Epidemiology of parkinsonism in Victoria

Exploring Parkinson's disease prevalence in regional, rural and remote Australia: A systematic scoping review

INTRODUCTION

Idiopathic Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder worldwide. Due to ageing populations, prevalence estimates for PD are set to increase in western countries including Australia.

OBJECTIVE

This study aims to investigate the prevalence of PD in regional, rural and remote areas of Australia, to inform the provision of equitable PD-specific care.

DESIGN

A scoping review, following the Joanna Briggs Institute methodology for scoping reviews and the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR), was conducted. An electronic search of four databases and the search engine google scholar was completed in May 2022 and updated in September 2023. Article screening and quality appraisal were undertaken independently by at least two reviewers.

FINDINGS

Of 514 records screened, six articles (between 1966 and 2019) were identified and included for review. Wide variations in PD prevalence were evident, ranging from 0.58 to 8.5 per 1000 people. Two studies suggested prevalence may be higher in regional, rural and remote areas of Australia than in urban localities.

DISCUSSION

The limited number of studies identified, and wide variation in prevalence rates makes it difficult to draw firm conclusions to inform heath care planning and resource allocation.

CONCLUSION

A paucity of reliable prevalence data indicates the need for well-designed, country-specific epidemiological studies to be conducted to estimate the actual impacts of the disease to inform public health planning, particularly in regional, rural and remote areas where access to PD-specific care is already inequitable.

Australian Parkinson's Genetics Study (APGS): pilot (n=1532)

PURPOSE

Parkinson's disease (PD) is a neurodegenerative disorder associated with progressive disability. While the precise aetiology is unknown, there is evidence of significant genetic and environmental influences on individual risk. The Australian Parkinson's Genetics Study seeks to study genetic and patient-reported data from a large cohort of individuals with PD in Australia to understand the sociodemographic, genetic and environmental basis of PD susceptibility, symptoms and progression.

PARTICIPANTS

In the pilot phase reported here, 1819 participants were recruited through assisted mailouts facilitated by Services Australia based on having three or more prescriptions for anti-PD medications in their Pharmaceutical Benefits Scheme records. The average age at the time of the questionnaire was 64±6 years. We collected patient-reported information and sociodemographic variables via an online (93% of the cohort) or paper-based (7%) questionnaire. One thousand five hundred and thirty-two participants (84.2%) met all inclusion criteria, and 1499 provided a DNA sample via traditional post.

FINDINGS TO DATE

65% of participants were men, and 92% identified as being of European descent. A previous traumatic brain injury was reported by 16% of participants and was correlated with a younger age of symptom onset. At the time of the questionnaire, constipation (36% of participants), depression (34%), anxiety (17%), melanoma (16%) and diabetes (10%) were the most reported comorbid conditions.

FUTURE PLANS

We plan to recruit sex-matched and age-matched unaffected controls, genotype all participants and collect non-motor symptoms and cognitive function data. Future work will explore the role of genetic and environmental factors in the aetiology of PD susceptibility, onset, symptoms, and progression, including as part of international PD research consortia.

Parkinson's Disease and the Environment

Parkinson's disease (PD) is a heterogeneous neurodegenerative disorder that affects an estimated 10 million sufferers worldwide. The two forms of PD include familial and sporadic, and while the etiology of PD is still largely unknown, the condition is likely to be multifactorial with genetic and environmental factors contributing to disease genesis. Diagnosis of the condition is attained through the observation of cardinal clinical manifestations including resting tremor, muscle rigidity, slowness or loss of movement, and postural instability. Unfortunately, by the time these features become apparent extensive neurological damage has already occurred. A cure for PD has not been identified and the current therapy options are pharmaceutical- and/or surgical-based interventions to treat condition symptoms. There is no specific test for PD and most diagnoses are confirmed by a combination of clinical symptoms and positive responses to dopaminergic drug therapies. The prevalence and incidence of PD vary worldwide influenced by several factors such as age, gender, ethnicity, genetic susceptibilities, and environmental exposures. Here, we will present environmental factors implicated in sporadic PD onset. By understanding the mechanisms in which environmental factors interact with, and affect the brain we can stride toward finding the underlying cause(s) of PD.

Epidemiology of Parkinson disease in the city of Kolkata, India: a community-based study

OBJECTIVE

No well-designed longitudinal study on Parkinson disease (PD) has been conducted in India. Therefore, we planned to determine the prevalence, incidence, and mortality rates of PD in the city of Kolkata, India, on a stratified random sample through a door-to-door survey.

