Medication use and risk of amyotrophic lateral sclerosis: using machine learning for an exposome-wide screen of a large clinical database

BACKGROUND

Accumulating evidence suggests that non-genetic factors have important etiologic roles in amyotrophic lateral sclerosis (ALS), yet identification of specific culprit factors has been challenging. Many medications target biological pathways implicated in ALS pathogenesis, and screening large pharmacologic datasets for signals could greatly accelerate the identification of risk-modulating pharmacologic factors for ALS.

METHOD

We conducted a high-dimensional screening of patients' history of medication use and ALS risk using an advanced machine learning approach based on gradient-boosted decision trees coupled with Bayesian model optimization and repeated data sampling. Clinical and medication dispensing data were obtained from a large Israeli health fund for 501 ALS cases and 4,998 matched controls using a lag period of 3 or 5 years prior to ALS diagnosis for ascertaining medication exposure.

RESULTS

Of over 1,000 different medication classes, we identified 8 classes that were consistently associated with increased ALS risk across independently trained models, where most are indicated for control of symptoms implicated in ALS. Some suggestive protective effects were also observed, notably for vitamin E.

DISCUSSION

Our results indicate that use of certain medications well before the typically recognized prodromal period was associated with ALS risk. This could result because these medications increase ALS risk or could indicate that ALS symptoms can manifest well before suggested prodromal periods. The results also provide further evidence that vitamin E may be a protective factor for ALS. Targeted studies should be performed to elucidate the possible pathophysiological mechanisms while providing insights for therapeutics design.

Risk of Long-Term Ischemic Stroke in Patients With Traumatic Brain Injury and Incident Hypertension

Traumatic brain injury (TBI) is independently associated with hypertension and ischemic stroke. The goal of this study was to determine the interplay between TBI and incident hypertension in the occurrence of post-TBI stroke. This prospective study used a hospital-based registry to identify patients without pre-existing comorbidities. TBI patients (n = 3664) were frequency matched on age, sex, and race to non-TBI patients (n = 1848). Follow-up started 6 months post-TBI or study entry and extended up to 10 years. To examine hypertension's role in post-TBI stroke, we used logistic regression models to calculate the effect estimates for stroke in four exposure categories that included TBI or hypertension in isolation and in combination. Second, we calculated the conditional direct effect (CDE) of TBI in models that considered hypertension as intermediary. Third, we examined whether TBI effect was modified by antihypertensive medication use. The 10-year cumulative incidence of stroke was higher in the TBI group (4.7%) than the non-TBI group (1.3%; p < 0.001). TBI patients who developed hypertension had the highest risk of stroke (odds ratio [OR] = 4.83, 95% confidence interval [CI] = 2.53-9.23, p < 0.001). The combined effect estimates were less than additive, suggesting an overlapping biological pathway. The total effect of TBI (OR = 3.16, 95% CI = 1.94-5.16, p < 0.001) was higher than the CDE that accounted for hypertension (OR = 2.45, 95% CI = 0.93-6.47, p = 0.06). Antihypertensives attenuated the TBI effect, suggesting that the TBI effect on stroke is partially mediated through hypertension. TBI is an independent risk factor for long-term stroke, and the underlying biological pathway may partly operate through TBI-precipitated hypertension. These findings suggest that screening for hypertension may mitigate stroke risk in TBI.

Adolescent Body Mass Index and Early Chronic Kidney Disease in Young Adulthood

Importance

Despite increasing obesity rates in adolescents, data regarding early kidney sequelae are lacking.

Objective

To assess the association between adolescent body mass index (BMI) and early chronic kidney disease (CKD) in young adulthood (<45 years of age).

Design, Setting, and Participants

This cohort study linked screening data of mandatory medical assessments of Israeli adolescents to data from a CKD registry of a national health care system. Adolescents who were aged 16 to 20 years; born since January 1, 1975; medically evaluated for mandatory military service through December 31, 2019; and insured by Maccabi Healthcare Services were assessed. Individuals with kidney pathology, albuminuria, hypertension, dysglycemia, or missing blood pressure or BMI data were excluded. Body mass index was calculated as weight in kilograms divided by height in meters squared and categorized by age- and sex-matched percentiles according to the US Centers for Disease Control and Prevention. Follow-up started at the time of medical evaluation or January 1, 2000 (whichever came last), and ended at early CKD onset, death, the last day insured, or August 23, 2020 (whichever came first). Data analysis was performed from December 19, 2021, to September 11, 2023.

