated systematic review and meta-analysis

BACKGROUND

Diabetes mellitus is a known risk factor for Parkinson's disease (PD), but does this risk vary with antidiabetic medications is still unclear. This meta-analysis aims to compile evidence from the literature to assess the risk of idiopathic PD with various oral antidiabetic medications.

METHODS

Databases PubMed, CENTRAL, Scopus, Web of Science, and Embase were searched till 5th April 2023. Adjusted outcomes were pooled to generate a hazard ratio (HR) on the risk of PD with different antidiabetic medications.

RESULTS

Fifteen studies with 2,910,405 diabetic patients were eligible. Pooled analysis failed to show any significant difference in the risk of PD among users of metformin (HR: 1.05 95% CI: 0.91, 1.22 I2 = 81%), glitazones (HR: 0.84 95% CI: 0.68, 1.05 I2 = 91%), glucagon-like peptide-1 agonists (HR: 0.63 95% CI: 0.26, 1.55 I2 = 33%), and sulfonylureas (HR: 1.13 95% CI: 0.96, 1.32 I2 = 76%). However, a meta-analysis of four studies showed that dipeptidyl peptidase-4 inhibitor use was associated with reduced risk of PD in diabetics (HR: 0.69 95% CI: 0.56, 0.86 I2 = 46%). Insufficient data was available on sodium-glucose cotransporter-2 inhibitors, α-glucosidase inhibitors, and glinides.

CONCLUSIONS

Limited retrospective evidence indicates that DPP4i may reduce the risk of idiopathic PD in diabetics. Metformin, sulfonylureas, glucagon-like peptide-1 agonists, and glitazones were not associated with any change in the risk of PD. Further studies taking into confounding factors and using a common comparator group are needed to strengthen present evidence.

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.

Dopaminergic treatment strategies for people with Parkinson's disease in Europe: a retrospective analysis of PRISM trial data

BACKGROUND

Levodopa (LD) is the most effective drug to treat Parkinson's disease (PD). The recently concluded multinational Parkinson's Real-World Impact Assessment (PRISM) trial revealed highly variable prescription patterns of LD monotherapy across six European countries. The reasons remain unclear.

METHODS

In this post hoc analysis of PRISM trial data, we used multivariate logistic regression analysis to identify socio-economic factors affecting prescription practice. We applied receiver-operated characteristics and split sample validation to test model accuracy to predict treatment class (LD monotherapy vs. all other treatments).

RESULTS

Subject age, disease duration, and country of residence were significant predictors of treatment class. The chance of receiving LD monotherapy increased by 6.9% per year of age. In contrast, longer disease duration reduced the likelihood of receiving LD monotherapy by 9.7% per year. Compared to the other countries, PD patients in Germany were 67.1% less likely and their counterparts in the UK 86.8% more likely to receive an LD monotherapy. The model classification accuracy of treatment class assignment was 80.1%. The area under the curve to predict treatment condition was 0.758 (95% CI [0.715, 0.802]). Split sample validation revealed poor sensitivity (36.6%), but excellent specificity (92.7%) to predict treatment class.

CONCLUSION

The relative lack of socio-economic variables affecting prescription practice in the study sample and limited model accuracy to predict treatment class suggest the presence of additional, country-specific factors affecting prescription patterns that were not assessed in the PRISM trial. Our findings indicate that physicians still avoid prescribing LD monotherapy to younger PD patients.

Oral and intestinal dysbiosis in Parkinson's disease

The suspicion of an origin of Parkinson's disease (PD) at the periphery of the body and the involvement of environmental risk factors in the pathogenesis of PD have directed the attention of the scientific community towards the microbiota. The microbiota represents all the microorganisms residing both in and on a host. It plays an essential role in the physiological functioning of the host. In this article, we review the dysbiosis repeatedly demonstrated in PD and how it influences PD symptoms. Dysbiosis is associated with both motor and non-motor PD symptoms. In animal models, dysbiosis only promotes symptoms in individuals genetically susceptible to Parkinson's disease, suggesting that dysbiosis is a risk factor but not a cause of Parkinson's disease. We also review how dysbiosis contributes to the pathophysiology of PD. Dysbiosis induces numerous and complex metabolic changes, resulting in increased intestinal permeability, local and systemic inflammation, production of bacterial amyloid proteins that promote α-synuclein aggregation, as well as a decrease in short-chain fatty acid-producing bacteria that have anti-inflammatory and neuroprotective potential. In addition, we review how dysbiosis decreases the efficacy of dopaminergic treatments. We then discuss the interest of dysbiosis analysis as a biomarker of Parkinson's disease. Finally, we give an overview of how interventions modulating the gut microbiota such as dietary interventions, pro-biotics, intestinal decontamination and fecal microbiota transplantation could influence the course of PD.

Changes in smoking, alcohol consumption, and the risk of Parkinson's disease

Objective

There have been no studies on the association between changes in smoking and alcohol consumption or combined changes in smoking and alcohol consumption frequencies and PD risk. To assess the influence of changes in smoking and alcohol consumption on the risk of Parkinson's disease (PD).

Methods

National Health Insurance Service (NHIS) database between January 2009 to December 2011 was analyzed. A total of 3,931,741 patients were included. Study participants were followed up for the incidence of PD until December 2017.

Results

Compared to the sustained non-smokers, sustained light smokers (adjusted hazard ratio [aHR] 0.80, 95% confidence interval [CI] 0.75-0.85), sustained moderate smokers (aHR 0.54, 95% CI 0.47-0.61), and sustained heavy smokers (aHR 0.49, 95% CI 0.44-0.55) had a lower risk of PD. Compared to those who sustained non-drinking, sustained light drinkers (aHR 0.85 95% CI 0.89-0.91), sustained moderate drinkers (aHR 0.68, 95% CI 0.60-0.78), and sustained heavy drinkers (aHR 0.77, 95% CI 0.68-0.87) showed decreased risk of PD. Among non-drinkers, those who started drinking to a light level were at decreased risk of PD (aHR 0.84, 95% CI 0.77-0.91). Among non-smoking and non-drinking participants, those who initiated smoking only (aHR 0.78, 95% CI 0.70-0.86), drinking only (aHR 0.77, 95% CI 0.68-0.87), and both smoking and drinking (aHR 0.69, 95% CI 0.58-0.82) showed decreased risk of PD.