METHOD

This study was undertaken between 2003 to 2007 with a validated questionnaire by a team consisting of 4 trained field workers in 3 stages. Field workers screened the cases, later confirmed by a specialist doctor. In the third stage, a movement disorders specialist undertook home visits and reviewed all surviving cases after 1 year from last screening. Information on death was collected through verbal autopsy. A nested case-control study (1:3) was also undertaken to determine putative risk factors. The rates were age adjusted to the World Standard Population.

RESULT

A total population of 100,802 was screened. The age-adjusted prevalence rate (PR) and average annual incidence rate were 52.85/100,000 and 5.71/100,000 per year, respectively. The slum population showed significantly decreased PR with age compared with the nonslum population. The adjusted average annual mortality rate was 2.89/100,000 per year. The relative risk of death was 8.98. The case-control study showed that tobacco chewing protected and hypertension increased PD occurrence.

CONCLUSION

This study documented lower prevalence and incidence of PD as compared with Caucasian and a few Oriental populations. The mortality rates were comparable. The decreased age-specific PR among slum populations and higher relative risk of death need further probing.

Neurological disorders in a rural Western Australian population

BACKGROUND

There is limited information on the causes of neurological disorders in an Australian rural setting.

METHODS

This study reports on a prospective cohort of 160 patients (95 women and 65 men) with a mean age of 55.1 years (standard deviation 19.78 years, range 12-92 years) receiving a neurological work-up from one neurologist attending the Geraldton and Midwest region of Western Australia over a 12-month period.

RESULTS

Patients were divided into 15 diagnostic classifications. Movement disorders were the most common diagnostic classification (38 of 160 or 23.75%) and Parkinson's disease was the most common movement disorder (30 of 38 or 78.95%) with an estimated period of prevalence of 187.5 persons per 1000. Of the other neurological disorder diagnosis classifications the following number of patients per group was observed: epilepsy (27 or 16.87%); neuromuscular disorders (22 or 13.75%); multiple sclerosis (12 or 7.5%); cerebrovascular disease (10 or 6.25%); headaches (7 or 4.37%); neurodegenerative (7 or 4.37%); dementias (6 or 3.75%); memory dysfunction (6 or 3.75%); gait disorders (4 or 2.5%); vestibular syndrome (3 or 1.87%); pain syndrome (3 or 1.87%); sensory syndrome (2 or 1.25%); brain injury (1 or 0.62%) and miscellaneous (12 or 7.5%). A high number of persons having Parkinson's disease was found.

CONCLUSION

Possible risk factors for Parkinson's disease for individuals living in Geraldton and Midwest region need to be investigated. This study raises issues pertaining to the provision of services and allocation of resources in rural areas, especially for patients with Parkinson's disease.

Population prevalence and incidence of Parkinson’s disease in an Australian community

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting older individuals. Few studies have determined the prevalence and incidence of this disease in Australia. The aim of the study was to estimate the prevalence and 10-year incidence of PD in the Australian community.

METHODS

In the Blue Mountains Eye Study (BMES), a population-based health survey of Australian residents aged 49 years or more, we determined the cross-sectional prevalence (BMES2, 1997-1999, n = 3509) and 10-year incidence (BMES1, 2 and 3, 1992-1994, 1997-1999 and 2002-2004, respectively, n = 2545) of PD. We screened participants who took PD medications. PD diagnosis was confirmed by contacting the participant's medical/general practitioners.

RESULTS

Nineteen new cases of PD were identified over the 10-year period, a 10-year incidence of 0.84% (95% confidence interval (CI) 0.54-1.33%). In the cross-sectional study, 16/3509 participants were confirmed to have PD (0.46%), with age-specific prevalence rates of 0.48% in persons aged 60-69 years, 0.82% for ages 70-79 years and 0.56% in persons aged 80 years or older. No PD cases were identified among participants less than 60 years of age. When age standardized to the 2001 Australian population, the prevalence of PD was 362 per 100,000 (95%CI 183-541) among persons aged 50 years or older and 104 per 100,000 for the Australian population at all ages, assuming no prevalent cases in persons aged less than 50 years.

CONCLUSION

This study estimates a 0.46% (95%CI 0.23-0.68) prevalence of PD patients treated with medications aged 50 years or older and a 10-year incidence of 0.84% (95%CI 0.54-1.33).

