High plasma concentrations of organic pollutants negatively impact survival in amyotrophic lateral sclerosis

Occupational lead exposure and amyotrophic lateral sclerosis survival in the Danish National Patient Registry

OBJECTIVES

We investigated the relationship between occupational lead exposure and amyotrophic lateral sclerosis (ALS) survival in Denmark.

METHODS

We identified 2,161 ALS cases diagnosed from 1982 to 2013 with at least 5 years of employment history before ALS diagnosis, via the Danish National Patient Registry. Cases were followed until March 2017. We defined lead exposure as never employed in a lead job, ever employed in a lead job, and ever employed in a lead job by exposure probability (<50% vs. ≥50%), excluding jobs held in the 5 years before diagnosis in main analyses. Survival was evaluated using Cox proportional hazards models and stratified by sex and age of diagnosis.

RESULTS

Median age of diagnosis was 63.5 years, and individuals in lead-exposed jobs were diagnosed at a younger age. Adjusted hazard ratios (aHR) were slightly decreased for men ever lead-exposed (aHR:0.92, 95%CI: 0.80, 1.05) and more so among those diagnosed at age 60-69 (lead ≥ 50% aHR: 0.66, 95%CI: 0.45, 0.98), but reversed for men diagnosed at age 70 and later (aHR: 2.03, 95%CI: 1.13, 3.64). No apparent pattern was observed among women.

CONCLUSIONS

Occupational lead exposure contributed to shorter survival among men diagnosed at older ages. The inverse associations observed for men diagnosed earlier could relate to possible healthy worker hire effect or health advantages of working in lead-exposed jobs. Our results are consistent with an adverse impact of lead exposure on ALS survival at older ages, with the age at which lead's effects on survival worsen later on among those in lead-exposed jobs.

Multiple metal exposures associate with higher amyotrophic lateral sclerosis risk and mortality independent of genetic risk and correlate to self-reported exposures: a case-control study

BACKGROUND

The pathogenesis of amyotrophic lateral sclerosis (ALS) involves both genetic and environmental factors. This study investigates associations between metal measures in plasma and urine, ALS risk and survival and exposure sources.

METHODS

Participants with and without ALS from Michigan provided plasma and urine samples for metal measurement via inductively coupled plasma mass spectrometry. ORs and HRs for each metal were computed using risk and survival models. Environmental risk scores (ERS) were created to evaluate the association between exposure mixtures and ALS risk and survival and exposure source. ALS (ALS-PGS) and metal (metal-PGS) polygenic risk scores were constructed from an independent genome-wide association study and relevant literature-selected single-nucleotide polymorphisms.

RESULTS

Plasma and urine samples from 454 ALS and 294 control participants were analysed. Elevated levels of individual metals, including copper, selenium and zinc, significantly associated with ALS risk and survival. ERS representing metal mixtures strongly associated with ALS risk (plasma, OR=2.95, CI=2.38-3.62, p<0.001; urine, OR=3.10, CI=2.43-3.97, p<0.001) and poorer ALS survival (plasma, HR=1.37, CI=1.20-1.58, p<0.001; urine, HR=1.44, CI=1.23-1.67, p<0.001). Addition of the ALS-PGS or metal-PGS did not alter the significance of metals with ALS risk and survival. Occupations with high potential of metal exposure associated with elevated ERS. Additionally, occupational and non-occupational metal exposures were associated with measured plasma and urine metals.

CONCLUSION

Metals in plasma and urine associated with increased ALS risk and reduced survival, independent of genetic risk, and correlated with occupational and non-occupational metal exposures. These data underscore the significance of metal exposure in ALS risk and progression.

What do you think caused your ALS? An analysis of the CDC national amyotrophic lateral sclerosis patient registry qualitative risk factor data using artificial intelligence and qualitative methodology

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is an incurable, progressive neurodegenerative disease with a significant health burden and poorly understood etiology. This analysis assessed the narrative responses from 3,061 participants in the Centers for Disease Control and Prevention's National ALS Registry who answered the question, "What do you think caused your ALS?"

METHODS

Data analysis used qualitative methods and artificial intelligence (AI) using natural language processing (NLP), specifically, Bidirectional Encoder Representations from Transformers (BERT) to explore responses regarding participants' perceptions of the cause of their disease.

RESULTS

Both qualitative and AI analysis methods revealed several, often aligned themes, which pointed to perceived causes including genetic, environmental, and military exposures. However, the qualitative analysis revealed detailed themes and subthemes, providing a more comprehensive understanding of participants' perceptions. Although there were areas of alignment between AI and qualitative analysis, AI's broader categories did not capture the nuances discovered using the more traditional, qualitative approach. The qualitative analysis also revealed that the potential causes of ALS were described within narratives that sometimes indicate self-blame and other maladaptive coping mechanisms.

CONCLUSIONS

This analysis highlights the diverse range of factors that individuals with ALS consider as perceived causes for their disease. Understanding these perceptions can help clinicians to better support people living with ALS (PLWALS). The analysis highlights the benefits of using traditional qualitative methods to supplement or improve upon AI-based approaches. This rapidly evolving area of data science has the potential to remove barriers to accessing the rich narratives of people with lived experience.

Residential exposure associations with ALS risk, survival, and phenotype: a Michigan-based case-control study

BACKGROUND

Environmental exposures impact amyotrophic lateral sclerosis (ALS) risk and progression, a fatal and progressive neurodegenerative disease. Better characterization of these exposures is needed to decrease disease burden.

OBJECTIVE

To identify exposures in the residential setting that associate with ALS risk, survival, and onset segment.

METHODS

ALS and control participants recruited from University of Michigan completed a survey that ascertained exposure risks in the residential setting. ALS risk was assessed using logistic regression models followed by latent profile analysis to consider exposure profiles. A case-only analysis considered the contribution of the residential exposure variables via a Cox proportional hazards model for survival outcomes and multinomial logistic regression for onset segment, a polytomous outcome.

RESULTS

This study included 367 ALS and 255 control participants. Twelve residential variables were associated with ALS risk after correcting for multiple comparison testing, with storage in an attached garage of chemical products including gasoline or kerosene (odds ratio (OR) = 1.14, padjusted < 0.001), gasoline-powered equipment (OR = 1.16, padjusted < 0.001), and lawn care products (OR = 1.15, padjusted < 0.001) representing the top three risk factors sorted by padjusted. Latent profile analysis indicated that storage of these chemical products in both attached and detached garages increased ALS risk. Although residential variables were not associated with poorer ALS survival following multiple testing corrections, storing pesticides, lawn care products, and woodworking supplies in the home were associated with shorter ALS survival using nominal p values. No exposures were associated with ALS onset segment.

CONCLUSION

Residential exposures may be important modifiable components of the ALS susceptibility and prognosis exposome.

