Rising amyotrophic lateral sclerosis mortality in France 1968-1990: increased life expectancy and inter-disease competition as an explanation

The role of environmental factors on sporadic Creutzfeldt-Jakob disease mortality: evidence from an age-period-cohort analysis

Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common form of prion diseases. The causes of sCJD are still unknown and exogenous factors may play a role. Worldwide, the number of patients with sCJD has progressively increased over time. This increase can be partly explained by increasing life expectancy and better case ascertainment, but a true increase in the number of sCJD cases cannot be excluded. We estimated mortality rates from sCJD in France (1992-2016) and studied variation in mortality rates by age, period, and time.We included all cases aged 45-89 years old who died with a probable/definite sCJD diagnosis based on the French national surveillance network. We used age-period-cohort (APC) Poisson regression models to study variation in mortality rates by sex, age, period, and time.A total of 2475 sCJD cases aged 45-89 years were included. Mortality rates increased with age, reached a peak between 75 and 79 years, and decreased thereafter. Mortality rates were higher in women than men at younger ages and lower at older ages. The full APC model with a sex×age interaction provided the best fit to the data, thus in favour of sex, age, period, and cohort effects on mortality rates. In particular, mortality rates increased progressively with successive birth cohorts.Based on 25 years of active surveillance in France, we show evidence for sex, age, period, and cohort effects on sCJD mortality. The identification of cohort effects suggests that environmental exposures may play a role in sCJD etiology.

An amyotrophic lateral sclerosis hot spot in the French Alps associated with genotoxic fungi

Between 1990 and 2018, 14 cases of amyotrophic lateral sclerosis (ALS) were diagnosed in residents of, and in visitors with second homes to, a mountainous hamlet in the French Alps. Systematic investigation revealed a socio-professional network that connected ALS cases. Genetic risk factors for ALS were excluded. Several known environmental factors were scrutinized and eliminated, notably lead and other chemical contaminants in soil, water or home-grown vegetation used for food, radon and electromagnetic fields. Some lifestyle-related behavioral risk factors were identified: Prior to clinical onset of motor neuron disease, some patients had a high degree of athleticism and smoked tobacco. Recent investigations on site, based on a new hypothesis, showed that all patients had ingested wild mushrooms, notably poisonous False Morels. Half of the ALS cohort reported acute illness following Gyromitra gigas mushroom consumption. This finding supports the hypothesis that genotoxins of fungal origin may induce motor neuron degeneration.

Epidemiology of amyotrophic lateral sclerosis in Southern Germany

The objective of this study is to determine the current distribution of clinical phenotypes and to estimate future trends of ALS incidence in Western societies. We report on a clinical-epidemiological registry with a capture-recapture rate of >80% and population-based case-control study in ALS patients in South Western Germany. 1163 incidents of ALS were registered. Clinical and neuropsychological data were prospectively collected from 699 cases. The mean age at onset was 66.6 (SD = 11.6) years in prospective cases (N = 699). The site of onset was more frequently bulbar (34.1%) than lumbosacral (30.7%), cervical (27.0%), or thoracic (3.1%). Cognitive deficits (ranging from 27.5 to 42.1%, depending on the screening instrument) and behavioral changes (29%) were frequently detected. The incidence rate dropped markedly after 79 years of age, and bulbar onset as well as cognitive impairment were more frequent in ALS cases >75 years. The mean survival time of ALS cases from first paresis was 31 months. The age-standardized incidence rate (ASR) of ALS in 2012/2013 was found to be 2.4 (95% CI 2.2-2.7) per 100,000 person-years (resulting in an ASR of 3.1/100,000 with 100% coverage). Based on the predicted age distribution of the German population, the incidence of ALS was estimated to be 4.5/100,000 for men and 3.3/100,000 for women in the year 2050. ALS prevalence will rise to about 9.2-9.8/100,000 person-years in Germany in 2050. An increased proportion of patients with bulbar onset and/or cognitive deficits can be used as basic epidemiologic data on ALS for future health care decisions.

Incidence of amyotrophic lateral sclerosis in the province of Novara, Italy, and possible role of environmental pollution

OBJECTIVE AND METHODS

Based on nationwide death certificates, a cluster of amyotrophic lateral sclerosis (ALS) has been reported in the area of Briga (Novara province, northern Italy), known for its severe environmental contamination. We further investigated this finding, by following up with the collection of recent incidence ALS data in 2002-2012 of Novara province, also to assess the possible long-term effects of environmental pollution in that area.