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.

Prevalence of Parkinson’s disease in metropolitan and rural Queensland: A general practice survey

The prevalence of idiopathic Parkinson's disease (IPD) in Australia is unclear. We estimated the prevalence of IPD, and other forms of parkinsonism, through the study of typical caseloads in general practice. A random sample of general practitioners (GPs) throughout Queensland (401 responses from 528 validated practice addresses) was asked to estimate the numbers of patients with IPD and parkinsonism seen in the preceding year. The estimated prevalence of diagnosed IPD in Queensland was 146 per 100,000 (95% CI=136-155). A further 51 per 100,000 in the population were suspected by doctors to have IPD without formal diagnosis, whereas another 51 per 100,000 people may have non-idiopathic parkinsonism. Idiopathic Parkinson's disease was more common in rural than metropolitan areas. Although most GPs were confident in making diagnoses of IPD, the majority had little or no confidence in their ability to treat the disease, especially in its later stages. Support from neurologists was perceived by GPs to be very good in cities, but poor in remote areas.

Prevalence of Parkinson's disease in Sydney

OBJECTIVE

To examine the prevalence of Parkinson's disease (PD) in Bankstown, Sydney, using the same methodology as a previous study in Randwick, Sydney, Australia (1998-1999).

PARTICIPANTS AND METHODS

Twenty census districts (CDs) for the Bankstown local government area were randomly selected. Research personnel door-knocked every household within the CDs to locate people aged > or =55 years. A structured questionnaire (containing four screening questions for PD) was administered to those agreeing to participate. Screened positive participants were invited to come for a clinical examination. This is a continuation of the previous study and data have been combined.

RESULTS

Combining data for Bankstown and Randwick gave 1028 participants; crude prevalence, 780 per 100,000 (CI: 546-1077). In Bankstown, there were 501 participants aged > or =55 years (response rate 70%); 135 were screened positive with 101 (74.8%) agreeing to a clinical examination. The prevalence of PD in the Bankstown community was 3.4% (17 of 501) (95% CI: 1.98-5.43) for those aged > or =55 years; crude prevalence 776 per 100,000 (CI: 452-1241).

CONCLUSION

The combined results of two Sydney studies appear to indicate that Sydney has one of the highest prevalence estimates of PD in developed countries.

The cognitive ability of an incident cohort of Parkinson's patients in the UK. The CamPaIGN study

We have used multiple sources to identify a population-representative cohort of newly diagnosed patients with parkinsonism and Parkinson's disease in the UK over a 2-year period. All patients have been invited to participate in a detailed clinical assessment either at home or in an outpatient clinic. These assessments have been used to refine clinical diagnoses of parkinsonism using established criteria, and describe some of the phenotypic variability of Parkinson's disease at the time of diagnosis. The crude incidence of Parkinson's disease was 13.6/10(5yr-1) [confidence interval (CI) 11.8-15.6 and of parkinsonism was 20.9/10(5yr-1) (CI 18.7-23.3). Age-standardized to the 1991 European population, the incidence figures become 10.8/10(5yr-1) (CI 9.4-12.4) for Parkinson's disease and 16.6/10(5yr-1) (CI 14.8-18.6) for parkinsonism. Thirty-six per cent of the Parkinson's disease patients had evidence of cognitive impairment based on their performance in the Mini-Mental State Examination, a pattern recognition task, and the Tower of London task. The pattern of cognitive deficits seen among these patients using these and further cognitive tasks suggests that sub-groups of patients based on cognitive ability might be identifiable even in the early stages of disease, which may reflect regional differences in the underlying neuropathological processes.

Current status of Parkinson's disease treatment in Korea

The health insurance system in Korea has been under governmental control, and has covered whole population since 1989. About 97% of Korean people have benefits from this system, while 3% are covered by a Medical Aid system for poor people. According to the statistical yearbook of Health Insurance Review in Korea, the number of claims under Parkinson's Disease, in whole country increased steeply from 44619 in 1995 to 96229 in 2000. If each patient were to take medication for the full duration of their insurance coverage, the average number of visits per year would be 11 in 2000. Thus the number of PD patients calculated using these statistics is about 8600. The prevalence is 19/100000, which is much lower than that in Japan. Considering the significant increase in the number of claims in last few years, however, there are still many PD patients who do not receive an accurate diagnosis and appropriate treatment. The other factor influencing these statistics is the fact that patients were able to buy their medications in drug stores without prescription, i.e. without visiting a hospital (since 2001 this has no longer been allowed). Almost all PD medications are available in Korea. There are several forms of levodopa drugs. Dopamine agonists include bromocriptine, pergolide, dihydroergocriptine, ropinirol, and pramipexole. Other parkinsonian medications are amantadine, benztropin, trihexyphenydil, deprenyl, and entacapone. Recently multicentre clinical trials were performed using ropinirol and entacapone, which showed reliable results. Currently deep brain stimulation is available in a number of medical institutes.

