Stroke and idiopathic Parkinson's disease: does a shortage of dopamine offer protection against stroke?

Investigating the role of rotenone on human blood platelets: Molecular insights into abnormal platelet functions in Parkinson's disease

Parkinson's disease (PD) is a predominant neuromotor disorder characterized by the selective death of dopaminergic neurons in the midbrain. The majority of PD cases are sporadic or idiopathic, with environmental toxins and pollutants potentially contributing to its development or exacerbation. However, clinical PD patients are often associated with a reduced stroke frequency, where circulating blood platelets are indispensable. Although platelet structural impairment is evident in PD, the platelet functional alterations and their underlying molecular mechanisms are still obscure. Therefore, we investigated rotenone (ROT), an environmental neurotoxin that selectively destroys dopaminergic neurons mimicking PD, on human blood platelets to explore its impact on platelet functions, thus replicating PD conditions in vitro. Our study deciphered that ROT decreased thrombin-induced platelet functions, including adhesion, activation, secretion, and aggregation in human blood platelets. As ROT is primarily responsible for generating intracellular reactive oxygen species (ROS), and ROS is a key player regulating the platelet functional parameters, we went on to check the effect of ROT on platelet ROS production. In our investigation, it became evident that ROT treatment resulted in the stimulation of ROS production in human blood platelets. Additionally, we discovered that ROT induced ROS production by augmenting Ca2+ mobilization from inositol 1,4,5-trisphosphate receptor. Apart from this, the treatment of ROT triggers protein kinase C associated NADPH oxidase-mediated ROS production in platelets. In summary, this research, for the first time, highlights ROT-induced abnormal platelet functions and may provide a mechanistic insight into the altered platelet activities observed in PD patients.

Assessing the association between white matter lesions and Parkinson's disease

BACKGROUND

The association between white matter (WM) lesions and Parkinson's disease (PD) was not fully established. We therefore applied Mendelian randomization (MR) analyses to identify the causal effect between white matter lesions and PD.

METHODS

We performed a bidirectional two-sample Mendelian randomization (MR) study to investigate the association between three WM phenotypes-white matter hyperintensities (WMH, N = 18,381), fractional anisotropy (FA, N = 17,673), and mean diffusivity (MD, N = 17,467)-with PD (N = 482,730) using summary statistics from genome-wide association studies (GWAS). The inverse variance weighted (IVW), weighted median, MR-Egger, and MR-PRESSO methods were used to evaluate the causal estimate.

RESULTS

Significant evidence was suggested that higher MD was associated with a higher PD risk (OR = 1.049, 95% CI = 1.018-1.081, p = 0.022) when the outlier was removed using MR-PRESSO method. Moreover, genetically predicted PD was associated with a lower WMH load (IVW β = - 0.047, 95% CI = - 0.085 to - 0.009, p = 0.016) and a higher FA (β = 0.185, 95% CI = 0.021-0.349, p = 0.027). No evidence of pleiotropy was found using MR-Egger intercept.

CONCLUSION

Our findings provided genetic support that white matter microstructural integrity lesions might increase the risk of PD. However, genetically predicted PD was potentially associated with a lower load of white matter lesions.

Stroke in Parkinson's disease: a review of epidemiological studies and potential pathophysiological mechanisms

Parkinson's disease (PD) is the fastest growing neurological disorder and one of the leading neurological causes of disability worldwide following stroke. An overall aging global population, as well as general changes in lifestyle associated with mass industrialization in the last century, may be linked to both increased incidence rates of PD and an increase in cumulative cardiovascular risk. Recent epidemiological studies show an increased risk of stroke, post-stroke complications, and subclinical ischemic insults in PD. PD patients have a host of characteristics that might contribute to increasing the risk of developing ischemic stroke including motor impairment, dysautonomia, and sleep disorders. This increases the urgency to study the interplay between PD and other neurological disorders, and their combined effect on mortality, morbidity, and quality of life. In this review, we provide a comprehensive overview of the studied etiological factors and pathological processes involved in PD, specifically with regard to their relationship to stroke. We hope that this review offers an insight into the relationship between PD and ischemic stroke and motivates further studies in this regard.

Machine learning analysis of the UK Biobank reveals IGF-1 and inflammatory biomarkers predict Parkinson's disease risk

INTRODUCTION

Parkinson's disease (PD) is the most common movement disorder, and its prevalence is increasing rapidly worldwide with an ageing population. The UK Biobank is the world's largest and most comprehensive longitudinal study of ageing community volunteers. The cause of the common form of PD is multifactorial, but the degree of causal heterogeneity among patients or the relative importance of one risk factor over another is unclear. This is a major impediment to the discovery of disease-modifying therapies.

METHODS

We used an integrated machine learning algorithm (IDEARS) to explore the relative effects of 1,753 measured non-genetic variables in 334,062 eligible UK Biobank participants, including 2,719 who had developed PD since their recruitment into the study.

RESULTS

Male gender was the highest-ranked risk factor, followed by elevated serum insulin-like growth factor 1 (IGF-1), lymphocyte count, and neutrophil/lymphocyte ratio. A group of factors aligned with the symptoms of frailty also ranked highly. IGF-1 and neutrophil/lymphocyte ratio were also elevated in both sexes before PD diagnosis and at the point of diagnosis.

