Evaluation of how age modifies the risk for Parkinson''s disease, based on stratified comparisons of descriptive data

This is a study of selected information on incidence and prevalence of Parkinson's disease (PD), mortality from Parkinsonism, and levodopa use (LDU). The concept of effect modification (EM) by age (EMA), a variation across age of incidence or odds ratios, was here extended to comparisons of prevalences, mortalities and drug use, and mathematically defined following a reported model. Age-specific EM from comparisons of empirical data was measured and combined with figures for calendar time and the annual infant mortality rates (IMRs) in the population of each observation, using linear regression analysis. Statistically significant associations of EM at ages 70-79 and 80+ were found: with IMR from prevalence comparisons; and with IMR and calendar time in comparisons of proportionate mortalities in longitudinal observations. A similar age-specific pattern of associations was observed with time from incidence in Rochester. The observations for LDU and PD incidence in Iceland and Turku, Finland, fitted well the age-specific regression lines of the IMRs with the age-specific EM components from prevalence data. We concluded that there is a universal age-specific pattern of variation of epidemiological characteristics of PD related to calendar time, and to local factors represented by the IMR. Moreover, this change can be perceived from different parameters under certain conditions. Comparisons of survey, death-records, and LDU data when used for generation of causal hypotheses for PD require that EMA be taken into account.     

The incidence of amyotrophic lateral sclerosis in southwestern Ontario, Canada

The incidence, prevalence, and mortality rates of amyotrophic lateral sclerosis in southwestern Ontario, Canada, were determined for the years 1978 through 1982. The average annual incidence rate was 1.63 per 100,000 population. The prevalence rate was 4.9 per 100,000 on January 1, 1983. The average annual mortality rate was 1.52 per 100,000 population and increased with age, reaching a peak in the 70 to 79-year decade in both sexes. The male:female ratio was 1.2:1. The average age at diagnosis was 62.5 years, and the average duration from date of diagnosis was 2.5 years. The distribution of the disease was uneven in 12 counties, with the highest incidence in Perth (3.33) and Essex (2.43) counties. The city of Windsor, in an industrial region, had a high average annual incidence rate of 2.81.     

Prevalence of Parkinson's disease in Estonia

OBJECTIVES: To investigate the prevalence of idiopathic Parkinson's disease (PD) in Tartu district of South Estonia, with a population of 153,240 on prevalence day, 1 January 1996. METHODS: The community-based method of case ascertainment was used, followed by neurologic examination. RESULTS: The age-adjusted prevalence was 152 per 100,000 population, 159 for urban and 139 for the rural group, 154 for men and 153 for women. The age-specific prevalence increased from 22 per 100,000 population in the age group 40-49 years up to 1232 per 100,000 population in the age group 70-79 years. The mean age of PD patients was 71.4 years, the mean age at onset of the symptoms - 66.9 years. CONCLUSIONS: When comparing the prevalence rates with other studies of Caucasian populations in Europe, the results are similar except for slightly but not significantly higher prevalence rates in the urban population in Estonia.     

Epidemiology of Parkinson's disease—An overview

Summary 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 heredity 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.Further epidemiological research on Parkinson's discase, with strict diagnostic criteria, is needed to clarify the racial occurrence, to establish the true role of heredity, and to uncover possible enviornmental risks.     

Incidence of Parkinson's disease in estonia

The incidence of Parkinson's disease (PD) was studied over a 9-year period (1990-1998) in Tartu county, Estonia, with a mean population of 156,417. Based on 264 patients, the average crude incidence rate of PD was 18.8 per 100,000 person-years. The age-adjusted incidence was 16.8/100,000; 18.3 for the urban group and 14.0 for the rural group; 16.6 for men and 17.1 for women. The age-specific incidence was 1.0/100,000 in the age range 30-39 years, reached a maximum of 117.2/100,000 in the age range 70-79 years and declined in the elderly. The incidence of PD was comparable with that found in developed countries, except for a slightly higher (not significant) incidence rate in the urban compared with the rural population in Estonia.     

