Study of epidemiological and etiological factors of amyotrophic lateral sclerosis in the province of Florence, Italy

Epidemiology of amyotrophic lateral sclerosis in the north east Tuscany in the 2018–2021 period

Background

The incidence of Amyotrophic Lateral Sclerosis (ALS) varies among different geographical areas and seems to increase over time. This study aimed to examine the epidemiologic data of ALS in the north-east Tuscany and compare the results with those of similar surveys.

Methods

Data from ALS cases diagnosed in Florence and Prato Hospitals were prospectively collected from 1st June 2018 to 31st May 2021.

Results

The age- and sex-adjusted incidence rate of ALS in cases per 100,000 population was 2.71 (M/F ratio: 1.21), significantly higher as compared to that reported in the 1967-1976 decade in the same geographical area (0.714). The age- and sex-adjusted incidence rate among resident strangers was similar to that of the general population (2.69). A slightly higher incidence rate (4.36) was observed in the north-east area of Florence province, which includes the Mugello valley. The mean prevalence was of 7.17/100,00. The mean age at diagnosis was 69.7 years, with a peak between 70 and 79 years among men and a smoother age curve among women.

Conclusions

ALS epidemiological features in north-east Tuscany are in line with other Italian and European Centers. The dramatic increase of the local disease burden over the last decades probably reflects better ascertainment methods and health system.

Occupation and amyotrophic lateral sclerosis risk: a case-control study in the isolated island population of Malta

Objective: Amyotrophic lateral sclerosis (ALS) is a mostly sporadic neurodegenerative disease. The role of environmental factors has been extensively investigated but associations remain controversial. Considering that a substantial proportion of adult life is spent at work, identifying occupations and work-related exposures is considered an effective way to detect factors that increase ALS risk. This process may be further facilitated in population isolates due to environmental and genetic homogeneity. Our study investigated occupations and occupational exposures potentially associated with ALS risk in the isolated island population of Malta, using a case-control study design. Methods: Patients with ALS and randomly identified matched controls (1:1) were recruited throughout a four-year window, from 2017 through 2020. Data on educational level, residence, main occupation, smoking, and alcohol history were collected. Results: We found that compared to controls (44.4%), a higher percentage (73.7%) of ALS patients reported a blue-collar job as their main occupation (OR 2.04, 95% CI 1.2-3.72; p = 0.0072). Through regression analysis, craft and related trades occupations such as carpentry and construction (ISCO-08 major group 7), were found to be positively associated with ALS, with patients in this occupational category found to be more prone to develop bulbar-onset ALS (p = 0.0297). Overall, patients with ALS reported a significantly higher exposure to work-related strenuous physical activity (OR 2.35, 95% CI 1.53-3.59; p = 0.0002). Conclusion: Our findings suggest that manual workers particularly those working in the carpentry and construction industries have an increased ALS risk, possibly due to a history of intense or sustained physical activity.

Geographic Variation of Amyotrophic Lateral Sclerosis Incidence in New Jersey, 2009-2011

Few analyses in the United States have examined geographic variation and socioeconomic disparities in amyotrophic lateral sclerosis (ALS) incidence, because of lack of population-based incidence data. In this analysis, we used population-based ALS data to identify whether ALS incidence clusters geographically and to determine whether ALS risk varies by area-based socioeconomic status (SES). This study included 493 incident ALS cases diagnosed (via El Escorial criteria) in New Jersey between 2009 and 2011. Geographic variation and clustering of ALS incidence was assessed using a spatial scan statistic and Bayesian geoadditive models. Poisson regression was used to estimate the associations between ALS risk and SES based on census-tract median income while controlling for age, sex, and race. ALS incidence varied across and within counties, but there were no statistically significant geographic clusters. SES was associated with ALS incidence. After adjustment for age, sex, and race, the relative risk of ALS was significantly higher (relative risk (RR) = 1.37, 95% confidence interval (CI): 1.02, 1.82) in the highest income quartile than in the lowest. The relative risk of ALS was significantly lower among blacks (RR = 0.57, 95% CI: 0.39, 0.83) and Asians (RR = 0.63, 95% CI: 0.41, 0.97) than among whites. Our findings suggest that ALS incidence in New Jersey appears to be associated with SES and race.