RESULTS

In the whole Novara province we identified 106 ALS cases, of which 35 were from the Briga area. Incidence rates of Novara province were 3.98, 5.14 and 2.97 for the total population, males and females, respectively, compared with the Briga area where they were 4.65, 4.27 and 4.98, respectively. The ratio of observed-to-expected ALS cases in the Briga area, using incidence of the rest of Novara province as a reference, was 1.17 (95% CI 0.81-1.62), with a value of 0.83 (95% CI 0.47-1.37) in males and 1.68 (95% CI 1.03-2.60) in females.

CONCLUSIONS

Overall, our study did not confirm previous findings of an excess ALS incidence in an area characterised by severe environmental heavy metal pollution, and it suggests the need to interpret with caution clusters identified through mortality data.

Survey of cannabis use in patients with amyotrophic lateral sclerosis

Cannabis (marijuana) has been proposed as treatment for a widening spectrum of medical conditions and has many properties that may be applicable to the management of amyotrophic lateral sclerosis (ALS). This study is the first, anonymous survey of persons with ALS regarding the use of cannabis. There were 131 respondents, 13 of whom reported using cannabis in the last 12 months. Although the small number of people with ALS that reported using cannabis limits the interpretation of the survey findings, the results indicate that cannabis may be moderately effective at reducing symptoms of appetite loss, depression, pain, spasticity, and drooling. Cannabis was reported ineffective in reducing difficulties with speech and swallowing, and sexual dysfunction. The longest relief was reported for depression (approximately two to three hours).

A Temporal Association between Accumulated Petrol (Gasoline) Lead Emissions and Motor Neuron Disease in Australia

Background: The age standardised death rate from motor neuron disease (MND) has increased from 1.29 to 2.74 per 100,000, an increase of 112.4% between 1959 and 2013. It is clear that genetics could not have played a causal role in the increased rate of MND deaths over such a short time span. We postulate that environmental factors are responsible for this rate increase. We focus on lead additives in Australian petrol as a possible contributing environmental factor. Methods: The associations between historical petrol lead emissions and MND death trends in Australia between 1962 and 2013 were examined using linear regressions. Results: Regression results indicate best fit correlations between a 20 year lag of petrol lead emissions and age-standardised female death rate (R² = 0.86, p = 4.88 × 10⁻²³), male age standardised death rate (R² = 0.86, p = 9.4 × 10⁻²³) and percent all cause death attributed to MND (R² = 0.98, p = 2.6 × 10⁻⁴⁴). Conclusion: Legacy petrol lead emissions are associated with increased MND death trends in Australia. Further examination of the 20 year lag between exposure to petrol lead and the onset of MND is warranted.

The expanding syndrome of amyotrophic lateral sclerosis: a clinical and molecular odyssey

Recent advances in understanding amyotrophic lateral sclerosis (ALS) have delivered new questions. Disappointingly, the initial enthusiasm for transgenic mouse models of the disease has not been followed by rapid advances in therapy or prevention. Monogenic models may have inadvertently masked the true complexity of the human disease. ALS has evolved into a multisystem disorder, involving a final common pathway accessible via multiple upstream aetiological tributaries. Nonetheless, there is a common clinical core to ALS, as clear today as it was to Charcot and others. We stress the continuing relevance of clinical observations amid the increasing molecular complexity of ALS.

Risk factors for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease. It is typically fatal within 2-5 years of symptom onset. The incidence of ALS is largely uniform across most parts of the world, but an increasing ALS incidence during the last decades has been suggested. Although recent genetic studies have substantially improved our understanding of the causes of ALS, especially familial ALS, an important role of non-genetic factors in ALS is recognized and needs further study. In this review, we briefly discuss several major genetic contributors to ALS identified to date, followed by a more focused discussion on the most commonly examined non-genetic risk factors for ALS. We first review factors related to lifestyle choices, including smoking, intake of antioxidants, physical fitness, body mass index, and physical exercise, followed by factors related to occupational and environmental exposures, including electromagnetic fields, metals, pesticides, β-methylamino-L-alanine, and viral infection. Potential links between ALS and other medical conditions, including head trauma, metabolic diseases, cancer, and inflammatory diseases, are also discussed. Finally, we outline several future directions aiming to more efficiently examine the role of non-genetic risk factors in ALS.