Conclusion

Smoking is associated with decreased risk of PD with a dose-response relationship. Alcohol consumption at a light level may also be associated with decreased risk of PD. Further studies are warranted to find the possible mechanisms for the protective effects of smoking and drinking on PD, which may present insights into the etiology of PD.

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.

Parkinson's Disease: A Tale of Many Players

In 2020, more than 9 million patients suffering from Parkinson's disease (PD) were reported worldwide, and studies predict that the burden of this disease will grow substantially in industrial countries. In the last decade, there has been a better understanding of this neurodegenerative disorder, clinically characterized by motor disturbances, impaired balance, coordination, memory difficulties, and behavioral changes. Various preclinical investigations and studies on human postmortem brains suggest that local oxidative stress and inflammation promote misfolding and aggregation of alpha-synuclein within Lewy bodies and cause nerve cell damage. Parallel to these investigations, the familial contribution to the disease became evident from studies on genome-wide association in which specific genetic defects were linked to neuritic alpha-synuclein pathology. As for treatment, currently available pharmacological and surgical interventions may improve the quality of life but do not stop the progress of neurodegeneration. However, numerous preclinical studies have provided insights into the pathogenesis of PD. Their results provide a solid base for clinical trials and further developments. In this review, we discuss the pathogenesis, the prospects, and challenges of synolytic therapy, CRISPR, gene editing, and gene- and cell-based therapy. We also throw light on the recent observation that targeted physiotherapy may help improve the gait and other motor impairments.

Time Taken for and Causes of a Decline to Hoehn and Yahr Stage 5 in Patients with Parkinson's Disease

Objective Prediction of time until and causes of becoming bedridden may help patients with Parkinson's disease (PD) plan their productive lives. This study assessed the relationship between the age at the PD onset and time taken to reach Hoehn and Yahr stage (HY) 5 as well as the causes of motor decline to HY5 in Japanese patients with PD. Patients We enrolled patients with PD who visited our institute between April 2015 and December 2020, met the UK brain bank criteria, had medical records from the early PD stage, and had had HY5 for over three months. The relationship between the age at the PD onset and the disease duration was evaluated. Data on the possible causes of motor decline to HY5 were obtained from patients, caregivers or medical records. Results In total, 123 patients with PD (mean age at the PD onset was 69.3 years old; 80 women and 43 men) were included. The age at the PD onset was significantly and negatively correlated with the time until the decline to HY5. Among the 123 patients, 49 reported that the natural course of PD caused the decline to HY5. Possible events that accelerated the motor decline to HY5 included traumatic injury, pneumonia, and other medical or social conditions that might have resulted in reduced daily activities. Conclusion The time until the decline to HY5 can be estimated based on the age at the PD onset. In addition to natural PD progression, medical or social conditions that reduce physical activity may accelerate motor decline to HY5.

Plasma extracellular vesicle tau, β-amyloid, and α-synuclein and the progression of Parkinson's disease: a follow-up study

Background

Plasma extracellular vesicle (EV) contents are promising biomarkers of Parkinson's disease (PD). The pathognomonic proteins of PD, including α-synuclein, tau, and β-amyloid, are altered in people with PD (PwP) and are associated with clinical presentation in previous cross-sectional studies. However, the dynamic changes in these plasma EV proteins in PwP and their correlation with clinical progression remain unclear.

Objective

We investigated the dynamic changes in plasma EV α-synuclein, tau, and β-amyloid and their correlation with/prediction of clinical progression in PwP.

Design

A cohort study.

Methods

In total, 103 PwP and 37 healthy controls (HCs) completed baseline assessment and 1-year follow-up. Clinical assessments included Unified Parkinson's Disease Rating Scale (UPDRS) parts II and III, Mini-Mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA). Plasma EVs were isolated, and immunomagnetic reduction-based immunoassay was used to assess α-synuclein, tau, and β-amyloid 1-42 (Aβ1-42) levels within the EVs.

Results

Compared with HCs, significant differences were noted in the annual changes in all three EV pathognomonic proteins in PwP. Although the absolute changes in plasma EV pathognomonic proteins did not significantly correlate with clinical changes, PwP with elevated baseline plasma EV tau (upper-half) levels demonstrated significantly greater decline in motor and cognition, and increased plasma EV α-synuclein levels were associated with postural instability and the gait disturbance motor subtype. For PwP with elevated levels of all three biomarkers, clinical deterioration was significant, as indicated by UPDRS-II scores, postural instability and gait disturbance subscores of UPDRS-III, and MMSE score.

Conclusion

The combination of plasma EV α-synuclein, tau, and Aβ1-42 may identify PwP with a high risk of deterioration. Our findings can elucidate the interaction between these pathognomonic proteins, and they may serve as treatment response markers and can be applied in treatment approaches for disease modification.

A Review of Genetic and Gene Therapy for Parkinson's Disease

Parkinson's disease (PD) is a syndrome with deterioration of neurons, with its onset starting in the '20s, known as the young beginning of Parkinson's to the late inception of the ailment in the 60s. The majority of the environmental risk associated with PD is age. The pathophysiology of PD is related to the accretion of synuclein alpha (SNCA) protein leading to toxicity. This toxicity further leads to a depletion in dopamine levels, creating both motor and non-motor symptoms. PD is the combination of genetic and environmental risk factors. Linkage and association studies provided data on autosomal dominant and recessive genes linked to PD. Current treatment regimes involve using levodopa, catechol-O-methyl transferase inhibitors, anticholinergics, and monoamine oxidase B (MAO-B) inhibitors. Genetic treatment is done by identifying possible targets. Gene therapy includes silencing, replacing, or correcting the flawed gene with a good gene. This therapy has the advantage of eliminating significant PD symptoms with fewer to no adverse effects than conventional treatment. These targets are organized into disease-modifying or non-disease modifying. The distinction between these two is that disease-modifying treatment stops the degeneration of neurons, while non-disease modifying treatment involves dopaminergic enzyme expression. In non-modifying targets, aromatic L-amino acid decarboxylase (AADC) therapy is used but not as a standalone, so the presentation of AADC, tyrosine hydroxylase (TH), and GTP cyclohydrolase 1 (GCH) is done together as a tricistronic system. With these developments, a drug named prosavin is under clinical phase 1 trial. Disease-modifying targets involve glial cell-derived neurotrophic factor (GDNF). Direct GDNF delivery reduces PD symptoms. This GDNF infusion technique works with a tetracycline-controlled transactivator. Gene therapy introduction into the treatment of PD would be beneficial as there would be lesser adverse effects seen as linked with conventional treatment involving levodopa, MAO-B inhibitors, and anticholinergics, among a few. This article discusses the genetic basis and genetic model of therapy for PD.