Epidemiological evidence that physical activity is not a risk factor for ALS

To elucidate whether physical activity (PA) and sport increase the risk of developing amyotrophic lateral sclerosis (ALS), a literature review of epidemiological studies was conducted according to the Meta-analysis of Observational Studies in Epidemiology guidelines. Six databases (Pubmed, Scopus, ScienceDirect, IngentaConnect, Refdoc and the Cochrane database) were searched to April 2014. Experts were asked to identify studies in press. Studies of interest were examined for their level of evidence and synthetized using Armon's classification for exogenous risk factors for ALS. Of 37 epidemiological works included in the review, two (5.5%) provided class I evidence, and five (13.5%) class II. Others offered evidence of class III (n = 8, 21.6%), IV (n = 16, 43.2%) and V (n = 6, 16.2%). Results were stratified according to type of exposure: (1) PA related to sport and work (n = 14), (2) soccer and American football (n = 9), (3) occupation (n = 12), (4) proxies of PA (n = 2). Among articles which considered "PA related to sport and work", two class I studies and one class II study concluded that PA is not a risk factor for ALS. This evidence establishes (level A) that PA is not a risk factor for ALS. As regards "occupational related activity" a level of evidence of U was obtained (it is unknown whether the professional category "physical worker" is a risk factor for ALS). Football/soccer may be considered as a possible risk factor for ALS (level C) and there is a need for further research taking into account the numerous confounding factors that may arise in this field.

Spinal cord trauma and the molecular point of no return

A mechanical trauma to the spinal cord can be followed by the development of irreversible and progressive neurodegeneration, as opposed to a temporary or partially reversible neurological damage. An increasing body of experimental and clinical evidence from humans and animal models indicates that spinal cord injury may set in motion the development of disabling and at times fatal neuromuscular disorders, whose occurrence is not normally associated with any major environmental event. This outcome appears to be dependent on the co-occurrence of a particular form of mechanical stress and of a genetically-determined vulnerability. This increased vulnerability to spinal cord injury may depend on a change of the nature and of the timing of activation of a number of neuroprotective and neurodestructive molecular signals in the injured cord. Among the main determinants, we could mention an altered homeostasis of lipids and neurofilaments, an earlier inflammatory response and the failure of the damaged tissue to rein in oxidative damage and apoptotic cell death. These changes could force injured tissue beyond a point of no return and precipitate an irreversible neurodegenerative process. A better knowledge of the molecular signals activated in a state of increased vulnerability to trauma can inform future treatment strategies and the prediction of the neurological outcome after spinal cord injury.

[Exogenous risk factors in sporadic ALS: a review of the literature]

The latest reviews of the literature devoted to the epidemiology of ALS all agree that exogenic risk factors play a role in sporadic ALS. Nevertheless, there is no convincing evidence demonstrating in a reproducible manner an association between an environmental risk factor and ALS. This discordance is mainly explained by methodological skews. Over the last ten years, exogenic factors have been analyzed within the framework of specific lifestyle factors such as place of residence, smoking or not, or certain eating practices. The most recent work suggests that interactions between genetic and environmental factors depend on the age at exposure and the duration of exposure. The objectives of this general review is: to analyze the principal case-control studies, historical cohort studies or mortality studies which looked at the associations between an environmental factor and ALS, to present main results of studies having analyzed lifestyles in relation to one or more exogenic factors, and to discuss the limitations of epidemiologic studies on ALS.

F wave study in amyotrophic lateral sclerosis: Assessment of balance between upper and lower motor neuron involvement

OBJECTIVE

We sought to record significant F wave variable changes in ALS patients having no advanced disease. Furthermore, an interpretation of these F wave abnormalities in the context of upper (UMN) and lower motor neuron (LMN) dysfunction was attempted.

METHODS

Standard motor and sensory conduction study was performed to the ulnar nerves of 23 patients with ALS (13 males and 10 females with mean age 67.2+/-5.3 years), having a clinically predominant LMN syndrome. A series of 40 electrical stimuli were also delivered to both their ulnar nerves in order to obtain F waves. The following F wave variables were estimated: F persistence, F wave latency, amplitude, duration and F chronodispersion. Twenty-three, age-and gender-matched healthy volunteers served as controls.

RESULTS

Both the distal and proximal ulnar a-CMAPs (P=0.001) and the MCV (P=0.014) values were significantly decreased in patients, than the controls. The sensory conduction study was normal. The ulnar F wave persistence in the ALS patients was significantly lower than that of the controls (P=0.0007). The mean (P=0.0001), minimal (P=0.0001) and maximal (P=0.0001) F wave latencies were significantly prolonged, the F wave amplitudes (P=0.0001) were significantly higher and the F wave chronodispersion (P=0.014) was significantly increased in the patients than the controls.