DISCUSSION

The use of machine learning with the UK Biobank provides the best opportunity to explore the multidimensional nature of PD. Our results suggest that novel risk biomarkers, including elevated IGF-1 and NLR, may play a role in, or are indicative of PD pathomechanisms. In particular, our results are consistent with PD being a central manifestation of a systemic inflammatory disease. These biomarkers may be used clinically to predict future PD risk, improve early diagnosis and provide new therapeutic avenues.

Development of Parkinson Disease and Its Relationship with Incidentally Discovered White Matter Disease and Covert Brain Infarction in a Real-World Cohort

OBJECTIVE

This study aimed to examine the relationship between covert cerebrovascular disease, comprised of covert brain infarction and white matter disease, discovered incidentally in routine care, and subsequent Parkinson disease.

METHODS

Patients were ≥50 years and received neuroimaging for non-stroke indications in the Kaiser Permanente Southern California system from 2009 to 2019. Natural language processing identified incidentally discovered covert brain infarction and white matter disease and classified white matter disease severity. The Parkinson disease outcome was defined as 2 ICD diagnosis codes.

RESULTS

230,062 patients were included (median follow-up 3.72 years). A total of 1,941 Parkinson disease cases were identified (median time-to-event 2.35 years). Natural language processing identified covert cerebrovascular disease in 70,592 (30.7%) patients, 10,622 (4.6%) with covert brain infarction and 65,814 (28.6%) with white matter disease. After adjustment for known risk factors, white matter disease was associated with Parkinson disease (hazard ratio 1.67 [95%CI, 1.44, 1.93] for patients <70 years and 1.33 [1.18, 1.50] for those ≥70 years). Greater severity of white matter disease was associated with increased incidence of Parkinson disease(/1,000 person-years), from 1.52 (1.43, 1.61) in patients without white matter disease to 4.90 (3.86, 6.13) in those with severe disease. Findings were robust when more specific definitions of Parkinson disease were used. Covert brain infarction was not associated with Parkinson disease (adjusted hazard ratio = 1.05 [0.88, 1.24]).

INTERPRETATION

Incidentally discovered white matter disease was associated with subsequent Parkinson disease, an association strengthened with younger age and increased white matter disease severity. Incidentally discovered covert brain infarction did not appear to be associated with subsequent Parkinson disease. ANN NEUROL 2022;92:620-630.

The interplay between small vessel disease and Parkinson disease pathology: A longitudinal study

BACKGROUND

Cerebral small vessel disease (SVD) related brain changes have been found associated with various clinical symptoms of Parkinson disease (PD). On the other hand, PD pathology and treatment may also accelerate SVD progression.

OBJECTIVE

The aim of this study is to explore the interplay between SVD and PD pathology using longitudinal dataset.

METHODS

We screened 66 healthy controls (HCs) and 114 patients from the Parkinson Progression Markers Initiative (PPMI) database. The peak width of skeletonized mean diffusivity (PSMD) was quantified from diffusion tensor images to reflect vascular pathologies at baseline and 24 months follow-up, and dopamine transporter (DAT) imaging data was used to represent the extent of dopaminergic neuronal degeneration at the same point time. We compared the PSMD between PD patients and HCs, and analyzed whether PSMD and DAT availability could predict each other's progression using multiple regression analyses in PD patients.

RESULTS

PSMD at baseline had no significant difference between the HCs and patients with PD (P = 0.169). Higher baseline PSMD was associated with less DAT reduction in the caudate (β = 0.216, P = 0.029), but not the putamen (β = 0.058, P = 0.552) in PD patients. Baseline caudate and putamen DAT availability had no significant association with PSMD progression (β = -0.006, P = 0.950; β = 0.017, P = 0.860, respectively).

CONCLUSIONS

Mild SVD might slow down PD pathology progression, while the effect of PD pathology on the progression of SVD was not significant.

Exogenous human α-Synuclein acts in vitro as a mild platelet antiaggregant inhibiting α-thrombin-induced platelet activation

α-Synuclein (αSyn) is a small disordered protein, highly conserved in vertebrates and involved in the pathogenesis of Parkinson’s disease (PD). Indeed, αSyn amyloid aggregates are present in the brain of patients with PD. Although the pathogenic role of αSyn is widely accepted, the physiological function of this protein remains elusive. Beyond the central nervous system, αSyn is expressed in hematopoietic tissue and blood, where platelets are a major cellular host of αSyn. Platelets play a key role in hemostasis and are potently activated by thrombin (αT) through the cleavage of protease-activated receptors. Furthermore, both αT and αSyn could be found in the same spatial environment, i.e. the platelet membrane, as αT binds to and activates platelets that can release αSyn from α-granules and microvesicles. Here, we investigated the possibility that exogenous αSyn could interfere with platelet activation induced by different agonists in vitro. Data obtained from distinct experimental techniques (i.e. multiple electrode aggregometry, rotational thromboelastometry, immunofluorescence microscopy, surface plasmon resonance, and steady-state fluorescence spectroscopy) on whole blood and platelet-rich plasma indicate that exogenous αSyn has mild platelet antiaggregating properties in vitro, acting as a negative regulator of αT-mediated platelet activation by preferentially inhibiting P-selectin expression on platelet surface. We have also shown that both exogenous and endogenous (i.e. cytoplasmic) αSyn preferentially bind to the outer surface of activated platelets. Starting from these findings, a coherent model of the antiplatelet function of αSyn is proposed.