The mortality of motor neuron disease in Sweden

The age-standardized mortality from motor neuron disease in Sweden doubled from 1961 to 1985. The average annual rate during the period was 1.9 per 100,000 population. The male to female ratio was 1.2:1. The age-specific mortality rates had a peak at 70 to 79 years of age. When each birth cohort was followed up separately over time, the peak was less clear and in some cohorts the mortality rates increased continuously with advancing age. A significant increase of motor neuron disease among men was found in one Swedish county.     

Epidemiology of dementia in a Finnish population

An epidemiological study of dementia was carried out in the city of Turku (population 164,568) in Finland. A total of 421 patients with moderate to severe dementia were found. Degenerative dementia, i.e. presenile and senile dementia, was present in 218 patients (51.8 %), and in 152 patients (36.1 %) the dementia was associated with arteriosclerosis, including multi-infarct and combined dementia. The prevalence rate of dementia, all types, was 256 per 100,000 population, and 1,961 per 100,000 population over 65 years old. The age-specific prevalence rates of dementia increased with advancing age from 0.1 % in the age group 55–64 years to 11 % in the age group over 85 years. The peak annual incidence rate for all types of dementia was 58 per 100,000 population, and 447 per 100,000 population over 65 years old. Both prevalence and incidence figures suggested a female preponderance in dementia of degenerative origin and in dementia with associated arteriosclerosis.     

Neurological disorders in Nigerian Africans: a community-based study

In a Nigerian town with a stable population of 20,000, a door-to-door survey was conducted, using a questionnaire involving a complete census and a simple neurological evaluation which had previously showed a 95% sensitivity and an 80% specificity for detecting neurological disease. Positive responders were evaluated and categorised, using agreed criteria for diagnoses. Nearly 100% cooperation was obtained. Life prevalence ratio for at least one episode of headache was 51/1000. Crude point prevalence ratio for migrainous headache was 5.3/100, and peak age-specific ratio was in the first decade. Prevalence ratio for epilepsy was 533/100,000 and peak age-specific prevalence ratio occurred in the 5-14 years age groups. The prevalence ratio for peripheral nerve disorders was 268/100,000, and age-specific prevalence ratio for tropical neuropathy increased with age. Prevalence ratio for stroke was rather low at 58/100,000, but was probably due to the people's attitude to the disabled elderly and high mortality of stroke which showed annual mortality rate of 70/100,000 which increased with age to 1519/100,000 per year in the eighth decade. Crude prevalence ratios (cases per 100,000) for others are 112 for neurological complications (including sciatica) of spondylosis, 15 each for poliomyelitis, motor neurone disease, development speech disorders, 10 each for syncope, hereditary neuropathies. Parkinson's disease, benign essential tremor, primary cerebellar degeneration, cerebral palsy, mental retardation, organic psychosis (probable intracranial tumor) and 5 each for muscular dystrophy, pyomyositis, spina bifida occulta, alcohol dependence and cerebral malaria. The implications of the findings are important for development of community neurological services in the developing countries.     

Prevalence of chronic inflammatory demyelinating polyneuropathy in New South Wales, Australia

A prevalence study of chronic inflammatory demyelinating polyneuropathy (CIDP) was performed in New South Wales (NSW), Australia, with a prevalence day of August 6, 1996, which coincided with a national census. The population of NSW was 5,995,544, and the crude prevalence of CIDP was 1.9 per 100,000 population. It was higher in male patients than in female patients, and the age-specific prevalence reached a maximum of 6.7 per 100,000 population in the 70- to 79-year-old age group. The prevalence in the city of Newcastle, with a population of 448,663, was 2.0 per 100,000 population and is representative of the whole of NSW. The estimated crude annual incidence was 0.15 per 100,000 population. The mean age of onset was 47.6 years (median, 53.5 years), 51% of patients had a relapsing-remitting course, the mean duration on prevalence day was 7.1 years (median, 5 years), and 87% of patients were able to walk without walking aids or other assistance.     

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.     

Hemifacial spasm in Rochester and Olmsted County, Minnesota, 1960 to 1984

The incidence of hemifacial spasm in residents of Olmsted County, Minnesota, was studied by reviewing the medical records of patients residing in the community between 1960 and 1984. The average annual incidence rate was 0.74 per 100,000 in men and 0.81 per 100,000 in women, age-adjusted to the 1970 US white population. The average prevalence rate was 7.4 per 100,000 population in men and 14.5 per 100,000 in women. The incidence and prevalence rates were highest in those from 40 to 79 years of age.     