Nanoplastics and Neurodegeneration in ALS

Plastic production, which exceeds one million tons per year, is of global concern. The constituent low-density polymers enable spread over large distances and micro/nano particles (MNPLs) induce organ toxicity via digestion, inhalation, and skin contact. Particles have been documented in all human tissues including breast milk. MNPLs, especially weathered particles, can breach the blood-brain barrier, inducing neurotoxicity. This has been documented in non-human species, and in human-induced pluripotent stem cell lines. Within the brain, MNPLs initiate an inflammatory response with pro-inflammatory cytokine production, oxidative stress with generation of reactive oxygen species, and mitochondrial dysfunction. Glutamate and GABA neurotransmitter dysfunction also ensues with alteration of excitatory/inhibitory balance in favor of reduced inhibition and resultant neuro-excitation. Inflammation and cortical hyperexcitability are key abnormalities involved in the pathogenic cascade of amyotrophic lateral sclerosis (ALS) and are intricately related to the mislocalization and aggregation of TDP-43, a hallmark of ALS. Water and many foods contain MNPLs and in humans, ingestion is the main form of exposure. Digestion of plastics within the gut can alter their properties, rendering them more toxic, and they cause gut microbiome dysbiosis and a dysfunctional gut-brain axis. This is recognized as a trigger and/or aggravating factor for ALS. ALS is associated with a long (years or decades) preclinical period and neonates and infants are exposed to MNPLs through breast milk, milk substitutes, and toys. This endangers a time of intense neurogenesis and establishment of neuronal circuitry, setting the stage for development of neurodegeneration in later life. MNPL neurotoxicity should be considered as a yet unrecognized risk factor for ALS and related diseases.

Role of the Exposome in Neurodegenerative Disease: Recent Insights and Future Directions

Neurodegenerative diseases are increasing in prevalence and place a significant burden on society. The causes are multifactorial and complex, and increasing evidence suggests a dynamic interplay between genes and the environment, emphasizing the importance of identifying and understanding the role of lifelong exposures, known as the exposome, on the nervous system. This review provides an overview of recent advances toward defining neurodegenerative disease exposomes, focusing on Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease. We present the current state of the field based on emerging data, elaborate on key themes and potential mechanisms, and conclude with limitations and future directions. ANN NEUROL 2024;95:635-652.

Sex biology in amyotrophic lateral sclerosis

Although sex differences in amyotrophic lateral sclerosis (ALS) have not been studied systematically, numerous clinical and preclinical studies have shown sex to be influential in disease prognosis. Moreover, with the development of advanced imaging tools, the difference between male and female brain in structure and function and their response to neurodegeneration are more definitive. As discussed in this review, ALS patients exhibit a sex bias pertaining to the features of the disease, and their clinical, pathological, (and pathophysiological) phenotypes. Several epidemiological studies have indicated that this sex disparity stems from various aetiologies, including sex-specific brain structure and neural functioning, genetic predisposition, age, gonadal hormones, susceptibility to traumatic brain injury (TBI)/head trauma and lifestyle factors.

Metal mixtures associate with higher amyotrophic lateral sclerosis risk and mortality independent of genetic risk and correlate to self-reported exposures: a case-control study

Background

The pathogenesis of amyotrophic lateral sclerosis (ALS) involves both genetic and environmental factors. This study investigates associations between metal measures in plasma and urine, ALS risk and survival, and exposure sources.

Methods

Participants with and without ALS from Michigan provided plasma and urine samples for metal measurement via inductively coupled plasma mass spectrometry. Odds and hazard ratios for each metal were computed using risk and survival models. Environmental risk scores (ERS) were created to evaluate the association between exposure mixtures and ALS risk and survival and exposure source. ALS (ALS-PGS) and metal (metal-PGS) polygenic risk scores were constructed from an independent genome-wide association study and relevant literature-selected SNPs.

Results

Plasma and urine samples from 454 ALS and 294 control participants were analyzed. Elevated levels of individual metals, including copper, selenium, and zinc, significantly associated with ALS risk and survival. ERS representing metal mixtures strongly associated with ALS risk (plasma, OR=2.95, CI=2.38-3.62, p<0.001; urine, OR=3.10, CI=2.43-3.97, p<0.001) and poorer ALS survival (plasma, HR=1.42, CI=1.24-1.63, p<0.001; urine, HR=1.52, CI=1.31-1.76, p<0.001). Addition of the ALS-PGS or metal-PGS did not alter the significance of metals with ALS risk and survival. Occupations with high potential of metal exposure associated with elevated ERS. Additionally, occupational and non-occupational metal exposures associated with measured plasma and urine metals.

Conclusion

Metals in plasma and urine associated with increased ALS risk and reduced survival, independent of genetic risk, and correlated with occupational and non-occupational metal exposures. These data underscore the significance of metal exposure in ALS risk and progression.

Avocational exposure associations with ALS risk, survival, and phenotype: A Michigan-based case-control study

INTRODUCTION

Environmental exposures strongly influence ALS risk and identification is needed to reduce ALS burden. Participation in hobbies and exercise may alter ALS risk and phenotype, warranting an assessment to understand their contribution to the ALS exposome.

METHODS

Participants with ALS and healthy controls were recruited from University of Michigan and self-completed a survey to ascertain hobbies, exercise, and avocational exposures. Exposure variables were associated with ALS risk, survival, onset segment, and onset age.

RESULTS

ALS (n = 400) and control (n = 287) participants self-reported avocational activities. Cases were slightly older (median age 63.0 vs. 61.1 years, p = 0.019) and had a lower educational attainment (p < 0.001) compared to controls; otherwise, demographics were well balanced. Risks associating with ALS after multiple comparison correction included golfing (odds ratio (OR) 3.48, padjusted = 0.004), recreational dancing (OR 2.00, padjusted = 0.040), performing gardening or yard work (OR 1.71, padjusted = 0.040) five years prior to ALS and personal (OR 1.76, padjusted = 0.047) or family (OR 2.21, padjusted = 0.040) participation in woodworking, and personal participation in hunting and shooting (OR 1.89, padjusted = 0.040). No exposures associated with ALS survival and onset. Those reporting swimming (3.86 years, padjusted = 0.016) and weightlifting (3.83 years, padjusted = 0.020) exercise 5 years prior to ALS onset had an earlier onset age.

DISCUSSION

The identified exposures in this study may represent important modifiable ALS factors that influence ALS phenotype. Thus, exposures related to hobbies and exercise should be captured in studies examining the ALS exposome.

Environmental risk scores of persistent organic pollutants associate with higher ALS risk and shorter survival in a new Michigan case/control cohort

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurogenerative disease caused by combined genetic susceptibilities and environmental exposures. Identifying and validating these exposures are of paramount importance to modify disease risk. We previously reported that persistent organic pollutants (POPs) associate with ALS risk and survival and aimed to replicate these findings in a new cohort.

METHOD

Participants with and without ALS recruited in Michigan provided plasma samples for POPs analysis by isotope dilution with triple quadrupole mass spectrometry. ORs for risk models and hazard ratios for survival models were calculated for individual POPs. POP mixtures were represented by environmental risk scores (ERS), a summation of total exposures, to evaluate the association with risk (ERSrisk) and survival (ERSsurvival).

RESULTS

Samples from 164 ALS and 105 control participants were analysed. Several individual POPs significantly associated with ALS, including 8 of 22 polychlorinated biphenyls and 7 of 10 organochlorine pesticides (OCPs). ALS risk was most strongly represented by the mixture effects of OCPs alpha-hexachlorocyclohexane, hexachlorobenzene, trans-nonachlor and cis-nonachlor and an interquartile increase in ERSrisk enhanced ALS risk 2.58 times (p<0.001). ALS survival was represented by the combined mixture of all POPs and an interquartile increase in ERSsurvival enhanced ALS mortality rate 1.65 times (p=0.008).

