Comparison of the prevalence of Parkinson's disease in black populations in the rural United States and in rural Nigeria: door-to-door community studies

Racial and Ethnic Disparities in Parkinson Disease: A Call to Action

Health disparities are pervasive in the United States. In the field of Parkinson disease (PD), profound racial and ethnic disparities exist in diagnosis, treatment, and research participation, leading to differential health outcomes and lack of generalizable research data. Racial and ethnic disparities not only limit our understanding of this complex heterogeneous disorder but also hamper our ability to provide new evidence-based care for America's most vulnerable populations. In this report, we summarize findings from our comprehensive white paper for the Michael J. Fox Foundation that reviews the current state of knowledge on racial and ethnic disparities in PD care in the following areas: epidemiology, etiology, phenotype and diagnosis, treatment, and research. We also identify knowledge gaps and necessary policy changes to ensure equitable, high-value care for all persons with PD. These strategies are designed to help identify and reduce health disparities among persons with PD and may serve as a model for other neurologic diseases.

Prevalence of parkinsonism and Parkinson disease in urban and rural populations from Latin America: A community based study

Background

Age and gender specific prevalence rates for parkinsonism and Parkinson's disease (PD) are important to guide research, clinical practice, and public health planning; however, prevalence estimates in Latin America (LatAm) are limited. We aimed to estimate the prevalence of parkinsonism and PD and examine related risk factors in a cohort of elderly individuals from Latin America (LatAm).

Methods

Data from 11,613 adults (65+ years) who participated in a baseline assessment of the 10/66 study and lived in six LatAm countries were analyzed to estimate parkinsonism and PD prevalence. Crude and age-adjusted prevalence were determined by sex and country. Diagnosis of PD was established using the UK Parkinson's Disease Society Brain Bank's clinical criteria.

Findings

In this cohort, the prevalence of parkinsonism was 8.0% (95% CI 7.6%-8.5%), and the prevalence of PD was 2.0% (95% CI 1.7%-2.3%). PD prevalence increased with age from 1.0 to 3.5 (65-69vs. 80 years or older, p < 0.001). Age-adjusted prevalence rates were lower for women than for men. No significant differences were found across countries, except for lower prevalence in urban areas of Peru. PD was positively associated with depression (adjusted prevalence ratio [aPR] 2.06, 95% CI 1.40-3.01, I ² = 56.0%), dementia (aPR 1.57, 95% CI 1.07- 2.32, I ² = 0.0%) and educational level (aPR 1.14, 95% CI 1.01- 1.29, I ² = 58.6%).

Interpretation

The reported prevalence of PD in LatAm is similar to reports from high-income countries (HIC). A significant proportion of cases with PD did not have a previous diagnosis, nor did they seek any medical or neurological attention. These findings underscore the need to improve public health programs for populations currently undergoing rapid demographic aging and epidemiological transition.

Funding

The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Availability of Therapies and Services for Parkinson's Disease in Africa: A Continent-Wide Survey

BACKGROUND

The growing burden of Parkinson's disease (PD) in Africa necessitates the identification of available therapies and services to improve patient care.

OBJECTIVE

To investigate the availability, affordability, frequency of usage, and insurance coverage of PD therapies (pharmacological, surgical, physical, and speech therapies) and services including specialized clinics, specialists, and nurses across Africa.

METHODS

A comprehensive web-based survey was constructed and distributed to neurologists/physicians with a special interest in PD across Africa. The survey instrument includes components that address availability, affordability, frequency of use, and insurance coverage of different therapies and services.

RESULTS

Responses were received from 28 (of 43 contacted) countries. Levodopa-based oral preparations were always available in 13 countries (46.4%) with variable affordability and "partial or no" insurance coverage in 60% of countries. Bromocriptine was the most available (50%) and affordable ergot dopamine agonists (DA), whereas non-ergot DA was always available in only six countries (21.4%). Trihexyphenidyl was the most available and affordable anticholinergic drug (46.4%). Tricyclic antidepressants and selective serotonin reuptake inhibitors were available in most countries (89.3% and 85.7% respectively), with variable affordability. Quetiapine and clozapine were less available. Specialized clinics and nurses were available in 25% and 7.1% of countries surveyed, respectively. Other services were largely unavailable in the countries surveyed.

CONCLUSION

PD-specific therapies and services are largely unavailable and unaffordable in most African countries. The data provide a platform for organizing strategies to initiate or scale up existing services and drive policies aimed at improving access to care and tailoring education programs in Africa. © 2021 International Parkinson and Movement Disorder Society.

Disparities in diagnosis, treatment and survival between Black and White Parkinson patients

INTRODUCTION

Racial disparities in diagnosis, treatment and survival in Black patients with Parkinson's disease (PD) compared to White patients have not been well studied, largely due to limited number of studies and information on Black patients in healthcare systems. Studying racial disparities and identifying underlying factors in large populations are important to understand PD and improve care.

METHODS

We retrospectively identified PD patients on both races from 1/1/2006 to 10/31/2017 and compared demographics, socioeconomic status (educations, incomes and insurances), comorbidities (all categories, including mood, cognition and psychosis), treatment (medications for parkinsonism and major non-motor symptoms, and frequency and locations of healthcare) and survival, and identified factors associated with medication usage and survival.

RESULTS

We retrospectively studied 2033 PD patients, of whom 725 were Black. Black patients lacked male predominance, were 4 years older at first diagnosis here, more likely to smoke and live in a low education and income community, and possessed limited insurances compared to White patients. Black patients also had more comorbidities and were more likely to receive care through emergency or inpatient service, but less likely to be on medications for parkinsonism and mood disorders. Race, age, smoking status, insurance type, frequency and locations of healthcare and comorbidities were associated with medication usage. Black race, older age, inpatient admission and malignancy were associated with increased risk of death.

CONCLUSION

We revealed racial disparities in diagnosis, treatment and survival, and factors associated with medication usage and survival in the largest reported Black PD cohort from a single center.