Main Outcomes and Measures

Early CKD, defined as stage 1 to 2 CKD by moderately or severely increased albuminuria, with an estimated glomerular filtration rate of 60 mL/min/1.73 m2 or higher.

Results

Of 629 168 adolescents evaluated, 593 660 (mean [SD] age at study entry, 17.2 [0.5] years; 323 293 [54.5%] male, 270 367 [45.5%] female) were included in the analysis. During a mean (SD) follow-up of 13.4 (5.5) years for males and 13.4 (5.6) years for females, 1963 adolescents (0.3%) developed early CKD. Among males, the adjusted hazard ratios were 1.8 (95% CI, 1.5-2.2) for adolescents with high-normal BMI, 4.0 (95% CI, 3.3-5.0) for those with overweight, 6.7 (95% CI, 5.4-8.4) for those with mild obesity, and 9.4 (95% CI, 6.6-13.5) for those with severe obesity. Among females, the hazard ratios were 1.4 (95% CI, 1.2-1.6) for those with high-normal BMI, 2.3 (95% CI, 1.9-2.8) for those with overweight, 2.7 (95% CI, 2.1-3.6) for those with mild obesity, and 4.3 (95% CI, 2.8-6.5) for those with severe obesity. The results were similar when the cohort was limited to individuals who were seemingly healthy as adolescents, individuals surveyed up to 30 years of age, or those free of diabetes and hypertension at the end of the follow-up.

Conclusions and Relevance

In this cohort study, high BMI in late adolescence was associated with early CKD in young adulthood. The risk was also present in seemingly healthy individuals with high-normal BMI and before 30 years of age, and a greater risk was seen among those with severe obesity. These findings underscore the importance of mitigating adolescent obesity rates and managing risk factors for kidney disease in adolescents with high BMI.

Late diagnosis of autism spectrum disorder-Journey, parents' concerns, and sex influences

Despite increasing awareness for diagnosing autism spectrum disorder (ASD) and initiating treatments early in life, many children and adolescents continue to be diagnosed at a relatively older age. Focusing on children who first received an ASD diagnosis at age six or older, this study aimed to describe the symptoms that parents reported when ASD was diagnosed, follow the patients' clinical trajectory prior to receiving the diagnosis, and describe differences in symptoms and prior diagnoses between males and females cases. We included 258 children (205 males and 53 females) who were first diagnosed with autism at age 6-18 in 2017-2018. We retrieved demographic information, neurologic and developmental symptoms, diagnoses, and medications dispensing history from the children's electronic medical charts. The data indicated that prior diagnoses of language delays and attention deficit hyperactivity disorder were common among children with a late ASD diagnosis. Two thirds of the children were prescribed one or more medications to treat psychosocial and behavioral conditions before receiving a late ASD diagnosis. Difficulties in social relationships with peers were the leading reported symptoms by parents at the time of ASD diagnosis. Across these different domains, some differences were found between males and females, including a somewhat higher cognitive level in males, who were also more likely to present aggressive behavior.

Adolescent Blood Pressure and the Risk for Early Kidney Damage in Young Adulthood

BACKGROUND

Recent guidelines classified blood pressure above 130/80 mm Hg as hypertension. However, outcome data were lacking.

OBJECTIVE

To determine the association between blood pressure in adolescence and the risk for early kidney damage in young adulthood.

METHODS

In this nationwide cohort study, we included 629 168 adolescents aged 16 to 20 who underwent medical examinations before mandatory military service in Israel. We excluded 30 466 adolescents with kidney pathology, hypertension, or missing blood pressure or anthropometric data at study entry. Blood pressure measurements at study entry were categorized according to the Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents: group A (<120/<80 mm Hg; Reference group), group B (120/<80-129/<80 mm Hg), group C (130/80-139/89 mm Hg), and group D (≥140/90 mm Hg). Early kidney damage in young adulthood was defined as albuminuria of ≥30 mg/g with an estimated glomerular filtration rate of 60 mL/(min·1.73 m²) or over.

