Epidemiology of amyotrophic lateral sclerosis in the province of Modena, Italy. Influence of environmental exposure to lead

Toxic Damage to Motor Neurons

Abstract—Amyotrophic lateral sclerosis (ALS) is a multifactor disease in the development of which both genetic and environmental factors play a role. Specifically, the effects of organic and inorganic toxic substances can result in an increased risk of ALS development and the acceleration of disease progression. It was described that some toxins can induce potentially curable ALS-like syndromes. In this case, the specific treatment for the prevention of the effects of the toxic factor may result in positive clinical dynamics. In this article, we review the main types of toxins that can damage motor neurons in the brain and spinal cord leading to the development of the clinical manifestation of ALS, briefly present historical data on studies on the role of toxic substances, and describe the main mechanisms of the pathogenesis of motor neuron disease associated with their action.

A meta-analysis of observational studies of the association between chronic occupational exposure to lead and amyotrophic lateral sclerosis

OBJECTIVE

The association between occupational exposure to lead and amyotrophic lateral sclerosis (ALS) was examined through systematic review and meta-analyses of relevant epidemiological studies and reported according to PRISMA guidelines.

METHODS

Relevant studies were searched in multiple bibliographic databases through September 2013; additional articles were tracked through PubMed until submission. All records were screened in DistillerSR, and the data extracted from included articles were synthesized with meta-analysis.

RESULTS

The risk of developing ALS among individuals with a history of exposure to lead was almost doubled (odds ratio, 1.81; 95% confidence interval, 1.39 to 2.36) on the basis of nine included case-control studies with specific lead exposure information, with no apparent heterogeneity across included studies (I = 14%). The attributable risk of ALS because of exposure to lead was estimated to be 5%.

CONCLUSIONS

Previous exposure to lead may be a risk factor for ALS.

The epidemiology of amyotrophic lateral sclerosis in Reggio Emilia, Italy

Incidence and mortality rates of amyotrophic lateral sclerosis (ALS) vary between countries, and in some studies appear to increase over time. We performed a study to assess ALS incidence in a northern Italy area over a 10-year period. We identified the new cases of probable or definite ALS diagnosed among residents in Reggio Emilia province between 1996 and 2005 using several sources of data, such as death certificates, clinical records, hospital discharge registers and drug prescriptions. A total of 94 newly-diagnosed patients were identified. The average standardized incidence in the period was 2.0 and 1.0 cases/100,000/year, using the Italian and the world population, respectively, as reference. There was no variation in rates over time. Incidence was 1.3 in males and 0.8 in females. No cases were observed in patients under 35 years of age. Incidence increased after the age of 55 years, reaching a peak in the group aged 70-74 years and declining thereafter. We concluded that ALS incidence in this population was similar to that observed in other Italian regions and European countries, and no variation was identified during the study period.

A clinical epidemiological study of 251 cases of amyotrophic lateral sclerosis in the south of Brazil

OBJECTIVE

To study the clinical forms of amyotrophic lateral sclerosis (ALS) and the possible presence of risk factors in order to verify if there is any difference between cases in Paraná, Brazil.

METHOD

We studied 251 cases, all of which fulfilled the diagnosis criteria proposed in El Escorial (WFN). Between 1977 and 2004, 157 male and 94 female patients were examined.

RESULTS

220 cases were classified as ALS-Spinal Onset (ALS-SO), 24 as ALS-Bulbar Onset (ALS-BO) and 7 as Familial ALS. The mean age at time of evaluation was 54.4+/-12.3 years, and symptoms had started 17.9+/-15.7 months previously. In the group studied, statistical relationships were found between heavy occupations and males; previous surgeries and females; ALS-BO and dysphagia and dysarthria in females; and ALS-SO and males, cramps, weakness, muscle atrophy, hypertonia, increased deep tendon reflex and abnormal gait.

CONCLUSION

The average age at time of evaluation was lower than that registered in the literature but similar to the Brazilian series. Domestic work and heavy occupations appear to be related to precocious perception of the symptoms by interference with daily functions. The socioeconomically higher classes seek medical care early. There was no relationship with exposure to toxic agents or trauma.