CONCLUSIONS

These data continue to support POPs as important factors for ALS risk and progression and replicate findings in a new cohort. The assessments of POPs in non-Michigan ALS cohorts are encouraged to better understand the global effect and the need for targeted disease risk reduction strategies.

Brain-Gut-Microbiota Axis in Amyotrophic Lateral Sclerosis: A Historical Overview and Future Directions

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease which is strongly associated with age. The incidence of ALS increases from the age of 40 and peaks between the ages of 65 and 70. Most patients die of respiratory muscle paralysis or lung infections within three to five years of the appearance of symptoms, dealing a huge blow to patients and their families. With aging populations, improved diagnostic methods and changes in reporting criteria, the incidence of ALS is likely to show an upward trend in the coming decades. Despite extensive researches have been done, the cause and pathogenesis of ALS remains unclear. In recent decades, large quantities of studies focusing on gut microbiota have shown that gut microbiota and its metabolites seem to change the evolvement of ALS through the brain-gut-microbiota axis, and in turn, the progression of ALS will exacerbate the imbalance of gut microbiota, thereby forming a vicious cycle. This suggests that further exploration and identification of the function of gut microbiota in ALS may be crucial to break the bottleneck in the diagnosis and treatment of this disease. Hence, the current review summarizes and discusses the latest research advancement and future directions of ALS and brain-gut-microbiota axis, so as to help relevant researchers gain correlative information instantly.

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Dietary intakes of dioxins and polychlorobiphenyls (PCBs) and mortality: EPIC cohort study in 9 European countries

Dioxins and polychlorinated biphenyls (PCBs) are toxic, endocrine disruptors and persistent chemicals for which the main exposure source is diet due to their bioaccumulation and biomagnification in food chains. Cohort studies in the general populations have reported inconsistent associations between these chemicals in serum/plasma and mortality. Our objective was to study the association between dietary intake of 17 dioxins and 35 PCBs and all-cause, cancer-specific and cardiovascular-specific mortalities were assessed in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Dietary intake of dioxins and PCBs was assessed combining EPIC food consumption data with European food contamination data provided by the European Food Safety Authority. We applied multivariable Cox regressions. The analysis included 451,390 adults (mean ± SD age:51.1 ± 9.7 years) with 46,627 deaths and a median follow-up of 17.4 years (IQR = 15.2-19.1). A U-shaped non-linear association with all-cause mortality for dietary intake of dioxins (Pnon-linearity<0.0001), DL-PCB (Pnon-linearity = 0.0001), and NDL-PCBs (Pnon-linearity<0.01) was observed. For example, the hazard ratios (95%Confidance interval) for all-cause mortality obtained with the spline model was equal to 1.03 (1.02-1.05) for low levels of intake to dioxins (7 pg TEQ/day), 0.93 (0.90-0.96) for moderate levels of intake (25 pg TEQ/day), while for high levels of intake (55 pg TEQ/day) it was 1.03 (0.97-1.09). Intake of dioxins, DL-PCBs and NDL-PCBs was not associated with cardiovascular mortality. There was no association between intakes of dioxins and cancer mortality, but a U-shaped association was observed for intake of DL-PCBs and intakes of NDL-PCBs and cancer mortality. The PCBs and dioxins are known to have endocrine disrupting properties which can lead to non-monotonic dose responses. These results need to be interpreted with caution and further studies are needed to better clarify the association between dietary intake of dioxins and PCB and mortality in the general population.

The amyotrophic lateral sclerosis exposome: recent advances and future directions

Amyotrophic lateral sclerosis (ALS) is a fatal disease of motor neuron degeneration with typical survival of only 2-5 years from diagnosis. The causes of ALS are multifactorial: known genetic mutations account for only around 70% of cases of familial ALS and 15% of sporadic cases, and heritability estimates range from 8% to 61%, indicating additional causes beyond genetics. Consequently, interest has grown in environmental contributions to ALS risk and progression. The gene-time-environment hypothesis posits that ALS onset occurs through an interaction of genes with environmental exposures during ageing. An alternative hypothesis, the multistep model of ALS, suggests that several hits, at least some of which could be environmental, are required to trigger disease onset, even in the presence of highly penetrant ALS-associated mutations. Studies have sought to characterize the ALS exposome - the lifetime accumulation of environmental exposures that increase disease risk and affect progression. Identifying the full scope of environmental toxicants that enhance ALS risk raises the prospect of preventing disease by eliminating or mitigating exposures. In this Review, we summarize the evidence for an ALS exposome, discussing the strengths and limitations of epidemiological studies that have identified contributions from various sources. We also consider potential mechanisms of exposure-mediated toxicity and suggest future directions for ALS exposome research.

Cumulative Genetic Score and C9orf72 Repeat Status Independently Contribute to Amyotrophic Lateral Sclerosis Risk in 2 Case-Control Studies

Background and Objectives

Most patients with amyotrophic lateral sclerosis (ALS) lack a monogenic mutation. This study evaluates ALS cumulative genetic risk in an independent Michigan and Spanish replication cohort using polygenic scores.

Methods

Participant samples from University of Michigan were genotyped and assayed for the chromosome 9 open reading frame 72 hexanucleotide expansion. Final cohort size was 219 ALS and 223 healthy controls after genotyping and participant filtering. Polygenic scores excluding the C9 region were generated using an independent ALS genome-wide association study (20,806 cases, 59,804 controls). Adjusted logistic regression and receiver operating characteristic curves evaluated the association and classification between polygenic scores and ALS status, respectively. Population attributable fractions and pathway analyses were conducted. An independent Spanish study sample (548 cases, 2,756 controls) was used for replication.

Results

Polygenic scores constructed from 275 single-nucleotide variation (SNV) had the best model fit in the Michigan cohort. An SD increase in ALS polygenic score associated with 1.28 (95% CI 1.04-1.57) times higher odds of ALS with area under the curve of 0.663 vs a model without the ALS polygenic score (p value = 1 × 10-6). The population attributable fraction of the highest 20th percentile of ALS polygenic scores, relative to the lowest 80th percentile, was 4.1% of ALS cases. Genes annotated to this polygenic score enriched for important ALS pathomechanisms. Meta-analysis with the Spanish study, using a harmonized 132 single nucleotide variation polygenic score, yielded similar logistic regression findings (odds ratio: 1.13, 95% CI 1.04-1.23).

Discussion

ALS polygenic scores can account for cumulative genetic risk in populations and reflect disease-relevant pathways. If further validated, this polygenic score will inform future ALS risk models.

Occupational history associates with ALS survival and onset segment

OBJECTIVE

To identify associations between occupational settings and self-reported occupational exposures on amyotrophic lateral sclerosis (ALS) survival and phenotypes.

METHODS

All patients seen in the University of Michigan Pranger ALS Clinic were invited to complete an exposure assessment querying past occupations and exposures. Standard occupational classification (SOC) codes for each job and the severity of various exposure types were derived. Cox proportional hazards models associated all-cause mortality with occupational settings and the self-reported exposures after adjusting for sex, diagnosis age, revised El Escorial criteria, onset segment, revised ALS Functional Rating Scale (ALSFRS-R), and time from symptom onset to diagnosis. Multinomial logistic regression models with three categories, adjusted for age, assessed the association between occupational settings and exposures to onset segment.