RESULTS

Of 598 702 adolescents (54% men), 2004 (0.3%) developed early kidney damage during a mean follow-up of 15.1 (7.2) years. The adjusted hazard ratios for early kidney damage in blood pressure group C were 1.17 (1.03-1.32) and 1.51 (1.22-1.86) among adolescents with lean (body mass index <85th percentile) and high body mass index (body mass index ≥85th percentile), respectively. Corresponding hazard ratios for kidney disease in group D were 1.49 (1.15-1.93) and 1.79 (1.35-2.38) among adolescents with lean and high body mass index, respectively.

CONCLUSIONS

Blood pressure of ≥130/80 mm Hg was associated with early kidney damage in young adulthood, especially in adolescents with overweight and obesity.

Maternal Thyroid Anomalies and Attention-Deficit Hyperactivity Disorder in Progeny

Previous epidemiologic investigations suggested that maternal thyroid anomalies are a possible causal factor in attention-deficit hyperactivity disorder (ADHD) in progeny, yet clinical trials indicated that levothyroxine treatment was ineffective in preventing neurodevelopmental impairments. We used an Israeli cohort of 385,542 singleton births from 1999-2012 to explore the interrelated roles of maternal thyroid conditions, laboratory gestational thyroid hormone measurements, use of thyroid medications, and offspring ADHD. Analyses were performed using Cox proportional hazards models. Results indicated that maternal hypothyroidism diagnosis was associated with an elevated progeny ADHD hazard (adjusted hazard ratio = 1.14, 95% confidence interval = 1.10, 1.18). However, this association was unmitigated by gestational use of levothyroxine and was unexplained by maternal gestational thyroid hormone levels. Associations with gestational thyrotropin values and hypothyroxinemia were also observed but were robust only in mothers without other records indicative of a thyroid problem. Results indicated that maternal thyroid hypofunction was associated with progeny ADHD but possibly not due to a direct causal relationship. Instead, maternal thyroid hypofunction may serve as a proxy indicator for other factors that affect neurodevelopment through thyroid hormone independent pathways, which are thus unaffected by pharmaceutical treatments for thyroid hypofunction. Factors known to disrupt thyroid functioning should be examined for their independent ADHD-related effects.

On the Nature of Informative Presence Bias in Analyses of Electronic Health Records

Electronic health records (EHRs) offer unprecedented opportunities to answer epidemiologic questions. However, unlike in ordinary cohort studies or randomized trials, EHR data are collected somewhat idiosyncratically. In particular, patients who have more contact with the medical system have more opportunities to receive diagnoses, which are then recorded in their EHRs. The goal of this article is to shed light on the nature and scope of this phenomenon, known as informative presence, which can bias estimates of associations. We show how this can be characterized as an instance of misclassification bias. As a consequence, we show that informative presence bias can occur in a broader range of settings than previously thought, and that simple adjustment for the number of visits as a confounder may not fully correct for bias. Additionally, where previous work has considered only underdiagnosis, investigators are often concerned about overdiagnosis; we show how this changes the settings in which bias manifests. We report on a comprehensive series of simulations to shed light on when to expect informative presence bias, how it can be mitigated in some cases, and cases in which new methods need to be developed.

Association Between BNT162b2 Vaccination and Incidence of SARS-CoV-2 Infection in Pregnant Women

IMPORTANCE

Data on BNT162b2 messenger RNA (mRNA) vaccine (Pfizer-BioNTech) effectiveness and safety in pregnancy are currently lacking because pregnant women were excluded from the phase 3 trial.

OBJECTIVE

To assess the association between receipt of BNT162b2 mRNA vaccine and risk of SARS-CoV-2 infection among pregnant women.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective cohort study within the pregnancy registry of a large state-mandated health care organization in Israel. Pregnant women vaccinated with a first dose from December 19, 2020, through February 28, 2021, were 1:1 matched to unvaccinated women by age, gestational age, residential area, population subgroup, parity, and influenza immunization status. Follow-up ended on April 11, 2021.

EXPOSURES

Exposure was defined by receipt of the BNT162b2 mRNA vaccine. To maintain comparability, nonexposed women who were subsequently vaccinated were censored 10 days after their exposure, along with their matched pair.

