Physical Reality
Racial Disparities in Mortality by Sex, Age, and Cause of Death
Robert Kaestner, Anuj Gangopadhyaya & Cuiping Schiman
NBER Working Paper, June 2025
Abstract:
Racial differences in mortality are large, persistent and likely caused, at least in part, by racism. While the causal pathways linking racism to mortality are conceptually well defined, empirical evidence to support causal claims related to its effect on health is incomplete. In this study, we provide a unique set of facts about racial disparities in mortality that all theories of racism and health need to confront to be convincing. We measure racial disparities in mortality between ages 40 and 80 for both males and females and for several causes of death and, measure how those disparities change with age. Estimates indicate that racial disparities in mortality grow with age but at a decreasing rate. Estimates also indicate that the source of racial disparities in mortality changes with age, sex and cause of death. For men in their fifties, racial disparities in mortality are primarily caused by disparities in deaths due to external causes. For both sexes, it is racial disparities in death from healthcare amenable causes that are the main cause of racial disparities in mortality between ages 55 and 75. Notably, racial disparities in cancer and other causes of death are relatively small even though these causes of death account for over half of all deaths. Adjusting for economic resources and health largely eliminate racial disparities in mortality at all ages and the mediating effect of these factors grows with age. The pattern of results suggests that, to the extent that racism influences health, it is primarily through racism’s effect on investments to treat healthcare amenable diseases that cause racial disparities in mortality.
The prevalence of functional limitations in the US workforce
Hailey Clark et al.
Proceedings of the National Academy of Sciences, 10 June 2025
Abstract:
This research paper investigates the prevalence of functional limitations among employed adults in the United States and the association between these limitations and medical conditions. The authors administered a survey adapted from the Dutch Functional Abilities List to a nationally representative sample of US adults ages 22 and older, finding that nearly three-quarters of working adults report at least one functional limitation, with an average of nearly six functional limitations per working adult. The most common limitations were in upper body strength and torso range of motion, and with respect to the ambient environment. The study also found that mental illness, arthritis, and substance use disorder are associated with the greatest number of functional limitations in working adults. The findings have implications for economic performance, workforce planning, and social policies to support displaced and vulnerable workers with significant functional limitations. Identifying the occupations and industries with large numbers of workers with functional limitations is critical to addressing short-term labor supply disruptions (e.g., public health crises) and preparing for longer-term workforce needs (e.g., long-term care workers for an aging population).
Do vertical ID laws curb teenage drinking and tobacco use?
Russell Leonard & Joseph Sabia
Contemporary Economic Policy, forthcoming
Abstract:
Vertical identification laws (VILs) -- which require state drivers' licenses issued to individuals under age 21 to be vertically oriented -- have been adopted widely across the United States. We find no evidence that VIL adoption has a statistically significant or economically important effect on teenage drinking and smoking. This result persists using Callaway and Sant'Anna estimates and extends to binge drinking, marijuana use, and drinking and driving. Finally, we show that prior estimates reported in the literature are sensitive to sample period studied, choice of Youth Risk Behavior Survey dataset, and accounting for heterogeneous and dynamic treatment effects.
Nicotine Vaping and Youth Mental Health: New Evidence from E-Cigarette Regulations
Chad Cotti et al.
NBER Working Paper, June 2025
Abstract:
The confluence of a youth mental health crisis and high rates of teenage nicotine vaping has led some U.S. tobacco control advocates to argue that reducing access to electronic nicotine delivery systems (ENDS) -- through policies such as ENDS taxation -- may improve youth and young adult mental health. Using data from several nationally representative surveys (Youth Risk Behavior Survey, Behavioral Risk Factor Surveillance System, and Population Assessment of Tobacco and Health) and a generalized difference-in-differences approach, we find no evidence that ENDS taxation improves youth and young adult mental health. With 95 percent confidence, we can rule out that the mean state ENDS tax increase adopted during our analysis sample ($0.34 per mL of e-liquid in 2023$) reduces persistent depressive symptoms among youths by more than 0.3 percent and suicide ideation by more than 1.0 percent. Moreover, discrete-time hazard models provide little evidence that ENDS taxes affect dynamics in youth mental health. A similar pattern of results emerges when we examine a wider set of ENDS regulations, including minimum legal purchasing ages, e-cigarette licensure laws, online sales restrictions, and restrictions on indoor nicotine vaping.
Early life high fructose impairs microglial phagocytosis and neurodevelopment
Zhaoquan Wang et al.
