Physical Activity and Parkinson Disease Risk: An Intriguing Link

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.

Physical activity and risk of Parkinson's disease: an updated systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Although recent meta-analyses have shown that the association between physical activity (PA) and the risk of developing Parkinson's disease (PD) is influenced by gender differences, a growing number of studies are revealing the general applicability of this association across genders. This study aimed to reassess the association and dose-response relationship between PA and PD risk in populations.

METHODS

A systematic search of PubMed, Embase, Cochrane Library, and Web of Science databases was conducted in this study from inception to February 1, 2024, without language restrictions. Stratified analyses were conducted to explore the association between PA and PD risk, combining multivariate-adjusted effect estimates via random-effects models, and to validate the dose-response relationship between the two.

RESULTS

This study included 21 observational studies, comprising 13 cohort studies and 8 case-control studies. The pooled analysis revealed that PA significantly reduced the risk of developing PD [relative risk (RR) = 0.77, 95% CI 0.70-0.85]. In addition, the dose-response analysis revealed both linear and nonlinear associations, with linear results indicating a 9% reduction in PD risk for every 10 MET-h/wk increase in PA. The study also demonstrated that the protective effect of PA against PD was significant for both sexes. Moreover, no statistically significant effects of PA on preventing PD were observed in individuals with a BMI > 26 (RR = 0.35, 95% CI 0.12-1.02) or in Asian populations (RR = 0.78, 95% CI 0.60-1.01); however, the trends suggest potential protective effects, warranting further investigation. Sensitivity analyses confirmed the robustness of these findings.

CONCLUSION

This meta-analysis produced substantial evidence to reaffirm the protective effect of high PA on PD across various population groups and the inverse dose-response relationship with PD risk, and to validate the protective effect of PA among different demographic groups.

Rehabilitation for non-motor symptoms for patients with Parkinson's disease from an α-synuclein perspective: a narrative review

Parkinson's disease (PD) is a common neurodegenerative disorder affecting aged population around the world. PD is characterized by neuronal Lewy bodies present in the substantia nigra of the midbrain and the loss of dopaminergic neurons with various motor and non-motor symptoms associated with the disease. The protein α-synuclein has been extensively studied for its contribution to PD pathology, as α-synuclein aggregates form the major component of Lewy bodies, a hallmark of PD. In this narrative review, the authors first focus on a brief explanation of α-synuclein aggregation and circumstances under which aggregation can occur, then present a hypothesis for PD pathogenesis in the peripheral nervous system (PNS) and how PD can spread to the central nervous system from the PNS via the transport of α-synuclein aggregates. This article presents arguments both for and against this hypothesis. It also presents various non-pharmacological rehabilitation approaches and management techniques for both motor and non-motor symptoms of PD and the related pathology. This review seeks to examine a possible hypothesis of PD pathogenesis and points to a new research direction focus on rehabilitation therapy for patients with PD. As various non-motor symptoms of PD appear to occur earlier than motor symptoms, more focus on the treatment of non-motor symptoms as well as a better understanding of the biochemical mechanisms behind those non-motor symptoms may lead to better long-term outcomes for patients with PD.

Residential greenness, air pollution and incident neurodegenerative disease: A cohort study in China

BACKGROUND

Neurodegenerative disease has a great adverse impact on population's death and disability worldwide. However, the association of air pollution and residential greenness with neurodegenerative disease and their potential mechanisms still remain uncertain.

METHODS

We used data from a population-based prospective cohort in Ningbo, China. Exposure to PM_2.5, PM₁₀ and NO₂ were assessed by land-use regression (LUR) models and residential greenness was estimated by Normalized Difference Vegetation Index (NDVI). Our primary outcomes were all neurodegenerative diseases, Parkinson's disease (PD) and Alzheimer's disease (AD). Cox proportional hazards regression models were used to examine the association of air pollution and residential greenness with risk of incident neurodegenerative disease. Furthermore, we also explored the potential mediation relationship and effect modification between greenness and air pollutants.