MAIN OUTCOMES AND MEASURES

The primary outcome was polymerase chain reaction-validated SARS-CoV-2 infection at 28 days or more after the first vaccine dose.

RESULTS

The cohort included 7530 vaccinated and 7530 matched unvaccinated women, 46% and 33% in the second and third trimester, respectively, with a mean age of 31.1 years (SD, 4.9 years). The median follow-up for the primary outcome was 37 days (interquartile range, 21-54 days; range, 0-70). There were 118 SARS-CoV-2 infections in the vaccinated group and 202 in the unvaccinated group. Among infected women, 88 of 105 (83.8%) were symptomatic in the vaccinated group vs 149 of 179 (83.2%) in the unvaccinated group (P ≥ .99). During 28 to 70 days of follow-up, there were 10 infections in the vaccinated group and 46 in the unvaccinated group. The hazards of infection were 0.33% vs 1.64% in the vaccinated and unvaccinated groups, respectively, representing an absolute difference of 1.31% (95% CI, 0.89%-1.74%), with an adjusted hazard ratio of 0.22 (95% CI, 0.11-0.43). Vaccine-related adverse events were reported by 68 patients; none was severe. The most commonly reported symptoms were headache (n = 10, 0.1%), general weakness (n = 8, 0.1%), nonspecified pain (n = 6, <0.1%), and stomachache (n = 5, <0.1%).

CONCLUSIONS AND RELEVANCE

In this retrospective cohort study of pregnant women, BNT162b2 mRNA vaccination compared with no vaccination was associated with a significantly lower risk of SARS-CoV-2 infection. Interpretation of study findings is limited by the observational design.

The effectiveness of the TWO-DOSE BNT162b2 vaccine: analysis of real-world data

Background

COVID-19 mRNA vaccines were shown to be highly efficacious in preventing the disease in randomized controlled trials; nonetheless, evidence on the real-world effectiveness of this vaccine is limited. Study objective was to evaluate the effectiveness of BNT162b2 vaccine in preventing SARS-CoV-2 infection and COVID-19-related hospitalization and mortality.

Methods

This historical cohort study included members of a large health provider in Israel that were vaccinated with at least one dose of BNT162b2. The primary outcome was incidence rate of a SARS-CoV-2 infection confirmed with rt-PCR, between 7 to 27 days after second dose (protection-period), as compared to days 1 to 7 after the first dose, where no protection by the vaccine is assumed (reference-period).

Results

Data of 1,178,597 individuals vaccinated with BNT162b2 were analyzed (mean age 47.7 years [SD=18.1], 48.4% males) of whom 872,454 (74.0%) reached the protection period. Overall, 4514 infections occurred during the reference period compared to 728 during the protection period, yielding a weighted mean daily incidence of 54.8 per 100,000 (95%CI: 26.1-115.0 per 100,000) and 5.4 per 100,000 (95%CI: 3.5-8.4 per 100,000), respectively. The vaccine effectiveness in preventing infection was 90% (95%CI:79%- 95%) and 94% (95%CI:88%-97%) against COVID-19. Among immunosuppressed patients, vaccine effectiveness against infection was 71% (95%CI:37%-87%). The adjusted hazard ratios for hospitalization in those infected were 0.82 (95%CI:0.36-1.88), 0.45 (95%CI:0.23-0.90), and 0.56 (95%CI:0.36-0.89) in the age groups 16-44, 45-64 and 75 and above, respectively.

Conclusions

The effectiveness of the BNT162b2 vaccine is comparable to the one reported in the phase III clinical trial.

Associations of Maternal Androgen-Related Conditions With Risk of Autism Spectrum Disorder in Progeny and Mediation by Cardiovascular, Metabolic, and Fertility Factors