Perspective: Low Risk of Parkinson's Disease in Quasi-Vegan Cultures May Reflect GCN2-Mediated Upregulation of Parkin

Mitochondrial dysfunction in dopaminergic neurons of the substantia nigra (SN) appears to be a key mediating feature of Parkinson's disease (PD), a complex neurodegenerative disorder of still unknown etiology. Parkin is an E3 ubiquitin ligase that promotes mitophagy of damaged depolarized mitochondria while also boosting mitochondrial biogenesis-thereby helping to maintain efficient mitochondrial function. Boosting Parkin expression in the SN with viral vectors is protective in multiple rodent models of PD. Conversely, homozygosity for inactivating mutations of Parkin results in early-onset PD. Moderate protein plant-based diets relatively low in certain essential amino acids have the potential to boost Parkin expression by activating the kinase GCN2, which in turn boosts the expression of ATF4, a factor that drives transcription of the Parkin gene. Protein-restricted diets also upregulate the expression of PINK1, a protein that binds to the outer membrane of depolarized mitochondria and then recruits and activates Parkin. This effect of protein restriction is mediated by the downregulation of the kinase activity of mammalian target of rapamycin complex 1; the latter suppresses PINK1 expression at the transcriptional level. During the 20th century, cultures in East Asia and sub-Sahara Africa consuming quasi-vegan diets were found to be at notably decreased risk of PD compared with the USA or Europe. It is proposed that such diets may provide protection from PD by boosting Parkin and PINK1 expression in the SN. Other measures that might be expected to upregulate protective mitophagy include supplemental N-acetylcysteine (precursor for hydrogen sulfide) and a diet rich in spermidine-a polyamine notably high in corn.

Burden of adult neurological diseases in Odeda Area, Southwest Nigeria

Background

Few population-based studies have been conducted to determine the burden of neurological diseases in sub-Saharan Africa. A better understanding of the magnitude and impact of these disorders is pivotal to effective planning and provision of neurological services.

Methods

A cross-sectional survey of 2392 adults in Odeda Local Government Area, Ogun State, Southwest Nigeria was conducted between May and June 2015. Trained non-medical interviewers administered a screening instrument designed to measure the prevalence of neurological diseases and disability, while positive responders were subsequently examined by neurologists. Diagnoses were made clinically according to well-established criteria.

Results

The mean age of respondents was 37.2±16.1 years. A total of 842 cases of neurological diseases/disability were diagnosed in 815 individuals (26 individuals with more than one disorder). The all-cause neurological morbidity rate was 352 per 1000, while the crude prevalence rates of common neurological disorders were 304.3 per 1000 for primary headaches, 16.3 per 1000 for tropical ataxic neuropathy, 7.11 per 1000 for stroke, 5.85 per 1000 for essential tremor and 4.18 per 1000 for Parkinson’s disease. Neurological years lost due to disability was 2806.18 per 100 000.

Conclusion

This study provides evidence of a high neurological disease burden within the communities surveyed, which may be representative of Southwest Nigeria. In comparison with findings from previous studies within the same region, this report suggests a persistence of toxiconutritional disorders and postinfectious neurological sequelae on one hand and increased prevalence of non-communicable neurological disorders such as stroke and Parkinson’s disease.

Parkinson's Disease Research on the African Continent: Obstacles and Opportunities

The burden of Parkinson's disease (PD) is becoming increasingly important in the context of an aging African population. Although PD has been extensively investigated with respect to its environmental and genetic etiology in various populations across the globe, studies on the African continent remain limited. In this Perspective article, we review some of the obstacles that are limiting research and creating barriers for future studies. We summarize what research is being done in four sub-Saharan countries and what the key elements are that are needed to take research to the next level. We note that there is large variation in neurological and genetic research capacity across the continent, and many opportunities for unexplored areas in African PD research. Only a handful of countries possess appropriate infrastructure and personnel, whereas the majority have yet to develop such capacity. Resource-constrained environments strongly determines the possibilities of performing research locally, and unidirectional export of biological samples and genetic data remains a concern. Local-regional partnerships, in collaboration with global PD consortia, should form an ethically appropriate solution, which will lead to a reduction in inequality and promote capacity building on the African continent.

Nutraceuticals Targeting Generation and Oxidant Activity of Peroxynitrite May Aid Prevention and Control of Parkinson's Disease

Parkinson's disease (PD) is a chronic low-grade inflammatory process in which activated microglia generate cytotoxic factors-most prominently peroxynitrite-which induce the death and dysfunction of neighboring dopaminergic neurons. Dying neurons then release damage-associated molecular pattern proteins such as high mobility group box 1 which act on microglia via a range of receptors to amplify microglial activation. Since peroxynitrite is a key mediator in this process, it is proposed that nutraceutical measures which either suppress microglial production of peroxynitrite, or which promote the scavenging of peroxynitrite-derived oxidants, should have value for the prevention and control of PD. Peroxynitrite production can be quelled by suppressing activation of microglial NADPH oxidase-the source of its precursor superoxide-or by down-regulating the signaling pathways that promote microglial expression of inducible nitric oxide synthase (iNOS). Phycocyanobilin of spirulina, ferulic acid, long-chain omega-3 fatty acids, good vitamin D status, promotion of hydrogen sulfide production with taurine and N-acetylcysteine, caffeine, epigallocatechin-gallate, butyrogenic dietary fiber, and probiotics may have potential for blunting microglial iNOS induction. Scavenging of peroxynitrite-derived radicals may be amplified with supplemental zinc or inosine. Astaxanthin has potential for protecting the mitochondrial respiratory chain from peroxynitrite and environmental mitochondrial toxins. Healthful programs of nutraceutical supplementation may prove to be useful and feasible in the primary prevention or slow progression of pre-existing PD. Since damage to the mitochondria in dopaminergic neurons by environmental toxins is suspected to play a role in triggering the self-sustaining inflammation that drives PD pathogenesis, there is also reason to suspect that plant-based diets of modest protein content, and possibly a corn-rich diet high in spermidine, might provide protection from PD by boosting protective mitophagy and thereby aiding efficient mitochondrial function. Low-protein diets can also promote a more even response to levodopa therapy.

Divergent Expression Patterns of Drp1 and HSD10 in the Nigro-Striatum of Two Mice Strains Based on their MPTP Susceptibility

Alterations in the basal ganglia circuitry are critical events in the pathophysiology of Parkinson's disease (PD). We earlier compared MPTP-susceptible C57BL/6J and MPTP-resistant CD-1 mice to understand the differential prevalence of PD in different ethnic populations like Caucasians and Asian-Indians. The MPTP-resistant CD-1 mice had 33% more nigral neurons and lost only 15-17% of them following MPTP administration. In addition to other cytomorphological features, their basal ganglia neurons had higher calcium-buffering protein levels. During disease pathogenesis as well as in MPTP-induced parkinsonian models, the loss of nigral neurons is associated with reduction in mitochondrial complex-1. Under these conditions, mitochondria respond by undergoing fusion or fission. 17β-hydroxysteroid type 10, i.e., hydroxysteroid dehydrogenase10 (HSD10) and dynamin-related peptide1 (Drp1) are proteins involved in mitochondrial hyperfusion and fission, respectively. Each plays an important role in mitochondrial structure and homeostasis. Their role in determining susceptibility to the neurotoxin MPTP in basal ganglia is however unclear. We studied their expression using immunohistochemistry and Western blotting in the dorsolateral striatum, ventral tegmental area, and substantia nigra pars compacta (SNpc) of C57BL/6J and CD-1 mice. In the SNpc, which exhibits more neuron loss following MPTP, C57BL/6J had higher baseline Drp1 levels; suggesting persistence of fission under normal conditions. Whereas, HSD10 levels increased in CD-1 following MPTP administration. This suggests mitochondrial hyperfusion, as an attempt towards neuroprotection. Thus, the baseline differences in HSD10 and DRP1 levels as well as their contrasting MPTP-responses may be critical determinants of the magnitude of neuronal loss/survival. Similar differences may determine the variable susceptibility to PD in humans.

