The epidemiology of Parkinson's disease

No Evidence of Sensory Neuropathy in a Traditional Mouse Model of Idiopathic Parkinson's Disease

Parkinson's disease (PD) is the second-most common neurodegenerative disorder worldwide and is diagnosed based on motor impairments. Non-motor symptoms are also well-recognised in this disorder, and peripheral neuropathy is a frequent but poorly appreciated non-motor sign. Studying how central and peripheral sensory systems are affected can contribute to the development of targeted therapies and deepen our understanding of the pathophysiology of PD. Although the cause of sporadic PD is unknown, chronic exposure to the pesticide rotenone in humans increases the risk of developing the disease. Here, we aimed to investigate whether peripheral neuropathy is present in a traditional model of PD. Mice receiving intrastriatal rotenone showed greatly reduced dopamine terminals in the striatum and a reduction in tyrosine hydroxylase-positive neurons in the Substantia nigra pars compacta and developed progressive motor impairments in hindlimb stepping and rotarod but no change in spontaneous activity. Interestingly, repeated testing using gold-standard protocols showed no change in gut motility, a well-known non-motor symptom of PD. Importantly, we did not observe any change in heat, cold, or touch sensitivity, again based upon repeated testing with well-validated protocols that were statistically well powered. Therefore, this traditional model fails to replicate PD, and our data again reiterate the importance of the periphery to the disorder.

Prevalence of Parkinson's disease among adults aged 45 years and older in China: a cross-sectional study based on the China health and retirement longitudinal study

BACKGROUND

In recent decades, China has experienced a rapid increase in the number of elderly individuals and life expectancy, as well as industrialization, which is associated with an increased prevalence of Parkinson's disease (PD). However, inconsistent results have recently been reported. Therefore, this study aimed to investigate the prevalence and distribution characteristics of PD among individuals aged 45 years and older.

METHODS

Using data from the China Health and Retirement Longitudinal Study (CHARLS), we attempted to estimate the prevalence of PD and its distribution characteristics among 19,034 individuals aged 45 years and older residing in 446 communities/villages within 27 provinces/autonomous regions/municipalities in mainland China. Cases were established based on a doctor's previous diagnosis. Crude and age-adjusted prevalence rates were calculated and stratified by age, sex, area of residence, education level, marital status, and geographic region. Logistic regression models were used to identify risk factors associated with PD.

RESULTS

We identified 178 patients with PD among 19,034 residents aged 45 years and older. The crude prevalence was 0.94%, and the age-adjusted prevalence was 0.82% for individuals aged 45 years and older. The prevalence of PD increased with age (P < 0.001). No significant differences were found in terms of sex, area of residence, or education level. Stratified by geographic region, the prevalence of PD was greater in North and Northwest China and lower in southern China (p < 0.001). Multiple regression analyses showed that age was a significant risk factor for PD.

CONCLUSION

The prevalence of PD increased with age in the Chinese population.

Network Pharmacology and Molecular Docking Identify the Potential Mechanism and Therapeutic Role of Scutellaria baicalensis in Alzheimer's Disease

Aim

Scutellaria baicalensis, a traditional Chinese medicinal herb renowned for its anti-inflammatory, antioxidant, and anti-tumor properties, has shown promise in alleviating cognitive impairment associated with Alzheimer's disease. Nonetheless, the exact neuroprotective mechanism of Scutellaria baicalensis against Alzheimer's disease remains unclear. In this study, network pharmacology was employed to explore the possible mechanisms by which Scutellaria baicalensis protects against Alzheimer's disease.

Methods

The active compounds of Scutellaria baicalensis were retrieved from the TCMSP database, and their corresponding targets were identified. Alzheimer's disease-related targets were obtained through searches in the GeneCards and OMIM databases. Cytoscape 3.6.0 software was utilized to construct a regulatory network illustrating the "active ingredient-target" relationships. Subsequently, the target genes affected by Scutellaria baicalensis in the context of Alzheimer's disease were input into the String database to establish a PPI network. GO analysis and KEGG analysis were conducted using the DAVID database to predict the potential pathways associated with these key targets. Following this, the capacity of these active ingredients to bind to core targets was confirmed through molecular docking. In vitro experiments were then carried out for further validation.

Results

A total of 36 active ingredients from Scutellaria baicalensis were screened out, which corresponded to 365 targets. Molecular docking results demonstrated the robust binding abilities of Baicalein, Wogonin, and 5,2'-Dihydroxy-6,7,8-trimethoxyflavone to key target proteins (SRC, PIK3R1, and STAT3). In vitro experiments showed that the active components of Scutellaria baicalensis can inhibit STAT3 expression by downregulating the PIK3R1/SRC pathway in Neuro 2A cells.

Conclusion

In summary, these findings collectively suggest that Scutellaria baicalensis holds promise as a viable treatment option for Alzheimer's disease.