CONCLUSIONS

Significant F wave abnormalities occur in patients with ALS, even those patients having no advanced disease. Increased F wave amplitudes combined with low persistence is a pattern consistent with ALS.

SIGNIFICANCE

Our results show that patients with ALS having predominantly LMN involvement also have electrophysiological UMN dysfunction.

Clinical and epidemiological features of motor neuron disease in south-western Greece

OBJECTIVE

To evaluate the epidemiological and clinical features of motor neuron disease (MND) in a region (835,000 inhabitants) of south-western Greece.

PATIENTS AND METHODS

The medical records of all patients diagnosed with adult-onset MND at the Department of Neurology of the University Hospital of Patras from 1990 to 2003 were reviewed.

RESULTS

Overall 133 patients were identified, corresponding to a mean annual incidence rate of 1.13/100,000 population with male preponderance. Eighty-five of them were males (63.9%) and 48 (36.1%) females with a mean age of 61.4 +/- 13.3 years. The most common type of MND was amyotrophic lateral sclerosis (ALS) being identified in 111 (83.5%) patients, whereas 19 cases (14.3%) were classified as progressive spinal muscular atrophy (PSMA) and three (2.2%) cases as progressive bulbar palsy (PBP). The mean age at onset was 60.3 +/- 13.5 years, while the mean delay between age at onset and age at diagnosis was 1.3 +/- 1.1 years. The symptoms at onset involved the lower limbs in 76 (57.2%) cases, upper limbs in 32 (24%) cases, bulbar region in 22 (16.5%) cases and respiratory muscles in three (2.3%) cases. The mean survival time after onset of disease was 20.4 +/- 8.3 months for ALS patients, 15.3 +/- 4.5 months for PBP and 38.1 +/- 26.4 months for PSMA patients.

CONCLUSIONS

There was no statistically significant difference in the results of the considered epidemiological parameters of our study to those reported by other similar studies. The study of the patients with MND showed a predominance of ALS patients. No potentially causative clinical associations were found and no relation between socioeconomic factors, occupational exposure and the disease was noted.

Amyotrophic lateral sclerosis: a review of current concepts

Amyotrophic lateral sclerosis (ALS), once thought to be a rare neurodegenerative disease, affects between 1.2 and 1.8/100,000 individuals. This age-dependent disorder, similar to other major neurological disorders of the aging population (Alzheimer's and Parkinson's disease) is increasing in incidence at a rate which cannot be accounted for by population aging alone. Multiple clinical variants of ALS are now recognized which are associated with a spectrum of clinical outcomes from aggressive to rather indolent. Three variants of ALS are generally accepted, including the western Pacific type (often associated with dementia), familial (the majority of which are autosomal dominant in their inheritance) and classic sporadic ALS. Considerable biological heterogeneity underlies the disease process of ALS. By the time ALS is clinically evident, derangements at the cellular level in ALS are extensive and include alterations in the cytoskeleton, mitochondrial function, microglial activation, and the metabolism of reactive oxygenating species and glutamate. Our understanding of the genetic aspects of the disease continues to expand. These observations have led to the suggestion that multiple distinct etiologies may be responsible. Recent advances have also included the observation that cognitive decline may be present in a population of patients not previously recognised. Significant advances in both symptomatic and adjunctive therapy have resulted in prolonged quality and duration of life.

The basic aspects of therapeutics in amyotrophic lateral sclerosis

Once thought to be a single pathological disease state, amyotrophic lateral sclerosis (ALS) is now recognized to be the limited phenotypic expression of a complex, heterogeneous group of biological processes, resulting in an unrelenting loss of motor neurons. On average, individuals affected with the disease live <5 years. In this article, the complex nature of the pathogenesis of ALS, including features of age dependency, environmental associations, and genetics, is reviewed. Once held to be uncommon, it is now clear that ALS is associated with a frontotemporal dementia and that this process may reflect disturbances in the microtubule-associated tau protein metabolism. The motor neuron ultimately succumbs in a state where significant disruptions in neurofilament metabolism, mitochondrial function, and management of oxidative stress exist. The microenvironment of the neuron becomes a complex milieu in which high levels of glutamate provide a source of chronic excitatory neurotoxicity, and the contributions of activated microglial cells lead to further cascades of motor neuron death, perhaps serving to propagate the disease once established. The final process of motor neuron death encompasses many features of apoptosis, but it is clear that this alone cannot account for all features of motor neuron loss and that aspects of a necrosis-apoptosis continuum are at play. Designing pharmacological strategies to mitigate against this process thus becomes an increasingly complex issue, which is reviewed in this article.