Parkinson's disease in Nigeria: A review of published studies and recommendations for future research

Parkinson's disease (PD) affects 1-2% of individuals above 60 years amounting to over 7 million people worldwide. Thus, PD has become an important contributor to the neurological disease burden. Nigeria is the most populous country in Africa, and alarmingly, approximately 5.25 million Nigerians are above 65 years and are therefore at risk for developing PD. We carried out a critical review of published literature on PD in Nigeria to summarize the findings and to evaluate gaps in knowledge. Seven electronic databases were searched for studies published in English before 18th July 2018. Search terms were ["Parkinson's disease" OR "Parkinson disease" OR "parkinsonian disorders" OR "Parkinsonism"] AND "Nigeria". A total of 44 articles (including eight reviews) published since 1969 were identified and reviewed. Amongst the original research articles, most (23) were on PD symptoms or prevalence. There were only two studies on genetics and two on environmental factors. The estimated crude prevalence of PD in Nigeria was lower (10-249/100 000) compared to studies published in Europe (65.6-12 500/100 000). Our findings suggest that PD is under-diagnosed in Nigeria. Possible environmental risk factors identified include blacksmithing and well-water contaminated with trace metals. Given the rising numbers of the ageing population in Nigeria, more studies to evaluate the prevalence and causes of PD in this country are urgently needed. To this end, more funding, resources and a workforce of well-trained neurologists and scientists are essential to manage the impending health burden of PD and related disorders in this country.

Admixing MPTP-resistant and MPTP-vulnerable mice enhances striatal field potentials and calbindin-D28K expression to avert motor behaviour deficits

Asian-Indians are less vulnerable to Parkinson's disease (PD) than the Caucasians. Their admixed populace has even lesser risk. Studying this phenomenon using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-susceptible C57BL/6J, MPTP-resistant CD-1 and their resistant crossbred mice revealed differences in the nigrostriatal cyto-molecular features. Here, we investigated the electrophysiological and behavioural correlates for differential MPTP-susceptibility and their outcome upon admixing. We recorded local field potentials (LFPs) from dorsal striatum and assessed motor co-ordination using rotarod and grip strength measures. Nigral calbindin-D28K expression, a regulator of striatal activity through nigrostriatal projections was evaluated using immunohistochemistry. The crossbreds had significantly higher baseline striatal LFPs. MPTP significantly increased the neuronal activity in delta (0.5-4 Hz) and low beta (12-16 Hz) ranges in C57BL/6J; significant increase across frequency bands till high beta (0.5-30 Hz) in CD-1, and caused no alterations in crossbreds. MPTP further depleted the already low nigral calbindin-D28K expression in C57BL/6J. While in crossbreds, it was further up-regulated. MPTP affected the rotarod and grip strength performance of the C57BL/6J, while the injected CD-1 and crossbreds performed well. The increased striatal β-oscillations are comparable to that in PD patients. Higher power in CD-1 may be compensatory in nature, which were also reported in pre-symptomatic monkeys. Concurrent up-regulation of nigral calbindin-D28K may assist maintenance of striatal activity by buffering calcium overload in nigra. Thus, preserved motor behaviour in PD reminiscent conditions in CD-1 and crossbreds complement compensated/unaffected striatal LFPs. Similar electrophysiological correlates and cytomorphological features are envisaged in human phenomenon of differential PD prevalence, which are modulated upon admixing.

Clinical Profile of Parkinson's Disease: Experience of Niger

Background:

Parkinson's disease (PD) is a chronic neurodegenerative pathology with unknown etiology. It is characterized clinically by the classic triad that associated tremors, bradykinesia, and rigidity. In Niger, there are no data on PD.

Aims:

We aimed to provide the demographic and clinical profile of PD in patients from Niger to create a database on PD in Niger.

Patients and Methods:

We conducted a retrospective study at the Neurology Outpatient Clinic of the Hôpital National de Niamey (HNN, Niger) over a period of 4.42 years from February 2009 to July 2013 collecting all cases of PD. The demographic and clinical features of all patients were collected and analyzed.

Results:

During the period of the study, 1695 patients consulted at the Neurology Outpatient Clinic of the HNN, among which 76 patients (4.48%) had secondary parkinsonism and 25 patients (1.47%) had features compatible with PD. Only patients with PD were included in this study. The mean age at onset of symptoms was 58 years (range: 42–74 years). The male sex was predominant (60%) with a sex ratio of 1.5. The mean time interval from the onset of symptoms to diagnosis of PD was 1.8 years (range: 1–5 years). The tremor was the most common symptom (84%). Bradykinesia represented 64% of the symptoms and rigidity 20%. At the time of the diagnosis of PD, 8 patients (32%) were in Stage I of the classification of Hoehn and Yahr, 16 patients (64%) in Stage II, and 1 patient (4%) in Stage III. The levodopa/carbidopa combination was the most used antiparkinsonian drug in our patients (88%). The mean time of follow-up of the patients was 2.5 years (range: 1–4.42 years). During the course of the disease, 9 patients (36%) were in Stage II of the classification of Hoehn and Yahr, 13 patients (52%) in Stage III, and 3 patients (12%) in Stage IV.

Conclusion:

Our study provides demographic and clinical data of PD in patients from Niger and shows that the hospital frequency of this disease is low (1.47%). The demographic and clinical features of our patients are similar to those of the patients of the prior studies reported in sub-Saharan Africa.