RESULTS

Among the 378 ALS participants (median age, 64.7 years; 54.4% male), poorer survival was associated with work in SOC code "Production Occupations" and marginally with work in "Military Occupation"; poor survival associated with self-reported occupational pesticide exposure in adjusted models. Among onset segments: cervical onset was associated with ALS participants having ever worked in "Buildings and Grounds Cleaning and Maintenance Occupations," "Construction and Extraction Occupations," and "Production Occupations"; bulbar onset with self-reported occupational exposure to radiation; and cervical onset with exposure to particulate matter, volatile organic compounds, metals, combustion and diesel exhaust, electromagnetic radiation, and radiation.

CONCLUSION

Occupational settings and self-reported exposures influence ALS survival and onset segment. Further studies are needed to explore and understand these relationships, most advantageously using prospective cohorts and detailed ALS registries.

Prevalence of amyotrophic lateral sclerosis in the United States using established and novel methodologies, 2017

Objective:To estimate the prevalence of amyotrophic lateral sclerosis (ALS) in the United States for 2017 using data from the National ALS Registry (Registry) as well as capture-recapture methodology to account for under-ascertainment. Established in 2010, the Registry collects and examines data on ALS patients in the US to better describe the epidemiology of ALS (i.e. risk factor exposures, demographics).Methods: The Registry compiled data from national administrative databases (from the Centers for Medicare and Medicaid Services, the Veterans Health Administration, and the Veterans Benefits Administration) and a voluntary enrollment data through a web portal (www.cdc.gov/als). To estimate the number of missing cases, capture-recapture methodology was utilized.Results: The Registry conservatively identified 17,800 adult persons (lower-bound estimate) who met the Registry definition of ALS for an age-adjusted prevalence of 5.5 per 100,000 US population. Using capture-recapture methodology, we obtained a "mean case count" of 24,821 ALS cases (prevalence of 7.7 per 100,000 U.S. population) and estimated the upper-bound estimate to be 31,843 cases (prevalence of 9.9 per 100,000 U.S. population). The pattern of patient characteristics (e.g. age, sex, and race/ethnicity) remained unchanged from previous Registry reports. Overall, ALS was most common among whites, males, and persons aged 60-69 years. The age groups with the lowest number of cases were persons aged 18-39 years. Males had a higher prevalence than females overall and across all data sources.Conclusions: Existing Registry methodology, along with capture-recapture methodology, are being used to better describe the epidemiology and demographics of ALS in the US.

Metabolomics identifies shared lipid pathways in independent amyotrophic lateral sclerosis cohorts

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease lacking effective treatments. This is due, in part, to a complex and incompletely understood pathophysiology. To shed light, we conducted untargeted metabolomics on plasma from two independent cross-sectional ALS cohorts versus control participants to identify recurrent dysregulated metabolic pathways. Untargeted metabolomics was performed on plasma from two ALS cohorts (cohort 1, n = 125; cohort 2, n = 225) and healthy controls (cohort 1, n = 71; cohort 2, n = 104). Individual differential metabolites in ALS cases versus controls were assessed by Wilcoxon, adjusted logistic regression and partial least squares-discriminant analysis, while group lasso explored sub-pathway level differences. Adjustment parameters included age, sex and body mass index. Metabolomics pathway enrichment analysis was performed on metabolites selected using the above methods. Additionally, we conducted a sex sensitivity analysis due to sex imbalance in the cohort 2 control arm. Finally, a data-driven approach, differential network enrichment analysis (DNEA), was performed on a combined dataset to further identify important ALS metabolic pathways. Cohort 2 ALS participants were slightly older than the controls (64.0 versus 62.0 years, P = 0.009). Cohort 2 controls were over-represented in females (68%, P < 0.001). The most concordant cohort 1 and 2 pathways centred heavily on lipid sub-pathways, including complex and signalling lipid species and metabolic intermediates. There were differences in sub-pathways that were enriched in ALS females versus males, including in lipid sub-pathways. Finally, DNEA of the merged metabolite dataset of both ALS and control cohorts identified nine significant subnetworks; three centred on lipids and two encompassed a range of sub-pathways. In our analysis, we saw consistent and important shared metabolic sub-pathways in both ALS cohorts, particularly in lipids, further supporting their importance as ALS pathomechanisms and therapeutics targets.

Exposure to short-chain chlorinated paraffins induces astrocyte activation via JAK2/STAT3 signaling pathway

In the last few decades, short-chain chlorinated paraffins (SCCPs) have become the most heavily produced monomeric organohalogen compounds, and have been reported to induce multiple organ toxicity. However, the effects of SCCPs on the central nervous system are unknown. In the present study, we show that SCCP exposure induced astrocyte proliferation and increased the expression of two critical markers of astrocyte activation, glial fibrillary acidic protein and inducible nitric oxide synthase, in vivo and in vitro. SCCP exposure also increased inflammatory factory gene expression. Moreover, SCCP treatment triggered Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signalling, as shown by increased phosphorylation and STAT3 translocation to the nucleus. Both JAK2 and STAT3 inhibition effectively attenuated SCCP-induced astrocyte activation. Finally, JAK2 inhibition significantly rescued STAT3 phosphorylation and nuclear translocation. Taken together, JAK2/STAT3 pathway activation contributed to SCCP-induced astrocyte activation. These data will help elucidate the molecular mechanism underlying SCCP-induced neurotoxicity.

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a fatal CNS neurodegenerative disease. Despite intensive research, current management of amyotrophic lateral sclerosis remains suboptimal from diagnosis to prognosis. Recognition of the phenotypic heterogeneity of amyotrophic lateral sclerosis, global CNS dysfunction, genetic architecture, and development of novel diagnostic criteria is clarifying the spectrum of clinical presentation and facilitating diagnosis. Insights into the pathophysiology of amyotrophic lateral sclerosis, identification of disease biomarkers and modifiable risks, along with new predictive models, scales, and scoring systems, and a clinical trial pipeline of mechanism-based therapies, are changing the prognostic landscape. Although most recent advances have yet to translate into patient benefit, the idea of amyotrophic lateral sclerosis as a complex syndrome is already having tangible effects in the clinic. This Seminar will outline these insights and discuss the status of the management of amyotrophic lateral sclerosis for the general neurologist, along with future prospects that could improve care and outcomes for patients with amyotrophic lateral sclerosis.

A revision to the United States national ALS registry's algorithm to improve Case-Ascertainment

Objective: To evaluate the impact of 1) updating the existing algorithm to improve case-finding sensitivity and 2) reclassifying the Registry's diagnostic status nomenclature into four new categories ("confirmed ALS," "likely ALS," "undetermined ALS," or "not ALS") versus the current three ("definite ALS," "possible ALS," or "not ALS") to be more inclusive and descriptive of cases and individuals. Methods: A retrospective analysis of Registry data from 2011-2017 was conducted to follow "possible ALS" individuals over time to determine what qualifier caused them to convert, if at all and when, to Registry-eligible cases (i.e. "confirmed ALS" or "likely ALS"). Results: In 2011, 720 individuals were classified by the Registry algorithm as having "possible ALS". By 2017, 42% of these had converted to Registry-eligible ALS cases. Approximately 14% of those who were identified solely based on an ALS prescription drug never converted to Registry-eligible cases. This analysis indicates that "possible ALS" individuals with a single prescription for an ALS drug should be converted to Registry-eligible cases which would add between 300-500 cases per year on average. Conclusions: The Registry's existing algorithm likely results in the under-ascertainment of ALS cases. However, updating the algorithm with the inclusion of patients having been prescribed ALS-specific drugs, even with a single prescription, leads to improved epidemiologic estimates of ALS in the US. This and future algorithmic updates will help the Registry more accurately depict the true disease burden of ALS in the US.