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.

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.

Amyotrophic lateral sclerosis in Sweden in relation to occupation

All cases of ALS in Sweden during the period 1970-1983, i.e., 1961 cases, were compared with an age-stratified random sample of 2245 individuals from the Swedish population. On the basis of census information, the male cases were found to be heterogeneously distributed over occupational groups. Significantly more male cases than expected were found among office workers (OR = 1.8; 34 cases) as well as among farm workers (OR = 1.7; 56 cases). There was a cluster of male cases in agricultural work in one south-western county (OR = 3.4; 25 cases). Significantly more female cases than expected were medical service workers (OR = 1.7; 33 cases).

Hypotheses to explain the association between vigorous physical activity and amyotrophic lateral sclerosis

Many epidemiologic studies indicate a relation between vigorous physical activity and amyotrophic lateral sclerosis. Physical activity itself is unlikely to cause amyotrophic lateral sclerosis, but could it modify the effects of other etiologic factors such as neurotoxins? Vigorous physical activity could potentiate the effect of a toxin to motor neurons by any of several mechanisms, especially if the toxin's effects were mediated through excitation. Exercise could alter the extent of exposure or could influence the distribution, metabolism or potency of an excitotoxin. Future epidemiologic studies of amyotrophic lateral sclerosis should include sufficient detail about vigorous physical exercise to explore this relationship further.

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.

Amyotrophic lateral sclerosis in Palermo, Italy: an epidemiological study

The incidence, prevalence and natural course of ALS were determined in the population of the province of Palmero, Italy. The average annual incidence calculated for the years 1973 through 1984, was 044./100.000 inhabitants. The prevalence rate on prevalence day December 31, 1984, was 1.67/100.000 population. The male/female ratio was 1.38. The mean age at onset was 54.3 +/- 11.02. The most common clinical form was the conventional one (61.4%); the bulbar form was more frequent among females than males. The mean duration of the disease was 33.7 +/- 35.8 months. The longest duration belongs to the pseudopolyneuritic form. The median survival was 36 months: 16 months for the bulbar, 36 months for the conventional and 51 months for the pseudopolyneuritic form.

Evidence for clustering of amyotrophic lateral sclerosis in Wisconsin

Clustering of amyotrophic lateral sclerosis (ALS) occurs in the western Pacific, but has not been convincingly demonstrated for the sporadic form of the disease which occurs throughout the rest of the world. Using death certificate data we identified 529 ALS-associated deaths in Wisconsin during the interval 1973-82, representing a statewide mortality rate of 1.12 deaths/100,000/yr. Using computer simulation we show that cases were not homogeneously distributed throughout the population and that there exists a significant cluster of cases in northeastern Wisconsin.

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

A retrospective study of all admissions to the University of Modena Neurological Department from 1976-1986; 51 cases of amyotrophic lateral sclerosis (ALS) were found. ALS mean annual incidence was 0.78/100,000 inhabitants, while prevalence was 2.35/100,000. Mean age at onset was 61.43 years, mean and median duration of illness were, respectively, 28.83 and 24.5 months, and survival at 5 years post-onset was 24.4%. A tendency to higher incidence and prevalence of ALS in the ceramic district, when compared with those of the rest of the province was found. However, the small number of cases did not allow any conclusive statistical correlation between environmental exposure to lead and frequency of ALS.

Motor neuron disease in Cantabria

Sixty-two patients with motor neuron disease (MND), encompassing amyotrophic lateral sclerosis (ALS), progressive bulbar palsy (PBP) and progressive muscular atrophy (PMA), were selected from within a defined area (Cantabria) in northern Spain, from 1974 to 1985. The annual incidence of MND was 1.01 per 100,000 inhabitants and the prevalence rate was 3.52 per 100,000. The male to female ratio was 1.78:1. Age-specific incidence rates increased with advanced age, with a maximum between 60 and 69 years for males and over 70 years for females. The median age at onset was 60.5 years. The average interval between the onset symptoms and diagnosis was 11 months. Fifty-three per cent of the patients had conventional or pseudopolyneuritic ALS, 36% had PBP and 11% had PMA. There were three familial cases. Two PMA patients had had acute poliomyelitis. The mean duration of the disease was 26.6 months and was significantly longer in males aged under 60 years. The survival rates in 50 patients with adequate follow-up were 18% after 5 years from onset and 6% after 10 years.