Parkinson's Disease in Sub-Saharan Africa: A Review of Epidemiology, Genetics and Access to Care

A low prevalence of Parkinson's disease (PD) has been reported in the Sub-Saharan Africa (SSA) region. The genetic causes and clinical features of PD in this region have been poorly described. Very few reports have examined the availability and access to evidence-based quality care for people living with PD in this region. We reviewed all publications focusing on idiopathic PD from SSA published up to May 2016 and observed a prevalence of PD ranging from 7/100,000 in Ethiopia to 67/100,000 in Nigeria. The most recent community-based study reported a mean age at onset of 69.4 years. The infrequent occurrence of mutations in established PD genes was also observed in the region. Treatments were non-existent or at best irregular. Additionally, there is a lack of well-trained medical personnel and multidisciplinary teams in most countries in this region. Drugs for treating PD are either not available or unaffordable. Large-scale genetic and epidemiological studies are therefore needed in SSA to provide further insights into the roles of genetics and other etiological factors in the pathogenesis of PD. The quality of care also requires urgent improvement to meet the basic level of care required by PD patients.

Baseline striatal and nigral interneuronal protein levels in two distinct mice strains differ in accordance with their MPTP susceptibility

Epidemiological studies reveal an ethnicity-based bias in prevalence of Parkinson's disease (PD), deriving from the differences that exist between Caucasians and African or Asian populations. Experimental mice models provide a scope to analyse the cellular mechanisms of differential susceptibility to PD. C57BL/6J mice, for instance, are more susceptible to MPTP-induced Parkinsonism whereas CD-1 mice are resistant. In PD-pathogenesis, interneuronal contribution is also likely, although they comprise only 5-10% of the striatal cells. The interneurons harbour calcium binding proteins, like calretinin (Cal-R) and parvalbumin (PV), which are crucial in Ca²⁺ homeostasis for preventing calcium-induced excitotoxicity. GAD-67-immunoreactive interneurons are the other prominent set of GABAergic interneurons. In PD, dopamine loss up-regulates GAD-67 expression in striatal projection neurons and other basal ganglia circuit. We studied the possible contribution of interneurons in determining variable susceptibility by assessing the expression of calretinin, PV and GAD-67 in both striatum and substantia nigra pars compacta (SNpc) in two distinct mice strains, i.e. C57BL/6J and CD-1 under normal conditions, using unbiased stereology for quantification of immunoreactive cells and immunoblotting. The vulnerable C57BL/6J had lesser basal parvalbumin expression in both nigra and striatum whereas the calretinin levels were low only in the striatum. GAD-67 expression showed no perceptible differences in the striatum or SNpc of either of the strains. Differential expression of calcium buffering/binding proteins under normal physiological condition proffers a role for interneurons in the differential susceptibility to PD. Thus, even the baseline susceptibility indices i.e. without using the neurotoxin; can provide vital mechanistic insights into PD pathogenesis.

Epidemiology of Parkinson's Disease-East Versus West

Background

The cause of PD at present remains unknown. A number of epidemiological studies have been conducted across the globe to ascertain the disease burden and the possible risk factors. In this review, we analyze the various studies from East and West with an aim to observe the important similarities and differences in the disease occurrence and risk factor profile.

Methods

A comprehensive search of descriptive and analytical epidemiological studies was undertaken. The descriptive studies and meta-analysis providing the standardised population rates were selected. The demographics, ethnicity and geographical differences between East and West were analysed. In analytical epidemiology, more established and well-studied non-genetic risk factors for PD were reviewed utilising the prospective cohort studies, case control studies and meta-analysis where available.

Results and Conclusion

PD is more common with increasing age and shows male predominance, which is more obvious in Western studies. The PD prevalence and incidence rates are slightly lower in the East compared to the West. Incidence studies on different ethnic populations in the same country have also found a lower occurrence of PD amongst Easterners compared to Westerners. Setting methodological differences aside, studies from East and West suggest a role for both environmental and genetic risk factors in PD causation. Smoking, caffeine intake and pesticide exposure are well-established risk factors across regions. There is a robust data for dairy product consumption, urate levels and physical activity in the West while studies on certain risk factors like head injury and alcohol show conflicting and mixed results.

The analysis of relationship between selected sociodemografic factors and disorders of speech organs in Parkinson`s patients

Background

Evaluation of speech disorders in PD taking into account sociodemographic conditions is not frequent. This paper aims to establish correlations between articulation disorders in PD patients and factors such as the patients’ sex, age, education and residence.

Methods

The study included 92 patients with idiopathic PD diagnosed by means of multiple neurological examinations, biochemical tests, MRI and CT scanning carried out in accordance with the United Kingdom Parkinson’s Disease Society Brain Bank (UKPDSBB) criteria. A speech and language test involved the assessment of the mobility of the speech organs as well as the reflexes inside the oral cavity. Frenchay Dysarthria Assessment was applied for an objective evaluation of dysarthria.

Results

The study revealed the existence of significant relationship between the functionality of articulators in PD patients and their education and residence. Big city dwellers demonstrated lower incidence of disorders within speech organs, particularly those affecting mobility of the soft palate while eating. Disorders of moderate intensity were more frequently found in subjects living in villages. Subjects with a university education displayed better position of the lips at rest and better performance of both lips and the mandible while speaking.

Conclusions

Abnormal functioning of the articulatory organs was observed more frequently in PD patients residing in rural areas than in those inhabiting urban areas. As for education, our cohort university graduates displayed a better position of the lips at rest and better performance of the lips and jaw during speaking than those with secondary and vocational education.

Admixing of MPTP-Resistant and Susceptible Mice Strains Augments Nigrostriatal Neuronal Correlates to Resist MPTP-Induced Neurodegeneration

Disease genetics in admixed populations like Hispanic-Americans, African-Americans, etc. are gaining importance due to high disease burden in them. Furthermore, epidemiological studies conclusively prove ethnicity-based differential prevalence of Parkinson's disease (PD), since the American-Caucasians are more susceptible than Asian-Indians and Africans. Contradictorily, Anglo-Indians, an admixture of Europeans and Asian-Indians are five-times less susceptible than Indians. We evaluated the neural basis of this phenomenon using the cytomorphological features of susceptibility to nigrostriatal neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The nigral dopaminergic neuronal numbers, their size and tyrosine hydroxylase (TH), PitX3 and Nurr1 expression were compared in MPTP-susceptible C57BL/6J mice, MPTP-resistant CD-1 mice and their crossbreds using stereology, morphometry and densitometry. Apoptotic index was evaluated by TUNEL-assay and caspase-3 expression. Striatal volume, TH and glial derived neurotrophic factor (GDNF) expression were studied. The normal CD-1 and crossbreds had significantly more, although smaller, nigral dopaminergic neurons than C57BL/6J, and a larger striatum. The crossbreds had higher TH, Nurr1 and PitX3 levels. MPTP administration caused loss of ~50-60 % nigral dopaminergic neurons in C57BL/6J and ~15 % in CD-1, but none in crossbreds. MPTP-induced cellular shrinkage in C57BL/6J was contrasted by nuclear enlargement without somal alterations in resistant strains. MPTP lowered the striatal TH and GDNF in C57BL/6J. Elevated striatal GDNF in CD-1 and crossbreds could be of compensatory nature and complemented the reduced nigral caspase-3 expression to attenuate and/or block apoptosis. Similar neural correlates of resilience are envisaged in the Anglo-Indian population. Thus, we present the core neuroanatomical features of resilience against PD and evidence for ethnicity-based differential prevalence.