Associations of self-reported occupational exposures and settings to ALS: a case-control study

BACKGROUND

Environmental exposures contribute to the pathogenesis of amyotrophic lateral sclerosis (ALS), a fatal and progressive neurological disease. Identification of these exposures is important for targeted screening and risk factor modification.

OBJECTIVE

To identify occupational exposures that are associated with a higher risk of ALS using both survey and standard occupational classification (SOC) coding procedures, and to highlight how exposure surveys can complement SOC coding.

METHODS

ALS participants and neurologically healthy controls recruited in Michigan completed a detailed exposure assessment on their four most recent and longest held occupations. Exposure scores were generated from the exposure survey, and occupations were assigned to SOC codes by experienced exposure scientists.

RESULTS

This study included 381 ALS and 272 control participants. ALS participants reported higher duration-adjusted occupational exposure to particulate matter (OR = 1.45, 95% CI 1.19-1.78, p < 0.001), volatile organic compounds (OR = 1.22, 95% CI 1.02-1.45, p = 0.029), metals (OR = 1.48, 95% CI 1.21-1.82, p < 0.001), and combustion and diesel exhaust pollutants (OR = 1.20, 95% CI 1.01-1.43, p = 0.041) prior to ALS diagnosis, when adjusted for sex, age, and military service compared to controls. In multivariable models, only occupational exposure to metals remained significant risk (OR = 1.56, 95% CI 1.11-2.20, p = 0.011), although in an adaptive elastic net model, particulate matter (OR = 1.203), pesticides (OR = 1.015), and metals (1.334) were all selected as risk factors. Work in SOC code "Production Occupations" was associated with a higher ALS risk. SOC codes "Building and Grounds Cleaning and Maintenance Occupations", "Construction and Extraction Occupations", "Installation, Maintenance, and Repair Occupations", and "Production Occupations" were all associated with a higher exposure to metals as determined using survey data.

DISCUSSION

Occupational exposure to particulate matter, volatile organic compounds, metals, pesticides, and combustion and diesel exhaust and employment in "Production Occupations" was associated with an increased ALS risk in this cohort.

Emerging insights into the complex genetics and pathophysiology of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease. The discovery of genes associated with amyotrophic lateral sclerosis, commencing with SOD1 in 1993, started fairly gradually. Recent advances in genetic technology have led to the rapid identification of multiple new genes associated with the disease, and to a new understanding of oligogenic and polygenic disease risk. The overlap of genes associated with amyotrophic lateral sclerosis with those of other neurodegenerative diseases is shedding light on the phenotypic spectrum of neurodegeneration, leading to a better understanding of genotype-phenotype correlations. A deepening knowledge of the genetic architecture is allowing the characterisation of the molecular steps caused by various mutations that converge on recurrent dysregulated pathways. Of crucial relevance, mutations associated with amyotrophic lateral sclerosis are amenable to novel gene-based therapeutic options, an approach in use for other neurological illnesses. Lastly, the exposome-the summation of lifetime environmental exposures-has emerged as an influential component for amyotrophic lateral sclerosis through the gene-time-environment hypothesis. Our improved understanding of all these aspects will lead to long-awaited therapies and the identification of modifiable risks factors.

A perspective on persistent toxicants in veterans and amyotrophic lateral sclerosis: identifying exposures determining higher ALS risk

Multiple studies indicate that United States veterans have an increased risk of developing amyotrophic lateral sclerosis (ALS) compared to civilians. However, the responsible etiological factors are unknown. In the general population, specific occupational (e.g. truck drivers, airline pilots) and environmental exposures (e.g. metals, pesticides) are associated with an increased ALS risk. As such, the increased prevalence of ALS in veterans strongly suggests that there are exposures experienced by military personnel that are disproportionate to civilians. During service, veterans may encounter numerous neurotoxic exposures (e.g. burn pits, engine exhaust, firing ranges). So far, however, there is a paucity of studies investigating environmental factors contributing to ALS in veterans and even fewer assessing their exposure using biomarkers. Herein, we discuss ALS pathogenesis in relation to a series of persistent neurotoxicants (often emitted as mixtures) including: chemical elements, nanoparticles and lipophilic toxicants such as dioxins, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. We propose these toxicants should be directly measured in veteran central nervous system tissue, where they may have accumulated for decades. Specific toxicants (or mixtures thereof) may accelerate ALS development following a multistep hypothesis or act synergistically with other service-linked exposures (e.g. head trauma/concussions). Such possibilities could explain the lower age of onset observed in veterans compared to civilians. Identifying high-risk exposures within vulnerable populations is key to understanding ALS etiopathogenesis and is urgently needed to act upon modifiable risk factors for military personnel who deserve enhanced protection during their years of service, not only for their short-term, but also long-term health.

Variable selection with multiply-imputed datasets: choosing between stacked and grouped methods

Penalized regression methods are used in many biomedical applications for variable selection and simultaneous coefficient estimation. However, missing data complicates the implementation of these methods, particularly when missingness is handled using multiple imputation. Applying a variable selection algorithm on each imputed dataset will likely lead to different sets of selected predictors. This paper considers a general class of penalized objective functions which, by construction, force selection of the same variables across imputed datasets. By pooling objective functions across imputations, optimization is then performed jointly over all imputed datasets rather than separately for each dataset. We consider two objective function formulations that exist in the literature, which we will refer to as "stacked" and "grouped" objective functions. Building on existing work, we (a) derive and implement efficient cyclic coordinate descent and majorization-minimization optimization algorithms for continuous and binary outcome data, (b) incorporate adaptive shrinkage penalties, (c) compare these methods through simulation, and (d) develop an R package miselect. Simulations demonstrate that the "stacked" approaches are more computationally efficient and have better estimation and selection properties. We apply these methods to data from the University of Michigan ALS Patients Biorepository aiming to identify the association between environmental pollutants and ALS risk. Supplementary materials are available online.

Systems Biology to Address Unmet Medical Needs in Neurological Disorders

Neurological diseases are highly prevalent and constitute a significant cause of mortality and disability. Neurological disorders encompass a heterogeneous group of neurodegenerative conditions, broadly characterized by injury to the peripheral and/or central nervous system. Although the etiology of neurological diseases varies greatly, they share several characteristics, such as heterogeneity of clinical presentation, non-cell autonomous nature, and diversity of cellular, subcellular, and molecular pathways. Systems biology has emerged as a valuable platform for addressing the challenges of studying heterogeneous neurological diseases. Systems biology has manifold applications to address unmet medical needs for neurological illness, including integrating and correlating different large datasets covering the transcriptome, epigenome, proteome, and metabolome associated with a specific condition. This is particularly useful for disentangling the heterogeneity and complexity of neurological conditions. Hence, systems biology can help in uncovering pathophysiology to develop novel therapeutic targets and assessing the impact of known treatments on disease progression. Additionally, systems biology can identify early diagnostic biomarkers, to help diagnose neurological disease preceded by a long subclinical phase, as well as define the exposome, the collection of environmental toxicants that increase risk of certain neurological diseases. In addition to these current applications, there are numerous potential emergent uses, such as precision medicine.