Effect of modifiable risk factors in Parkinson's disease: A case-control study looking at common dietary factors, toxicants, and anti-inflammatory medications

OBJECTIVE

To investigate how common modifiable exposures, including dietary factors, select toxicants, and anti-inflammatory medications, may affect Parkinson's disease.

METHODS

Using surveys, a case-control study was conducted at a medical center, comparing Parkinson's disease patients (N  =  149) and healthy controls (N  =  105). Subjects reported exposure to red meats, vegetables, alcohol, tobacco, anti-inflammatory medications, and pesticides. The relationship between exposures and Parkinson's disease diagnosis was analyzed by logistic regression to generate odds ratio and 95% confidence interval.

RESULTS

Consuming red meat "sometimes" or "always" was positively associated with Parkinson's disease as compared to eating red meats "rarely" or "never"; (odds ratio  =   2.15, 95% confidence interval   =   1.06, 4.39; p  =  0.03) and (odds ratio   =   4.47, 95% confidence interval   =   1.67, 11.94; p  =  0.003), respectively. Exposure to pesticides showed a positive association with Parkinson's disease (odds ratio  =   2.84, 95% confidence interval   =   1.34, 6.00; p  =  0.007). "Always" use of aspirin was inversely associated with Parkinson's disease (odds ratio  =   0.32, 95% confidence interval   =   0.14, 0.70; p  =  0.004). "Ever" having used anti-histamines was inversely associated with Parkinson's disease (odds ratio  =   0.37, 95% confidence interval  =  0.17, 0.81; p  =  0.01).

DISCUSSION

Our study suggests that there are modifiable external factors that are associated with Parkinson's disease. The present study can thus assist clinicians, policy makers, and people living with Parkinson's disease in improving the experience and management of Parkinson's disease.

The Role of Diet and Dietary Patterns in Parkinson's Disease

Parkinson's Disease (PD) is a neurodegenerative disorder associated with diminished nutrition status and decreased quality of life. While the prevalence of PD is expected to increase, no preventative or curative therapy for PD exists at this time. Although nutrition and diet represent modifiable risk factors for reducing chronic disease risk, research on the impact of single nutrients on PD has yielded mixed results. As a result, this single-nutrient approach may be the driving force behind the inconsistency, and a holistic dietary approach may overcome this inconsistency by accounting for the interactions between nutrients. The following review aims to examine the impact of a generally healthy dietary pattern, the protein-restricted diet (PRD), the ketogenic diet (KD), the Mediterranean diet (MD), and the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet on PD risk, progression, and severity. While most of the included studies support the role of diet and dietary patterns in reducing the risk of PD or alleviating PD severity, the inconsistent results and need for further evidence necessitate more research being conducted before making dietary recommendations. Research on the potential beneficial effects of dietary patterns on PD should also investigate potential risks.

Oxidative stress and synaptic dysfunction in rodent models of Parkinson's disease

Parkinson's disease (PD) is a multifactorial disorder involving a complex interplay between a variety of genetic and environmental factors. In this scenario, mitochondrial impairment and oxidative stress are widely accepted as crucial neuropathogenic mechanisms, as also evidenced by the identification of PD-associated genes that are directly involved in mitochondrial function. The concept of mitochondrial dysfunction is closely linked to that of synaptic dysfunction. Indeed, compelling evidence supports the role of mitochondria in synaptic transmission and plasticity, although many aspects have not yet been fully elucidated. Here, we will provide a brief overview of the most relevant evidence obtained in different neurotoxin-based and genetic rodent models of PD, focusing on mitochondrial impairment and synaptopathy, an early central event preceding overt nigrostriatal neurodegeneration. The identification of early deficits occurring in PD pathogenesis is crucial in view of the development of potential disease-modifying therapeutic strategies.

What to Test in Parkinson Disease Prevention Trials? Repurposed, Low-Risk, and Gene-Targeted Drugs

Despite the sound epidemiologic and basic science rationales underpinning numerous "disease modification" trials in manifest Parkinson disease (PD), none has convincingly demonstrated that a treatment slows progression. Rapidly expanding knowledge of the genetic determinants and prodromal features of PD now allows realistic planning of prevention trials with initiation of putatively neuroprotective therapies earlier in the disease. In this article, we outline the principles of drug selection for PD prevention trials, focused on proof-of-concept opportunities that will help establish a methodological foundation for this fledgling field. We describe prototypical, relatively low-risk drug candidates for such trials (e.g., albuterol, ambroxol, caffeine, ibuprofen), tailored to specific at-risk populations ranging from pathogenic LRRK2 or GBA gene variant carriers to those defined by prodromal PD and α-synucleinopathy. Finally, we review gene-targeted approaches currently in development targeting clinically manifest PD for their potential in future prevention trials.

New hope for Parkinson's disease treatment: Targeting gut microbiota

There might be more than 10 million confirmed cases of Parkinson's disease (PD) worldwide by 2040. However, the pathogenesis of PD is still unclear. Host health is closely related to gut microbiota, which are affected by factors such as age, diet, and exercise. Recent studies have found that gut microbiota may play key roles in the progression of a wide range of diseases, including PD. Changes in the abundance of gut bacteria, such as Helicobacter pylori, Enterococcus faecalis, and Desulfovibrio, might be involved in PD pathogenesis or interfere with PD therapy. Gut microbiota and the distal brain achieve action on each other through a gut‐brain axis composed of the nervous system, endocrine system, and immune system. Here, this review focused on the current understanding of the connection between Parkinson's disease and gut microbiota, to provide potential therapeutic targets for PD.