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.

Association of Parkinson's disease with ischemic stroke in Korea: A nationwide longitudinal cohort study in Korea

OBJECTIVE

The aim of this nationwide age- and sex- matched longitudinal follow up study is to determine the risk of Parkinson's disease (PD) associated with ischemic stroke in Korea.

METHODS

Patient data were collected from the National Health Insurance Service-National Health Screening Cohort (NHIS-HEALS). PD was identified using the International Classification of Diseases (ICD) 10-CM code G 20. In total, 6,475 patients were enrolled in the PD group from the NHISS. After subtracting 1,039 patients who underwent hospitalization less than once or those who visited an outpatient clinic less than two times, 5,259 patients who were diagnosed after January 1, 2004 ultimately participated in this study. After case-control match was done through 1:5 age- and sex- stratified matching, 26,295 individuals were chosen as control. Kaplan-Meier method and Cox proportional hazard regression analysis were performed to evaluate the risk of ischemic stroke in PD.

RESULTS

The hazard ratio of ischemic stroke in the PD group was 3.848 (95% confidence interval (confidence interval [CI]): 3.14-4.70) after adjusting for age and sex. The adjusted hazard ratio of ischemic stroke in PD group was 3.885 (95% CI: 3.17-4.75) after adjusting for comorbidities. According to subgroup analysis, in male and female and non-diabetes and diabetes and non-hypertension and hypertension and dyslipidemia and non-dyslipidemia subgroups, ischemic stroke incidence rates were significantly higher in the PD group than those in the control group.

CONCLUSIONS

This nationwide longitudinal study suggests an increased risk of ischemic stroke in PD patients.

Stroke in Parkinson's disease

BACKGROUND

The association between Parkinson's disease (PD) and stroke remains completely understood.

AIM

We aimed to investigate stroke risk and post-stroke outcomes in patients with PD.

DESIGN

The retrospective cohort study included 1303 patients aged ≥ 40 years with new-diagnosed PD and 5212 non-PD adults were selected by frequency matching with age and sex in 2000-05. Both two groups were followed up until the end of 2013. Another nested stroke cohort study of 17 678 patients with stroke hospitalization in 2002-09 was conducted to compare the admission outcome in patients with and without PD history.

METHODS

We collected patients' characteristics and medical conditions in the present two studies from claims data of Taiwan's National Health Insurance. Incidences and risks of stroke in people with and without PD during the follow-up period were calculated by adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) in the Cox proportional hazard model. Complications and mortality during the stroke admission associated with PD were analysed by calculating adjusted odds ratios (ORs) and 95% CIs in the logistic regressions.

RESULTS

Incidences of stroke for people with and without PD were 19.8 and 9.93 per 1000 person-years, respectively, with corresponding HR of 1.96 (95% CI 1.67-2.30). History of PD was associated with post-stroke gastrointestinal bleeding (OR 1.25, 95% CI 1.05-1.49), epilepsy (OR 1.64, 95% CI 1.32-2.04), pneumonia (OR 1.34, 95% CI 1.20-1.49), urinary tract infection (OR 1.33, 95% CI 1.21-1.45) and mortality (OR 1.35, 95% CI 1.13-1.62).

CONCLUSION

PD increases stroke risk and influences post-stroke outcomes.

Association between carotid plaque and Parkinson's disease

Background

Epidemiological studies show that patients with Parkinson's disease (PD) are prone to have a reduced incidence of ischemic cerebrovascular disease. Previous studies show the correlation between PD and the lipids serum levels. The PD,s patients are found with a reduced serum level of triglyceride and low-density lipoprotein cholesterol (LDL-C); thus, the level of serum uric acid (UA) is closely related to the occurrence and development of PD. Patients with low serum UA levels have a higher chance of developing PD than the ones who do not. However, the relationship between carotid plaques and PD is still unknown.

Methods

Our study was based on 68 patients with PD (known as the PD group) and 81 people without PD (known as the control group). Patients in the PD group were of the same age and gender. Both groups were recorded and analyzed for UA, LDL-C, and carotid plaques or intima-media thickness (IMT). The PD group was then divided into three subgroups: the stable plaque group, the unstable plaque group, and the non-plaque group.

Results

In the present study, the PD group showed a significantly lower level of UA and LDL-C than the control group (P<0.01); somehow there were no statistically significant differences in the IMT and plaque incidence between the two groups (P>0.05). There were also no significant differences (P>0.05) in both the LDL-C and UA levels in all subgroups, but there was a close relation in both age and duration of disease to IMT. According to the Hoehn and Yahr staging scale, serum levels of LDL-C were inversely correlated in PD patients, while UA was related to the duration of the disease.

Conclusions

Our study suggested that there were no differences in carotid artery arteriosclerosis plaque and IMT, but the PD progress was indeed correlated with IMT. Meanwhile, LDL-C and UA had different priorities in H&Y and disease progression.