Parkinson's Disease and Homocysteine: A Community-Based Study in a Folate and Vitamin B12 Deficient Population

Background. Homocysteine (Hcy) levels were higher in patients with Parkinson's disease (PD). This could be partially explained by levodopa treatment. Whether untreated PD patients have higher Hcy levels is contradictory. Methods. A community-based study was conducted using a two-stage approach for subjects ≥ 55 years to find PD patients in 3 towns of Lüliang City. Blood samples were collected. Serum Hcy, folate, and vitamin B12 concentrations were measured. For each untreated PD patient, 5 controls were selected matched with age and sex to evaluate the relationship between Hcy levels and PD. Results. Of 6338 eligible residents, 72.7% participated in the study. 31 PD cases were identified. The crude prevalence of PD for people ≥ 55 years was 0.67%. Blood samples were collected from 1845 subjects, including 17 untreated PD patients. There was no difference for concentrations of serum Hcy, folate, and vitamin B12 between cases and controls (P > 0.05). In univariate and multivariate analysis, there was significant inverse relation between PD and current smoking (P < 0.05). No other factor was significant statistically. Conclusions. The prevalence of PD was comparable to earlier studies in China. Hyperhomocysteinemia was not a risk factor of PD, as well as folate and vitamin B12 deficiency.

Parkinsonism Treatment: Part III—Update

OBJECTIVE:

The purpose of this review is to update clinicians with recent advances in the management of parkinsonism, including drug therapy, transplantation, and diet.

DATA SOURCES:

Pertinent articles were obtained from an English-language literature search using MEDLINE (1970–1991), Index Medicus (1987–1991), Current Contents (1990), and bibliographic reviews of review articles. Index terms included parkinsonism, selegiline, pergolide, vitamin E, and transplantation. Fifty-five articles (representing 85 percent of the complete literature search) were selected by multiple reviewers for their contribution to the stated purpose. Emphasis was placed on double-blind, placebo-controlled, and randomized studies. Data from cited articles were examined by multiple reviewers for support of their stated hypothesis and were included as background for justification of major points in this article; critical studies were abstracted in more detail.

RESULTS:

New therapeutic measures have been added to the treatment of parkinsonism. Selegiline, a monoamine oxidase inhibitor type B, has shown beneficial results, especially in early stages. Pergolide, a dopamine agonist, may be an efficacious alternative to bromocriptine resistance or intolerable adverse effects. Vitamin E may have protective antioxidant properties, but very few clinical data are available. Fetal tissue transplantation needs continued research and remains very controversial. Diet modification may maximize the results of therapy with exogenous dopamine therapy.

CONCLUSIONS:

Clinicians should familiarize themselves with new alternatives for the management of parkinsonism in order to be reliable consultants for both professional and lay persons.

Profile of neurological disorders in an adult neurology clinic in Kumasi, Ghana

BACKGROUND

Although the burden of neurological disorders is highest among populations in developing countries there is a dearth of data on the clinical spectrum of these disorders.

OBJECTIVE

To profile the frequency of neurologic disorders and basic demographic data in an adult neurology out-patient service commissioned in 2011 in Kumasi, Ghana.

METHODS

The study was conducted at the neurology clinic of the Komfo Anokye Teaching Hospital in Kumasi, Ghana. Over a three year period, all medical records of patients enrolled at the out-patient neurology clinic was reviewed by a neurologist and neurological diagnoses classified according to ICD-10.

RESULTS

1812 adults enrolled for care in the neurology out-patient service between 2011 and 2013. This comprised of 882 males and 930 females (male: female ratio of 1.0: 1.1) with an overall median age of 54 (IQR, 39-69) years. The commonest primary neurological disorders seen were strokes, epilepsy and seizure disorders, and movement disorders at frequencies of 57.1%, 19.8%, and 8.2% respectively.

CONCLUSIONS

Cerebrovascular diseases, epilepsy and movement disorders were among the commonest neurological disorders and the major contributors to neurologic morbidity among Ghanaians in an urban neurology clinic.

Frequency and Cause of Parkinson’s Disease

Parkinson syndrome (PS) is a common disorder in the North American population. The annual incidence rate is 20.5/100,000 population and the mean survival after onset is approximately 12.3 years. The estimated prevalence rate is about 300/100,000 population. The incidence and prevalence rates rise with advancing age. Both the widespread use of levodopa and the improved health care in general have increased the longevity in PS. The survival in PS from the time of the first clinic visit is still significantly shorter when compared with the regional age and sex matched population. The cause of IPD may be related to some environmental factor(s) – most likely a toxin. Genetic factors are not the cause but in some families, may predispose to IPD.

The prevalence of Parkinson's disease: a systematic review and meta-analysis

Parkinson's Disease (PD) is a common neurodegenerative disorder. We sought to synthesize studies on the prevalence of PD to obtain an overall view of how the prevalence of this disease varies by age, by sex, and by geographic location. We searched MEDLINE and EMBASE for epidemiological studies of PD from 1985 to 2010. Data were analyzed by age group, geographic location, and sex. Geographic location was stratified by the following groups: 1) Asia, 2) Africa, 3) South America, and 4) Europe/North America/Australia. Meta-regression was used to determine whether a significant difference was present between groups. Forty-seven studies were included in the analysis. Meta-analysis of the worldwide data showed a rising prevalence of PD with age (all per 100,000): 41 in 40 to 49 years; 107 in 50 to 59 years; 173 in 55 to 64 years; 428 in 60 to 69 years; 425 in 65 to 74 years; 1087 in 70 to 79 years; and 1903 in older than age 80. A significant difference was seen in prevalence by geographic location only for individuals 70 to 79 years old, with a prevalence of 1,601 in individuals from North America, Europe, and Australia, compared with 646 in individuals from Asia (P < 0.05). A significant difference in prevalence by sex was found only for individuals 50 to 59 years old, with a prevalence of 41 in females and 134 in males (P < 0.05). PD prevalence increases steadily with age. Some differences in prevalence by geographic location and sex can be detected.