Amyotrophic Lateral Sclerosis

This chapter focuses on amyotrophic lateral sclerosis (ALS), the most common motor neuron disease. It discusses the three major forms of ALS: sporadic ALS, the familial or hereditary form of ALS, and the western Pacific (Mariana Islands) form. Considerable progress has been made in recent years on identifying genetic loci responsible for Mendelian forms of ALS; this evidence is summarized. The potential importance of geographic clusters is discussed, with particular emphasis on the western Pacific form of ALS because it often occurs in association with a parkinsonism and/or dementia complex (PDC). The incidence of Western Pacific ALS peaked and then declined in the mid-20th century, which strongly implicated an environmental cause. The chapter also presents detailed information regarding putative risk factors for sporadic ALS, which includes environmental toxicants, skeletal trauma, cigarette smoking, diet, and vigorous physical activity.

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.

Amyotrophic lateral sclerosis with dementia. Case report

A patient is described in whom a profound and rapidly progressive dementia occurred in association with clinical features of amyotrophic lateral sclerosis. A magnetic resonance imaging showed signs of frontal and especially left temporal atrophy. The pattern of dementia indicated impaired frontotemporal lobe functions, evidenced by reduced tracer uptake in the frontotemporal lobes on brain single photon emission computed tomography. Neuropathological examination in this patient revealed mild frontotemporal atrophy with spongiform changes and neuronal loss affecting mainly layers II and III of the frontotemporal cortices. There was atrophy of the hypoglossal nuclei. The spinal cord changes were consistent with motor neuron disease. The patient showed an irreversible and progressive course. A review of the relevant literature was made.

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.

Amyotrophic lateral sclerosis: mortality risk during the course of the disease and prognostic factors. The Netherlands ALS Consortium

We performed a historical cohort study of 307 untreated patients with probable or definite amyotrophic lateral sclerosis in order to investigate whether the mortality risk changed during the disease course and to identify prognostic factors at diagnosis. Patients were diagnosed in one of the academic hospitals in The Netherlands and followed-up for at least 6 years after diagnosis. The median survival from diagnosis was 1.4 years (95% confidence interval, 1.3-1.6 years) with an estimated 5- and 10-year survival of 20 and 8%, respectively. Mortality was at its maximum in the second year after diagnosis and declined considerably thereafter. Observed mortality approached the expected mortality in patients who survived diagnosis 6 or more years. In univariate and multivariate analyses, young age, limb onset, and a long delay between initial weakness and diagnosis were associated with lower mortality. The better prognosis of limb-onset patients was not observed in females. Patients with initial respiratory muscle weakness, had the worst prognosis with a median survival of only 2 months. The significantly greater mortality of older patients proved not to result from a rise in expected mortality only. In conclusion, the annual mortality risk in ALS does not remain constant throughout the disease and depends on age at diagnosis, site of onset, diagnostic delay, but also on the time since diagnosis. These findings may have consequences for the planning of symptomatic care and the design and analysis of therapeutic trials.

Epidemiological and clinical characteristics of ALS in Belgrade, Yugoslavia

We present the results of the first epidemiological study of ALS in Belgrade. The distribution of 58 newly discovered cases in a 7-year survey period (1985-1991) showed that the average annual age-adjusted incidence rate was 0.42 per 100,000 population (95% confidence interval, 0.18-0.83). The rate for males was 1.5 times higher than the rate for females. The greatest age-specific average incidence rate was observed in patients between 60 and 64 (3.66 per 100,000 population; 95% confidence interval, 2.17-5.78). The actual age-adjusted prevalence rate on December 31, 1991 was 1.07 per 100,000 (95% confidence interval, 0.71-1.71). The mean age at onset of the disease was 56.2 +/- 9.8 and it ranged from 24 to 74. We studied the natural course of the disease through the mean duration and cumulative probability of survival. The mean duration of the disease was 27.7 +/- 18.2 months. The cumulative probability of survival was 27% for the whole population in a 5-year interval. Elderly patients and those with bulbar signs at onset had a poorer prognosis. Patients under 49 at onset and those with the spinal form of the disease survived longer.