Prevalence and incidence of amyotrophic lateral sclerosis in Japan

BACKGROUND

Previous studies have reported a high incidence of amyotrophic lateral sclerosis (ALS) in endemic foci in the Kii Peninsula, Japan. However, little is known about the ALS frequency in the whole country. Furthermore, the presence of ethnic variation in the incidence of ALS remains unknown.

METHODS

We conducted a nationwide survey of ALS frequency in 2013 to estimate its annual prevalence and incidence. ALS was diagnosed based on the El Escorial Criteria. The study period was the 2009 fiscal year, from April 2009 to March 2010. To compare the incidence of ALS among prefectures, standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated under the assumption of Poisson distribution.

RESULTS

The annual crude prevalence and incidence rates per 100 000 people per year were 9.9 (95% CI 9.7-10.1) and 2.2 (95% CI 2.1-2.3), respectively. The age group with the highest prevalence as well as incidence was 70-79 years, and the male-female ratio was approximately 1.5. The annual incidence rate adjusted for age and sex using the 2000 U.S. standard population was 2.3 (95% CI 2.2-2.4) per 100 000 people. Some prefectures had significantly high SIRs: Okinawa, Nara and Wakayama in the Kii Peninsula, and Niigata for males; Kumamoto for females.

CONCLUSIONS

This is the first report on the annual prevalence and incidence of ALS in the representative population of Japan. We identified some prefectures with a high incidence of ALS. However, the incidence of ALS in the Japanese population was much lower than in the Caucasian populations of Europe and North America.

Incidence and geographical variation of amyotrophic lateral sclerosis (ALS) in Southern Germany--completeness of the ALS registry Swabia

Objective of this paper was to investigate the incidence, potential geographical clusters and the completeness of the amyotrophic lateral sclerosis (ALS) registry in Southern Germany (Swabia).

Age-standardized incidence rates (ASR) and ratios (SIR) as well as 95% confidence intervals (CI) were estimated at county level. Capture-recapture (CARE) procedures were applied taking data source dependency into account to estimate the quality of case ascertainment in the ALS registry Swabia. We identified 438 ALS cases (53% men, 47% women) in the target population of about 8.4 Mio inhabitants. The gender ratio (men∶women) was 1.1∶1. The mean age at onset of ALS was 63.8 (SD = 11.9) years for men and 66.0 (12.2) for women. The age distribution peaked in the age group 70–74 years. The ASR of ALS was 2.5 per 100,000 person years (PY; 95% CI: 2.3–2.7). The mean SIR was 1.1 per 100,000 PY (95% CI: 1.0–1.2). High SIR suggesting geographical clusters were observed in two counties (Göppingen and Bodenseekreis), but the variation was not statistically significant (p-values = 0.2 and 0.5). The percentage of CARE estimated missing cases was 18.9% in the registry yielding an ASR of 3.1 per 100,000 PY. The high coverage of the CARE estimated completeness of the ALS registry Swabia indicates excellent quality for future projects. Regional variations have to be investigated further.

Amyotrophic lateral sclerosis/motor neuron disease deaths in the United States, 1999-2009

Our objective was to examine trends and epidemiology of amyotrophic lateral sclerosis (ALS)/motor neuron disease (MND) associated deaths in the United States. ALS/MND associated death rates and trends in the United States for 1999-2009 were examined using the multiple cause-of-death mortality data. Age-specific and age-adjusted death rates were calculated. For 1999-2009, the average annual age-adjusted death rate was 2.17/100,000 persons. The age-specific rate increased with age until 75-79 years. Males experienced a higher death rate than females. There was no definitive trend in the annual ALS/MND associated death rate, although analyses suggested a possible decrease (p = 0.05); however, the rate increased for persons 20-49 years of age and declined for persons ≥ 65 years of age. The annual rate for males decreased whereas the rate for females showed no change. In conclusion, the suggested decreasing annual ALS/MND associated death rate for 1999-2009 contrasts with earlier reports indicating that the incidence and death rate of ALS were increasing. While the ALS/MND associated death rate slightly increased among adults 20-49 years of age, rates declined among two subpopulations at higher risk for ALS/MND--males and persons ≥ 65 years of age. Continued monitoring of ALS/MND mortality data and additional epidemiological studies will be important to further elucidate these epidemiological trends.