Fetal exposure to elevated androgens is thought to contribute to autism spectrum disorder (ASD) risk. However, data rely heavily on in utero androgens measurements, which also reflect fetal secretions. Thus, in utero hyperandrogenemia might indicate adverse autism-related neurogenesis that has already occurred affecting fetal androgen homeostasis, rather than being a cause of the disorder. Associations between maternal androgen-related conditions and ASD could more directly implicate androgens' etiological role. We examined the association between maternal hyperandrogenemia-related conditions, focusing primarily on polycystic ovarian syndrome (PCOS), and progeny ASD, in an Israeli cohort of 437,222 children born in 1999-2013. Odds ratios and 95% confidence intervals were estimated using generalized estimating equations. Multiple mediation analyses using natural effect models were conducted to evaluate combined mediation of the PCOS effect by androgen-related cardiovascular, metabolic, and fertility factors. Results indicated that children of mothers with PCOS had higher ASD odds compared with children of mothers without PCOS (odds ratio = 1.42, 95% confidence interval: 1.24,1.64), and this effect was only partly mediated by the factors considered. Elevated odds were also observed for other hyperandrogenemia-related conditions. Findings provide support for direct involvement of maternal hyperandrogenemia in ASD etiology. Alternatively, findings might reflect shared genetic and/or environmental factors independently affecting maternal androgen homeostasis and fetal neurodevelopment.

Joint and interactive effects between health comorbidities and environmental exposures in predicting amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a rare yet devastating neurodegenerative condition. The mechanisms leading to ALS are most certainly complex and likely involve a joint contribution of several factors with possible synergistic or antagonistic interactions. To provide a better understanding of the association between non-genetic factors and ALS, we evaluated the joint exposure to multiple health and environmental factors linked with ALS in our previous studies, also screening for high-dimensional interactions.

METHODS

We used data from a nested case-control study within the Danish population, with 1086 ALS cases from 1982 to 2009, jointly investigating 4 hospital-based diagnoses - diabetes, obesity, physical/stress trauma, cardiovascular disease (CVD) during 1977-2009; and 4 environmental exposures - lead, formaldehyde, diesel exhaust, and solvents, assessed from individual occupational history. All covariates were evaluated as ever/never exposed, and we used targeted machine learning techniques to screen for important joint predictors and interactions. These were then evaluated in a final logistic regression model adjusting for potential confounders (age, SES, geography). All analyses were stratified by sex.

RESULTS

Among men, trauma and solvents were associated with higher odds of ALS (OR = 1.55, 95% CI: 1.08-2.23; OR = 1.49, 95% CI: 1.17-1.89, respectively), and presented a negative interaction (OR = 0.49, 95% CI: 0.30-0.80). A positive diesel/CVD interaction was observed (OR = 1.56, 95% CI: 0.94-2.60). Among women, solvents, trauma, lead, and CVD were associated with higher odds of ALS, and a negative lead/solvents interaction was documented (OR = 0.52, 95% CI: 0.42-0.63).

CONCLUSIONS

This study is one of the first attempts to evaluate joint and interactive effects of multiple risk factors on ALS, identifying potential synergistic and antagonistic mechanisms.

Age-Specific Time Trends in Incidence Rates of Autism Spectrum Disorder Following Adaptation of DSM-5 and Other ASD-Related Regulatory Changes in Israel

We analyzed data on 879,029 children born in 1999-2017 from a large Israeli health fund to evaluate time-trends in incidence of autism spectrum disorder (ASD). This included examining possible effects associated with the adaptation of the DSM-5 criteria for ASD, and the implementation of regulatory changes affecting eligibility for ASD-related stipends and services. ASD cases were ascertained based on electronic medical records review, with complete verification of ASD case status. Results indicated a substantial increase in ASD incidence rate (IR) over time that was overall not appreciably affected by the above changes. Cumulative incidence through age 8 rose from 0.46% (boys: 0.73; girls: 0.18) in 2007 to 1.30% (boys: 2.12; girls: 0.45) in 2018. Age-specific analyzes indicated that the largest increase in IR occurred in toddlers and preschool children, with a more modest increase at older age groups. Results suggest that the rise in early diagnosed ASD does not stem from a downward shift in the distribution of ages at first diagnosis, but rather from early detection of cases not previously diagnosed. Findings highlight the need to expand research aimed at identifying exogenous factors that may underlie the rise in incidence, and to evaluate factors that may contribute to late diagnosis of some cases. Autism Res 2020, 13: 1893-1901. © 2020 International Society for Autism Research and Wiley Periodicals LLC LAY SUMMARY: In an analysis of nearly 900,000 Israeli children born in 1999-2017, we found that the incidence of autism spectrum disorder (ASD) increased significantly over time, especially among toddlers and preschool children but also at older age groups. We additionally observed that changes affecting diagnostic criteria for ASD and eligibility for ASD-related services did not appreciably affect these trends. Results highlight the need to continue research aimed at identifying factors causing this increase and reasons contributing to late diagnosis of some cases.

