Amyotrophic lateral sclerosis spatial epidemiology in the Mount Etna region, Italy

Presymptomatic geographical distribution of ALS patients suggests the involvement of environmental factors in the disease pathogenesis

BACKGROUND

Given that the pathogenetic process of ALS begins many years prior to its clinical onset, examining patients' residential histories may offer insights on the disease risk factors. Here, we analyzed the spatial distribution of a large ALS cohort in the 50 years preceding the disease onset.

METHODS

Data from the PARALS register were used. A spatial cluster analysis was performed at the time of disease onset and at 1-year intervals up to 50 years prior to that.

RESULTS

A total of 1124 patients were included. The analysis revealed a higher-incidence cluster in a large area (435,000 inhabitants) west of Turin. From 9 to 2 years before their onset, 105 cases were expected and 150 were observed, resulting in a relative risk of 1.49 (P = 0.04). We also found a surprising high number of patients pairs (51) and trios (3) who lived in the same dwelling while not being related. Noticeably, these occurrences were not observed in large dwellings as we would have expected. The probability of this occurring in smaller buildings only by chance was very low (P = 0.01 and P = 0.04 for pairs and trios, respectively).

CONCLUSIONS

We identified a higher-incidence ALS cluster in the years preceding the disease onset. The cluster area being densely populated, many exposures could have contributed to the high incidence ALS cluster, while we could not find a shared exposure among the dwellings where multiple patients had lived. However, these findings support that exogenous factors are likely involved in the ALS pathogenesis.

Early-onset, conjugal, twin-discordant, and clusters of sporadic ALS: Pathway to discovery of etiology via lifetime exposome research

The identity and role of environmental factors in the etiology of sporadic amyotrophic lateral sclerosis (sALS) is poorly understood outside of three former high-incidence foci of Western Pacific ALS and a hotspot of sALS in the French Alps. In both instances, there is a strong association with exposure to DNA-damaging (genotoxic) chemicals years or decades prior to clinical onset of motor neuron disease. In light of this recent understanding, we discuss published geographic clusters of ALS, conjugal cases, single-affected twins, and young-onset cases in relation to their demographic, geographic and environmental associations but also whether, in theory, there was the possibility of exposure to genotoxic chemicals of natural or synthetic origin. Special opportunities to test for such exposures in sALS exist in southeast France, northwest Italy, Finland, the U.S. East North Central States, and in the U.S. Air Force and Space Force. Given the degree and timing of exposure to an environmental trigger of ALS may be related to the age at which the disease is expressed, research should focus on the lifetime exposome (from conception to clinical onset) of young sALS cases. Multidisciplinary research of this type may lead to the identification of ALS causation, mechanism, and primary prevention, as well as to early detection of impending ALS and pre-clinical treatment to slow development of this fatal neurological disease.

Spatio-temporal clustering of amyotrophic lateral sclerosis in France: A population-based study

OBJECTIVE

To assess spatial aggregates of amyotrophic lateral sclerosis (ALS) incident cases, using a solid geo-epidemiological statistical method, in France.

METHODS

This population-based study (2003-2011) investigated 47.1 million person-years of follow-up (PYFU). Case ascertainment of incident ALS cases was based on multiple sources (ALS referral centers, hospital centres and health insurance data). Neurologists confirmed all ALS diagnoses. Exhaustiveness was estimated through capture-recapture. Aggregates were investigated in four steps: (a) geographical modelling (standardized incidence ratio (SIR) calculation), (b) analysis of the spatial distribution of incidence (Phothoff-Winttinghill's test, Global Moran's Index, Kulldorf's spatial scan statistic, Local Moran's Index), (c) classification of the level of certainty of spatial aggregates (i.e. definite cluster; probable over-incidence area; possible over-incidence area) and (d) evaluation of the robustness of the results.