Background exposure to polychlorinated biphenyls and all-cause, cancer-specific, and cardiovascular-specific mortality: A systematic review and meta-analysis

BACKGROUND

Polychlorinated biphenyls (PCBs) are a large family of man-made organic, ubiquitous, and persistent contaminants with endocrine-disrupting properties. PCBs have been associated with numerous adverse health effects and were classified as carcinogenic to humans, but their long-term impact on mortality risk in the general population is unknown.

OBJECTIVE

To conduct a systematic review and meta-analysis in order to assess whether background exposure levels of PCBs increase all-cause and cancer- and cardiovascular-specific mortality risk in the general population.

METHODS

We searched the Pubmed, Web of Science, Cochrane Library, and Embase databases for eligible studies up to 1st of January, 2021. We included cohort and nested-case control studies comparing the lowest vs. the highest background exposure level of PCBs in the general population and reporting data for all-cause mortality and/or cancer-/cardiovascular-specific mortality. Studies reporting occupational and accidental exposures were excluded. Random-effects meta-analysis was used to estimate summary relative risks (SRRs) and 95% confidence intervals (CIs). Heterogeneity across studies was assessed by I2 statistics, and publication bias both graphically and using Egger's and Begg's tests. Quality of included studies was assessed using the National Toxicology Program/Office of Health Assessment and Translation (NTP/OHAT). Confidence in the body of evidence and related level of evidence were assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) based on the NTP/OHAT framework. The protocol was registered in PROSPERO (CRD42020178079).

RESULTS

The initial search led to 2,132 articles. Eight prospective cohort studies met our inclusion criteria, leading to 72,852 participants including 17,805 deaths. Overall exposure to PCBs was not statistically significantly associated with all-cause mortality (SRR = 1.13, 95% CI = 0.90-1.41, n = 7 studies, low certainty); however, dietary exposure to PCBs was associated with an increased risk of cardiovascular-specific mortality (SRR = 1.38, 95% CI = 1.14-1.66, n = 3 studies, moderate certainty), while no association was found with cancer-specific mortality (SRR = 1.07, 95% CI = 0.72-1.59, n = 5 studies, low certainty).

CONCLUSION

Our meta-analysis suggests that background exposure to PCBs is associated with an increased risk of cardiovascular-specific mortality in the general population with a "moderate" level of evidence. These findings should be interpreted with caution given the small number of studies on mortality in the general population.

Amyotrophic Lateral Sclerosis Survival Associates With Neutrophils in a Sex-specific Manner

Objective

To determine whether neutrophils contribute to amyotrophic lateral sclerosis (ALS) progression, we tested the association of baseline neutrophil count on ALS survival, whether the effect was sex specific, and whether neutrophils accumulate in the spinal cord.

Methods

A prospective cohort study was conducted between June 22, 2011, and October 30, 2019. Blood leukocytes were isolated from ALS participants and neutrophil levels assessed by flow cytometry. Participant survival outcomes were analyzed by groups (<2 × 10⁶, 2–4 × 10⁶, and >4 × 10⁶ neutrophils/mL) with adjustments for relevant ALS covariates and by sex. Neutrophil levels were assessed from CNS tissue from a subset of participants.

Results

A total of 269 participants with ALS within 2 years of an ALS diagnosis were included. Participants with baseline neutrophil counts over 4 × 10⁶/mL had a 2.1 times higher mortality rate than those with a neutrophil count lower than 2 × 10⁶/mL (95% CI: 1.3–3.5, p = 0.004) when adjusting for age, sex, and other covariates. This effect was more pronounced in females, with a hazard ratio of 3.8 (95% CI: 1.8–8.2, p = 0.001) in the >4 × 10⁶/mL vs <2 × 10⁶/mL group. Furthermore, ALS participants (n = 8) had increased neutrophils in cervical (p = 0.049) and thoracic (p = 0.022) spinal cord segments compared with control participants (n = 8).

Conclusions

Higher neutrophil counts early in ALS associate with a shorter survival in female participants. Furthermore, neutrophils accumulate in ALS spinal cord supporting a pathophysiologic correlate. These data justify the consideration of immunity and sex for personalized therapeutic development in ALS.

Classification of Evidence

This study provides Class III evidence that in female participants with ALS, higher baseline neutrophil counts are associated with shorter survival.

Human Health and Ocean Pollution

Background

Pollution - unwanted waste released to air, water, and land by human activity - is the largest environmental cause of disease in the world today. It is responsible for an estimated nine million premature deaths per year, enormous economic losses, erosion of human capital, and degradation of ecosystems. Ocean pollution is an important, but insufficiently recognized and inadequately controlled component of global pollution. It poses serious threats to human health and well-being. The nature and magnitude of these impacts are only beginning to be understood.

Goals

(1) Broadly examine the known and potential impacts of ocean pollution on human health. (2) Inform policy makers, government leaders, international organizations, civil society, and the global public of these threats. (3) Propose priorities for interventions to control and prevent pollution of the seas and safeguard human health.

Methods

Topic-focused reviews that examine the effects of ocean pollution on human health, identify gaps in knowledge, project future trends, and offer evidence-based guidance for effective intervention.

Environmental Findings

Pollution of the oceans is widespread, worsening, and in most countries poorly controlled. It is a complex mixture of toxic metals, plastics, manufactured chemicals, petroleum, urban and industrial wastes, pesticides, fertilizers, pharmaceutical chemicals, agricultural runoff, and sewage. More than 80% arises from land-based sources. It reaches the oceans through rivers, runoff, atmospheric deposition and direct discharges. It is often heaviest near the coasts and most highly concentrated along the coasts of low- and middle-income countries. Plastic is a rapidly increasing and highly visible component of ocean pollution, and an estimated 10 million metric tons of plastic waste enter the seas each year. Mercury is the metal pollutant of greatest concern in the oceans; it is released from two main sources - coal combustion and small-scale gold mining. Global spread of industrialized agriculture with increasing use of chemical fertilizer leads to extension of Harmful Algal Blooms (HABs) to previously unaffected regions. Chemical pollutants are ubiquitous and contaminate seas and marine organisms from the high Arctic to the abyssal depths.

Ecosystem Findings

Ocean pollution has multiple negative impacts on marine ecosystems, and these impacts are exacerbated by global climate change. Petroleum-based pollutants reduce photosynthesis in marine microorganisms that generate oxygen. Increasing absorption of carbon dioxide into the seas causes ocean acidification, which destroys coral reefs, impairs shellfish development, dissolves calcium-containing microorganisms at the base of the marine food web, and increases the toxicity of some pollutants. Plastic pollution threatens marine mammals, fish, and seabirds and accumulates in large mid-ocean gyres. It breaks down into microplastic and nanoplastic particles containing multiple manufactured chemicals that can enter the tissues of marine organisms, including species consumed by humans. Industrial releases, runoff, and sewage increase frequency and severity of HABs, bacterial pollution, and anti-microbial resistance. Pollution and sea surface warming are triggering poleward migration of dangerous pathogens such as the Vibrio species. Industrial discharges, pharmaceutical wastes, pesticides, and sewage contribute to global declines in fish stocks.