Estimating the causal effect of prenatal lead exposure on prepulse inhibition deficits in children and adolescents

During pregnancy, maternal lead from earlier exposures mobilizes and crosses placental barriers, placing the developing fetus at risk for lead exposure and neurodevelopmental deficits. Some neuronal circuits known to be affected in neurodevelopment disorders can be probed with simple physiological behavioral paradigms. One such neural biomarker is Pre-Pulse Inhibition (PPI), an indicator of adequate sensorimotor gating processing. In clinical studies, deficits in PPI have been associated with neurodevelopmental disorders in human subjects. To our knowledge, no studies have examined the use of PPI as a biomarker of toxicant effects on the brain in epidemiological studies. We aimed to estimate the causal effect of prenatal lead exposure, assessed by maternal cortical bone lead concentrations, on PPI in 279 children from Mexico City. in vivo maternal cortical bone lead measurements were taken at four weeks postpartum at the mid-tibia shaft using a K-Shell X-ray fluorescence instrument. PPI recording occurred in an isolated clinical setting and eye blink responses were measured using electromyography. We assessed if the conditions for causal inference held in our study and used the results of our assessment to estimate the causal effect of prenatal lead exposure on PPI using an ordinary least squares regression model, a marginal structural model, and the parametric g-formula. Results were consistent across the three modeling approaches. For the parametric g-formula, a one standard deviation (10.0 μg/g) increase in prenatal lead significantly reduced PPI by approximately 19.0 % (95 % CI: 5.4 %, 34.3 %). This decrease is similar in magnitude to clinical studies on schizophrenia, which have observed PPI impairments in patients with schizophrenia as compared to controls. Our results are consistent with findings from other studies establishing an association between lead exposure and neurodevelopmental disorders in children and suggest that PPI may be useful as an objective biomarker of toxicant effects on the brain.

The use of Logic regression in epidemiologic studies to investigate multiple binary exposures: an example of occupation history and amyotrophic lateral sclerosis

Investigating the joint exposure to several risk factors is becoming a key component of epidemiologic studies. Individuals are exposed to multiple factors, often simultaneously, and evaluating patterns of exposures and high-dimension interactions may allow for a better understanding of health risks at the individual level. When jointly evaluating high-dimensional exposures, common statistical methods should be integrated with machine learning techniques that may better account for complex settings. Among these, Logic regression was developed to investigate a large number of binary exposures as they relate to a given outcome. This method may be of interest in several public health settings, yet has never been presented to an epidemiologic audience. In this paper, we review and discuss Logic regression as a potential tool for epidemiological studies, using an example of occupation history (68 binary exposures of primary occupations) and amyotrophic lateral sclerosis in a population-based Danish cohort. Logic regression identifies predictors that are Boolean combinations of the original (binary) exposures, fully operating within the regression framework of interest (e.g. linear, logistic). Combinations of exposures are graphically presented as Logic trees, and techniques for selecting the best Logic model are available and of high importance. While highlighting several advantages of the method, we also discuss specific drawbacks and practical issues that should be considered when using Logic regression in population-based studies. With this paper, we encourage researchers to explore the use of machine learning techniques when evaluating large-dimensional epidemiologic data, as well as advocate the need of further methodological work in the area.

Congenital Abnormalities of the Male Reproductive System and Risk of Autism Spectrum Disorders