RESULTS

During the follow-up period, we identified a total of 617 incident neurodegenerative diseases, 301 PD and 182 AD. In single-exposure models, PM_2.5 was positively associated with all outcomes (e.g. AD hazard ratio (HR): 1.41, 95 % confidence interval (CI): 1.09-1.84, per interquartile range (IQR) increment), whereas residential greenness showed protective effects (e.g. neurodegenerative disease, HR: 0.82, 95%CI: 0.75-0.90, per IQR increment for NDVI in 1000 m buffer). NO₂ was positively associated with risk of neurodegenerative disease and PM₁₀ was associated with neurodegenerative disease and AD. In two-exposure models, after adjustment for PM_2.5, the association for greenness generally attenuated towards null. Moreover, we identified the significant modification effect of greenness on PM2.5 on additive and multiplicative scales.

CONCLUSION

In this prospective study, we found that exposure to higher residential greenness and lower concentrations of particulate matter were associated with lower risk of neurodegenerative disease, PD and AD. Residential greenness could modify the association of PM_2.5 with neurodegenerative disease.

Global association of greenness exposure with risk of nervous system disease: A systematic review and meta-analysis

Nervous system disease (NSD) is a global health burden with increasing prevalence in the last 30 years. There is evidence that greenness can improve nervous system health through a variety of mechanisms; however, the evidence is inconsistent. In the present systematic review and meta-analysis, we examined the relationship between greenness exposure and NSD outcomes. Studies on the relationship between greenness and NSD health outcomes published till July 2022 were searched in PubMed, Cochrane, Embase, Scopus, and Web of Science. In addition, we searched the cited literature and updated our search on Jan 20, 2023, to identify any new studies. We included human epidemiological studies that assess the association of greenness exposure with the risk of NSD. Greenness exposure was measured using NDVI (the normalized difference vegetation index) and the outcome was the mortality or morbidity of NSD. The pooled relative risks (RRs) were estimated using a random effects model. Of 2059 identified studies, 15 studies were included in our quantitative evaluation, in which 11 studies found a significant inverse relationship between the risk of NSD mortality or incidence/prevalence and an increase in surrounding greenness. The pooled RRs for cerebrovascular diseases (CBVD), neurodegenerative diseases (ND), and stroke mortality were 0.98 (95 % CI: 0.97, 1.00), 0.98 (95 % CI: 0.98, 0.99), and 0.96 (95 % CI: 0.93, 1.00), respectively. The pooled RRs for PD incidence and stroke prevalence/incidence were 0.89 (95 % CI: 0.78, 1.02) and 0.98 (95 % CI: 0.97, 0.99), respectively. The confidence of evidence for ND mortality, stroke mortality, and stroke prevalence/incidence was downgraded to "low", while CBVD mortality and PD incidence were downgraded to "very low" due to inconsistency. We found no evidence of publication bias and the sensitivity analysis results of all subgroups are robust except for the stroke mortality subgroup. This is the first comprehensive meta-analysis of greenness exposure and NSD outcomes in which an inverse relationship was observed. It is necessary to conduct further research to ascertain the role greenness exposure plays in various NSDs and the management of greenness should be considered a public health strategy.

Parkinson's Disease Case Ascertainment in the Sister Study: A Cohort for Environmental Health Research

BACKGROUND

Large prospective studies are essential for investigating the environmental causes of Parkinson's disease (PD), but PD diagnosis via clinical exams is often infeasible in such studies.

OBJECTIVE

To present case ascertainment strategy and data collection in a US cohort of women.

METHODS

In the Sister Study (n = 50,884, baseline ages 55.6±9.0), physician-made PD diagnoses were first reported by participants or their proxies. Cohort-wide follow-up surveys collected data on subsequent diagnoses, medication usage and PD-relevant motor and nonmotor symptoms. We contacted self-reported PD cases and their treating physicians to obtain relevant diagnostic and treatment history. Diagnostic adjudication was made via expert review of all available data, except nonmotor symptoms. We examined associations of nonmotor symptoms with incident PD, using multivariable logistic regression models and reported odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

Of the 371 potential PD cases identified, 242 diagnoses were confirmed. Compared with unconfirmed cases, confirmed cases were more likely to report PD diagnosis from multiple sources, medication usage, and motor and nonmotor features consistently during the follow-up. PD polygenic risk score was associated with confirmed PD (ORinter-quartile range = 1.74, 95% CI: 1.45-2.10), but not with unconfirmed cases (corresponding OR = 1.05). Hyposmia, dream-enacting behaviors, constipation, depression, unexplained weight loss, dry eyes, dry mouth, and fatigue were significantly related to PD risk, with ORs from 1.71 to 4.88. Only one of the eight negative control symptoms was associated with incident PD.