Human Health Findings

Methylmercury and PCBs are the ocean pollutants whose human health effects are best understood. Exposures of infants in utero to these pollutants through maternal consumption of contaminated seafood can damage developing brains, reduce IQ and increase children's risks for autism, ADHD and learning disorders. Adult exposures to methylmercury increase risks for cardiovascular disease and dementia. Manufactured chemicals - phthalates, bisphenol A, flame retardants, and perfluorinated chemicals, many of them released into the seas from plastic waste - can disrupt endocrine signaling, reduce male fertility, damage the nervous system, and increase risk of cancer. HABs produce potent toxins that accumulate in fish and shellfish. When ingested, these toxins can cause severe neurological impairment and rapid death. HAB toxins can also become airborne and cause respiratory disease. Pathogenic marine bacteria cause gastrointestinal diseases and deep wound infections. With climate change and increasing pollution, risk is high that Vibrio infections, including cholera, will increase in frequency and extend to new areas. All of the health impacts of ocean pollution fall disproportionately on vulnerable populations in the Global South - environmental injustice on a planetary scale.

Conclusions

Ocean pollution is a global problem. It arises from multiple sources and crosses national boundaries. It is the consequence of reckless, shortsighted, and unsustainable exploitation of the earth's resources. It endangers marine ecosystems. It impedes the production of atmospheric oxygen. Its threats to human health are great and growing, but still incompletely understood. Its economic costs are only beginning to be counted.Ocean pollution can be prevented. Like all forms of pollution, ocean pollution can be controlled by deploying data-driven strategies based on law, policy, technology, and enforcement that target priority pollution sources. Many countries have used these tools to control air and water pollution and are now applying them to ocean pollution. Successes achieved to date demonstrate that broader control is feasible. Heavily polluted harbors have been cleaned, estuaries rejuvenated, and coral reefs restored.Prevention of ocean pollution creates many benefits. It boosts economies, increases tourism, helps restore fisheries, and improves human health and well-being. It advances the Sustainable Development Goals (SDG). These benefits will last for centuries.

Recommendations

World leaders who recognize the gravity of ocean pollution, acknowledge its growing dangers, engage civil society and the global public, and take bold, evidence-based action to stop pollution at source will be critical to preventing ocean pollution and safeguarding human health.Prevention of pollution from land-based sources is key. Eliminating coal combustion and banning all uses of mercury will reduce mercury pollution. Bans on single-use plastic and better management of plastic waste reduce plastic pollution. Bans on persistent organic pollutants (POPs) have reduced pollution by PCBs and DDT. Control of industrial discharges, treatment of sewage, and reduced applications of fertilizers have mitigated coastal pollution and are reducing frequency of HABs. National, regional and international marine pollution control programs that are adequately funded and backed by strong enforcement have been shown to be effective. Robust monitoring is essential to track progress.Further interventions that hold great promise include wide-scale transition to renewable fuels; transition to a circular economy that creates little waste and focuses on equity rather than on endless growth; embracing the principles of green chemistry; and building scientific capacity in all countries.Designation of Marine Protected Areas (MPAs) will safeguard critical ecosystems, protect vulnerable fish stocks, and enhance human health and well-being. Creation of MPAs is an important manifestation of national and international commitment to protecting the health of the seas.

Untargeted metabolomics yields insight into ALS disease mechanisms

OBJECTIVE

To identify dysregulated metabolic pathways in amyotrophic lateral sclerosis (ALS) versus control participants through untargeted metabolomics.

METHODS

Untargeted metabolomics was performed on plasma from ALS participants (n=125) around 6.8 months after diagnosis and healthy controls (n=71). Individual differential metabolites in ALS cases versus controls were assessed by Wilcoxon rank-sum tests, adjusted logistic regression and partial least squares-discriminant analysis (PLS-DA), while group lasso explored sub-pathway-level differences. Adjustment parameters included sex, age and body mass index (BMI). Metabolomics pathway enrichment analysis was performed on metabolites selected by the above methods. Finally, machine learning classification algorithms applied to group lasso-selected metabolites were evaluated for classifying case status.

RESULTS

There were no group differences in sex, age and BMI. Significant metabolites selected were 303 by Wilcoxon, 300 by logistic regression, 295 by PLS-DA and 259 by group lasso, corresponding to 11, 13, 12 and 22 enriched sub-pathways, respectively. 'Benzoate metabolism', 'ceramides', 'creatine metabolism', 'fatty acid metabolism (acyl carnitine, polyunsaturated)' and 'hexosylceramides' sub-pathways were enriched by all methods, and 'sphingomyelins' by all but Wilcoxon, indicating these pathways significantly associate with ALS. Finally, machine learning prediction of ALS cases using group lasso-selected metabolites achieved the best performance by regularised logistic regression with elastic net regularisation, with an area under the curve of 0.98 and specificity of 83%.

CONCLUSION

In our analysis, ALS led to significant metabolic pathway alterations, which had correlations to known ALS pathomechanisms in the basic and clinical literature, and may represent important targets for future ALS therapeutics.

Empty mesoporous silica particles significantly delay disease progression and extend survival in a mouse model of ALS

Amyotrophic lateral sclerosis (ALS) is a devastating incurable neurological disorder characterized by motor neuron (MN) death and muscle dysfunction leading to mean survival time after diagnosis of only 2-5 years. A potential ALS treatment is to delay the loss of MNs and disease progression by the delivery of trophic factors. Previously, we demonstrated that implanted mesoporous silica nanoparticles (MSPs) loaded with trophic factor peptide mimetics support survival and induce differentiation of co-implanted embryonic stem cell (ESC)-derived MNs. Here, we investigate whether MSP loaded with peptide mimetics of ciliary neurotrophic factor (Cintrofin), glial-derived neurotrophic factor (Gliafin), and vascular endothelial growth factor (Vefin1) injected into the cervical spinal cord of mutant SOD1 mice affect disease progression and extend survival. We also transplanted boundary cap neural crest stem cells (bNCSCs) which have been shown previously to have a positive effect on MN survival in vitro and in vivo. We show that mimetic-loaded MSPs and bNCSCs significantly delay disease progression and increase survival of mutant SOD1 mice, and also that empty particles significantly improve the condition of ALS mice. Our results suggest that intraspinal delivery of MSPs is a potential therapeutic approach for the treatment of ALS.

Amyotrophic lateral sclerosis in Antalya, Turkey. A prospective study, 2016-2018

OBJECTIVE

The aim of the study is to find the prevalence and incidence of amyotrophic lateral sclerosis in Antalya and to define patient characteristics.

METHODS

The study represents five major districts in the Antalya metropolitan region, with a population of 1,286,943, which is defined as the provincial center. In cooperation with the neurology departments of all hospitals and private practices, existing cases were identified and new cases were recorded with continuous monitoring. Detailed demographic and clinical features of each patient were recorded, Revised El-Escorial Criteria were used for diagnosis. Incidence and prevalence rates are standardized by age based on USA 2016 population.

RESULTS

Point prevalence rates of 2016, 2017 and 2018 are 3.7, 4.7 and 5.4 per hundred thousand, respectively. Standardized prevalence rates for the US population are 5.5, 7.1 and 8.6 per hundred thousand in the same order. The incidence rate in 2017 is 1.4 per hundred thousand, and 2018 is 1.2. Standardized incidence rates for the US population are 2.1 and 1.8 per hundred thousand, respectively. About 75.6% of the cases were classified as definite, 11.0% probable, 11.0% possible, 2.4% probable laboratory-supported. The male/female ratio is 2.0 for total cases and 2.8 for new cases. The site of onset is spinal in 81.7% of patients and bulbar in 18.3%.