Biogreen Synthesis of Carbon Dots for Biotechnology and Nanomedicine Applications

Over the past decade, carbon dots have ignited a burst of interest in many different fields, including nanomedicine, solar energy, optoelectronics, energy storage, and sensing applications, owing to their excellent photoluminescence properties and the easiness to modify their optical properties through doping and functionalization. In this review, the synthesis, structural and optical properties, as well as photoluminescence mechanisms of carbon dots are first reviewed and summarized. Then, we describe a series of designs for carbon dot-based sensors and the different sensing mechanisms associated with them. Thereafter, we elaborate on recent research advances on carbon dot-based sensors for the selective and sensitive detection of a wide range of analytes, including heavy metals, cations, anions, biomolecules, biomarkers, nitroaromatic explosives, pollutants, vitamins, and drugs. Lastly, we provide a concluding perspective on the overall status, challenges, and future directions for the use of carbon dots in real-life sensing.

Prevalent cerebrovascular and cardiovascular disease in people with Parkinson's disease: a meta-analysis

Background

People with Parkinson's disease (PwP) are speculated to be at a low risk of cerebrovascular and cardiovascular disease (CVD) because they have fewer vascular risk factors and lower smoking rate. However, emerging evidence suggests that PwP are at higher risk of CVD, which introduces controversy to the notion that there is no association between Parkinson's disease (PD) and CVD. Hence, we conducted a meta-analysis to analyze the risk of CVD in PwP.

Methods

Electronic databases were searched using terms related to PD and CVD. Articles were included in the meta-analysis only if they employed clear diagnostic criteria for PD and CVD. The reference lists of the relevant articles were reviewed to identify eligible studies not found during the keyword search.

Results

The enrolled studies were categorized into case-control and cohort studies, and the former was further divided into postmortem (three) and clinical (four) studies. In the clinical case-control studies group, PD was more associated with CVD (OR: 2.89, 95% CI: 1.36-6.13). Three studies were enrolled in the cohort studies group, and the merged results demonstrated that PwP were at higher risk of CVD during the follow-up period (HR: 1.84, 95% CI: 1.34-2.54).

Conclusion

PD is associated with CVD, which may be due to the shared pathogeneses between the two diseases or PD-related effects. PwP should be more aware of the risk of CVD despite having fewer traditional vascular risk factors.

A Comparative Study of Central Hemodynamics in Parkinson's Disease

Objective

To explore the central aortic pressure in patients with Parkinson’s disease (PD).

Methods

We investigated central arterial stiffness by measurement of the augmentation index (AIx) in PD patients. Patients were eligible for the study if they were de novo PD and 45 years of age or older. The patients’ demographics, vascular risk factors, and neurologic examinations were collected at baseline. The AIx was measured by applanation tonometry.

Results

A total of 147 subjects (77 in control and 70 in PD groups) were enrolled in the study. While there was no significant difference in peripheral systolic blood pressure (SBP), diastolic blood pressure (DBP), or mean arterial pressure between groups, peripheral pulse pressure (PP) was significantly lower in the PD group than in the control group (p = 0.012). Regarding central pressure, aortic DBP was significantly higher and PP was significantly lower in the PD group (p = 0.001, < 0.0001). Although there was no significant difference in the AIx between the groups, a trend toward a lower AIx was observed in the PD group (31.2% vs. 28.1%, p = 0.074).

Conclusion

This study showed that peripheral and central PP was significantly lower in the PD group than in the control group. Our study suggests that PD patients may have a low risk of a cardiovascular event by reason of a lower PP.

Parkinson's disease might increase the risk of cerebral ischemic lesions

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disease in the elderly. Cerebrovascular diseases such as cerebral ischemic lesion (CIL) also commonly occur in elderly adults. However, previous studies on the relationship between PD and cerebrovascular disease have not found consistent results. Therefore, we conducted this study to evaluate whether or not PD is related to an increased prevalence of ischemic cerebrovascular lesions.

METHODS

This study recruited 241 patients with PD and 112 healthy controls (HCs). All subjects underwent brain magnetic resonance imaging and general neuropsychological tests. The motor severity of PD was evaluated according to the Hoehn and Yahr stage (HY stage), and the severity of CIL in all subjects was classified according to Fazekas grade. The PD patients were classified into two subgroups according to HY stage (Group 1 - HY 1, 2; Group 2 - HY 3 to 5).

RESULTS

Among all PD patients, 76% had small vessel disease, while 44% of all HCs had small vessel disease (p<0.001). Regarding the difference between the two subgroups according to motor severity, group 2 showed significantly higher Fazekas scale score and more severe CIL, indicating a higher prevalence of small vessel disease compared to group 1.

CONCLUSION

This study demonstrates that PD patients have a significantly higher prevalence of CIL compared to HCs. Therefore, although the present study is not a large-scale study, we cautiously suggest that PD can play an important role as a risk factor in the occurrence of ischemic cerebrovascular disease.

Reduced serum levels of triglyceride, very low density lipoprotein cholesterol and apolipoprotein B in Parkinson's disease patients

BACKGROUND

Previous studies have shown a lower incidence of stroke in Parkinson's disease (PD) patients. The role of the lipids and lipoproteins as risk factors for stroke is uncertain in the lower prevalence of stroke in PD patients.

OBJECTIVES

To explore the lipids and lipoproteins serum levels in PD patients.