Amyotrophic lateral sclerosis in Sardinia (Italy): epidemiologic features from 1957 to 2000

OBJECTIVES

To evaluate epidemiological variables of amyotrophic lateral sclerosis (ALS) in Sardinia (Italy) in the 1991-2000 periods and compare them with the preceding decades.

MATERIAL AND METHODS

Survey, critical reappraisal or clinical re-evaluation of all ALS cases with onset in the decade 1991-2000; calculation of crude and age-adjusted incidence, duration of disease, survival rates and the latency between onset of symptoms and diagnosis.

RESULTS

A significant increase in the mean annual incidence was observed in comparison with the values found in the two previous decades, 1971-1980 and 1981-1990. The distribution of the disease in various areas of the island was found to be not at all homogeneous. No significant modifications of the duration of the disease and survival rates were observed.

CONCLUSION

The role of particular exogenous factors, albeit still unclear, can be invoked.

Late-onset patients with sporadic amyotrophic lateral sclerosis in Japan have a higher progression rate of ALSFRS-R at the time of diagnosis

OBJECTIVE

The population in Japan is aging at a faster rate than in other countries in the world. It is speculated that the number of patients with late-onset amyotrophic lateral sclerosis (ALS) will increase even more in the future. However, few studies have been undertaken on the characteristics of patients with late-onset ALS in Japan. This study sought to investigate the clinical features of patients with late-onset ALS compared with those with early-onset ALS using the progression rate (ΔFS).

METHODS

Forty-five patients with sporadic ALS were divided into 2 groups: 23 patients with early-onset of ALS (<65 years; early onset) and 22 patients with late-onset ALS (≥65 years; late onset). Every patient was followed up from the time of initial diagnosis to the primary endpoint (death or time culminating in death without tracheostomy or ventilation assistance including noninvasive positive pressure ventilation) or for at least 48 months after initial diagnosis.

RESULTS

ΔFS in the patient group with late onset was significantly higher than that of the group with early onset (p=0.010). Survival of patients with late onset was significantly decreased compared to that of patients with early onset (p=0.031).

CONCLUSION

Our finding suggested that patients with late-onset ALS showed more rapid disease progression than those with early-onset ALS using ΔFS.

Changing mortality for motor neuron disease in France (1968-2007): an age-period-cohort analysis

The incidence and mortality of motor neuron disease (MND) increase with age and appear to have increased with time. The examination of period and cohort effects using age-period-cohort (APC) models can help characterize temporal trends. Our objective was to describe mortality from MND in France (1968-2007), and to examine the role of age, period of death, and birth-cohort on changes in mortality. The number of people who died from MND and population statistics (1968-2007) were extracted from French national records. Annual standardized (age/sex) mortality ratios (SMRs) were computed. Using Poisson regression, APC models examined the relationship between mortality rates and age, period of death, and birth-cohort in subjects aged 40-89 years. Deviance/degrees-of-freedom ratios evaluated model fit; ratios close to one indicated adequate fit. Between 1968 and 2007, 38,863 individuals died from MND (mortality rate = 1.74/100,000); 37,624 were aged 40-89 years. SMRs increased from 54 (95% CI = 49-59) in 1968 to 126 (120-132) in 2007. Male-to-female ratios declined from 1.80 in 1968 to 1.45 in 2007. Changing mortality rates were best explained by cohort effects (deviance/degrees-of-freedom = 1.09). The relative risk of dying from MND increased markedly for persons born between 1880 and 1920, and more slowly after 1920. In conclusion, mortality rates for MND increased between 1968 and 2007, and more rapidly in women than men. This increase was better explained by the birth-cohort of individuals than by period effects. Changing environmental exposures may be a possible explanation and these findings warrant the continued search for environmental risk factors for MND.