Epidemiology of neurodegenerative diseases in sub-Saharan Africa: a systematic review

BACKGROUND

Sub-Saharan African (SSA) countries are experiencing rapid transitions with increased life expectancy. As a result the burden of age-related conditions such as neurodegenerative diseases might be increasing. We conducted a systematic review of published studies on common neurodegenerative diseases, and HIV-related neurocognitive impairment in SSA, in order to identify research gaps and inform prevention and control solutions.

METHODS

We searched MEDLINE via PubMed, 'Banque de Données de Santé Publique' and the database of the 'Institut d'Epidemiologie Neurologique et de Neurologie Tropicale' from inception to February 2013 for published original studies from SSA on neurodegenerative diseases and HIV-related neurocognitive impairment. Screening and data extraction were conducted by two investigators. Bibliographies and citations of eligible studies were investigated.

RESULTS

In all 144 publications reporting on dementia (n = 49 publications, mainly Alzheimer disease), Parkinsonism (PD, n = 20), HIV-related neurocognitive impairment (n = 47), Huntington disease (HD, n = 19), amyotrophic lateral sclerosis (ALS, n = 15), cerebellar degeneration (n = 4) and Lewy body dementia (n = 1). Of these studies, largely based on prevalent cases from retrospective data on urban populations, half originated from Nigeria and South Africa. The prevalence of dementia (Alzheimer disease) varied between <1% and 10.1% (0.7% and 5.6%) in population-based studies and from <1% to 47.8% in hospital-based studies. Incidence of dementia (Alzheimer disease) ranged from 8.7 to 21.8/1000/year (9.5 to 11.1), and major risk factors were advanced age and female sex. HIV-related neurocognitive impairment's prevalence (all from hospital-based studies) ranged from <1% to 80%. Population-based prevalence of PD and ALS varied from 10 to 235/100,000, and from 5 to 15/100,000 respectively while that for Huntington disease was 3.5/100,000. Equivalent figures for hospital based studies were the following: PD (0.41 to 7.2%), ALS (0.2 to 8.0/1000), and HD (0.2/100,000 to 46.0/100,000).

CONCLUSIONS

The body of literature on neurodegenerative disorders in SSA is large with regard to dementia and HIV-related neurocognitive disorders but limited for other neurodegenerative disorders. Shortcomings include few population-based studies, heterogeneous diagnostic criteria and uneven representation of countries on the continent. There are important knowledge gaps that need urgent action, in order to prepare the sub-continent for the anticipated local surge in neurodegenerative diseases.

The prevalence and genetics of Parkinson's disease in sub-Saharan Africans

Parkinson's disease (PD) is under-studied in Black Sub-Saharan African (SSA) populations. To date, there have been only six prevalence and no incidence studies. The crude prevalence of PD in SSA varies from 7 to 20 per 100,000, which is appreciably lower than in Caucasian populations. There are a limited number of published studies (nine) on the genetic factors associated with PD in SSA populations. Mutations have been reported in the parkin gene, and are restricted to only three patients (two Black South Africans and one Zambian). No mutations have been identified in the LRRK2, SNCA, PINK, or DJ-1 genes. Given the unique ancestry of SSA populations, their inclusion in genetic studies may provide a substantial contribution to the identification of novel genetic factors and genetic-environmental interactions underlying this disorder. More initiatives are needed to drive further research on PD in these populations and to facilitate collaborative projects across Africa.

A national registry to determine the distribution and prevalence of Parkinson's disease in Thailand: implications of urbanization and pesticides as risk factors for Parkinson's disease

BACKGROUND

Parkinson's disease (PD) occurs worldwide but prior to this review of data from the Thailand Parkinson's Disease Registry there had been no nationwide PD registry reported globally.

OBJECTIVE

To determine the distribution and prevalence of PD in Thailand and related risk factors in order to more adequately develop and allocate prevention and treatment resources where they are most needed and to ascertain risk factors that are specific to the Thai population.

DESIGN

The Thailand Parkinson's Disease Registry is a new resource, and data collection began in March 2008. Data is collected by the Registry from physicians, and a mechanism is also provided for patients to self-report. This data was further analyzed by the capture-recapture methodology (CRM) to assess reporting biases.

METHODS

The three main sources of data input to the Registry, i.e. (1) public hospitals, (2) private hospitals and (3) self-registration, require checking for duplicates and also allow estimation of completeness of recording (the degree of underreporting) in this disease registry. There is underreporting because of poor record keeping and administrative procedures in some facilities, and there is an unknown number of persons with PD who are not properly diagnosed because of inadequate facilities and staffing in some areas. Since our data sources should be overlapping in some way, and assuming that the likelihood of being detected in one system is independent of the others, we estimated these data sources' actual coverage and the expected total number of patients utilizing the 'capture-recapture' statistical technique.

RESULTS

As of March 2011, the Thailand PD Registry had identified 40,049 PD patients. Employing log-linear modeling, the CRM analysis based on the three data sets estimated underreporting of 20,516 cases. The revised estimated total is thus 60,565 cases, resulting in a crude and age-adjusted prevalence of 95.34 and 424.57 PD cases/100,000 population, respectively. The prevalence of PD was 126.83/100,000 in urban areas and 90.82/100,000 in rural areas (p < 0.001). Preliminary regional comparisons revealed a higher prevalence of PD in residents of the central plain valley of Thailand, an area with a large amount of pesticide use.

CONCLUSIONS

The combination of a passive registry and the CRM technique allowed us to derive population prevalence estimates for PD in Thailand. Thai PD prevalence estimates were similar to previous ones published for Asian countries; in addition, they suggested that urbanization and exposure to pesticides may both be risk factors for PD in the Thai population.

Parkinson’s disease in sub-Saharan Africa: step-by-step into the challenge

SUMMARY Nowadays, most developing countries are experiencing a demographic transition characterized by an increase in mean life expectancy, thus the prevalence of age-related disorders such as Parkinson’s disease (PD) are expected to increase accordingly. Previous reports suggest that PD is still largely underdiagnosed and undertreated in low-income areas because of the limited availability of trained staff and medication, as well as inadequate patient follow-up and education. In this article, we performed a step-by-step assessment of the main challenges encountered in the management of patients with PD in developing countries, ranging from diagnostic to therapeutic issues. These issues stem from published literature and, mostly, from our direct experience of PD management in Ghana and Zambia through personal contribution of local physicians who face this challenge in their routine clinical practice.