CONCLUSIONS

ALS rates detected in Antalya and the general features of the disease show similarities with European countries rather than Asian countries and comply with the literature.

ALS and fertility: does ALS affect number of children patients have?

OBJECTIVE

Amyotrophic Lateral Sclerosis is one major disease in the group of neurodegenerative conditions. As with most other neurodegenerative diseases, clinical signs of the disease usually show among the elderly population, and most commonly around 60-65 years of age. Therefore the disease is not expected to impact the fertility of ALS patients. When examined from an evolutionary medicine and evolutionary biology perspective, there should be no selection pressure on the patient population due to the late onset of ALS. Methods: In this study, we tested the hypothesis that ALS does not affect fertility on a group of patients with ALS that we collected in a multi-center study. We recruited 511 patients diagnosed with ALS according to the revised El Escorial criteria, and 236 control cases without a neurodegenerative disease. We compared the ALS group's number of offspring with the control group in three consecutive generations. Results: No statistically significant difference was found between the number of siblings of ALS and control groups (p = 0.44). A statistically significant difference was found between the number of children of ALS and control groups (p < 0.001), indicating ALS patients had more children than controls. When the number of children is assessed by gender, for women, there was no statistically significant difference between the number of children of ALS and control groups (p = 0.067). Conclusions: This finding supports the view that ALS does not have a negative selection pressure on the patient population's fertility.

Early life metal dysregulation in amyotrophic lateral sclerosis

OBJECTIVE

Deficiencies and excess of essential elements and toxic metals are implicated in amyotrophic lateral sclerosis (ALS), but the age when metal dysregulation appears remains unknown. This study aims to determine whether metal uptake is dysregulated during childhood in individuals eventually diagnosed with ALS.

METHODS

Laser ablation-inductively coupled plasma-mass spectrometry was used to obtain time series data of metal uptake using biomarkers in teeth from autopsies or dental extractions of ALS (n = 36) and control (n = 31) participants. Covariate data included sex, smoking, occupational exposures, and ALS family history. Case-control differences were identified in temporal profiles of metal uptake for individual metals using distributed lag models. Weighted quantile sum (WQS) regression was used for metals mixture analyses. Similar analyses were performed on an ALS mouse model to further verify the relevance of dysregulation of metals in ALS.

RESULTS

Metal levels were higher in cases than in controls: 1.49 times for chromium (1.11-1.82; at 15 years), 1.82 times for manganese (1.34-2.46; at birth), 1.65 times for nickel (1.22-2.01; at 8 years), 2.46 times for tin (1.65-3.30; at 2 years), and 2.46 times for zinc (1.49-3.67; at 6 years). Co-exposure to 11 elements indicated that childhood metal dysregulation was associated with ALS. The mixture contribution of metals to disease outcome was likewise apparent in tooth biomarkers of an ALS mouse model, and differences in metal distribution were evident in ALS mouse brains compared to brains from littermate controls.

INTERPRETATION

Overall, our study reveals direct evidence that altered metal uptake during specific early life time windows is associated with adult-onset ALS.

Epidemiology of amyotrophic lateral sclerosis: an update of recent literature

The cause of amyotrophic lateral sclerosis (ALS) remains unknown for most of the patients with the disease. Epidemiologic studies can help describe disease burden and examine its potential risk factors, providing thereby evidence base for future mechanistic studies. With this review, we aimed to provide a summary of epidemiologic studies published during the past 18 months, which studied the incidence and risk factors for ALS.

Dysregulated biodynamics in metabolic attractor systems precede the emergence of amyotrophic lateral sclerosis

Evolutionarily conserved mechanisms maintain homeostasis of essential elements, and are believed to be highly time-variant. However, current approaches measure elemental biomarkers at a few discrete time-points, ignoring complex higher-order dynamical features. To study dynamical properties of elemental homeostasis, we apply laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) to tooth samples to generate 500 temporally sequential measurements of elemental concentrations from birth to 10 years. We applied dynamical system and Information Theory-based analyses to reveal the longest-known attractor system in mammalian biology underlying the metabolism of nutrient elements, and identify distinct and consistent transitions between stable and unstable states throughout development. Extending these dynamical features to disease prediction, we find that attractor topography of nutrient metabolism is altered in amyotrophic lateral sclerosis (ALS), as early as childhood, suggesting these pathways are involved in disease risk. Mechanistic analysis was undertaken in a transgenic mouse model of ALS, where we find similar marked disruptions in elemental attractor systems as in humans. Our results demonstrate the application of a phenomological analysis of dynamical systems underlying elemental metabolism, and emphasize the utility of these measures in characterizing risk of disease.

The metabolism of essential elements in early life is essential to healthy growth and development. Elemental homeostasis is typically studied by characterizing distributions of elemental concentrations at the level of the population. Here, we introduce a new method of characterizing elemental metabolism at the level of the individual. Using tooth-based biomarkers, we tracked the longitudinal trajectory of essential elements throughout childhood at weekly temporal resolution from birth through approximately 10 years of life. We analyzed these trajectories to identify the formation of stable dynamic states (attractors) and transitions between these states throughout development. We found that metabolic dynamics were specific to discrete elemental pathways; copper metabolism typically involved the formation of multiple discrete states throughout childhood, whereas other elements, such as zinc, tended to persist in a single stable dynamic throughout development. Next, we compared elemental biodynamics in neurologically healthy cases and subjects that were later diagnosed with amyotrophic lateral sclerosis (ALS). We found these patterns were dysregulated in ALS, and also found similar results in a mouse model of ALS. Overall, our results provide a novel approach to characterize elemental biodynamics throughout development, and emphasize that the dysregulation of these processes may be predictive of later onset of disease.

Energy Balance as a Moderator of Neurologic Disease Risk and Progression

Amyotrophic lateral sclerosis (ALS) is a devastating disease that like multiple other neurologic diseases has no curative treatment currently available. Environmental exposures to known neurotoxic compounds (e.g., pesticides, heavy metals, cyanobacterial toxins, etc.) are identified as risk factors associated with ALS. Assuming these environmental factors have causative roles in disease risk and given the ubiquity of these types of exposures for the modern human, why are not more people afflicted with ALS? Herein is proposed an energy balance moderation framework (EBMF)-a framework that postulates energy balance as a key moderator of neurologic disease risk. The EBMF proposes that the ability of the body to handle toxic compound exposures through excretion, metabolism, and/or storage impacts the acute and chronic tissue-specific toxicity which is moderated by energy balance. In this model, positive energy balance (weight gain or excess body weight/mass) would be protective against acute neurotoxic exposure permitting the assimilation and sequestration of toxic compounds within body stores separate from the nervous system. However, this protective buffering could be lost during sustained negative energy balance (weight loss) with the release of sequestered compounds redistributing to the nervous system. The EBMF may have relevance beyond ALS for other neurologic diseases with demonstrated environmental risks (such as Alzheimer's and Parkinson's disease) and offers new insights into potential strategies to reduce disease risk and develop novel treatments.