Increase in motor neuron disease mortality in Spain: temporal and geographical analysis (1990-2005)

The aim of this study was to assess the trend of motor neuron disease mortality in Spain from 1990 to 2005, and to ascertain the existence of geographical differences in mortality rates. MND deaths are registered by the National Statistics Institute of Spain – International Classification of Diseases (ICD) codes ICD9 335.2 (1990-1998) and ICD10 G12.2 (1999-2005). Annual sex- and age-specific rates, as well as rates adjusted for the standard European population were obtained. Provincial standardized mortality ratios (SMRs) were calculated for the study period. Respective provincial SMRs were smoothed with data from adjacent provinces using a Poisson model. Results showed that MND mortality increased in Spain from 1990 to 2005. Geographical differences between provinces were evident throughout the study period. In general, risk of death due to MND was higher in regions lying to the north of Spain. In conclusion, the temporal and geographical variability observed might be explained by genetic factors, differences in environmental exposures and the possible influence of the type of medical care and treatment received. Mortality depends also on health service quality and diagnostic validity. All these factors may play a very important role in analysis of MND mortality in Spain, and the contribution of each of these will have to be examined in depth by ad hoc studies.

Drug therapy in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating condition characterized by progressive muscle wasting, inanition, respiratory failure, and death within approximately 2 to 5 years of onset. ALS is among the most common neuromuscular conditions, with an overall prevalence in the world of approximately 5 to 7 cases/100,000 population. Epidemiologic studies have identified some potential risk factors for developing ALS, including a high-fat, low-fiber diet; cigarette smoking; slimness and athleticism; and living in urban areas. Between 5% and 10% of ALS is genetic, with up to 11 genetic loci identified. Although understanding of the pathophysiology of this disease has advanced over the past 60 years, scant progress has been made regarding effective treatment. The authors review the current understanding of the pathogenic mechanisms of ALS and approaches to treating the disease.

Incidence and prevalence of amyotrophic lateral sclerosis in Uruguay: a population-based study

OBJECTIVE

To determine the incidence and prevalence of amyotrophic lateral sclerosis (ALS) in the Republic of Uruguay.

METHODS

The study was performed in Uruguay (3,241,003 inhabitants) during a 2-year period (2002-2003). To ensure complete case ascertainment, multiple sources of information were used, including all the neurologists, other medical specialties, general physicians, neurophysiology laboratories, hospital medical records and death certificates. ALS diagnosis was based on El Escorial criteria. Although all patients with motor neuron disease were enrolled in the follow-up, only probable and definite cases are included in the study.

RESULTS

Between January 1st, 2002, and December 31st, 2003, 89 new patients were diagnosed with probable or definite ALS. The mean annual incidence rate was 1.37 per 100,000 persons. The incidence was higher for men (1.95) than for women (0.84) with a male to female ratio of 2:1. For both, the incidence increased throughout the years showing a peak in the 65-74 age group among men and the 55-64 age group among women. Mean age at onset of ALS disease was 58.7 years. The estimated mean annual incidence for ALS calculated by the capture recapture method was 1.42 (95% CI, 1.13-1.72). On December 31st, 2002, the crude prevalence was 1.9 per 100,000 inhabitants.

CONCLUSIONS

ALS incidence is within a narrow range across countries despite the genetic, environmental and socioeconomic differences when similar prospective design, diagnosis criteria and data analyses are applied.

Ethnic variation in the incidence of ALS: a systematic review

BACKGROUND

The findings of recent genetic polymorphism studies in ALS suggest that the influence of genetic risk factors for the disease may vary by ethnicity. It is now widely accepted that the incidence of ALS is uniform across Caucasian populations, but whether racial variation across other ethnicities exists remains unknown.

METHOD

Systematic review of the known literature on the incidence, prevalence, and mortality of ALS across all ethnicities. To facilitate comparison, studies were grouped according to the type of data presented and examined for sources of case ascertainment and inclusion criteria.

RESULTS

The literature search identified 61 publications. Lower standardized incidence rates were observed in Asian than Caucasian populations. Within the United States, several incidence and mortality studies have identified lower ALS frequency among African American and Hispanic populations than among non-Hispanic Caucasians. These observations are supported by the other data sources.

CONCLUSIONS

The incidence of ALS may be lower among African, Asian, and Hispanic ethnicities than among whites. We conclude with proposals for a prospective epidemiologic study concentrating on non-Caucasian populations.