Epidemiology and etiology of Parkinson's disease: a review of the evidence

The etiology of Parkinson's disease (PD) is not well understood but likely to involve both genetic and environmental factors. Incidence and prevalence estimates vary to a large extent-at least partly due to methodological differences between studies-but are consistently higher in men than in women. Several genes that cause familial as well as sporadic PD have been identified and familial aggregation studies support a genetic component. Despite a vast literature on lifestyle and environmental possible risk or protection factors, consistent findings are few. There is compelling evidence for protective effects of smoking and coffee, but the biologic mechanisms for these possibly causal relations are poorly understood. Uric acid also seems to be associated with lower PD risk. Evidence that one or several pesticides increase PD risk is suggestive but further research is needed to identify specific compounds that may play a causal role. Evidence is limited on the role of metals, other chemicals and magnetic fields. Important methodological limitations include crude classification of exposure, low frequency and intensity of exposure, inadequate sample size, potential for confounding, retrospective study designs and lack of consistent diagnostic criteria for PD. Studies that assessed possible shared etiological components between PD and other diseases show that REM sleep behavior disorder and mental illness increase PD risk and that PD patients have lower cancer risk, but methodological concerns exist. Future epidemiologic studies of PD should be large, include detailed quantifications of exposure, and collect information on environmental exposures as well as genetic polymorphisms.

Clinical profile of parkinsonism and Parkinson's disease in Lagos, Southwestern Nigeria

Background

Current data on the pattern of parkinsonism and Parkinson's disease in Nigerians are sparse.

This database was designed to document the clinical profile of PD in Nigerians, and compare this to prior observations.

Methods

A database of patients presenting to the Neurology out-patients clinic of the Lagos University Teaching Hospital was established in October 1996. Demographic and clinical data at presentation (disease stage using Hoehn and Yahr scale; 'off' state severity on the Unified Parkinson's disease Rating Scale) were documented for patients diagnosed with parkinsonism between October 1996 and December 2006. Cases were classified as Parkinson's disease or secondary parkinsonism (in the presence of criteria suggestive of a secondary aetiology).

Results

The hospital frequency of parkinsonism (over a 2-year period, and relative to other neurologic disorders) was 1.47% (i.e. 20/1360). Of the 124 patients with parkinsonism, 98 (79.0%) had PD, while 26 (21.0%) had secondary parkinsonism. Mean age (SD) at onset of PD (61.5 (10.0) years) was slightly higher than for secondary parkinsonism (57.5 (14.0) years) (P = 0.10). There was a male preponderance in PD (3.3 to 1) and secondary parkinsonism (2.7 to 1), while a positive family history of parkinsonism was present in only 1.02% (1/98) of PD. There was a modestly significant difference in age at onset (SD) of PD in men (60.3 (10.4)) compared to women (65.2 (7.9)) (T = 2.08; P = 0.04). The frequency of young onset PD (≤ 50 years) was 16.3% (16/98). The mean time interval from onset of motor symptoms to diagnosis of PD was 24.6 ± 26.1 months with majority presenting at a median 12 months from onset. On the H&Y scale, severity of PD at presentation was a median 2.0 (range 1 to 4). PD disease subtype was tremor-dominant in 31 (31.6%), mixed 54 (55.1%) and akinetic-rigid 14 (14.3%). Hypertension was present as a co-morbidity in 20 (20.4%), and diabetes in 6 (6.12%).

Conclusions

The clinical profile of PD in Nigerians is similar to that in other populations, but is characterized by delayed presentation as has been reported in other developing countries. Young-onset disease occurs but may be less commonly encountered, and frequency of a positive family history is lower than in western populations.

Association between the ubiquitin carboxyl-terminal esterase L1 gene (UCHL1) S18Y variant and Parkinson's Disease: a HuGE review and meta-analysis

The ubiquitin carboxyl-terminal esterase L1 gene, UCHL1, located on chromosome 4p14, has been studied as a potential candidate gene for Parkinson's disease risk. The authors conducted a Human Genome Epidemiology review and meta-analysis of published case-control studies of the UCHL1 S18Y variant and Parkinson's disease in Asian and Caucasian samples. The meta-analysis of studies in populations of Asian ancestry showed a statistically significant association between the Y allele and reduced risk of Parkinson's disease under a recessive model (odds ratio (OR) for YY vs. SY + SS = 0.79, 95% confidence interval (CI): 0.67, 0.94; P = 0.006). For a dominant model, the association was not significant in Asian populations (OR for YY + SY vs. SS = 0.88, 95% CI: 0.68, 1.14; P = 0.33). For populations of European ancestry, the meta-analysis showed a significant association between the Y allele and decreased risk of Parkinson's disease under a dominant model (OR = 0.89, 95% CI: 0.81, 0.98; P = 0.02) but not under a recessive model (OR = 0.92, 95% CI: 0.66, 1.30; P = 0.65). Using the Venice criteria, developed by the Human Genome Epidemiology Network Working Group on the assessment of cumulative evidence, the authors concluded that moderate evidence exists for an association between the S18Y variant and Parkinson's disease.

Epidemiologic studies of environmental exposures in Parkinson's disease

Parkinson's disease (PD) is the most common cause of the parkinsonian syndromes and the most frequent neurodegenerative disease after Alzheimer's disease. Because of the ageing of Western populations, an increasing number of persons will be affected with PD in the future and neither curative treatments nor preventive measures have been identified. PD is considered as a multifactorial disease, resulting from the effect of environmental factors and genetic susceptibility. Increasing age and male sex appear to be associated with an increased risk of PD. In addition, recent epidemiological studies have identified environmental exposures that influence the risk of PD. This review provides an overview of the epidemiologic evidence for environmental etiologies in PD; we will focus on two environmental exposures that have been quite consistently associated with PD -- cigarette smoking and pesticide exposure -- and will summarize briefly the findings for other exposures. Understanding the mechanisms underlying these epidemiological associations is an essential step for the understanding of the etiology of this neurodegenerative condition and, ideally, to develop neuroprotective drugs.

An analysis of genetic studies of Parkinson's disease in Africa

Online databases (till April 30, 2007) revealed 12 studies describing genetics of Parkinson's disease (PD) in Africa. Two studied inheritance patterns of familial PD. Ten focused on one of three genes, i.e. parkin, PINK 1 and LRRK2 in familial PD. Most studies were from North Africa, where parkin mutations are the most common cause of autosomal recessive PD. Frequency of LRRK2 G2019S mutation is higher than North American and European populations. The LRRK2 G2019S mutation is frequent in apparently sporadic PD in North Africans. There is a need to extend research into genetics of sporadic and familial PD to more African subregions.