Stroke in the young: incidence and pattern in Benghazi, Libya

Out of 329 cases of stroke registered in Benghazi between November 1, 1983 and October 30, 1984, 63 patients comprising 32 males and 31 females belonged to the 15-40-year age group (stroke in the young). The annual age-specific crude incidence of stroke in the young was 39.3 and 40.3 per 100,000 for men and women, respectively. The age-adjusted incidence rate for both sexes for the age-specific (15-40 years) population was 47 per 100,000. The sex-dependent difference in the incidence was not statistically significant. These results emphasize that the high incidence of stroke in the young in Benghazi is not a reflection of the age distribution of the population. Hypertension, diabetes mellitus, heart disease and hypercholesterolemia were important components of high stroke profile in the young. One or more risk factors were identified in 78% of total young stroke victims and in all the patients under the age of 30. Eight young stroke subjects died during the study period.     

Incidence and clinical features of glossopharyngeal neuralgia, Rochester, Minnesota, 1945-1984.

The annual crude incidence rate of glossopharyngeal neuralgia per 100,000 population in Rochester, Minn., for 1945 through 1984, was 0.7 for both sexes combined, suggesting that glossopharyngeal neuralgia is a rare disease. There were no significant differences between the sexes (p greater than 0.10) in the overall age-adjusted (to the total 1980 US population) rates: 1.1 for men and 0.5 for women. Overall age-specific crude rates increased slightly with age. Our results and conclusions, achieved by comparing our data with a large referral study at Mayo Clinic, suggest that glossopharyngeal neuralgia is generally a mild disease, since mild attacks are not uncommon, the average annual recurrence rate for a second episode is low (3.6%), and only one fourth of the cases had to have surgery for relief of symptoms. Bilaterality is not uncommon; it was observed in one fourth of the patients, all of whom had mild disease.     

Epidemiology of amyotrophic lateral sclerosis in Hordaland county, western Norway

The incidence, prevalence and prognosis of amyotrophic lateral sclerosis (ALS) in the county of Hordaland, western Norway were determined for the years 1978 through 1988. The average annual incidence rate was 1.60 per 100,000 population with a male to female ratio of 1.26 (95% confidence interval: 0.76-2.09). The maximal age-specific annual incidence was 8.12 per 100,000 and occurred in the age-group between 61 and 65 years. The prevalence of ALS was 3.67 per 100,000 on December 31, 1988. The average age at the onset of the disease was 60.9 years ranging from 34 to 82 years of age. Survival was studied with life table techniques. Median survival from the onset of symptoms was 28.0 months overall. In patients with bulbar onset the median survival was 24.0 months whereas it was 40 months in patients with spinal onset of disease (log rank test, P = 0.0004). The difference in survival between ALS with bulbar or spinal onset was not explained by age or sex differences in the two groups.     

Prevalence and incidence of Parkinson's disease in The Faroe Islands

Objective –  A study in The Faroe Islands in 1995 suggested a high prevalence of idiopathic Parkinson's disease (IPD) and total parkinsonism of 187.6 and 233.4 per 100,000 inhabitants respectively.
Methods –  Detailed case-finding methods 10 years later were used and a neurologist has verified the diagnosis.
Results –  The crude prevalence of IPD and total parkinsonism was 206.7 per 100,000 and 227.4 per 100,000 respectively. The age-adjusted prevalence is twice as high as data from Norway and Denmark. Age at initiation of treatment and the fatality rate did not explain the increased prevalence. During 1995–2005, the average annual incidence was 21.1 per 100,000 persons for Parkinson's disease, and 22.9 per 100,000 persons, if including atypical parkinsonism.
Conclusion –  The high prevalence was verified and linked to a high incidence. The cause of the high prevalence is unknown, but neurotoxic contaminants in traditional food may play a role in the pathogenesis in this population, perhaps jointly with genetic predisposition.     