Neuropathology with clinical correlations of sporadic amyotrophic lateral sclerosis: 102 autopsy cases examined between 1962 and 2000

Sporadic amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder affecting adults. We studied the neuropathology and clinical correlations in 102 autopsy cases of ALS. The age at onset of the disease was significantly higher for the bulbaronset form (30 cases) than for the limb-onset form (72 cases). Dementia was confirmed in 7 cases. These 102 cases were divided into 4 pathological subgroups: typical ALS (59 cases), lower-motor-predominant ALS (23 cases), ALS with temporal lesions (18 cases), and ALS with pallido-nigro-luysian degeneration (2 cases). The age at onset was significantly higher for lower-motor-predominant ALS and ALS with temporal lesions than for typical ALS. In the lower motor neurons, Bunina bodies were detected in 88 cases, whereas ubiquitin-immunoreactive skein and/or spherical inclusions were detected in all 102 cases. Of the 100 available cases, 50 and 16 also showed ubiquitin-immunoreactive inclusions in the neostriatal and temporal small neurons, respectively. Ubiquitin-immunoreactive dystrophic neurites were also observed in the neostriatum in 3 of the 50 cases with neostriatal inclusions, and in the temporal cortex in 4 of the 16 cases with temporal inclusions. There was a significant association between the bulbar-onset form, temporal lesions, neostriatal inclusions and temporal inclusions, and between dementia, temporal lesions and temporal inclusions. Neostriatal and temporal dystrophic neurites were associated with dementia and bulbar-onset form through temporal lesions and temporal inclusions. The present findings may be helpful for designing further studies on the mechanisms underlying the development of ALS.

Amyotrophic lateral sclerosis mortality in the United States, 1979-2001

The etiology of nonfamilial amyotrophic lateral sclerosis (ALS) remains unknown. Earlier studies have suggested an increase in the incidence of ALS over time. We performed a retrospective analysis of ALS-associated death rates and trends in the United States for 1979-2001 using death records from the national multiple cause-of-death database. The US average annual age-adjusted ALS death rate was 1.84 per 100,000 persons for 1979 through 1998. Most deaths were among adults > or =65 years of age and the median age at death was 67 years. A small overall increase in the death rate was observed primarily between 1979 and 1983, with a subsequent plateau. This slight change in the overall rate reflected apparent increases in the rates among those persons > or =65 years of age, particularly women, and persons in the 20- to 49-year-old age group. The ALS-associated death rate appeared to differ by geographic area, with a higher occurrence among most northern states. Our findings suggest that the epidemiology of ALS-associated deaths in the United States demonstrated small increases in the overall age-adjusted death rate and in the death rates among elderly women and adults 20-49 years of age. Subpopulations at higher risk for ALS were males, whites, persons > or =65 years of age, and residents of northern states. This study provides information for further studies to examine the epidemiology and risk factors associated with ALS.

Descriptive epidemiology of amyotrophic lateral sclerosis in Japan, 1995-2001

BACKGROUND: This study was conducted to describe the epidemiologic features of amyotrophic lateral sclerosis (ALS) in Japan by examining annual trends in mortality (1995-2001), and to discuss the background factors possibly responsible for the recent variations in the mortality rate.

METHODS: Trends in both the age-adjusted and age-specific mortality rates of ALS were examined by using the data obtained from the vital statistics of Japan between 1995 and 2001.

RESULTS: There were small increases in the number of ALS deaths (from 1249 to 1400 per year) and the crude mortality rates (from 1.00 to 1.10 per 100,000 population) between 1995 and 2001. The age-adjusted mortality rate of ALS (adjusted using the 1985 model population of Japan) has decreased (from 0.84 per 100,000 population in 1995 to 0.74 in 2001). Age-specific mortality rates have been increasing particularly in the population older than 70 years of age, with the peak in mortality in the 70- to 80-year old age group.

CONCLUSIONS: ALS mortality rates increased proportionally more for elderly population during the study period. Further epidemiologic studies will be needed to clarify the possible background factors contributing to the increase in ALS mortality in the elderly.

The epidemiology of ALS in Modena, Italy

OBJECTIVE

To determine the incidence, prevalence, and mortality rates of ALS in the province of Modena, Northern Italy, from 1990 through 1999.

METHODS

A retrospective epidemiologic study was conducted, ascertaining cases from all neurologic centers and hospitals of the province, death certificates, and the Italian ALS Association, section of Modena. All clinical records were reviewed, and only patients fulfilling the El Escorial revised diagnostic criteria were included.