RESULTS

The standardized incidence of ALS was 2.46/100,000 PYFU (95% CI 2.31-2.63, European population as reference) based on 1199 incident cases. We identified 13 areas of spatial aggregates: one cluster (stable in robustness analysis), five probable over-incidence areas (2 stable in robustness analysis) and seven possible over-incidence areas (including 4 stable areas in robustness analysis). A cluster was identified in the Rhône-Alpes region: 100 observed vs 54.07 expected cases for 2,411,514 PYFU, SIR: 1.85 (95% CI 1.50-2.25).

CONCLUSION

We report here one of the largest investigations of incidence and spatial aggregation of ALS ever performed in a western country. Using a solid methodology framework for case ascertainment and cluster analysis, we identified 13 areas that warrant further investigation.

Incidence of amyotrophic lateral sclerosis in Sardinia, Italy: age-sex interaction and spatial-temporal variability

Objective: This study assessed amyotrophic lateral sclerosis (ALS) incidence in Sardinia, Italy, and the combined contribution of age and gender to disease risk. We also checked disease incidence for spatial-temporal variability. Methods: ALS patients from all neurological centers of the study area who had onset during 2010-2019 and fulfilled El Escorial revised diagnostic criteria were included. Incidence was calculated for the overall study area and each province separately. Additive interaction between age and sex on ALS incidence was assessed. Results: The average crude annual incidence rate was 3.6/100,000 person-years (95% CI, 3.2-4.1), 3.1/100,000 person-years (95% CI, 2.7-3.5) when age-adjusted. Incidence was greater among people aged ≥65 years and men, with the two variables undergoing significant additive interaction. Incidence increased yearly over the study period, with annual incidence correlating with the increasing yearly frequency of people aged ≥65 years, but not with the proportion of incident cases carrying genetic mutations. Stratifying by province, the rates from Oristano and South Sardinia were higher than the rate from Cagliari. ALS patients from areas at different risk were comparable for frequency of clinical/genetic features. Conclusion: ALS incidence in Sardinia was in the upper part of the European range of variability. We also provided new information about age and sex as risk factors for ALS, showing male sex as a modifier of the effect of aging on ALS incidence. Spatial-temporal variations in ALS incidence correlated to changes in the proportion of the aging population rather than to the distribution of genetic factors.

CSF neurotoxic metals/metalloids levels in amyotrophic lateral sclerosis patients: comparison between bulbar and spinal onset

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder of the central nervous system (CNS) that causes progressive and irreversible damage in motor neurons. Different causal hypotheses include genetic, viral, traumatic and environmental mechanisms, such as exposure to heavy metals. The aim of this study was to compare metal/metalloid levels in cerebro-spinal fluid of ALS subtypes (spinal vs bulbar clinical onset).

MATERIAL AND METHODS

This observational study consecutively screened all ALS patients referring to the Neurology Clinic of the University of Catania (Italy). Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify magnesium (Mg), cuprum (Cu), selenium (Se), iron (Fe), manganese (Mn), vanadium (V), zinc (Zn), alluminium (Al), arsenic (As), cobalt (Co), nickel (Ni), mercury (Hg), lead (Pb), cadmium (Cd) and palladium (Pd) levels.

RESULTS

Thirty-seven patients were enrolled (62.2% females), median age of 65 years (IQR: 59-71 years). Thirty-one (83.8%) patients had a spinal onset and 6 (16.2%) a bulbar onset. Se and As levels were higher compared to the reference values (RV) both in spinal and bulbar onset, while Cu was higher than RV only in bulbar onset. Moreover, Cu (129.8 μg/L vs 29.8 μg/L), Fe (54.5 μg/L vs 33.3 μg/L), Mn (3.4 μg/L vs 1.8 μg/L), Zn (46.1 μg/L vs 35.7 μg/L), Al (12.2 μg/L vs 6.7 μg/L), Ni (2.80 μg/L vs 1.40 μg/L), and Pb (0.60 μg/L vs 0.30 μg/L) levels were higher in bulbar than in spinal onset, conversely As was slightly higher in spinal than in bulbar onset (1.40 μg/L vs 1.10 μg/L). Overall, Cu (129 μg/L vs 31 μg/L), Fe (92.2 μg/L vs 32.9 μg/L), Mn (3.35 μg/L vs 1.80 μg/L), Zn (56.5 μg/L vs 35.2 μg/L), Al (14.45 μg/L vs 6.70 μg/L), and Cd (0.40 μg/L vs 0.08 μg/L) levels were higher in patients with disease duration less than 19 months.