Epidemiologic study of amyotrophic lateral sclerosis in Sardinia, Italy

From 1957 to 1980 in Sardinia, 182 cases of ALS with a mean annual incidence of 0.51 per 100,000 inhabitants and a prevalence rate of 3.65 per 100,000 inhabitants (prevalence day 21.10.1971) were observed. The disease was found to be more common in males, in subjects aged 50 to 70 years and in farmers and shepherds. Incidence in various areas of the island was found to be different. The common form was more frequent, had earlier onset and greater median survival rate.

Amyotrophic lateral sclerosis in the province of Parma, Italy: a clinical and epidemiological study in the period 1960-1980

A clinical and epidemiological study on ALS was conducted in the province of Parma, Italy, in the period 1960-1980. A total of 78 cases was collected from hospital records. The average annual incidence was 0.93 per 100,000 with no difference between rural and urban areas. On prevalence day (October 24, 1971) a prevalence rate of 2.27 was found. Mean age at onset was 59 years, with no sex difference. In 70% of cases the onset was between 50 and 70 years, this datum being statistically significant (p less than 0.001). Mean duration of the disease was 30.4 +/- 20 months, with no difference for sex and age at onset. A comparison was then made between two decades (1961-70 vs 1971-80), in order to verify the clinical impression of a worsening of some ALS parameters in recent years. Although statistical evaluation did not show any significant data, a tendency to a worsening of some parameters of the disease may be postulated.

Motor neuron disease in the Province of Turin, Italy, 1971-1980

The incidence and prevalence of motor neuron disease (MND) in the Province of Turin, North-West Italy, were investigated for the period 1971-1980. The crude incidence rate of MND was 0.67/100,000/year. The annual incidence rate, age and sex adjusted to the Italian population in 1971 was 0.69 cases per 100,000 inhabitants, 0.94 for men and 0.45 for women, with a male to female incidence ratio of 2.09:1. The prevalence of MND was 2.62/100,000, 3.57 for males and 1.71 for females. The mean age at the time of diagnosis was 55.6 years. Annual incidence rates increased with advancing age. Amyotrophic lateral sclerosis was found to be 4 times more frequent than progressive muscular atrophy (0.53/100,000/year v. 0.14/100,000/year). The distribution of MND was uneven in the Province suggesting a proportional relationship to the distribution of population density. Possible explanations of this finding are discussed.

Amyotrophic lateral sclerosis in Middle-Finland: an epidemiological study

Amyotrophic lateral sclerosis (ALS) was diagnosed in 36 patients in Middle-Finland Central Hospital District during 1976-1981. The annual incidence of ALS was 2.4 per 100,000 population and the prevalence rate was 6.4 per 100,000 population. The age-specific incidences of ALS were similar for men and women with a maximum of 14/100,000/year in the age group 60-69 years. The initial symptoms originated in 37% of the patients from bulbar and in 63% from spinal levels. Bulbar onset was more common in patients aged 60 years or more compared with younger patients. Patients with bulbar onset had a significantly poorer prognosis than those with spinal onset, which explained the poorer prognosis of older patients. 4 matched controls were chosen for each ALS patient from the files of the Central Hospital. There was no difference between the patients and the controls with respect to previous injuries, surgical operations, malignant neoplasms, or exposure to domestic animals. An earlier observation that evacuees from Karelia ceded to USSR after World War II should have a prevalence twice that of the remaining population was not substantiated.

Clinical features of amyotrophic amyotrophic lateral sclerosis

The clinical features and course of amyotrophic lateral sclerosis are discussed. The data on a series of 116 patients are compared with those of the literature. The following points emerge: 1) when the disease starts before the age of 50, the prognosis is often less poor than usual; 2) the forms with spinal, and especially cervical, onset appear to be less rapid than bulbar forms; 3) in 20% of the patients survival is over 5 years. There may be some unknown factor that increases the resistance of some subject to the disease.