Systematic review of incidence studies of Parkinson's disease

Incidence studies of Parkinson's disease (PD) are important for both health-care planning and epidemiological research. This report reviews the methods and results of previous incidence studies of PD and makes recommendations for future studies. Original articles that described the incidence of PD were located using several strategies. The methods were summarised, and the results of studies with similar methodologies were compared on a standardised population. Twenty-five incidence studies were included. Each used different methods to identify incident patients, although most screened both primary care and hospital records. Only eight studies were prospective, and only two of these had any follow-up. The diagnostic criteria for PD varied (11 studies used two or more cardinal motor features, four used the UK Brain Bank criteria), as did the exclusion criteria and the definition of an incident case. In 16 studies, attempts were made to confirm the diagnosis by examination of patients by a specialist as part of the study. None of the studies used identical methods, but five were sufficiently similar to merit comparison. Four of these gave a similar incidence (16-19/100000/year), but one from Italy had a much lower incidence (8.4/100000), the reason for which was unclear. Five studies found significantly greater incidence in men. This review highlights the difficulties in performing good quality incidence studies of PD. Further incidence studies using standardised methods are required. A set of minimal scientific criteria has been devised to improve the quality and consistency of future studies.

Delayed internal capsule infarctions following radiofrequency pallidotomy. Report of three cases

The authors report on a series of patients with idiopathic Parkinson's disease (IPD) who underwent stereotactic radiofrequency (RF) pallidotomies, three of whom suffered delayed postoperative strokes. These three belonged to a group consisting of 42 patients with medically intractable IPD in whom 50 pallidotomies were performed. All three patients had significant previous vascular disease and were in a high-risk group for cerebral infarction. A postoperative magnetic resonance (MR) image was obtained immediately after the pallidotomy was performed to document the placement of the RF lesion and to rule out any hematoma. The delayed strokes occurred on postoperative Days 10, 51, and 117 in patients with previous vascular disease (Group 1, 11 patients). No strokes occurred in the group with the vascular disease risk factor (Group 2, 11 patients) or in the group with no risk factors for vascular disease (Group 3, 20 patients). This observation is statistically significant (p < 0.05). The T2-weighted MR images showed the lesions as high-intensity signals extending to the posterior limb of the internal capsule ipsilateral to the pallidotomy site. The poststroke T1-weighted images obtained in two patients showed persistent contrast enhancement of the RF lesion and no enhancement around the stroke lesion. Clinically and radiographically, these discrete new lesions represent delayed infarctions, suggesting that RF lesioning can induce delayed injury in adjacent tissue. Patients with previously identified vasculopathy may be at risk for delayed capsular infarction following RF pallidotomy.

The prevalence of parkinsonism in Italy: an epidemiological survey of the disease in general practice. The Italian General Practitioner Study Group (IGPSG)

The prevalence and characteristics of parkinsonism have been assessed in two separate geographic areas in Italy (Arcisate and San Giovanni Rotondo). A total of 28,377 patients of 23 general practitioners (GPs) were the reference population. Fifty-eight patients were traced by the GP as having typical parkinsonian features or being treated with antiparkinson drugs. Among 53 subjects, 21 of them untreated, parkinsonism was subsequently confirmed neurologically. The overall crude prevalence rate was 1.87 cases per 1,000 (Arcisate 1.81; San Giovanni Rotondo 2.01). The age- and sex-adjusted prevalence rates were 1.84 in Arcisate and 2.04 in San Giovanni Rotondo. After exclusion of drug-related parkinsonism, the rates were 1.48 and 1.90, respectively. Even with some inconsistencies within the two study areas, the prevalence tended to be higher in San Giovanni Rotondo, to prevail in women, and to increase significantly with age. Presumed etiological factors for parkinsonism were recorded in 34% of the cases (mostly drugs). In two thirds of the cases the disease ran a mild course. The present study shows that the GP proves a valuable reference for surveys of parkinsonism in Italy.