CONCLUSION

Our results supported the hypothesis that metals/metalloids with neurotoxic effects could be involved in the etiology of ALS, showing higher levels of Cu, Se and As. Relevant differences in Cu and Mn levels were found between bulbar and spinal onset patients.

Incidence of multiple sclerosis in the province of Catania. A geo-epidemiological study

BACKGROUND

An increasing incidence of MS in the city of Catania was reported during 1975-2004, with a higher incidence along the south-eastern flank of the Mt.Etna. We evaluated the incidence of MS in the entire province of Catania during 2005-2015 and the spatial distribution of MS-cases using a cluster analysis.

METHODS

Patients were considered as incident MS-cases if they fulfilled the revised McDonald criteria for MS during 2005-2015 and were residents in the province of Catania at the time of disease onset. Cluster analysis was performed using both LISA and Kulldorff's spatial scan statistic. Residence address at disease onset was considered for each case. Communalities were assessed considering the centroid of their inhabited area.

RESULTS

A total of 973 MS-cases were identified. Mean annual incidence risk was 8.2/100,000 person-years (95%CI 7.7-8.7), significantly higher among women (10.5/100,000 versus 5.7/100,000). LISA identified a spatial aggregation of MS-cases in the eastern side of the province of Catania and Kulldorff's statistics confirmed the existence of a statistically significant spatial cluster in this area (SIR 1.23,95%CI 1.08-1.23, p-value 0.04).

CONCLUSIONS

Our study confirms a high incidence of MS in the province of Catania and the presence of a spatial cluster along the eastern side of the province. This area is considered the most exposed to volcanogenic ashes due to the prevailing westerly to north-westerly trade winds. Even if such distribution could be related with a greater exposure to volcanogenic metals, further studies are needed to explore possible alternative hypotheses.

Clinical and Lifestyle Factors and Risk of Amyotrophic Lateral Sclerosis: A Population-Based Case-Control Study

Background: Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease of the motor neurons. The etiology of ALS remains largely unknown, particularly with reference to the potential environmental determinants. Methods: We performed a population-based case-control study in four provinces from both Northern and Southern Italy in order to assess non-genetic ALS risk factors by collecting through tailored questionnaires information about clinical and lifestyle factors. We estimated ALS risk by calculating odds ratio (OR) with its 95% confidence interval (CI) using unconditional logistic regression models adjusted for sex, age and educational attainment. Results: We recruited 230 participants (95 cases and 135 controls). We found a possible positive association of ALS risk with trauma, particularly head trauma (OR = 2.61, 95% CI 1.19–5.72), electric shock (OR = 2.09, 95% CI 0.62–7.06), and some sports, although at a competitive level only. In addition, our results suggest an increased risk for subjects reporting use of private wells for drinking water (OR = 1.38, 95% CI 0.73–2.27) and for use of herbicides during gardening (OR = 1.95, 95% CI 0.88–2.27). Conversely, there was a suggestion of an inverse association with overall fish consumption (OR = 0.27, 95% CI 0.12–0.60), but with no dose-response relation. Consumption of some dietary supplements, namely those containing amino acids and, in the Southern Italy population, vitamins and minerals such as selenium, seemed associated with a statistically imprecise increased risk. Conclusions: Our results suggest a potential etiologic role a number of clinical and lifestyle factors with ALS risk. However, caution is needed due to some study limitations. These include the small sample size and the low number of exposed subjects, which affect statistical precision of risk estimates, the potential for exposure misclassification, and the uncertainties about mechanisms underpinning the possible association between these factors and disease risk.