Androgens have an extensive influence on brain development in regions of the brain that are relevant for autism spectrum disorder (ASD), yet their etiological involvement remains unclear. Hypospadias (abnormal positioning of the urethral opening) and cryptorchidism (undescended testes) are 2 relatively common male birth defects that are strongly associated with prenatal androgen deficiencies. Having either disorder is a proxy indicator of atypical gestational androgen exposure, yet the association between these disorders and autism has not been extensively studied. We analyzed male singleton live births (n = 224,598) occurring from January 1, 1999, through December 31, 2013, in a large Israeli health-care organization. Boys with autism, cryptorchidism, and hypospadias were identified via International Classification of Diseases, Ninth Revision, codes, with further verification of autism case status by review of medical records. In multivariable-adjusted analyses, the odds ratio for ASD among boys with either condition was 1.62 (95% confidence interval (CI): 1.44, 1.82). The odds ratio for boys with cryptorchidism only was 1.55 (95% CI: 1.34, 1.78), and that for boys with hypospadias only was 1.65 (95% CI: 1.38, 1.98). ASD risk was not elevated among unaffected brothers of hypospadias or cryptorchidism cases, despite familial aggregation of all 3 conditions, providing some indication for the possibility of pregnancy-specific risk factors driving the observed associations. Results suggest that in-utero hypoandrogenicity could play a role in ASD etiology.

Potential Sex Differences Relative to Autism Spectrum Disorder and Metals

PURPOSE OF REVIEW

This study aims to summarize the current body of literature on the relationship between various toxic metals exposures (i.e., aluminum, antimony, arsenic, beryllium, cadmium, chromium, lead, manganese, and nickel) and autism spectrum disorder (ASD), with a focus on potential sex differences in these associations.

RECENT FINDINGS

Sex differences in ASD diagnosis and mutagenic effects of toxic exposures indicate that sex differences may play a major part in the causal relationship of any potential associations seen; however, we were only able to find three studies that reported on sex differences in observed associations with toxic metals exposure and ASD. We also found several studies investigating associations between ASD and metals exposures, including 11 on aluminum, 6 on antimony, 15 on arsenic, 5 on beryllium, 17 on cadmium, 11 on chromium, 25 on lead, 14 on manganese, and 13 on nickel with markers of exposure in hair, urine, blood, teeth, fingernails, and air pollution. Results for each metal were conflicting, but studies on cadmium and lead yielded the highest proportion of studies with positive results (72% and 36%, respectively). Based on our examination of existing literature, the current evidence warrants a considerable need for evaluations of sex differences in future studies assessing the association between metals exposures and ASD. Additionally, failure to account for potential sex differences could result in bias and misinterpretation of exposure-disease relationships.

Diabetes Mellitus, Obesity, and Diagnosis of Amyotrophic Lateral Sclerosis: A Population-Based Study

IMPORTANCE

Although prior studies have suggested a role of cardiometabolic health on pathogenesis of amyotrophic lateral sclerosis (ALS), the association with diabetes mellitus has not been widely examined. Amyotrophic lateral sclerosis is the most common motor neuron disorder. Several vascular risk factors have been associated with decreased risk for ALS. Although diabetes is also a risk factor for vascular disease, the few studies of diabetes and ALS have been inconsistent.

OBJECTIVE

To examine the association between diabetes and obesity, each identified through International Statistical Classification of Diseases, Eighth or Tenth Revision codes in a hospital registry, and ALS using data from the Danish National Registers.

DESIGN, SETTING, AND PARTICIPANTS

Population-based nested case-control study of 3650 Danish residents diagnosed as having ALS between January 1, 1982, and December 31, 2009, and 365,000 controls (100 for each ALS case) matched on age and sex. The analysis was conducted in September and October 2014.

MAIN OUTCOMES AND MEASURES

Adjusted odds ratio for ALS associated with diabetes or obesity diagnoses at least 3 years prior to the ALS diagnosis date.

RESULTS

When considering diabetes and our obesity indicator together, the estimated odds ratio for ALS was 0.61 (95% CI, 0.46-0.80) for diabetes and 0.81 (95% CI, 0.57-1.16) for obesity. We observed no effect modification on the association with diabetes by sex. We did find a significant modification by age at ALS diagnosis and age at first mention of diabetes in the hospital registers. The protective association was stronger with increasing age at ALS diagnosis (P = .01), and the odds ratio for first mention of diabetes was 1.66 (95% CI, 0.85-3.21) before age 40 years but 0.52 (95% CI, 0.39-0.70) for older ages. These results are consistent with different associations for type 1 vs type 2 diabetes.

CONCLUSIONS AND RELEVANCE

In this Danish nationwide study to investigate the association between diabetes and ALS diagnosis, our findings are in agreement with previous reports of a protective association between vascular risk factors and ALS and suggest that type 2 diabetes, but not type 1, is protective for ALS.