RESULTS

During the period considered (1990 to 1999), 143 residents (67 men and 76 women) entered the study. The average annual incidence was 2.16 per 100,000, with a peak in the age class of 75 to 79 years. Mean prevalence rate was 4.02 per 100,000, and mean mortality rate was 1.69 per 100,000. The incidence rate remained constant over time, whereas the prevalence and mortality rates increased owing to a rise in survival time (ALS mean duration was 17.38 months in 1990, 43.18 months in 1999). In the mountainous areas, where agricultural work is more common, the incidence, prevalence, and mortality rates were higher than in urban areas and the disease onset occurred 10 years later. Of the risk factors examined, only agricultural work and rural residence were significant.

CONCLUSIONS

The incidence, prevalence, and mortality rates agree with those in recent Italian surveys and with most international studies, but the distribution of cases varied with higher rates in mountainous areas. Further prospective studies are required.

Genetic epidemiology of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late onset, rapidly progressive and ultimately fatal neurological disorder, caused by the loss of motor neurons in the brain and spinal cord. Familial aggregation of ALS, with an age-dependent but high penetrance, is a major risk factor for ALS. Familial ALS (FALS) is clinically and genetically heterogeneous. Three genes and linkage to four additional gene loci have been identified so far and may either predominantly lead to ALS (ALSI-ALS6) or cause multisystem neurodegeneration with ALS as an occasional symptom (tauopathies, ALS-dementia complex). This review presents a tentative classification of the "major" ALS genes and ALS "susceptibility" genes, that may act as susceptibility factors for neurodegeneration in interaction with other genetic or environmental risk factors. Considering that mutations in ALS genes explain approximately 10% of familial as well as sporadic ALS, and most remaining cases of the discase are thought to result form the interaction of several genes and environmental factors, ALS is a paradigm for multifactorial discases.

The epidemiology of motor neuron diseases: a review of recent studies

As the incidence and mortality rates of motor neuron diseases (MNDs) have been reported to increase steadily over the 1950s-1980s decades, we compared the results of the most recent studies (1990s decade) with the ones reported for those earlier periods. The relevant literature was retrieved on a keyword basis from online medical and official death statistics databases. Fifteen European and North American studies were analyzed, for comparison with the results reported in review papers. The 1990s incidence and mortality rates of MND average at 1.89 per 100,000/year and 1.91 per 100,000/year, respectively, thus yielding increases of 46% and 57% over the 1960s-1970s decades, respectively. This increase appears mainly due to Southern Europe countries, to female gender and to patients aged 75 years and over.Thus, the results of this analysis (i) confirm that the incidence of, and mortality from, MNDs continued to increase during the 1990s and, (ii) suggest that this increase could be partly due to increased life expectancy. Other factors might also contribute, such as better diagnosis since El Escorial criteria, and better accuracy of death certificate collection.However, a real increase in the incidence of MNDs, possibly related to environmental factors, cannot be excluded.

Genetics of sporadic ALS

The only known gene to be involved in ALS is the CuZn-superoxide dismutase (CuZn-SOD) gene. Since 1993, 89 disease-associated mutations have been found in this gene, 14 of them in cases with apparently sporadic ALS. Most frequent are the D90A (most often with recessive inheritance, but a few with dominant inheritance) and the I113T (dominant inheritance with variable penetrance). Statistical and genealogical evidence suggest that quite a number of diagnosed sporadic cases may in fact be familial cases in pedigrees with very low disease penetrance.

Estimation of the amyotrophic lateral sclerosis incidence by capture-recapture method in the Limousin region of France

Amyotrophic lateral sclerosis (ALS) is a rapidly fatal degenerative neurological disease categorized among motor neuron diseases. In the literature, the incidence of ALS varies between 0.7 and 2.4 per 100, 000 inhabitants. A study using the capture-recapture method (multiple records system analysis) was undertaken in Limousin (France) ascertaining all patients having onset of definite or probable ALS during the period 1994-1995. Three information sources able to identify these new ALS cases were selected: the first source was a computerized database of the Neurology Department of the University Hospital of Limoges; the second source consisted of the neurologists of the Limousin region and neighboring provinces (county-sized regions); the third source grouped the hospitals of the Limousin region and neighboring provinces (county-sized regions). During this period, 46 new cases of ALS were seen, corresponding to an observed mean annual incidence of 3.2 (+/-0.6) per 100,000 inhabitants. After standardization for age, the annual incidence was 2.5 per 100,000 inhabitants. The number of new cases estimated by the capture-recapture method was 70, corresponding to an estimated mean annual incidence of 4.9 (+/-1.0) for 100,000 inhabitants. Hence, statistical modeling utilizing partially overlapping information sources permitted a more exhaustive compendium of the new cases of ALS and may be a truer reflection of actual disease incidence than has been previously reported.