METHODS

A retrospective study was performed on 110 PD patients (PD group), 130 controls with non-cerebrovascular neurological diseases (OD group), 140 acute intracerebral hemorrhage patients (ICH group) and 140 acute cerebral infarction patients (CI group). The records about serum levels of lipids and lipoproteins were analyzed.

RESULTS

There were significant differences for the serum level of triglyceride (F = 5.031, p=0.002), very low density lipoprotein cholesterol (F = 5.313, p=0.001), apolipoprotein B (F = 16.038, p<0.0001) in the four groups. PD group had a significantly lower serum level of triglyceride (TG) than the OD (p=0.032), ICH (p=0.00047) and CI (p=0.001) groups. Very low density lipoprotein cholesterol (VLDL-C) serum level was significantly lower in PD group than in OD (p=0.039), ICH (p=0.00021) and CI (p=0.001) groups. There was a significantly lower serum level of apolipoprotein B (apo B) in PD group than in OD (p=0.002), ICH (p<0.0001) and CI (p<0.0001) groups.

CONCLUSIONS

There are reduced serum levels of TG, VLDL-C and apo B in PD patients, which may be related to the decreased prevalence of stroke in PD patients.

Parkinson's disease is related to an increased risk of ischemic stroke-a population-based propensity score-matched follow-up study

Objective

The risk of stroke in patients with Parkinson’s disease (PD) remains controversial. The purpose of this population-based propensity score-matched longitudinal follow-up study was to determine whether there is an increased risk of ischemic stroke after PD.

Methods

We used a logistic regression model that includes age, sex, pre-existing comorbidities and socioeconomic status as covariates to compute the propensity score. A total of 2204 patients with at least two ambulatory visits with the principal diagnosis of PD in 2001 was enrolled in the PD group. The non- PD group consisted of 2204, propensity score-matched subjects without PD. The ischemic stroke-free survival rates of the two groups were estimated using the Kaplan-Meier method. Stratified Cox proportional hazard regression with patients matched on propensity score was used to estimate the effect of PD on the occurrence of ischemic stroke.

Results

During the three-year follow-up period, 328 subjects in the PD group and 156 subjects in the non-PD group developed ischemic stroke. The ischemic stroke-free survival rate of the PD group was significantly lower than that of the non-PD group (P<0.0001). The hazard ratio (HR) of stroke for the PD group was 2.37 (95% confidence interval [CI], 1.92 to 2.93, P<0.0001) compared to the non- PD group.

Conclusions

This study shows a significantly increased risk of ischemic stroke in PD patients. Further studies are required to investigate the underlying mechanism.

Small-vessel disease in patients with Parkinson's disease: a clinicopathological study

Few studies have examined the relationship between cerebrovascular disease, vascular risk factors, and Parkinson's disease (PD), although 1 study found small-vessel disease (SVD) to be the main subtype of cerebrovascular disease. In this study we compared the extent and topography of SVD and assessed associated vascular risk factors in autopsy-proven PD cases and community-dwelling controls. Seventy-seven PD and 32 control brains from the Sydney Brain Bank were assessed microscopically by a single examiner blinded to the diagnosis. SVD was assessed by grading perivascular pallor, gliosis, hyaline thickening, and enlargement of perivascular spaces in the white matter underlying the superior frontal and primary motor cortices, basal ganglia, and white matter tracts. A history of vascular risk factors (hypertension, heart disease, diabetes, and cigarette smoking) was obtained. Groups were compared using stepwise multiple regression analysis. There was significantly greater frontal pallor (P = .004) and widening of perivascular spaces in the globus pallidus interna (P = .007) in controls compared with PD. Hyaline thickening and widening of perivascular spaces in the frontal white matter, hyaline thickening in the motor white matter, and widening of perivascular spaces in the caudate nucleus were more common in the control group, but did not reach significance. The prevalence of vascular risk factors and SVD pathology was significantly lower in autopsy-proven PD compared with controls (P = .03) living in the same community. The results of this study support the need for further research in this area.

The impact of MRI white matter hyperintensities on dementia in Parkinson's disease in relation to the homocysteine level and other vascular risk factors

BACKGROUND

The role of white matter hyperintensities (WMH) and homocysteine (Hcy) and other vascular risk factors in the pathogenesis of Parkinson's disease (PD) dementia (PDD) remains unclear.

OBJECTIVE

The aim of the study was to assess the impact of WMH, Hcy and other biochemical and vascular risk factors on PDD.

METHODS

A total of 192 patients with PD and 184 age- and sex-matched healthy controls were included. A semistructured interview was used to assess demographic and clinical variables with respect to vascular risk factors (arterial hypertension, diabetes mellitus, atrial fibrillation, ischemic heart disease, obliterative atherosclerosis, hypercholesterolemia, smoking, alcohol intake). Unified Parkinson's Disease Rating Scale score, Hoehn-Yahr staging and the Schwab-England activities of daily living scale were used to assess motor abilities and activities of daily living. A complex neuropsychological examination with a battery of tests was used to classify patients into a group with dementia (PDD) and a group without dementia (PD). Neuroradiological examination of MRI scans included visual rating scales for WMH (according to the Wahlund and Erkinjunntti rating scales) and the Scheltens scale for hippocampal atrophy. Blood samples for Hcy, folate, vitamin B12, fibrinogen, lipids, glucose, creatinine, transaminases and thyroid stimulating hormone (TSH) were examined.