Green Tea Intake and Parkinson's Disease Progression: A Mendelian Randomization Study

Epidemiological studies have suggested green tea intake was associated with a reduced risk of Parkinson's disease (PD). However, whether green tea intake has an effect on PD progression is unknown. To evaluate the role of green tea intake in PD progression, we conducted a two-sample Mendelian randomization analysis using summary statistics from genome-wide association studies of green tea intake (N = 64,949), age at onset (N = 28,568) and progression (N = 4,093) of PD. One standard deviation increase in genetically determined green tea intake was significantly associated with slower progression to dementia (OR: 0.87, 95% CI: 0.81-0.94, P: 3.48E-04) after the Bonferroni correction. Meanwhile, higher green tea intake was nominally associated with slower progression to depression, and lower risk of dementia, depression, hyposmia and insomnia at baseline. The results were robust under all sensitivity analyses. These results might facilitate novel therapeutic targets to slow down the progression of PD in clinical trials, and have clinical implications for patients with PD.

Application of neurotoxin- and pesticide-induced animal models of Parkinson's disease in the evaluation of new drug delivery systems

Parkinson's disease (PD) is the second most prevalent neuro-degenerative disease after Alzheimer´s disease. It is characterized by motor symptoms such as akinesia, bradykinesia, tremor, rigidity, and postural abnormalities, due to the loss of nigral dopaminergic neurons and a decrease in the dopa-mine contents of the caudate-putamen structures. To this date, there is no cure for the disease and available treatments are aimed at controlling the symptoms. Therefore, there is an unmet need for new treatments for PD. In the past decades, animal models of PD have been proven to be valuable tools in elucidating the nature of the pathogenic processes involved in the disease, and in designing new pharmacological approaches. Here, we review the use of neurotoxin-induced and pesticide-induced animal models of PD, specifically those induced by rotenone, paraquat, maneb, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and 6-OHDA (6-hydroxydopamine), and their application in the development of new drug delivery systems for PD.

Clinical Association between Gout and Parkinson's Disease: A Nationwide Population-Based Cohort Study in Korea

Background and Objectives: This retrospective cohort study aimed to investigate the association between gout and Parkinson’s disease (PD) in Korea. Materials and Methods: Overall, 327,160 patients with gout and 327,160 age- and sex-matched controls were selected from the Korean National Health Insurance Service (NHIS) database. PD incidence was evaluated by reviewing NHIS records during the period from 2002 to 2019. Patients with a diagnosis of gout (International Classification of Diseases-10 (ICD-10), M10) who were prescribed medications for gout, including colchicine, allopurinol, febuxostat, and benzbromarone for at least 90 days were selected. Patients with PD who were assigned a diagnosis code (ICD-G20) and were registered in the rare incurable diseases (RID) system were extracted. Results: During follow-up, 912 patients with gout and 929 control participants developed PD. The incidence rate (IR) of overall PD (per 1000 person-years) was not significantly different between both groups (0.35 vs. 0.36 in gout and control groups, respectively). The incidence rate ratio (IRR) was 0.98 (95% CI: 0.89–1.07). The cumulative incidence of PD was not significantly different between the groups. No association between gout and PD was identified in univariate analysis (HR = 1.00, 95% CI: 0.91–1.10, p = 0.935). HR increased significantly with old age (HR = 92.08, 198, and 235.2 for 60–69 years, 70–79 years, and over 80 years, respectively), female sex (HR = 1.21, 95% CI: 1.07–1.37, p = 0.002), stroke (HR = 1.95, 95% CI: 1.76–2.16, p < 0.001), and hypertension (HR = 1.16, 95% CI: 1.01–1.34, p = 0.04). Dyslipidemia exhibited an inverse result for PD (HR = 0.6, 95% CI: 0.52–0.68, p < 0.001). Conclusions: This population-based study did not identify an association between gout and PD. Age, female sex, stroke, and hypertension were identified as independent risk factors for PD, and dyslipidemia demonstrated an inverse result for PD.

The role of frailty in Parkinson's disease: a cross-sectional study

BACKGROUND

Frailty is an age-related state of increased risk for health-related adverse outcomes that reflects multisystem physiological changes and likely influences the clinical expression and disease progression of neurodegenerative disorders. The aim of the present study was to assess the potential relationship between frailty, as assessed by a frailty index (FI), and motor symptom severity, motor subtypes, and non-motor domains in Parkinson's disease (PD).

METHODS

We consecutively enrolled 150 PD patients. We administered an FI specifically designed for PD that included 50 age-related multidimensional biological deficits. Patients underwent a clinical assessment that evaluated motor and non-motor manifestations of PD. Using the FI score, we classified PD patients as relatively fit (FI ≤ 0.10), less fit (0.10 < FI ≤ 0.21), or frail (FI > 0.21). A linear regression model was designed to explore possible associations between frailty level and PD motor and non-motor manifestations.

RESULTS

Frail patients showed greater motor symptom severity and motor complications than fitter patients. A trend towards a higher prevalence of the postural instability/gait disorder subtype was also observed in frail versus relatively fit and less fit patients. The global burden of non-motor symptoms was higher in frail patients. Increased frailty was associated with more severe motor and non-motor symptoms, as well as with more pronounced cognitive deficits. These associations remained significant even when "traditional" predictors of PD severity (age, disease duration, and levodopa equivalent daily dose) were considered.

CONCLUSIONS

The present findings indicate that the FI is associated with both motor and non-motor features of PD.

Lifestyle Factors and Parkinson Disease Risk: Korean Nationwide Cohort Study With Repeated Health Screening Data

OBJECTIVE

Many previous studies, mostly performed in Western countries, on the effects of lifestyle factors on Parkinson's disease, used baseline lifestyle characteristics without directly accounting for changes in covariate values over time. The objective of this study was to evaluate the association of repeatedly measured lifestyle factors with Parkinson's disease risk in Korean population.

METHODS

We conducted a nationwide population-based cohort study. Among 512,836 Koreans in the national health checkup database, we selected individuals who underwent health screening ≥ 3 times between 2002 and 2015 and followed up until December 31, 2015. Parkinson's disease was defined using the International Classification of Diseases, Tenth Revision code G20 (with ≥ 3 times clinic visits for PD, to increase the diagnostic validity). Data on lifestyle factors such as smoking, alcohol consumption, and physical activity were collected using self-reported questionnaires. Logistic regression analysis with time-dependent covariates using generalized estimation equation models was performed to determine Parkinson's disease development.