Nature, forthcoming
Abstract:
Despite the success of fructose as a low-cost food additive, epidemiological evidence suggests that high fructose consumption during pregnancy or adolescence is associated with disrupted neurodevelopment. An essential step in appropriate mammalian neurodevelopment is the phagocytic elimination of newly formed neurons by microglia, the resident professional phagocyte of the central nervous system. Whether high fructose consumption in early life affects microglial phagocytosis and whether this directly affects neurodevelopment remains unknown. Here we show that offspring born to female mice fed a high-fructose diet and neonates exposed to high fructose exhibit decreased phagocytic activity in vivo. Notably, deletion of the high-affinity fructose transporter GLUT5 (also known as SLC2A5) in neonatal microglia completely reversed microglia phagocytic dysfunction, suggesting that high fructose directly affects neonatal development by suppressing microglial phagocytosis. Mechanistically, we found that high-fructose treatment of mouse and human microglia suppresses phagocytosis capacity, which is rescued in GLUT5-deficient microglia. Additionally, we found that high fructose drives significant GLUT5-dependent fructose uptake and catabolism to fructose 6-phosphate, rewiring microglial metabolism towards a hypo-phagocytic state in part by enforcing mitochondrial localization of the enzyme hexokinase 2. Mice exposed to high fructose as neonates develop anxiety-like behaviour as adolescents -- an effect that is rescued in GLUT5-deficient mice. Our findings provide a mechanistic explanation for the epidemiological observation that high-fructose exposure during early life is associated with increased prevalence of adolescent anxiety disorders.
Do Vaping Taxes Tip the Scale? The Effect of E-Cigarette Taxation on Obesity
Charles Courtemanche et al.
NBER Working Paper, June 2025
Abstract:
A large literature documents that quitting cigarette smoking may lead to weight gain because nicotine is an appetite suppressant and metabolic stimulant. However, researchers in this literature emphasize that the health benefits of smoking cessation exceed the harms from the weight typically gained. New products, such as electronic nicotine delivery systems (ENDS), that deliver nicotine with a lower health risk than combustible cigarettes could conceivably alter this tradeoff in favor of nicotine use. Accordingly, this study asks whether a leading policy tool to curb ENDS use -- ENDS taxes -- has the unintended consequence of causing weight gain. We find that, despite reducing nicotine vaping, ENDS taxes lead to robust reductions in weight and body mass index among female teens. A one-dollar (per mL of e-liquid) increase the ENDS tax rate (2023$) leads to a 0.8-1.0 percentage-point decline in the probability that a female youth is obese. For male teens and both female and male adults, the estimated impacts are generally smaller and statistically indistinguishable from zero. An investigation of mechanisms reveals possible explanations for the absence of weight gain from ENDS taxes. The first is ENDS-tax-induced substitution to cigarettes, which offsets reductions in nicotine consumption from ENDS. The second is indirect effects on weight-related behaviors, including reductions in alcohol and marijuana use and increased healthier food consumption.
Impact of medical and recreational cannabis laws on inpatient visits for asthma
Jayani Jayawardhana & Jose Fernandez
Health Services Research, June 2025
Study Setting and Design: Quasi-experimental difference-in-differences regression analysis was conducted while accounting for variations in cannabis laws implementation timing by states. Inpatient visits for asthma in states with a given type of cannabis law were compared with those in states that did not implement the specific law. Four different cannabis laws were examined in the study -- initial passage of medical cannabis law, opening of a medical cannabis dispensary, home cultivation of medical cannabis, and recreational cannabis legalization.
Data Sources and Analytic Sample: State-level quarterly inpatient visit data for asthma patients were utilized from the Healthcare Cost and Utilization Project Fast Stats database. The primary analysis included inpatient visits for asthma by all payer adult patients aged 19 and above in 38 states from 2005 to 2017, and the secondary analysis included inpatient visits for asthma by payer-type (i.e., private, Medicare, Medicaid, uninsured).
Principal Findings: States with medical cannabis dispensaries and legalized recreational cannabis experienced 14.12% (2.14; 95% CI, 0.74–3.53; p < 0.01) and 20.45% (3.08; 95% CI, 1.47–4.69; p < 0.001) increases in inpatient visits for asthma compared with states without these policies, respectively. These increases in inpatient visits for asthma were primarily driven by populations covered by Medicare and private insurance, with Medicare population showing larger effects of both recreational cannabis laws and medical cannabis dispensaries.
Unravelling cysteine-deficiency-associated rapid weight loss
Alan Varghese et al.
Nature, forthcoming
Abstract:
Around 40% of the US population and 1 in 6 individuals worldwide have obesity, with the incidence surging globally. Various dietary interventions, including carbohydrate, fat and, more recently, amino acid restriction, have been explored to combat this epidemic. Here we investigated the impact of removing individual amino acids on the weight profiles of mice. We show that conditional cysteine restriction resulted in the most substantial weight loss when compared to essential amino acid restriction, amounting to 30% within 1 week, which was readily reversed. We found that cysteine deficiency activated the integrated stress response and oxidative stress response, which amplify each other, leading to the induction of GDF15 and FGF21, partly explaining the phenotype. Notably, we observed lower levels of tissue coenzyme A (CoA), which has been considered to be extremely stable, resulting in reduced mitochondrial functionality and metabolic rewiring. This results in energetically inefficient anaerobic glycolysis and defective tricarboxylic acid cycle, with sustained urinary excretion of pyruvate, orotate, citrate, α-ketoglutarate, nitrogen-rich compounds and amino acids. In summary, our investigation reveals that cysteine restriction, by depleting GSH and CoA, exerts a maximal impact on weight loss, metabolism and stress signalling compared with other amino acid restrictions. These findings suggest strategies for addressing a range of metabolic diseases and the growing obesity crisis.