Here's to your health

Kevin Lewis

November 24, 2016

Consumers Prefer “Natural” More for Preventatives than for Curatives

Sydney Scott, Paul Rozin & Deborah Small

University of Pennsylvania Working Paper, October 2016

Consumers value “naturalness” in some contexts more than others. For example, genetically engineered foods and vaccines are avoided in part due to their perceived unnaturalness, but genetically engineered insulin and synthetic antibiotics are widely accepted. We propose a systematic explanation for variation in the preference for naturalness. Across multiple product categories, we find that natural is more strongly preferred when it is used to prevent a problem than when it is used to cure a problem. This increased preference for natural occurs because natural is perceived as safer and less potent, and when preventing, consumers prefer safer, less potent alternatives. Consistent with this explanation, when natural alternatives are viewed as more risky and more potent, then natural alternatives are more preferred for curing than for preventing. This research sheds light on when the marketing of “natural” can be most appealing to consumers.


A Comparison of the Prevalence of Dementia in the United States in 2000 and 2012

Kenneth Langa et al.

JAMA Internal Medicine, forthcoming

Design, Setting, and Participants: We used data from the Health and Retirement Study (HRS), a nationally representative, population-based longitudinal survey of individuals in the United States 65 years or older from the 2000 (n = 10 546) and 2012 (n = 10 511) waves of the HRS.

Results: The study cohorts had an average age of 75.0 years (95% CI, 74.8-75.2 years) in 2000 and 74.8 years (95% CI, 74.5-75.1 years) in 2012 (P = .24); 58.4% (95% CI, 57.3%-59.4%) of the 2000 cohort was female compared with 56.3% (95% CI, 55.5%-57.0%) of the 2012 cohort (P < .001). Dementia prevalence among those 65 years or older decreased from 11.6% (95% CI, 10.7%-12.7%) in 2000 to 8.8% (95% CI, 8.2%-9.4%) (8.6% with age- and sex-standardization) in 2012 (P < .001). More years of education was associated with a lower risk for dementia, and average years of education increased significantly (from 11.8 years [95% CI, 11.6-11.9 years] to 12.7 years [95% CI, 12.6-12.9 years]; P < .001) between 2000 and 2012. The decline in dementia prevalence occurred even though there was a significant age- and sex-adjusted increase between years in the cardiovascular risk profile (eg, prevalence of hypertension, diabetes, and obesity) among older US adults.

Conclusions and Relevance: The prevalence of dementia in the United States declined significantly between 2000 and 2012. An increase in educational attainment was associated with some of the decline in dementia prevalence, but the full set of social, behavioral, and medical factors contributing to the decline is still uncertain. Continued monitoring of trends in dementia incidence and prevalence will be important for better gauging the full future societal impact of dementia as the number of older adults increases in the decades ahead.


Shorter lives in stingier states: Social policy shortcomings help explain the US mortality disadvantage

Jason Beckfield & Clare Bambra

Social Science & Medicine, December 2016, Pages 30–38

The United States has a mortality disadvantage relative to its political and economic peer group of other “rich democracies”. Recently it has been suggested that there could be a role for social policy in explaining this disadvantage. In this paper, we test this ‘social policy’ hypothesis by presenting a time trend analysis from 1970 to 2011 of the association between welfare state generosity (for unemployment insurance, sickness benefits, and pensions) and life expectancy, for the US and 17 other high-income countries. Fixed-effects estimation with autocorrelation-corrected standard errors (robust to unmeasured between-country differences and serial autocorrelation of repeated measures) found strong associations between welfare generosity and life expectancy. A unit increase in overall welfare generosity yields a 0.17 year increase in life expectancy at birth (p < 0.001), and a 0.07 year increase in life expectancy at age 65 (p < 0.001). The strongest effects of the welfare state are in the domain of pension benefits (b = 0.439 for life expectancy at birth, p < 0.001; b = 0.199 for life expectancy at age 65, p < 0.001). Models that lag the measures of social policy by ten years produce similar results, suggesting that the results are not driven by endogeneity bias. There is evidence that the US mortality disadvantage is, in part, a welfare-state disadvantage. We estimate that life expectancy in the US would be approximately 3.77 years longer, if it had just the average social policy generosity of the other 17 OECD nations.


Can Paid Sick Leave Mandates Reduce Leave-Taking?