RESULTS

Among all patients, 57 (29.7%) fulfilled the diagnostic criteria for dementia. Significantly higher Hcy plasma levels were noted in PD and PDD groups compared to controls (p < 0.05) and in PDD when compared to PD (p < 0.05). According to multivariate regression analysis, WMH (Erkinjuntti scale), high Hcy, low vitamin B12 and folate plasma levels were independent risk factors for PDD. Vascular risk factors did not play any role in the pathogenesis of PDD and WMH.

CONCLUSIONS

WMH along with Hcy, folate and vitamin B12 may impact cognition in PD. Therapy with vitamin B12, folate and catechol-O-methyltransferase inhibitors may play a potential protective role against PDD.

Influence of left versus right hemibody onset Parkinson's disease on cardiovascular control

Whereas the left hemisphere is involved in regulating the parasympathetic nervous system, the right hemisphere regulates the sympathetic. Given the asymmetrical onset of motor symptoms and neuropathology in PD, differences in cardiovascular functions might be expected between PD patients with left hemibody onset (LHO) versus right hemibody onset (RHO). A total of 66 PD patients served as participants, including 31 LHO patients and 35 RHO PD patients. All participants had their resting heart rate (HR) and blood pressure (BP) recorded. Although the LHO group had lower systolic BP, it had higher resting HR than did the RHO group. The reason for this dissociation is not known but might be related to asymmetrical vagus nerve control of the heart (SA node). Future researchers might want to use additional indices of cardiovascular functioning that are more precise measures of parasympathetic and sympathetic functioning, as well as learn the influence of dopaminergic medications.

Inhibition of platelet aggregation by 1-methyl-4-phenyl pyridinium ion (MPP+) through ATP depletion: Evidence for the reduced platelet activities in Parkinson's disease

Neuronal accumulation of 1-methyl-4-phenylpyridinium ion (MPP(+)), the metabolite of neural toxin, 1-methyl-4-phenyl-1,2,3,6-tetrahyropyridine (MPTP), induces a rapid depletion of cellular ATP level and loss of neuronal cell viability which simulates human Parkinson's disease (PD). Since ATP plays an important role in the physiology and function of platelets, which share many biochemical and physiological features with neuronal cells, we examined the effect of MPP(+) on platelet aggregation and viability using freshly isolated rat platelets. While the treatment of MPP(+) to platelets did not induce cytotoxicity, it significantly attenuated agonist-induced platelet aggregation in a concentration dependent manner. The inhibition of aggregation by MPP(+) was mediated by the depletion of the cytoplasmic ATP pool and resultant decreased ATP secretion. Different from the previous reports in neuronal cells, MPP(+) did not affect intracellular levels of glutathione and cytoplasmic Ca(2+) in platelets. The combined treatment with MPP(+) and 2-deoxyglucose, a glycolysis inhibitor, showed the additive effect in the decrease of ATP secretion and intracellular content. Consistent with these findings, inhibitory effects of MPP(+) on platelet aggregation was significantly enhanced by the treatment with 2-deoxyglucose. In conclusion, these results suggested that MPP(+) can induce ATP depletion in platelets and attenuate platelet aggregation providing a new theory on the reduced platelet activities in PD patients.

Plasma Homocysteine Levels and Parkinson Disease

OBJECTIVE

To determine whether plasma homocysteine (Hcy) levels are associated with clinical characteristics, neuropsychological and psychiatric manifestations and cardiovascular comorbidity in patients with Parkinson disease (PD).

BACKGROUND

Elevated Hcy levels are linked to atherosclerosis, vascular disease, depression, and dementia. Patients with PD treated with L-dopa have been shown to have elevated Hcy levels.

DESIGN/METHODS

Idiopathic PD patients were evaluated using the Unified Parkinson's Disease Rating Scale, Hoehn and Yahr stage, Parkinson Psychosis Rating Scale, Beck Depression Inventory, Frontal Assessment Battery, Mini-Mental Status Examination, and several tests for frontal type cognitive functions. Fasting blood samples were collected for the measurement of Hcy, and carotid B-mode ultrasound was performed to measure intima-media thickness of the common carotid arteries.

RESULTS

Seventy-two consecutive PD patients (46 men; average age, 68.7 +/- 11.6 years; average disease duration, 7.0 +/- 4.7 years) were recruited. All but 10 patients were treated with L-dopa. The average level of Hcy was 16.4 +/- 7.8 micromol/L, and 38.9% of the patients had Hcy level above the reference range (>15.0 micromol/L). The Hcy levels were associated with PD duration as they were with L-dopa treatment duration but were not associated with the parameters of disease severity or with L-dopa dose. The Hcy levels were associated neither with the common carotid intima-media thickness nor with cardiovascular morbidity. No association was found between Hcy and the neuropsychiatric features of PD such as depression, cognitive performance, or psychosis.

CONCLUSIONS

Hyperhomocystinemia is common in L-dopa-treatedPD patients but was not associated with neuropsychological complications (depression, dementia, and cognitive decline associated with frontal lobe functioning or psychosis), enhanced disease severity, or vascular comorbidity.