CONCLUSION

Findings support our PD case ascertainment approach in this large cohort of women. PD prodromal presentation is likely beyond its well-documented profile.

Association of Osteoarthritis With Increased Risk of Parkinson's Disease: A Population-Based, Longitudinal Follow-Up Study

OBJECTIVE

To investigate whether patients with osteoarthritis (OA) are at a higher risk of developing Parkinson's disease (PD).

METHODS

This retrospective cohort study was conducted using Taiwan's Longitudinal Health Insurance Database 2005. We enrolled 33,360 patients who were 50-64 years old and had OA in 2002-2005 to form the OA group. The comparison group consisted of 33,360 age- and sex-matched, randomly sampled subjects without OA. Then, their PD-free survival curves were generated using the Kaplan-Meier method. Multivariable Cox proportional hazards regression analysis was employed to estimate the effect of having OA on patients' subsequent risk of PD.

RESULTS

Of the 2 groups, the OA group had a significantly higher risk of developing PD (adjusted hazard ratio [HR_adj ] 1.41 [95% confidence interval (95% CI) 1.16-1.70], P = 0.0003). The PD-free survival rate of the OA group was also significantly lower than that of the comparison group (P = 0.0004). The subgroup analysis showed that patients with knee or hip OA appeared to have a higher magnitude of PD risk (HR_adj 1.55 [95% CI 1.14-2.11]) than patients with non-knee and non-hip OA (HR_adj 1.42 [95% CI 1.06-1.89]) or with uncategorized OA (HR_adj 1.32 [95% CI 1.05-1.64]).

CONCLUSION

Our findings suggest that OA is linked to an increased risk of developing PD.

Association between Residential Greenness and Incidence of Parkinson's Disease: A Population-Based Cohort Study in South Korea

It is widely known that exposure to residential greenness is beneficial for health. However, few studies have analyzed the association between greenery and Parkinson’s disease (PD). We selected 313,355 participants who matched the inclusion criteria from the National Health Insurance Service-National Sample Cohort, followed up from 2007 to 2015. Residential greenness, represented by the normalized difference vegetation index (NDVI), was obtained from satellite measurements. We estimated hazard ratios of PD associated with a 0.1-unit increase in long-term greenness exposure at the district level for the previous 1 year of each year until a censoring/event occurred, using time-varying Cox proportional hazard models, adjusted for individual- and area-level characteristics. During the 2,745,389 person-years of follow-up, 2621(0.8%) participants developed PD. Exposure to higher levels of residential greenness was found to be associated with a decreased risk of PD incidence (21% per 0.1-unit increase, 95% confidence interval (CI): 0.74–0.84). In subgroup analyses, stronger protective effects were observed in participants aged over 50 years, females, overweight/obese participants, non-urban residents, non-smokers, alcoholics, and those with comorbidities. Long-term exposure to greenness was beneficial to incident PD, and our findings could aid in the development of public-health strategies.

What and How Can Physical Activity Prevention Function on Parkinson's Disease?

Aim

This study was aimed at investigating the effects and molecular mechanisms of physical activity intervention on Parkinson's disease (PD) and providing theoretical guidance for the prevention and treatment of PD.

Methods

Four electronic databases up to December 2019 were searched (PubMed, Springer, Elsevier, and Wiley database), 176 articles were selected. Literature data were analyzed by the logic analysis method.

Results

(1) Risk factors of PD include dairy products, pesticides, traumatic brain injury, and obesity. Protective factors include alcohol, tobacco, coffee, black tea, and physical activity. (2) Physical activity can reduce the risk and improve symptoms of PD and the beneficial forms of physical activity, including running, dancing, traditional Chinese martial arts, yoga, and weight training. (3) Different forms of physical activity alleviate the symptoms of PD through different mechanisms, including reducing the accumulation of α-syn protein, inflammation, and oxidative stress, while enhancing BDNF activity, nerve regeneration, and mitochondrial function.

Conclusion

Physical activity has a positive impact on the prevention and treatment of PD. Illustrating the molecular mechanism of physical activity-induced protective effect on PD is an urgent need for improving the efficacy of PD therapy regimens in the future.