Jenna Stearns & Corey White

University of California Working Paper, June 2016

Since 2006, several cities and states have implemented paid sick leave mandates. We examine the effects of paid sick leave mandates in Washington, D.C. (2008) and Connecticut (2011) on leave-taking behavior. After these policies are implemented, there are significant decreases in the aggregate rate of illness-related leave taking, relative to control groups, for both those directly affected and those not directly affected by the policy. Our results suggest that such policies can provide large positive public health externalities by allowing sick workers to stay home rather than coming to work and spreading their illness to customers and coworkers.


Patterns of allergen sensitization and self-reported allergic disease in parents of food allergic children

Melanie Makhija et al.

Annals of Allergy, Asthma & Immunology, October 2016, Pages 382–386

Methods: A total of 1,252 mothers and 1,225 fathers of food allergic children answered standardized questionnaires about demographics, home environment, history of atopic diseases, and food allergy. Skin prick testing and sIgE serum tests were performed to 9 foods and 5 aeroallergens.

Results: A total of 66.1% of parents were sensitized to either a food or aeroallergen. Mean sIgE levels were low for all foods tested. A total of 14.5% of mothers and 12.7% of fathers reported current food allergy. Only 28.4% had sensitization to their reported allergen. Fathers had significantly higher rates of sensitization to both foods and aeroallergens (P < .01) than mothers. Logistic regression evaluating predictors of self-reported food allergy revealed statistically significant positive associations in fathers with self-reported asthma, environmental allergy, and eczema. For mothers, significant positive associations were found with environmental allergy and having more than 1 food allergic child.

Conclusion: This cohort of parents of food allergic children found higher rates of sensitization to foods and aeroallergens compared with the general population. However, food sIgE levels were low and correlated poorly with self-reported food allergy. Sex differences in sensitization to foods and aeroallergens were seen.


Exposure to endocrine-disrupting chemicals in the USA: A population-based disease burden and cost analysis

Teresa Attina et al.

Lancet Diabetes & Endocrinology, December 2016, Pages 996–1003

Background: Endocrine-disrupting chemicals (EDCs) contribute to disease and dysfunction and incur high associated costs (>1% of the gross domestic product [GDP] in the European Union). Exposure to EDCs varies widely between the USA and Europe because of differences in regulations and, therefore, we aimed to quantify disease burdens and related economic costs to allow comparison.

Methods: We used existing models for assessing epidemiological and toxicological studies to reach consensus on probabilities of causation for 15 exposure–response relations between substances and disorders. We used Monte Carlo methods to produce realistic probability ranges for costs across the exposure–response relation, taking into account uncertainties. Estimates were made based on population and costs in the USA in 2010. Costs for the European Union were converted to US$ (€1=$1.33).

Findings: The disease costs of EDCs were much higher in the USA than in Europe ($340 billion [2.33% of GDP] vs $217 billion [1.28%]). The difference was driven mainly by intelligence quotient (IQ) points loss and intellectual disability due to polybrominated diphenyl ethers (11 million IQ points lost and 43 000 cases costing $266 billion in the USA vs 873 000 IQ points lost and 3290 cases costing $12.6 billion in the European Union). Accounting for probability of causation, in the European Union, organophosphate pesticides were the largest contributor to costs associated with EDC exposure ($121 billion), whereas in the USA costs due to pesticides were much lower ($42 billion).

Interpretation: EDC exposure in the USA contributes to disease and dysfunction, with annual costs taking up more than 2% of the GDP. Differences from the European Union suggest the need for improved screening for chemical disruption to endocrine systems and proactive prevention.


Misplaced Paternalism and other Mistakes in the Debate over Kidney Sales

Luke Semrau

Bioethics, forthcoming

Erik Malmqvist defends the prohibition on kidney sales as a justifiable measure to protect individuals from harms they have not autonomously chosen. This appeal to ‘group soft paternalism’ requires that three conditions be met. It must be shown that some vendors will be harmed, that some will be subject to undue pressure to vend, and that we cannot feasibly distinguish between the autonomous and the non-autonomous. I argue that Malmqvist fails to demonstrate that any of these conditions are likely to obtain. His argument involves two common errors. First, he, like many, proceeds on a mistaken understanding of how to assess harm. What matters is not the balance of costs and benefits of vending, but a comparison of potential vendors’ welfare across two possible courses of action. Second, Malmqvist's concerns about third-party pressure are predicated on an empirically unrealistic understanding of the operation of a regulated market. A widely underappreciated fact is that kidney sales will be relatively rare, and most who try to vend will be unable to. Because pressure on another to vend will not result in the desired outcome, few will exert it.