RESULTS

During the 14-year follow-up, 2,655 patients developed Parkinson's disease. Smoking showed a dose-response inverse association with Parkinson's disease only in males (ex-smoker, Odds ratio [OR] =0.782, 95% confidence interval [CI] 0.713-0.858; current smoker, OR = 0.556, 95% CI 0.488-0.632). Alcohol consumption and regular physical activity were related to reduced Parkinson's disease development in both sexes; however, alcohol consumption in males (≤ 3 per week, OR=0.717, 95% CI 0.658-0.780; ≥ 4 per week, OR = 0.745, 95% CI 0.644-0.861) and physical activity in females (moderate, OR=0.792, 95% CI 0.748-0.840; vigorous, OR = 0.830, 95% CI 0.756-0.911) had more consistent associations with Parkinson's disease development compared to those of either sex. Participants with regular health screening showed a consistent relationship between lifestyle factors and Parkinson's disease development, whereas lifestyle factors in those without regular health screening had a decreased relationship with PD, even smoking habit.

CONCLUSIONS

Analysis using repeatedly measured lifestyle factors showed an association between lifestyle factors and Parkinson's disease development. Characteristics of lifestyle data including repeated measurements, timing, or regularity might influence results, and future studies with appropriate lifestyle factors could increase Parkinson's disease risk prediction.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that smoking, alcohol use, and physical activity are associated with reduced risk of Parkinson's disease in a Korean population.

Parkinsonism and cerebrovascular disease

The relationship between cerebrovascular disease and parkinsonism is commonly seen in everyday clinical practice but remains ill-defined and under-recognised with little guidance for the practising neurologist. We attempt to define this association and to illustrate key clinical, radiological and pathological features of the syndrome of Vascular Parkinsonism (VaP). VaP is a major cause of morbidity in the elderly associated with falls, hip fractures and cognitive impairment. Although acute parkinsonism is reported in the context of an acute cerebrovascular event, the vast majority of VaP presents as an insidious syndrome usually in the context of vascular risk factors and radiological evidence of small vessel disease. There may be an anatomic impact on basal ganglia neuronal networks, however the effect of small vessel disease (SVD) on these pathways is not clear. There are now established reporting standards for radiological features of SVD on MRI. White matter hyperintensities and lacunes have been thought to be the representative radiological features of SVD but other features such as the perivascular space are gaining more importance, especially in context of the glymphatic system. It is important to consider VaP in the differential diagnosis of Parkinson disease (PD) and in these situations, neuroimaging may offer diagnostic benefit especially in those patients with atypical presentations or refractoriness to levodopa. Proactive management of vascular risk factors, monitoring of bone density and an exercise program may offer easily attainable therapeutic targets in PD and VaP. Levodopa therapy should be considered in patients with VaP, however the dose and effect may be different from use in PD. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Health Promotion and Wellness in Neurologic Physical Therapy: Strategies to Advance Practice

BACKGROUND AND PURPOSE

Neurologic physical therapy (PT) can assist people with neurologic conditions and injuries to optimize their health and well-being by addressing barriers at the individual, relationship, community, and societal levels. The purpose of this special interest article is to provide consensus-driven strategies to address barriers to implementing health promotion and wellness (HPW)-related neurologic PT practice.

SUMMARY OF KEY POINTS

Environmental scan, literature review, and expert input were used to determine barriers and develop strategies. Barriers include lack of time; low knowledge, self-efficacy, and awareness; client complexity; and lack of HPW resources; as well as concerns regarding payment and scope of practice. Four key strategies emerged: (1) develop and disseminate a consensus-based scope of practice for HPW in neurologic PT; (2) increase knowledge of resources related to HPW; (3) promote delivery models for HPW-related neurologic PT; and (4) encourage advocacy, community building and partnership along the continuum of care.

RECOMMENDATIONS FOR CLINICAL PRACTICE

Clinicians should practice to their full scope of HPW-related PT practice. This includes optimizing movement, including physical activity and fitness, as well as reinforcing the importance of healthy sleep, nutrition, stress, and smoking cessation. These activities address primary, secondary, and tertiary prevention. Clinicians are encouraged to report their experiences with HPW-focused delivery models and outcomes. Additional research is needed to understand the full impact of HPW on PT practice (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A364).

Potentials of autophagy enhancing natural products in the treatment of Parkinson disease

Parkinson disease (PD) is a progressive neurodegenerative movement disorder characterized by motor and non-motor symptoms due to loss of striatal dopaminergic neurons and disruption of degradation signaling leading to the formation of Lewy bodies (aggregation of α-synuclein). Presently, there are no disease modifying therapy for PD despite improvement in the understanding of the disease pathogenesis. However, the drugs currently used in PD management provide symptomatic relieve for motor symptoms without significant improvement in non-motor complications, thus, a public health burden on caregivers and healthcare systems. There is therefore the need to discover disease modifying therapy with strong potential to halt the disease progression. Recent trend has shown that the dysfunction of lysosomal-autophagy pathway is highly implicated in PD pathology, hence, making autophagy a key player owing to its involvement in degradation and clearance of misfolded α-synuclein (a major hallmark in PD pathology). In this review, we described the current drugs/strategy in the management of PD including targeting the autophagy pathway as a novel approach that could serve as potential intervention for PD management. The discovery of small molecules or natural products capable of enhancing autophagy mechanism could be a promising strategy for PD treatment.

Potentials of autophagy enhancing natural products in the treatment of Parkinson disease

Parkinson disease (PD) is a progressive neurodegenerative movement disorder characterized by motor and non-motor symptoms due to loss of striatal dopaminergic neurons and disruption of degradation signaling leading to the formation of Lewy bodies (aggregation of α-synuclein). Presently, there are no disease modifying therapy for PD despite improvement in the understanding of the disease pathogenesis. However, the drugs currently used in PD management provide symptomatic relieve for motor symptoms without significant improvement in non-motor complications, thus, a public health burden on caregivers and healthcare systems. There is therefore the need to discover disease modifying therapy with strong potential to halt the disease progression. Recent trend has shown that the dysfunction of lysosomal-autophagy pathway is highly implicated in PD pathology, hence, making autophagy a key player owing to its involvement in degradation and clearance of misfolded α-synuclein (a major hallmark in PD pathology). In this review, we described the current drugs/strategy in the management of PD including targeting the autophagy pathway as a novel approach that could serve as potential intervention for PD management. The discovery of small molecules or natural products capable of enhancing autophagy mechanism could be a promising strategy for PD treatment.