The genetics of Parkinson's disease

The possibility of a major contribution of hereditary factors to the cause of Parkinson's disease (PD) is being reconsidered by many. The studies preceding the 1980s presented conflicting evidence and suffered from procedural difficulties. The emergence of the MPTP hypothesis and the failure of three twin studies to document a strong hereditary component in the early 1980s turned attention toward an environmental cause of PD. However more recent descriptions of deficiencies in genetically-coded biochemical functions in PD, more sophisticated clinical family analyses, re-analysis and extension of the twin studies and the emergence of several large autopsy-proven PD kindreds raise the possibility of an important heritable factor in PD.

Epidemiology of Parkinson's disease

Additional epidemiologic studies may provide important insights into the etiology of Parkinson's disease. Moreover as the elderly population of Europe and the United States grows, accurate public health planning requires accurate incidence and prevalence estimates. The recent development of a therapy that may slow disease progression (see article by Tetrud elsewhere in this issue) makes early identification and treatment of Parkinson's disease particularly important. Investigations of early markers of Parkinson's disease or markers of disease susceptibility are critical areas of future research, requiring careful collaboration between epidemiologists and laboratory scientists.

Environment, genetics and idiopathic Parkinson's disease

Since Idiopathic Parkinson's disease (IPD) was first described more than 170 years ago, there have been major advances in the understanding of the etiology of the disease as well as in its treatment. This article will review current knowledge concerning the role of the environment, genetic hypotheses and the aging factor in the etiology of IPD and proposes a complex interaction involving all these factors. Hypotheses regarding mitochondrial inhibition and free radical generation in IPD are discussed in relation to the mechanism of action of neurotoxins known to produce parkinsonian syndromes.

The epidemiology of primary degenerative dementia and related neurological disorders

Observation of cytopathological similarities between the changes of Alzheimer-type dementia, Parkinson's disease and motor neuron disease, as well as of some degree of clinical association between these conditions, has led to the suggestion that all three belong to a common class of degenerative neurological disorders, each of which as a rule first becomes manifest when age-related neuronal attrition is superimposed on subclinical damage caused by environmental noxae earlier in life. The importance of this model lies in its potential relevance to prevention. The epidemiological data reviewed here suggest that, while the three disease groups are all strongly linked with ageing, there may be major differences between their patterns of occurrence in populations, which make it doubtful if the same environmental pathogens are responsible in each instance. The most plausible unifying hypothesis at present is that the predisposing neuronal damage can be caused by a number of widely distributed metallic neurotoxins, each of which has a tendency to pick out specific areas or cell groups within the CNS and thus to give rise to distinct though overlapping clinical syndromes. The evidence bearing on this and other causal hypotheses is, however, still tenuous because of the scarcity of empirical data. Population-based case-control and cohort studies are called for, as part of a co-ordinated research endeavour.

Environmental risk factors for Parkinson's disease: the epidemiologic evidence

Descriptive data from several studies suggest variations in the frequency of Parkinson's disease in different population groups. Door-to-door surveys were carried out among a biracial U.S. population (blacks and whites) and in communities in Nigeria and the People's Republic of China. The U.S. investigation revealed no substantial differences in the age-adjusted prevalence ratios by race. However, blacks in Nigeria have a much lower prevalence ratio than blacks in the U.S., suggesting an environmental etiologic factor. Prevalence ratios derived from China are also lower than the U.S. figures. Studies of temporal trends in the incidence rates in one U.S. population (Rochester, Minnesota) show virtually no change over 35 years, indicating that the primary cause(s) of Parkinson's disease must have been present in this nonindustrialized community for many years. Analytic studies generally reveal an inverse association between Parkinson's disease and cigarette smoking, although epidemiologic evidence does not support a direct protective effect of smoking. Preliminary investigations suggest an increased risk associated with the rural environment and the consumption of well water. Further studies are required to discover as yet unknown environmental factors that heighten the risk of Parkinson's disease.

The age of onset of Parkinson's disease: etiological implications

We have conducted a hospital-based survey of the age-specific prevalence of Parkinson's disease in 551 patients from Helsinki and Vancouver. We conclude that the disorder may be starting earlier than previously and we discuss the implications of this finding for the etiology of Parkinson's disease.