Modeling The Economic Burden Of Adult Vaccine-Preventable Diseases In The United States

Sachiko Ozawa et al.

Health Affairs, November 2016, Pages 2124-2132

Vaccines save thousands of lives in the United States every year, but many adults remain unvaccinated. Low rates of vaccine uptake lead to costs to individuals and society in terms of deaths and disabilities, which are avoidable, and they create economic losses from doctor visits, hospitalizations, and lost income. To identify the magnitude of this problem, we calculated the current economic burden that is attributable to vaccine-preventable diseases among US adults. We estimated the total remaining economic burden at approximately $9 billion (plausibility range: $4.7–$15.2 billion) in a single year, 2015, from vaccine-preventable diseases related to ten vaccines recommended for adults ages nineteen and older. Unvaccinated individuals are responsible for almost 80 percent, or $7.1 billion, of the financial burden. These results not only indicate the potential economic benefit of increasing adult immunization uptake but also highlight the value of vaccines. Policies should focus on minimizing the negative externalities or spillover effects from the choice not to be vaccinated, while preserving patient autonomy.


Evidence for a limit to human lifespan

Xiao Dong, Brandon Milholland & Jan Vijg

Nature, 13 October 2016, Pages 257–259

Driven by technological progress, human life expectancy has increased greatly since the nineteenth century. Demographic evidence has revealed an ongoing reduction in old-age mortality and a rise of the maximum age at death, which may gradually extend human longevity1, 2. Together with observations that lifespan in various animal species is flexible and can be increased by genetic or pharmaceutical intervention, these results have led to suggestions that longevity may not be subject to strict, species-specific genetic constraints. Here, by analysing global demographic data, we show that improvements in survival with age tend to decline after age 100, and that the age at death of the world’s oldest person has not increased since the 1990s. Our results strongly suggest that the maximum lifespan of humans is fixed and subject to natural constraints.


1970s and ‘Patient 0’ HIV-1 genomes illuminate early HIV/AIDS history in North America

Michael Worobey et al.

Nature, 3 November 2016, Pages 98–101

The emergence of HIV-1 group M subtype B in North American men who have sex with men was a key turning point in the HIV/AIDS pandemic. Phylogenetic studies have suggested cryptic subtype B circulation in the United States (US) throughout the 1970s and an even older presence in the Caribbean. However, these temporal and geographical inferences, based upon partial HIV-1 genomes that postdate the recognition of AIDS in 1981, remain contentious and the earliest movements of the virus within the US are unknown. We serologically screened >2,000 1970s serum samples and developed a highly sensitive approach for recovering viral RNA from degraded archival samples. Here, we report eight coding-complete genomes from US serum samples from 1978–1979—eight of the nine oldest HIV-1 group M genomes to date. This early, full-genome ‘snapshot’ reveals that the US HIV-1 epidemic exhibited extensive genetic diversity in the 1970s but also provides strong evidence for its emergence from a pre-existing Caribbean epidemic. Bayesian phylogenetic analyses estimate the jump to the US at around 1970 and place the ancestral US virus in New York City with 0.99 posterior probability support, strongly suggesting this was the crucial hub of early US HIV/AIDS diversification. Logistic growth coalescent models reveal epidemic doubling times of 0.86 and 1.12 years for the US and Caribbean, respectively, suggesting rapid early expansion in each location. Comparisons with more recent data reveal many of these insights to be unattainable without archival, full-genome sequences. We also recovered the HIV-1 genome from the individual known as ‘Patient 0’ and found neither biological nor historical evidence that he was the primary case in the US or for subtype B as a whole. We discuss the genesis and persistence of this belief in the light of these evolutionary insights.


Eradicating infectious disease using weakly transmissible vaccines

Scott Nuismer et al.