Coffee and Tea Consumption Impact on Amyotrophic Lateral Sclerosis Progression: A Multicenter Cross-Sectional Study

Background/objectives: Amyotrophic lateral sclerosis (ALS) is a devastating and still untreatable motor neuron disease. The causes of ALS are unknown, but nutritional factors may impact the rate of disease progression. We aimed to ascertain the influence of coffee and tea consumption on ALS progression rate.

Subjects/methods: In this multicenter cross-sectional study, we recruited 241 patients, 96 females, and 145 males; the mean age at onset was 59.9 ± 11.8 years. According to El Escorial criteria, 74 were definite ALS, 77 probable, 55 possible, and 35 suspected; 187 patients had spinal onset and 54 bulbar. Patients were categorized into three groups, according to their ΔFS (derived from ALS Functional Rating Scale-Revised score and disease duration from onset): slow (81), intermediate (80), and fast progressors (80).

Results: Current coffee consumers were 179 (74.3%), 34 (14.1%) were non-consumers, and 22 (9.1%) were former consumers, whereas six (2.5%) consumed decaffeinated coffee only. The log-ΔFS was weakly correlated with the duration of coffee consumption (p = 0.034), but not with the number of cup-years, or the intensity of coffee consumption (cups/day). Current tea consumers were 101 (41.9%), 6 (2.5%) were former consumers, and 134 (55.6%) were non-consumers. Among current and former consumers, 27 (25.2%) consumed only green tea, 51 (47.7%) only black tea, and 29 (27.1%) both. The log-ΔFS was weakly correlated only with the consumption duration of black tea (p = 0.028) but not with the number of cup-years.

Conclusions: Our study does not support the hypothesis that coffee or tea consumption is associated with the ALS progression rate.

One-carbon epigenetics and redox biology of neurodegeneration

One-carbon metabolism provides the methyl groups for both DNA and histone tail methylation reactions, two of the main epigenetic processes that tightly regulate the chromatin structure and gene expression levels. Several enzymes involved in one-carbon metabolism, as well as several epigenetic enzymes, are regulated by intracellular metabolites and redox cofactors, but their expression levels are in turn regulated by epigenetic modifications, in such a way that metabolism and gene expression reciprocally regulate each other to maintain homeostasis and regulate cell growth, survival, differentiation and response to environmental stimuli. Increasing evidence highlights the contribution of impaired one-carbon metabolism and epigenetic modifications in neurodegeneration. This article provides an overview of DNA and histone tail methylation changes in major neurodegenerative disorders, namely Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, discussing the contribution of oxidative stress and impaired one-carbon and redox metabolism to their onset and progression.

Probing the Pre-diagnostic Phase of Parkinson's Disease in Population-Based Studies

Parkinson's disease covers a wide spectrum of symptoms, ranging from early non-motor symptoms to the characteristic bradykinesia, tremor and rigidity. Although differences in the symptomatology of Parkinson's disease are increasingly recognized, there is still a lack of insight into the heterogeneity of the pre-diagnostic phase of Parkinson's disease. In this perspective, we highlight three aspects regarding the role of population-based studies in providing new insights into the heterogeneity of pre-diagnostic Parkinson's disease. First we describe several specific advantages of population-based cohort studies, including the design which overcomes some common biases, the broad data collection and the high external validity. Second, we draw a parallel with the field of Alzheimer's disease to provide future directions to uncover the heterogeneity of pre-diagnostic Parkinson's disease. Finally, we anticipate on the emergence of prevention and disease-modification trials and the potential role of population-based studies herein. In the coming years, bridging gaps between study designs will be essential to make vital advances in elucidating the heterogeneity of pre-diagnostic Parkinson's disease.

Bilirubin: A Promising Therapy for Parkinson's Disease

Following the increase in life expectancy, the prevalence of Parkinson's disease (PD) as the most common movement disorder is expected to rise. Despite the incredibly huge efforts in research to find the definitive biomarker, to date, the diagnosis of PD still relies mainly upon clinical symptoms. A wide range of treatments is available for PD, mainly alleviating the clinical symptoms. However, none of these current therapies can stop or even slow down the disease evolution. Hence, disease-modifying treatment is still a paramount unmet medical need. On the other side, bilirubin and its enzymatic machinery and precursors have offered potential benefits by targeting multiple mechanisms in chronic diseases, including PD. Nevertheless, only limited discussions are available in the context of neurological conditions, particularly in PD. Therefore, in this review, we profoundly discuss this topic to understand bilirubin's therapeutical potential in PD.

Salivary caffeine in Parkinson's disease

We aimed to investigate salivary caffeine content, caffeine absorption and metabolism in Parkinson’s disease (PD) and verify whether salivary caffeine can be used as a biomarker of PD. We enrolled 98 PD patients and 92 healthy subjects. Caffeine and its major metabolite, paraxanthine, were measured in saliva samples collected before and 4 h after the oral intake of caffeine (100 mg). We measured caffeine absorption as the normalized increase in caffeine levels, and caffeine metabolism as the paraxanthine/caffeine ratio. The Movement Disorder Society Unified Parkinson's Disease Rating Scale part III, the Hoehn & Yahr, the presence of motor complications, and levodopa equivalent dose (LED) were assessed and correlated with caffeine levels, absorption, and metabolism. The effects of demographic and environmental features possibly influencing caffeine levels were also investigated. Caffeine levels were decreased in patients with moderate/advanced PD, while caffeine levels were normal in patients with early and de-novo PD, unrelated to caffeine intake. Caffeine absorption and metabolism were normal in PD. Decreased salivary caffeine levels in PD were associated with higher disease severity, longer duration, and the presence of motor complications, no significant association was found with LED. Salivary caffeine decrease correlates with PD progression.