Monozygotic twins with Parkinson's disease

A pair of monozygotic twins concordant for Parkinson's disease are described. The issue of genetic factors in Parkinson's disease is discussed.

Parkinson's disease in a Scottish city

In a detailed community study the total prevalence of idiopathic Parkinson's disease in Aberdeen was 164.2/10(5) of the population. The age and sex specific prevalence rose to 2657.8/10(5) (2.7%) of men and 2071.0/10(5) (2.0%) of women aged over 84. The mean age at onset, irrespective of sex, was 65.3 years (SD 12.6) and varied little compared with similar studies over the past 25 years. Half of patients were independent but 78/225 (34.7%) were considerably disabled and 23/225 (10.2%) were confined to bed or a wheelchair. Disability increased with age and also with a low minimental state questionnaire score. The score was less than or equal to 7/10 (graded 0-10) in 93/252 (37%) of patients and less than 5/10 in 28/252 (11%). Parkinson's disease remains a common and disabling condition in the community.

Epidemiology of Parkinson's disease in Benghazi, North-East Libya

An epidemiological study of Parkinsonism was carried out in Benghazi situated in North-Eastern Libya. On the prevalence day, January 1, 1985, a total of 163 patients with Parkinson's disease were found living in the investigated area, which had a population of 518,745. The crude prevalence rate was 31.4 per 100,000 population and the incidence rate was 4.5 per 100,000 population per year. The average age at death was 71.2 years and the mean duration of the illness was 6.7 years. Our findings suggest that the risk of Parkinson's disease observed in the present study is intermediate to that reported among the white and black races and comparable with the yellow race and the Sardinians.

Parkinson's disease in the district of the Northampton Health Authority, United Kingdom. A study of prevalence and disability

The study of a population of 208,000 in a Midlands district of England has shown the prevalence of idiopathic Parkinson's disease to be 108.4 per 100,000. This is comparable with past studies in Carlisle, England, Rochester, Minnesota, and South-West Finland. Parkinsonism associated with cerebrovascular disease is evidently recognised and differentiated by general practitioners; post-encephalitic parkinsonism is not encountered and drug-induced parkinsonism is not common in this district. The major functional disability of a carefully assessed randomly selected group was found to relate to walking and hygiene. Nevertheless, the essential physical needs of those with Parkinson's disease appear to be well met in general.

Diagnosis and epidemiology of Parkinson's disease

The diagnosis of Parkinson's disease is purely a clinical diagnosis. The most common types of diagnostic error are a failure either to recognize the early, or unusual symptoms, or to differentiate other tremors and extrapyramidal syndromes from Parkinson's disease. The prevalence of Parkinson's disease is increasing. This has resulted from the reduction of the excess mortality by levodopa treatment. In the near future, there will be more older parkinsonian patients with a more prolonged duration of the disease.

Epidemiology of Parkinson's disease--an overview

Among the white races, the prevalence rates of Parkinson's disease range from 66 to 187 per 100,000 population, through without any obvious geographical pattern. A similar variation is found in the annual incidence rates with estimates from 5 to 24 per 100,000 population. The black races may be partially protected against the disease. Both sexes are probably equally affected by the disease. Parkinson's disease usually begins after the age of 50 years, and the risk of the disease steeply rises with advancing age. Parkinson's disease is often omitted in death certificates; mortality rates with Parkinson's disease as an underlying cause of death vary from 0.5 to 3.8 per 100,000. Levodopa treatment, by reducing the excess mortality accompanying the natural course of Parkinson's disease, may increase the number of patients living with this disease in the near future. Postencephalitic Parkinson's disease, developing as a sequel to lethargic encephalitis and accounting for some two thirds of parkinsonian cases shortly after the epidemic, has probably been a transient phase in the epidemiology of Parkinson's disease and is now disappearing. Data from epidemiological investigations have advanced our understanding of the cause of Parkinson's disease only to a small extent. No other characteristic than race has been found to influence the susceptibility to the disease. The environmental risks for Parkinson's disease have not been unequivocally demonstrated. Highly conflicting information is available as to the contribution of hereditary to the pathogenesis of Parkinson's disease. Seroepidemiological investigations have shown an increased antibody response against herpes simplex virus in parkinsonian patients, but attempts to detect herpes virus specific products or DNA sequences in the brain material have been unsuccessful.