Vascular complications in dementia with Lewy bodies: a postmortem study

The effects of cerebrovascular lesions on DLB are not yet fully understood, whereas the development of Alzheimer's disease (AD) is known to be associated with cerebrovascular lesions. In this study, we investigated the frequency of concomitant cerebrovascular pathologies in autopsy-proven DLB cases (n = 25) in comparison with AD cases (n= 63). We also investigated the correlation between cerebrovascular pathologies and the clinical features of DLB cases. On gross inspection, five cases of DLB and seven cases of AD were complicated by cerebral hemorrhages and the difference was significant; most of the lesions in DLB were subdural hemorrhages, possibly related to trauma. Nine cases of DLB and 25 cases of AD had grossly identified infarctions, but no significant difference was observed. Three cases of DLB and four cases of AD had concomitant hemorrhages, while 10 cases of DLB and 43 cases of AD had infarcts on microscopic inspection. There was a significant difference in the frequency of microscopic infarcts between DLB and AD, whereas no significant difference was noted in the frequency of microscopic hemorrhages. In DLB cases without vascular complications, memory disturbance was common as the initial symptom, while parkinsonism was more common in those with vascular complications. However, no significant difference was observed between DLB cases with and without vascular complications with respect to the frequency of individual clinical symptoms over the whole clinical course. These findings suggest that grossly identified hemorrhages are more common in DLB because of trauma, while microinfarcts are less common in DLB than AD, although the reason remains unclear. Such vascular complications might affect the clinical manifestations, in particular, the initial symptom, of DLB.

Visual rating of white matter hyperintensities in Parkinson's disease

Dementia is a common complication of Parkinson's disease (PD), but the cause is incompletely understood. In previous studies, dementia has been associated with an increase in hyperintense lesions in the cerebral white matter. The aim of this study was to explore whether white matter hyperintensities (WMH) on cerebral magnetic resonance imaging (MRI) are associated with dementia in PD. For this study, 35 patients with PD, 16 with dementia (PDD) and 19 without (PDND), and 20 control subjects were recruited. MRI scans of patients and controls were rated for WMH, blind to diagnosis, using the Scheltens visual rating scale. Both bivariate and multivariate statistical analyses were carried out. Cerebrovascular risk factors, education, gender, or age were similar across groups. Compared with the PDND group, the PDD group had significantly higher level of WMH in the deep white matter and in the periventricular areas. WMH in the deep white matter was the only variable that was associated significantly with Mini-Mental State Examination score and explained 38% of the variance in the multivariate linear regression analysis. Our findings suggest that WMH in the deep white matter may contribute to dementia in PD.

Parkinson's disease, stroke, and related epidemiology

We investigated the prevalence of cerebrovascular disease and other comorbidities in Parkinson's disease (PD) patients compared to the general population. Five hundred PD patients were chosen randomly from one author's (A.H.R.) database. Age- and sex-matched controls were derived from 270 patients with essential tremor from the same database and from 490 patients in a general practitioner's database. Age, hypertensive status, smoking status, coronary artery disease, orthostatic hypotension, diabetes mellitus, and symptomatic cerebrovascular disease (stroke or transient ischemic attack) were assessed. Statistical analysis was performed using Pearson chi(2) testing and binary logistic regression analysis. The prevalence of coronary artery disease, hypertension, diabetes mellitus, and orthostatic hypotension was similar among groups. The PD group had more patients who never smoked and less current smokers than the other groups. While there were similar frequencies of symptomatic cerebrovascular disease among groups, the prevalence of stroke was lower in PD patients. This difference disappeared upon stratification into groups based on smoking status and in the addition of smoking as a covariate in the multivariate analysis. Diminished smoking in PD patients likely plays a role in our finding of decreased stroke in patients with PD. Increased access to appropriate neurological care and subsequent prevention of stroke after a warning transient ischemic attack may also play a role, as may diminished levels of excitotoxic neurotransmitters in PD patients.

Endothelial function markers in parkinsonian patients with hyperhomocysteinemia

Hyperhomocysteinemia is considered a risk factor for vascular disease causing endothelial damage and consequently atherogenesis. The purpose of this study was to investigate the effect of elevated homocysteine on certain biochemical markers of endothelial function in patients with idiopathic Parkinson's disease (PD). Blood homocysteine levels were assessed in 57 PD patients and 40 matched normal controls. Investigation of the C677T 5,10 methylenetetrahydrofolate reductase (MTHFR) genotype was also performed in 43 PD patients. The following markers of endothelial function were assessed: superoxide dismutase (SOD), nitric oxide (NO), sICAM-1 and sE-selectin. Homocysteine levels were found mildly elevated in PD patients particularly in those treated with L-Dopa. MTHFR genotype did not influence significantly this finding. SOD activity was found reduced but it was not correlated to homocysteine levels. All other parameters measured were normal and were not related to hyperhomocysteinemia. Our findings indicate that mild hyperhomocysteinemia in PD patients was not associated with endothelial dysfunction.