The Impact of Environmental Factors on Monogenic Mendelian Diseases

Environmental factors and gene-environment interactions modify the variable expressivity, progression, severity, and onset of some classic (monogenic) Mendelian-inherited genetic diseases. Cystic fibrosis, Huntington disease, Parkinson's disease, and sickle cell disease are examples of well-known Mendelian disorders that are influenced by exogenous exposures. Environmental factors may act by direct or indirect mechanisms to modify disease severity, timing, and presentation, including through epigenomic influences, protein misfolding, miRNA alterations, transporter activity, and mitochondrial effects. Because pathological features of early-onset Mendelian diseases can mimic later onset complex diseases, we propose that studies of environmental exposure vulnerabilities using monogenic model systems of rare Mendelian diseases have high potential to provide insight into complex disease phenotypes arising from multi-genetic/multi-toxicant interactions. Mendelian disorders can be modeled by homologous mutations in animal model systems with strong recapitulation of human disease etiology and natural history, providing an important advantage for study of these diseases. Monogenic high penetrant mutations are ideal for toxicant challenge studies with a wide variety of environmental stressors, because background genetic variability may be less able to alter the relatively strong phenotype driving disease-causing mutations. These models promote mechanistic understandings of gene-environment interactions and biological pathways relevant to both Mendelian and related sporadic complex disease outcomes by creating a sensitized background for relevant environmental risk factors. Additionally, rare disease communities are motivated research participants, creating the potential of strong research allies among rare Mendelian disease advocacy groups and disease registries and providing a variety of translational opportunities that are under-utilized in genetic or environmental health science.

The Impact of Lifetime Alcohol and Cigarette Smoking Loads on Amyotrophic Lateral Sclerosis Progression: A Cross-Sectional Study

Background—Amyotrophic lateral sclerosis (ALS) is a devastating and untreatable motor neuron disease; smoking and alcohol drinking may impact its progression rate. Objective—To ascertain the influence of smoking and alcohol consumption on ALS progression rates. Methods—Cross-sectional multicenter study, including 241 consecutive patients (145 males); mean age at onset was 59.9 ± 11.8 years. Cigarette smoking and alcohol consumption data were collected at recruitment through a validated questionnaire. Patients were categorized into three groups according to ΔFS (derived from the ALS Functional Rating Scale-Revised and disease duration from onset): slow (n = 81), intermediate (80), and fast progressors (80). Results—Current smokers accounted for 44 (18.3%) of the participants, former smokers accounted for 10 (4.1%), and non-smokers accounted for 187 (77.6%). The age of ALS onset was lower in current smokers than non-smokers, and the ΔFS was slightly, although not significantly, higher for smokers of >14 cigarettes/day. Current alcohol drinkers accounted for 147 (61.0%) of the participants, former drinkers accounted for 5 (2.1%), and non-drinkers accounted for 89 (36.9%). The log(ΔFS) was weakly correlated only with the duration of alcohol consumption (p = 0.028), but not with the mean number of drinks/day or the drink-years. Conclusions: This cross-sectional multicenter study suggested a possible minor role for smoking in worsening disease progression. A possible interaction with alcohol drinking was suggested.

Farming, well water consumption, rural living, and pesticide exposure in early life as the risk factors for Parkinson disease in Igdir province

OBJECTIVE

To investigate potential risk factors for Parkinson`s disease (PD) in elderly individuals rural living in Turkey.

METHODS

In total, 72 consecutive elderly Parkinson disease patients referred to the Neurology Clinic, Igdir State Hospital, Igdir, Turkey were included in the study. A structured questionnaire comprising questions on history of pastoral living, pit water consumption, and exposure to ionizing radiation and pesticides was administered to the patients. The patients were divided into 2 groups on the basis of water consumption: well water consumption group and city network consumption group.

RESULTS

Of 72 patients with PD, 49 (68.1%) exposed to well water while 23 (31.9%) did not exposed to well water. The average duration of well water consumption was 20 (standard deviation 6) years (p less than 0.01) in group 1. Nitrate, sulfate and heavy metal levels were significantly higher in well water than in city network water (p less than 0.05).

CONCLUSION

Consumption of well water containing heavy metals and nitrates in early life may contribute to the etiology of Parkinson disease in elderly individuals in Igdir province of Turkey.

Influence of dopamine, noradrenaline, and serotonin transporters on the pharmacogenetics of Atremorine in Parkinson's disease

Atremorine is a potent dopamine (DA) enhancer obtained by nondenaturing biotechnological processes from a genetic species of Vicia faba. Atremorine affects the neuronal dopaminergic system by acting as a neuroprotective agent against Parkinson's disease (PD). PD patients (N = 127) responded to a single dose of Atremorine (5 g, p.o.) 1 h after administration in a sex-, time-, dose-, and genotype-dependent fashion. Drug-free patients (N = 81) showed an increase in DA levels from 12.14 ± 0.34 pg/ml to 6463.21 ± 1306.90 pg/ml; and patients chronically treated with anti-PD drugs (N = 46) showed an increase in DA levels from 1321.53 ± 389.94 pg/ml to 16,028.54 ± 4783.98 pg/ml, indicating that Atremorine potentiates the dopaminergic effect of conventional anti-PD drugs. The variability in Atremorine-induced DA response is strongly attributable to pharmacogenetic factors. Polymorphic variants in pathogenic, mechanistic, metabolic, transporter, and pleiotropic genes influence the DA response to Atremorine. Genetic variation in the DA (SLC6A3; rs460000), noradrenaline (NA) (SLC6A2; rs12708954, rs3785143, rs5569), and serotonin (5-HT) transporter (SLC6A4; rs2020934, rs2020936, rs4251417, rs6354) genes exert a genotype-dependent Atremorine-induced DA response in PD, with potential impact on the DA-related pharmacogenetic outcome and minimum effects on NA and 5-HT levels.

Diet Quality and Risk of Parkinson's Disease: A Prospective Study and Meta-Analysis

BACKGROUND

Several dietary components have been shown to be neuroprotective against risk of neurodegeneration. However, limited observational studies have examined the role of overall diet quality on risk of Parkinson's disease.