DNA Damage and Parkinson's Disease

The etiology underlying most sporadic Parkinson's' disease (PD) cases is unknown. Environmental exposures have been suggested as putative causes of the disease. In cell models and in animal studies, certain chemicals can destroy dopaminergic neurons. However, the mechanisms of how these chemicals cause the death of neurons is not understood. Several of these agents are mitochondrial toxins that inhibit the mitochondrial complex I of the electron transport chain. Familial PD genes also encode proteins with important functions in mitochondria. Mitochondrial dysfunction of the respiratory chain, in combination with the presence of redox active dopamine molecules in these cells, will lead to the accumulation of reactive oxygen species (ROS) in dopaminergic neurons. Here, I propose a mechanism regarding how ROS may lead to cell killing with a specificity for neurons. One rarely considered hypothesis is that ROS produced by defective mitochondria will lead to the formation of oxidative DNA damage in nuclear DNA. Many genes that encode proteins with neuron-specific functions are extraordinary long, ranging in size from several hundred kilobases to well over a megabase. It is predictable that such long genes will contain large numbers of damaged DNA bases, for example in the form of 8-oxoguanine (8-oxoG), which is a major DNA damage type produced by ROS. These DNA lesions will slow down or stall the progression of RNA polymerase II, which is a term referred to as transcription stress. Furthermore, ROS-induced DNA damage may cause mutations, even in postmitotic cells such as neurons. I propose that the impaired transcription and mutagenesis of long, neuron-specific genes will lead to a loss of neuronal integrity, eventually leading to the death of these cells during a human lifetime.

Common genetic risk for Parkinson's disease and dysfunction of the endo-lysosomal system

Parkinson's disease is a progressive neurological disorder, characterized by prominent movement dysfunction. The past two decades have seen a rapid expansion of our understanding of the genetic basis of Parkinson's, initially through the identification of monogenic forms and, more recently, through genome-wide association studies identifying common risk variants. Intriguingly, a number of cellular pathways have emerged from these analysis as playing central roles in the aetiopathogenesis of Parkinson's. In this review, the impact of data deriving from genome-wide analyses for Parkinson's upon our functional understanding of the disease will be examined, with a particular focus on examples of endo-lysosomal and mitochondrial dysfunction. The challenges of moving from a genetic to a functional understanding of common risk variants for Parkinson's will be discussed, with a final consideration of the current state of the genetic architecture of the disorder. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.

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.

Joint Exposure to Multiple Air Pollutants, Genetic Susceptibility, and Incident Dementia: A Prospective Analysis in the UK Biobank Cohort

Objectives: This study aimed to evaluate the joint effects of multiple air pollutants including PM2.5, PM10, NO2, and NOx with dementia and examined the modifying effects of genetic susceptibility. Methods: This study included 220,963 UK Biobank participants without dementia at baseline. Weighted air pollution score reflecting the joint exposure to multiple air pollutants were constructed by cross-validation analyses, and inverse-variance weighted meta-analyses were performed to create a pooled effect. The modifying effect of genetic susceptibility on air pollution score was assessed by genetic risk score and APOE ε4 genotype. Results: The HR (95% CI) of dementia for per interquartile range increase of air pollution score was 1.13 (1.07∼1.18). Compared with the lowest quartile (Q1) of air pollution score, the HR (95% CI) of Q4 was 1.26 (1.13∼1.40) (P trend = 2.17 × 10-5). Participants with high air pollution score and high genetic susceptibility had higher risk of dementia compared to those with low air pollution score and low genetic susceptibility. Conclusion: Our study provides evidence that joint exposure to multiple air pollutants substantially increases the risk of dementia, especially among individuals with high genetic susceptibility.

The pathogenesis of Parkinson's disease

Parkinson's disease is a progressive neurodegenerative condition associated with the deposition of aggregated α-synuclein. Insights into the pathogenesis of Parkinson's disease have been derived from genetics and molecular pathology. Biochemical studies, investigation of transplanted neurons in patients with Parkinson's disease, and cell and animal model studies suggest that abnormal aggregation of α-synuclein and spreading of pathology between the gut, brainstem, and higher brain regions probably underlie the development and progression of Parkinson's disease. At a cellular level, abnormal mitochondrial, lysosomal, and endosomal function can be identified in both monogenic and sporadic Parkinson's disease, suggesting multiple potential treatment approaches. Recent work has also highlighted maladaptive immune and inflammatory responses, possibly triggered in the gut, that accelerate the pathogenesis of Parkinson's disease. Although there are currently no disease-modifying treatments for Parkinson's disease, we now have a solid basis for the development of rational neuroprotective therapies that we hope will halt the progression of this disabling neurological condition.

Parkinson's Disease in Sub-Saharan Africa: Pesticides as a Double-Edged Sword

Long-term exposure to pesticides used in agriculture is increasingly being identified as a risk factor for developing Parkinson's disease. How chronic pesticide exposure might contribute to the growth of Parkinson's disease in the mainly agricultural communities of Sub-Saharan Africa has thus far received limited attention. There are specific concerns in this area of the world: aging of the population, in combination with chronic exposure to widely used pesticides, including those that have been restricted elsewhere in the world because of neurotoxicity and other health risks. Of interest, the prevalence of Parkinson's disease among specific (semi)nomadic populations in Tanzania seems very low, possibly due to their lack of exposure to agricultural chemicals. But at the same time, pesticides have also brought important benefits to this part of the world. Specifically, in Sub-Saharan Africa, pesticides have been directly helpful in preventing and controlling famine and in containing major human infectious diseases. This creates a complex risk-benefit ratio to the use of pesticides within a global perspective, and urgently calls for the development and implementation of affordable alternatives for areas such as Sub-Saharan Africa, including non-neurotoxic compounds and non-chemical alternatives for the use of pesticides.