Proceedings of the Royal Society: Biological Sciences, 26 October 2016

Viral vaccines have had remarkable positive impacts on human health as well as the health of domestic animal populations. Despite impressive vaccine successes, however, many infectious diseases cannot yet be efficiently controlled or eradicated through vaccination, often because it is impossible to vaccinate a sufficient proportion of the population. Recent advances in molecular biology suggest that the centuries-old method of individual-based vaccine delivery may be on the cusp of a major revolution. Specifically, genetic engineering brings to life the possibility of a live, transmissible vaccine. Unfortunately, releasing a highly transmissible vaccine poses substantial evolutionary risks, including reversion to high virulence as has been documented for the oral polio vaccine. An alternative, and far safer approach, is to rely on genetically engineered and weakly transmissible vaccines that have reduced scope for evolutionary reversion. Here, we use mathematical models to evaluate the potential efficacy of such weakly transmissible vaccines. Our results demonstrate that vaccines with even a modest ability to transmit can significantly lower the incidence of infectious disease and facilitate eradication efforts. Consequently, weakly transmissible vaccines could provide an important tool for controlling infectious disease in wild and domestic animal populations and for reducing the risks of emerging infectious disease in humans.


Prenatal paracetamol exposure is associated with shorter anogenital distance in male infants

B.G. Fisher et al.

Human Reproduction, November 2016, Pages 2642-2650

Study question: What is the relationship between maternal paracetamol intake during the masculinisation programming window (MPW, 8–14 weeks of gestation) and male infant anogenital distance (AGD), a biomarker for androgen action during the MPW?

Study design, size, duration: Prospective cohort study (Cambridge Baby Growth Study), with recruitment of pregnant women at ~12 post-menstrual weeks of gestation from a single UK maternity unit between 2001 and 2009, and 24 months of infant follow-up. Of 2229 recruited women, 1640 continued with the infancy study after delivery, of whom 676 delivered male infants and completed a medicine consumption questionnaire.

Participants/materials, setting, method: Mothers self-reported medicine consumption during pregnancy by a questionnaire administered during the perinatal period. Infant AGD (measured from 2006 onwards), penile length and testicular descent were assessed at 0, 3, 12, 18 and 24 months of age, and age-specific Z scores were calculated. Associations between paracetamol intake during three gestational periods (<8 weeks, 8–14 weeks and >14 weeks) and these outcomes were tested by linear mixed models. Two hundred and twenty-five (33%) of six hundred and eighty-one male infants were exposed to paracetamol during pregnancy, of whom sixty-eight were reported to be exposed during 8–14 weeks. AGD measurements were available for 434 male infants.

Main results and the role of chance: Paracetamol exposure during 8–14 weeks of gestation, but not any other period, was associated with shorter AGD (by 0.27 SD, 95% CI 0.06–0.48, P = 0.014) from birth to 24 months of age. This reduction was independent of body size. Paracetamol exposure was not related to penile length or testicular descent.

Wider implications of the findings: Our observational findings support experimental evidence that intrauterine paracetamol exposure during the MPW may adversely affect male reproductive development.


Exercise during pregnancy enhances cerebral maturation in the newborn: A randomized controlled trial

Elise Labonte-Lemoyne, Daniel Curnier & Dave Ellemberg

Journal of Clinical and Experimental Neuropsychology, forthcoming

Accumulating research indicates that the regular practice of physical exercise is beneficial to the human brain. From the improvement of academic achievement in children to the prevention of Alzheimer’s disease in the elderly, exercise appears beneficial across the developmental spectrum. Recent work from animal studies also indicates that a pregnant mother can transfer the benefits of exercise during gestation to her offspring’s brain. Exercising pregnant rats give birth to pups that have better memory and spatial learning as well as increased synaptic density. To investigate whether this transfer from the pregnant mother to her child also occurs in humans, we conducted a randomized controlled trial (n = 18) and measured the impact of exercise during pregnancy on the neuroelectric response of the neonatal brain with electroencephalography (EEG). Here we show that, compared to the newborns of mothers who were inactive during their pregnancy, the children of exercising pregnant women are born with more mature brains. This was measured with the infant slow positive mismatch response (SPMMR), an electroencephalographic potential known to decrease in amplitude with age. The SPMMR reflects processes associated with brain maturation via its response to sound discrimination and auditory memory. In this study, the children of the mothers who exercised throughout their pregnancy have a smaller SPMMR than the children of mothers who remained sedentary (p = .019). Our results demonstrate the impact regular exercise during pregnancy can have on the development of the human fetal brain.


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