Progressing stroke with neurological deterioration in a group of Israeli elderly

Progressing stroke with neurological deterioration (PSND), i.e., neurological deterioration of patients during the first days following a stroke, although not an infrequent event, has hitherto been addressed only by few studies. This is the first investigation conducted in Israel with the aim to determine its prevalence and characteristics. Data regarding 140 patients with first ever stroke were collected prospectively between May 1999 and October 2000. All patients underwent a thorough daily neurological examination over the first 7 days, using the Canadian Neurological Scale. Most (90%), patients had hemiparesis, with dysarthria, aphasia and dysphagia being the most frequent associated neurological deficits. Thirty percent of the patients were on anti-aggregant therapy prior to the stroke. The prevalence of PSND was 23%. The 1-month in-hospital death rate of these PSND patients was 31%. Univariate analysis showed that previous anti-aggregant therapy, Parkinson's disease (PD), obesity, hyperlipidemia, and presence of aphasia were significantly more frequent in the PSND group. In addition, these patients arrived earlier to the emergency room. However, logistic regression analysis showed that only PD and obesity could possibly be considered as predictors for development of PSND. The prevalence as well as the death rate of PSND in this group of Israeli elderly is within the range reported in the literature. However, prior anti-aggregant treatment and PD, are here reported for the first time as associated conditions. Future research will possibly clarify the links between these entities and PSND.

Occupations and Parkinson’s Disease: A Multi-Center Case-Control Study in South Korea

OBJECTIVE

We performed a hospital based case-control study in South Korea (1) to clarify the role of occupational exposure, and especially manganese (Mn) exposure in the etiology of Parkinson's disease (PD) and (2) to discover the association between any occupations and PD.

METHODS

We selected two groups, PD patient group (N1) and controls (N2). Three hundred sixty-seven consecutive outpatients with PD (177 men, 190 women) and 309 controls were interviewed about life style, past history, family history, education level, and occupational history etc. We employed a range of industrial categories as defined by section (the most broad category) and division (sub-category) of the Korea Standard Industry Code (KSIC) Manual. Along with KSIC, we also used the Korea Standard Classification of Occupations (KSCO) as proxies of occupational exposure. The odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for age, sex, smoking status, and education level are presented.

RESULTS

As regarding the exposure to hazardous materials, especially Mn, more subjects in the control group than the PD patient group have worked in the occupations with potential exposure to Mn (P < 0.001). Ever having worked in 'agriculture, hunting, and forestry' section of industry was positively associated with PD (OR 1.88), and 'agriculture production crops (OR 1.96)' division of industry was positively associated with PD. On the other hand, ever having worked in the 'manufacturing (OR 0.56)', 'transportation (OR 0.28)' section of industry, and 'transporting (OR 0.20)' division of industry were negatively associated with PD. 'Drivers (OR 0.13)' division of occupation also was negatively associated with PD.

CONCLUSIONS

To our knowledge, this is the first case-control studies to find an inverse relationship between 'transporting' or 'technicians like machinery engineers' as his/her longest job and PD risk. Because of this unexpected finding, our work should be replicated in various populations.

Synaptic plasticity in the ischaemic brain

Activity-dependent long-term potentiation (LTP) of excitatory neurotransmission underlies specific forms of associative learning and memory. A brief period of energy deprivation induces LTP in specific subsets of neurons; this synaptic plasticity might contribute to the delayed effects of brain ischaemia. In this review, we discuss the similarities and differences between LTP induced by energy deprivation and "physiological" LTP. On the basis of recent studies, we propose that pathological plasticity induced by energy deprivation can play a part in delayed neuronal death in the hippocampus and the striatum after global ischaemia and in the conversion of ischaemic penumbra to infarct core after focal ischaemia. We discuss evidence that ischaemia could also induce protective and reparative forms of neuronal plasticity that may play a part in ischaemic tolerance and poststroke recovery.

Prevalence of cerebrovascular lesions in Parkinson's disease. A postmortem study

Data on the relationship between Parkinson's disease (PD) and stroke have been conflicting, some studies showing a reduced risk of stroke during life, and others indicating an increased risk of stroke-related death. Consecutive cases (n=617) of autopsy-proven idiopathic PD (Lewy body disease of the brain stem type) and age-matched controls (n=535) were compared using current routine and immunohistochemical methods. The total frequency of cerebrovascular lesions (lacunes, amyloid angiopathy, white matter lesions, old and recent ischemic infarcts and hemorrhages) in PD (44.0%) was higher than in controls (32.8%), while acute, often fatal ischemic or hemorrhagic strokes were less frequent in parkinsonian patients (1.8% vs 2.6%). Like previous postmortem findings in a smaller cohort, these findings neither indicate a protective effect against stroke nor a greater susceptibility to death from stroke in the populations studied. Cognitive impairment in PD appears to be largely independent from coexistent vascular pathology except in cases with severe cerebrovascular lesions.

Prevalence of stroke in Parkinson's disease: a postmortem study

The results of previous epidemiological studies of the relationship between Parkinson's disease and stroke have been conflicting; some showing a reduced risk of ischaemic and haemorrhagic stroke during life, and others indicating an increased likelihood of stroke-related death. We compared the frequency of cerebral infarcts and haemorrhages at postmortem in 100 cases of pathologically verified idiopathic Parkinson's disease and 100 age-matched control brains. No significant differences were found in the numbers of infarcts or haemorrhages or stroke-related deaths between the two groups. Our findings do not indicate either a protective effect against stroke, or a greater susceptibility to death from stroke, in the population studied.