Changing epidemiology of Parkinson's disease: predicted effects of levodopa treatment

Recent studies suggest that levodopa treatment reduces the excess mortality due to Parkinson's disease, found to be three times that expected in the general population. This will affect the equilibrium state of the epidemiology of Parkinson's disease. The predicted increase in prevalence of Parkinson's disease was calculated according to two mortality patterns, one the same as expected in the general population and the other 1.5 times that expected; the proportional increase in prevalence is 1.8 and 1.4, respectively. The predicted increase in the duration of the disease if 6.3 or 3.2 years. As a consequence, there will be an increase of patients with long-term levodopa treatment difficulties, and with Parkinson's disease symptoms not treatable with levodopa, e.g. dementia. This seriously warrants the research of new approaches in the treatment of Parkinson's disease.

Age distribution of patients with Parkinsonism

The modal age at onset of the parkinsonian syndrome during the past thrity years is less than a decade higher than it was in the late 19th and early 20th centuries, suggesting that the same disease entity is affecting parkinsonian patients now as then. The evidence points to the existence of two distinct clinical entities: 1) parkinsonism secondary to encephalitis lethargica, which had its greatest influence on the epidemiology of parkinsonism between 1920 and 1945; and 2) classic parkinsonism, which has undergone little change in the past hundred years.

Epidemiology of Parkinson's disease in Finland

This investigation was conducted to clarify the epidemiology of Parkinson's disease in Finland. A community survey was made in a selected area in southwest Finland in addition to an analysis of Finnish mortality statistics for Parkinson's disease. The annual mortality rate from Parkinson's disease was found to average 2 per 100,000 population. Almost 70 per cent of the deaths occurred between 65-79 years of age. The total and age-specific mortality rates for males were greater than those for females whereas the proportionate mortality rates were almost identical. This was considered to indicate that suggestions of greater male prevalence, based on mortality statistics, do not appear justified. On prevalence day, Dec. 31st, 1971, 484 patients with Parkinson's disease (of which 444 were personally examined) lived in the area of investigation (population 402,988), the prevalence rate being 120.1 per 100,000 population. The highest annual incidence rate was 16.6 per 100,000 population. The age-specific prevalence rates showed a rapid increase after the 50th year of age. The greatest prevalence was shown by the age group 70-79 years of age in which almost 0.8 per cent of the population are affected. Age-specific incidence rates also displayed an increase after the 50th year of age. The greatest incidence was observed in the age group 70-79 years of age in which almost 1 per 1,000 of the population are annually affected by the disease. A difference between the sexes was demonstrable in the prevalence and incidence rates showing greater values for females, but in the age-specific frequencies the differences were reduced. This probably reflects the difference between the age structures of the male and female populations, suggesting that both sexes have a similar risk of being affected by the disease. The permanent age structure shown by idiopathic patients in comparison with previous investigations as well as the increased mean age and proportionate decrease of postencephalitic patients was found to be in disagreement with the cohort theory according to which all parkinsonian patients are previously victims of encephalitis lethargica.

Arteriosclerosis, heredity, and some previous infections in the etiology of Parkinson's disease. A case-control study

A case-control study was performed to investigate the significance of arteriosclerosis, heredity and some infections in the etiology of Parkinson's disease. The study group consisted of all traceable patients with Parkinson's disease living in a defined area, a total of 444 patients, and of control subjects for each patient, matched in sex and age, chosen from among the general population residing in the same area. No significant differences were found between the patients and the controls concerning the occurrence of cardiac insufficiency, coronary heart disease, or stroke. The Parkinsonian patients, however, had a significantly lower incidence of clinical arterial hypertension when compared with the controls. In addition, the patients more often had low systolic blood pressures and more rarely high pressures than the controls. Even the mean systolic blood pressure was significantly lower in the patients than in the controls. The low blood pressure seems to be an effect of Parkinson's disease itself with a minor contribution of levodopa therapy. The observations above are considered to indicate that arteriosclerosis and Parkinson's disease are probably only concurrent disorders and not in etiological relationship with each other. There was no statistically significant difference in the proportion of the patients and the controls with relatives with Parkinson's disease or essential tremor, which suggests that genetic factors do not have a significant role in Parkinson's disease and on the other hand that essential tremor and Parkinson's disease are two separate disease entities. No other encephalitis than a lethargic one was found to precede Parkinson's disease and the occurrence of meningitis was rare both among the patients and the controls. The history of Spanish influenza was found to be as frequent in the patients as in the controls, thus not supporting the idea that influenza has etiological importance in Parkinson's disease.