In vivo measurement of density and affinity of the monoamine vesicular transporter in a unilateral 6-hydroxydopamine rat model of PD

This is the first in vivo determination of the vesicular monoamine transporter (VMAT2) density (B(max)) and ligand-transporter affinity (K(d)(app)) in six unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats using micro-positron emission tomography (PET) imaging with [(11)C]-(+)-alpha-dihydrotetrabenazine (DTBZ). A multiple ligand concentration transporter assay (MLCTA) was used to determine a B(max) value of 178+/-32 pmol/mL and a K(d)(app) of 47.7+/-9.3 pmol/mL for the non-lesioned side and 30.52+/-5.84 and 43.4+/-15.52 pmol/mL for the lesioned side, respectively. While B(max) was significantly different between the two sides, no significant difference was observed for the K(d)(app). In addition to demonstrating the feasibility of in vivo Scatchard analysis in rats, these data confirm the expectation that a 6-OHDA lesion does not affect the affinity; a much simpler binding potential (BP) measure can thus be used as a marker of lesion severity (LS) in this rat model of Parkinson's disease. A transporter occupancy curve demonstrated negligible transporter occupancy ( approximately 1%) at a specific activity (SA) of 1100 nCi/pmol (assuming an injected dose of 100 microCi/100 g), while 10% occupancy was estimated at 100 nCi/pmol. An indirect measurement indicated that the degree of occupancy as a function of SA is independent of LS. Finally, BP measurement reproducibility was assessed and found to be 11%+/-7% for the healthy and 8%+/-12% for the lesioned side. Quantitative PET results can thus be obtained even for severely lesioned animals with the striatum on one side not clearly visible provided accurate image analysis methods are used.

Melanized nigral neuronal numbers in Nigerian and British individuals

The role of genetic and environmental factors in etiopathogenesis of Parkinson's disease (PD) is debated. The prevalence of PD is higher among white than nonwhite populations, yet it is five times higher in nonwhites living in the United States than in Nigeria. We compare counts of melanized nigral neurons between neurologically normal Nigerians and British brains. Neuronal counts were estimated in an age-matched sample of 23 Nigerian and 7 British brains from neurologically normal individuals who had no Lewy bodies and Lewy neurites on alpha-synuclein immunostaining. Two investigators blind to age and ethnicity performed counts of melanized neurons in a single 7-mum hemisections showing the substantia nigra pars compacta. No significant difference exits in the number of neurons between the Nigerian and the British subjects (P = 0.1, NS). Differences in melanized nigral neuronal numbers may not explain differences in the prevalence of PD between white and nonwhite populations, suggesting factors other than neuronal numbers contribute to differential susceptibility of black vs. white races to PD.

Epidemiology of Parkinson's disease

This chapter discusses the epidemiology of Parkinson's disease (PD). Classically, PD refers to progressive parkinsonism caused by loss of pigmented aminergic brainstem neurons without an identifiable cause, while parkinsonism refers simply to the syndrome of bradykinesia, resting tremor, rigidity and postural reflex impairment. Over nearly two centuries, Parkinson's clinical description has provided the framework for clinical investigations, including epidemiologic ones. Descriptions of PD were limited to selected clinical settings until the middle of the 20th century. Since then, epidemiologic approaches have been used not only to investigate the population distribution of PD, but also as a way to glean clues as to the cause of this “idiopathic” disorder. Because PD is relatively infrequent, a large base population must be surveyed to identify sufficient numbers of cases for a study. In some instances, PD cases can be identified through health service rosters within defined geographic areas or in enumerated populations. In others, cases of PD are sought independently of the health care system, such as through door-to-door surveys. While the latter approach is theoretically least likely to exclude cases, the time and cost involved are also greatest using this approach.

Epidemiology of Parkinson's disease

The causes of Parkinson's disease (PD), the second most common neurodegenerative disorder, are still largely unknown. Current thinking is that major gene mutations cause only a small proportion of all cases and that in most cases, non-genetic factors play a part, probably in interaction with susceptibility genes. Numerous epidemiological studies have been done to identify such non-genetic risk factors, but most were small and methodologically limited. Larger, well-designed prospective cohort studies have only recently reached a stage at which they have enough incident patients and person-years of follow-up to investigate possible risk factors and their interactions. In this article, we review what is known about the prevalence, incidence, risk factors, and prognosis of PD from epidemiological studies.

Parkinsonism and Parkinson's disease in the elderly: A community-based survey in Brazil (the Bambuí study)

Several community-based surveys on the prevalence of Parkinsonism and Parkinson's disease have been conducted worldwide, with variations on their methodology and results. The objective of this study is to assess the prevalence of Parkinsonism and its causes in a cohort of individuals age 64 years or older in Bambuí, a Brazilian town. In phase I, 1,186 people older than 64 years responded to a 9-question screening questionnaire for Parkinsonism. In phase II, all subjects who scored > or = 2 points on the test were examined independently by at least 2 movement disorder-trained physicians. A movement disorder senior specialist excluded or confirmed the diagnosis in all suspected cases. The response rate was high for both phases (96% for phase I and 94% for phase II). The prevalence rate per 100 population over 64 years of age in this group was 7.2% for Parkinsonism of all types (n = 86). The most frequent causes were idiopathic Parkinson's disease and drug-induced Parkinsonism, with prevalence rates of 3.3% (n = 39) and 2.7% (n = 32), respectively. The prevalence of vascular Parkinsonism was 1.1% (n = 13). We found 1 case of posttraumatic Parkinsonism and another with multiple system atrophy. In this first population-based study of Parkinsonism conducted in Brazil, the prevalence in a cohort of elderly subjects was higher than the observed in other populations worldwide, especially because of the high rates of drug-induced and vascular Parkinsonism. The prevalence of Parkinson's disease was similar to that observed in elderly people in door-to-door surveys in other American, European, and Eastern countries.

Pesticides and Parkinson's disease--is there a link?

Parkinson's disease (PD) is an idiopathic disease of the nervous system characterized by progressive tremor, bradykinesia, rigidity, and postural instability. It has been postulated that exogenous toxicants, including pesticides, might be involved in the etiology of PD. In this article we present a comprehensive review of the published epidemiologic and toxicologic literature and critically evaluate whether a relationship exists between pesticide exposure and PD. From the epidemiologic literature, there does appear to be a relatively consistent relationship between pesticide exposure and PD. This relationship appears strongest for exposure to herbicides and insecticides, and after long durations of exposure. Toxicologic data suggest that paraquat and rotenone may have neurotoxic actions that potentially play a role in the development of PD, with limited data for other pesticides. However, both the epidemiology and toxicology studies were limited by methodologic weaknesses. Particular issues of current and future interest include multiple exposures (both pesticides and other exogenous toxicants), developmental exposures, and gene-environment interactions. At present, the weight of evidence is sufficient to conclude that a generic association between pesticide exposure and PD exists but is insufficient for concluding that this is a causal relationship or that such a relationship exists for any particular pesticide compound or combined pesticide and other exogenous toxicant exposure.