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.

Steadiness of amyotrophic lateral sclerosis in the province of Parma, Italy, 1960-1990

A clinical and epidemiological study on amyotrophic lateral sclerosis (ALS) was conducted in the province of Parma, Italy, from 1960-1990. A total of 121 cases were collected from hospital records. The average annual incidence was 0.98 per 100,000 inhabitants, with a male/female ratio of 1.1. Age-specific incidence was maximal in the age group 60-69 years. No difference between rural and urban areas was found. Prevalence on October 26th, 1981 was 2.5 per 100,000. Mean age at onset was 60 years, with no significant sex difference. Mean duration of the disease was 30 (sd 21.4) months. Bulbar forms were significantly (p < 0.05) shorter than conventional forms, with a mean duration of 23.4 (sd 21.4) months. Age at onset did not influence prognosis. A comparison of three decades was made, to verify whether possible variations of the disease had occurred with time. From our data a definite stability was found in such epidemiological parameters as incidence, prevalence, mean duration and mortality of ALS in the period.

The prognosis of adult-onset motor neuron disease: a prospective study based on the Scottish Motor Neuron Disease Register

The Scottish Motor Neuron Disease Register (SMNDR) is a prospective, collaborative, population-based project which has been collecting data on incident patients since 1989. In this report we present the clinical features of 229 patients with motor neuron disease (218 sporadic and 11 familial) diagnosed in 1989 and 1990 and compare their prognosis with previous studies of survival. The overall 50% survival from symptom onset was 2.5 years (95% CI, 2.2-3.0) and 5-year survival 28% (95% CI, 20-36%). The presence of progressive bulbar palsy (PBP), either at presentation or developing during the course of the illness, significantly reduced survival and was the most important prognostic indicator. Patients who survived longer than 5 years from symptom onset did not have PBP as part of their presenting illness. The prognosis was worse for women, and this was in part related to the higher frequency of PBP in older women, but age was also an independent adverse risk factor. Differences in survival between this and previous series can probably be explained on the basis of variation in case definition and ascertainment methods.

Amyotrophic lateral sclerosis in Sardinia, Italy: an epidemiologic study

The authors carried out an epidemiologic study on amyotrophic lateral sclerosis in Sardinia for the years 1957 through 1990. The duration of the disease and survival were significantly shorter in bulbar form. The distribution of ALS in various areas of the island was found to be not at all homogeneous. Mean yearly incidence showed no significant variations in the decades 1971-80 and 1981-90. In the last decade, an increase of bulbar forms was observed.

Adult onset motor neuron disease: worldwide mortality, incidence and distribution since 1950

This review examines the commonly held premise that, apart from the Western Pacific forms, motor neuron disease (MND), has a uniform worldwide distribution in space and time; the methodological problems in studies of MND incidence; and directions for future epidemiological research. MND is more common in men at all ages. Age-specific incidence rises steeply into the seventh decade but the incidence in the very elderly is uncertain. A rise in mortality from MND over recent decades has been demonstrated wherever this has been examined and may be real rather than due to improved case ascertainment. Comparison of incidence studies in different places is complicated by non-standardised methods of case ascertainment and diagnosis but there appear to be differences between well studied populations. In developed countries in the northern hemisphere there is a weak positive correlation between standardised, age-specific incidence and distance from the equator. There is now strong evidence for an environmental factor as the cause of the Western Pacific forms of MND. A number of clusters of sporadic MND have been reported from developed countries, but no single agent identified as responsible.

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.

Population frequencies of neuromuscular diseases--II. Amyotrophic lateral sclerosis (motor neurone disease)

A summary of the world literature on the prevalence of amyotrophic lateral sclerosis (motor neurone disease) has been carried out. Excluding those particular isolates with especially high prevalences (e.g. Guam and the Kii Peninsula of Japan), the mean prevalence among both sexes in other populations is around 41.6 x 10(-6) or 1 in 24,000.