The biphasic pattern of age-specific malignant brain tumor mortality rates

Many aging-associated neurologic disorders, including primary malignant brain tumors (MBT), share a common biphasic age-specific mortality rate pattern: initially increasing exponentially with age, and then declining. A modeling study using MBT mortality was conducted to determine if the observed biphasic pattern of MBT age-specific mortality rates emerges if one assumes that there exists a population subset that is inherently susceptible to MBT, and that the risk of mortality from MBT in that susceptible population subset continues to increase exponentially with age. A hypothetical population was subjected to 1988 general mortality risks. A population subset susceptible to MBT was subjected to both exponentially increasing 1988 general and MBT mortality risks. Expected MBT age-specific mortality rates in the total population (both general and MBT susceptible subsets) were determined. Expected MBT age-specific mortality rates in the total population initially increase exponentially with age, and then decline. Moreover, when the size of the MBT-susceptible population subset was set at 1/125 of the size of the general population size, the modeled pattern of age-specific MBT mortality rates closely mimicked the observed pattern of age-specific MBT mortality rates. The observed biphasic pattern of age-specific MBT mortality rates can be explained by the existence of an MBT-susceptible population subset in whom the risk of MBT mortality increases exponentially with age and population subset depletion occurs.

Amyotrophic lateral sclerosis in Brazil: 1998 national survey

OBJECTIVES

To assess the epidemiologic characteristics of amyotrophic lateral sclerosis (ALS) in Brazil in 1998.

METHOD

Structured Clinical Report Forms (CRFs) sent to 2,505 Brazilian neurologists from January to September 1998 to be filled with demographic and clinical data regarding any ALS patient seen at any time during that year.

RESULTS

Five hundred and forty CRFs were returned by 168 neurologists. Data on 443 patients meeting the criteria of probable or definite ALS according to El Escorial definition were analysed: 63 probable (14.2%) and 380 definite (85. 8%). Two hundred and fifty-nine (58.5%) of the patients were male, mean age of onset was 52. Spinal onset occurred in 306 patients (69%); bulbar onset in 82 (18.5%), and both in 52 (11.7%). Twenty-six (5.9%) had a family history of ALS. Two hundred and fifty-nine (58.6%) were seen by private practitioners, and 178 (40. 2%) at a hospital clinic. Age-ajusted incidence shows a peak incidence at the 65-74 years old range.

CONCLUSIONS

The disease's characteristics are similar to those described in international studies, except for age of onset (Brazilian patients are younger). This difference is not confirmed when figures are age-adjusted.

The risk of motor neurone disease and multiple sclerosis is different in Estonians and Russians. Data from South Estonia

Epidemiological studies were performed in South Estonia to establish the prevalence rate of multiple sclerosis (MS) and motor neurone disease (MND). The case finding method included information from the hospital records of the central hospital in the region-the University Hospital (for MS from 1942 to 1989), from all neurologists in the region, from the Estonian MS Society and Association of Muscular Disorders, and from nursing homes in the region. The prevalence day was 31 December 1989. MND incidence was established for the period of 1986-1995. The results demonstrated high prevalence rates of MS among native Estonians (55.3 per 100 000), somewhat lower prevalence among native-born representatives of other nationalities (43.6 per 100 000) and the lowest prevalence rate of MS among non-Estonian immigrants (26.6 per 100 000). The differences were not statistically significant. The results for MND demonstrated the opposite pattern. The mean annual incidence rate of MND for 10 years was statistically significantly higher among people of other nationalities (2.5 per 100 000) and Russians (2.6 per 100 000), and lower in native-born Estonians (1.1 per 100 000). No differences in health care or clinical picture were established. The reasons for the demonstrated differences in MND incidence remain unclear.

Clinical epidemiology of amyotrophic lateral sclerosis

The introduction of palliative therapies in amyotrophic lateral sclerosis (ALS) will alter the epidemiology of ALS as it is known now. Although incidence rates will remain unchanged in the near future, prevalence rates will likely increase dramatically. Better understanding of the age-specific presentation of motor neuron diseases worldwide will shed light on the vexing questions concerning the variable incidence rates in some countries and apparent incidence gradients in North America and Europe.