OBJECTIVES

We examined the associations between diet quality and risk of Parkinson's disease in a prospective cohort study and meta-analysis.

METHODS

Included in the cohort study were 3,653 participants (1,519 men and 2,134 women; mean age: 81.5 years) in the Geisinger Rural Aging Study longitudinal cohort in Pennsylvania. Diet quality was assessed using a validated dietary screening tool containing 25 food- and behavior-specific questions in 2009. Potential Parkinson's cases were identified using electronic health records based on ICD9 (332.*), ICD10 (G20), and Parkinson-related treatments. Hazard ratios (HRs) and 95% confidence intervals (CIs) across diet quality tertiles were calculated using Cox proportional hazards models after adjusting for potential confounders. We further performed a meta-analysis by pooling our study with four published papers on this topic. Random-effects model was utilized to calculate the pooled risk ratios and 95% CIs.

RESULTS

During a mean of 6.94 years of follow-up, 47 incident Parkinson's cases were documented. Having high diet quality at baseline was associated with lower Parkinson's disease risk (adjusted HR for the highest vs the lowest diet quality tertile = 0.39; 95% CI: 0.17, 0.89; p-trend = 0.02). The meta-analysis including 140,617 individuals also showed that adherence to high diet quality or a healthy dietary pattern was associated with lower risk of Parkinson's disease (pooled risk ratio = 0.64; 95% CI: 0.49, 0.83).

CONCLUSION

Having high diet quality or a healthy dietary pattern was associated with lower future risk of Parkinson's disease.

Risk factors of Parkinson disease: Simultaneous assessment, interactions, and etiologic subtypes

OBJECTIVE

To perform a simultaneous evaluation of potential risk/protective factors of Parkinson disease (PD) to identify independent risk/protective factors, to assess interaction among factors, and to determine whether identified risk factors predict etiologic subtypes of PD.

METHODS

We designed a large case-control study assessing 31 protective/risk factors of PD, including environmental and lifestyle factors, comorbid conditions, and drugs. The study enrolled 694 patients with PD and 640 healthy controls from 6 neurologic centers. Data were analyzed by logistic regression models, additive interaction models, and cluster analysis.

RESULTS

The simultaneous assessment of 31 putative risk/protective factors of PD showed that only coffee consumption (odds ratio [OR] 0.6; 95% confidence interval [CI] 0.4-0.9), smoking (OR 0.7, 95% CI 0.6-0.9), physical activity (OR 0.8, 95% CI 0.7-0.9), family history of PD (OR 3.2, 95% CI 2.2-4.8), dyspepsia (OR 1.8, 95% CI 1.3-2.4), and exposure to pesticides (OR 2.3, 95% CI1.3-4.2), oils (OR 5.6, 95% CI 2.3-13.7), metals (OR 2.8, 95% CI 1.5-5.4), and general anesthesia (OR 6.1, 95% CI 2.9-12.7) were independently associated with PD. There was no evidence of interaction among risk/protective factors, but cluster analysis identified 4 subtypes with different risk factor profiles. In group 1, all patients had a family history of PD, while dyspepsia or exposure to toxic agents was present in 30% of patients. In groups 2 and 3, a family history of PD was lacking, while exposure to toxic agents (group 2) and dyspepsia (group 3) played major roles. Group 4 consisted of patients with no risk factors.

CONCLUSIONS

This study demonstrated that 9 factors independently modify PD risk by coexisting in the same patient rather than interacting with others. Our study suggests the need for future preventive strategies aimed at reducing the coexistence of different risk factors within the same participant.

Ryanodine Receptors: A Potential Treatment Target in Various Neurodegenerative Disease

Progressive neuronal demise is a key contributor to the key pathogenic event implicated in many different neurodegenerative disorders (NDDs). There are several therapeutic strategies available; however, none of them are particularly effective. Targeted neuroprotective therapy is one such therapy, which seems a compelling option, yet remains challenging due to the internal heterogeneity of the mechanisms underlying various NDDs. An alternative method to treat NDDs is to exploit common modalities involving molecularly distinct subtypes and thus develop specialized drugs with broad-spectrum characteristics. There is mounting evidence which supports for the theory that dysfunctional ryanodine receptors (RyRs) disrupt intracellular Ca²⁺ homeostasis, contributing to NDDs significantly. This review aims to provide direct and indirect evidence on the intersection of NDDs and RyRs malfunction, and to shed light on novel strategies to treat RyRs-mediated disease, modifying pharmacological therapies such as the potential therapeutic role of dantrolene, a RyRs antagonist.

Preventive treatments to slow substantia nigra damage and Parkinson's disease progression: A critical perspective review

Restoring the lost physiological functions of the substantia nigra in Parkinson's disease (PD) is an important goal of PD therapy. The present article reviews a) novel drug targets that should be targeted to slow PD progression, and b) clinical and experimental research data reporting new treatments targeting immune-inflammatory and oxidative pathways. A systematic search was performed based on the major databases, i.e., ScienceDirect, Web of Science, PubMed, CABI Direct databases, and Scopus, on relevant studies performed from 1900 to 2020. This review considers the crucial roles of mitochondria and immune-inflammatory and oxidative pathways in the pathophysiology of PD. High levels of oxidative stress in the substantia nigra, as well as modifications in glutathione regulation, contribute to mitochondrial dysfunction, with a decline in complex I of the mitochondrial electron transport chain reported in PD patients. Many papers suggest that targeting antioxidative systems is a crucial aspect of preventive and protective therapies, even justifying the utilization of N-acetylcysteine (NAC) supplementation to fortify the protection afforded by intracellular glutathione. Dietary recommended panels including ketogenetic diet, muscular exercise, nutraceutical supplementation including NAC, glutathione, nicotine, caffeine, melatonin, niacin, and butyrate, besides to nonsteroidal anti-inflammatory drugs (NSAIDs), and memantine treatment are important aspects of PD therapy. The integration of neuro-immune, antioxidant, and nutritional approaches to treatment should afford better neuroprotection, including by attenuating neuroinflammation, nitro-oxidative stress, mitochondrial dysfunction, and neurodegenerative processes. Future research should clarify the efficacy, and interactions, of nicotine receptor agonists, gut microbiome-derived butyrate, melatonin, and NSAIDs in the treatment of PD.