Subarachnoid hemorrhage in an isolated population. Incidence on the Faroes during the period 1962-1975

In a retrospective study of a 14-year period (1962-1975) the annual incidence of subarachnoid hemorrhage (SAH) was found to be 7.4 per 100,000 in an isolated population of about 40,000. The age-specific incidences in the age groups from 15-25 to 60 years are on the same level as found in Sweden, Rochester USA, England, and Iceland, but lower than the findings in Finland. The age-specific incidence among persons over 60 years of age was far lower than in Sweden, Rochester USA, and Finland. The possible causes of the lower incidence in all age groups than reported in the above-mentioned studies are discussed. Forty patients had a history of SAH. Two months after the episode 38% had died and at the end of 5 years 53%. The recurrence rate at 5 years was 24%.     

Epidemiological and clinical characteristics of myasthenia gravis in Belgrade, Yugoslavia (1983–1992)

This is the first epidemiological study of myasthenia gravis (MG) in the area of Belgrade. During the survey period (1983 1992), 124 incidental cases of MG were observed, producing an average annual incidence rate of 7.1 per million population (women, 8.3; men, 5.8). Age and sex specific incidence rates for females demonstrated a bimodal pattern, with the first peak in the age group between 20 and 40, and the second peak in the age group 70-80. The age-specific rates for males showed unimodal pattern, reaching a maximum in the age group between 60 and 80. There was a tendency of more frequent disease appearance in the urban as opposed to the suburban districts. On the prevalence day, December 31, 1992, the point prevalence rate was 121.5 per million (women, 142.5; men, 98.8). Only for incidental cases, the point prevalence rate was 77.1 (women, 83.2; men, 70.4). The average annual mortality rate was 0.47 per million (females, 0.52; males, 0.42), while cumulative lethality was 5.6 (women, 5.6; men, 5.7). Most frequently initial symptoms were ocular, occurring in 58% patients. Through the period of investigation ocular symptoms were generalized in 68%, most frequently in the first 2 years (62.5%). Thymoma was confirmed in 11.3% of patients. In this group there was equal presence of both sexes, older median age at onset, and more severe clinical course of MG. Associated autoimmune disease was found in 17 out of 124 incidental cases (13.7%). The most common were thyroid diseases (7.3%). Family history of MG was recorded in 2 cases belonging to 1 family (1.6%).     

Epidemiologic survey of multiple sclerosis in the Bucharest city and suburban area

Epidemiologic survey over a restricted area of Romanian territory, i.e. the city of Bucharest with a population of 1,934,052 and a surface of 605 km², established the following values for the MS parameters studied.
On January 5, 1977 the prevalence rate for "probable" and "possible" cases was 46.4 per 100,000 inhabitants and for "probable" cases alone (with certain clinical diagnosis) 41.3 per 100,000.
The specific 20- to 60-year age adjusted prevalence rate was 79.4 per 100,000. The incidence rate over the 1969–1976 period was 1.78 per 100,000.
The prevalence and incidence rates in this survey are similar to those reported for two other large urban centers of Romania (population over 100,000 each), Romania being therefore situated in a geographical area of "high risk" for MS.
The 0.61 per 100,000 nationwide and the 0.65 per 100,000 Bucharest mortality rates are lower than those reported in other geographical areas of "high risk" for MS.     

Epidemiology of motor neuron disease in northern Sweden

All cases of motor neuron disease (MND), encompassing amyotrophic lateral sclerosis (ALS), progressive bulbar paralysis (PBP) and progressive spinal muscular atrophy (PSMA), in northern Sweden, diagnosed between 1969-1980 have been analysed. 128 cases were found, corresponding to an average annual incidence rate of 1.67 per 100,000. The prevalence on December 31, 1980 was 4.8 per 100,000. Age-specific incidence rates were higher in the high age groups with a maximum at 60-64 years for males, at 70-74 years for females and at 65-69 years for the sexes combined. The median age at onset was 61 years. Clustering was not found in mining districts and overrepresentation of miners and stone treaters was not observed. Minor differences in incidence rates, as measured by the standardized morbidity ratio, SMR, were found between the inland, coastal and mountain areas. The median survival time after onset of disease was 32 months for ALS, 30 months for PBP and 70 months for PSMA. The combined survival rate for all MND cases was 28% after 5 years and 15% after 10 years. The male to female ratio was 1.1:1, and 4.7% were familial cases.