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Posts Tagged ‘obesity

Science Policy Around the Web – May 14th, 2019

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By: Mary Weston, Ph.D.

Source: Pixabay

Rural areas drive increases in global obesity

While past studies have found that the increase in global obesity is largely driven by urban regions, a newly published paper argues that this rise is actually being led by those in rural areas. 

Global increases in BMI (body mass index) have been observed for decades, but no one had evaluated differences in urban and rural regions on a large-scale across many countries. The new Nature study evaluated BMI values in 200 countries from 1985-2017, finding that rural areas are responsible for more than 55% of the global rise in the average BMI and more than 80% of the rise in some low- and middle-income countries (LMICs). 

Previous theories argued that urbanization caused rising BMI largely because of the availability of cheap, ultra-processed foods, a lifestyle that provides more transportation options, and greater access to non-physical leisure activities (smartphones, cable television). In contrast, rural areas were thought more likely to consume more local produce, have less access to ultra-processed and packaged food, and participate in high energy expending activities. However, rural areas, even in LMICs, have now begun to resemble urban areas because of access to ultra-processed foods and cheap mechanized devices that reduce transport and farming energy expenditure.

Obesity results in higher health care costs, lower life expectancy, and reduced quality of life. Thus, prevention strategies are vital but currently, most preventative measures are targeted towards urban areas. Given this new data, funding priorities and strategies need to adjust to address this growing issue. 

(Barry M. Popkin, Nature)

After outcry, USDA will no longer require scientists to label research as ‘preliminary’

After protests, the US Department of Agriculture (USDA) has stopped requiring their staff scientists to label all published peer-reviewed research as “preliminary.” Released last week, the revised USDA guidelines now require the following language when disclaimers are necessary: “The findings and conclusions in this [publication/presentation/blog/report] are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.” Not all publications will be obliged to contain this statement. 

Previous USDA guidelines, implemented last July, required publications to carry the label: “The findings and conclusions in this preliminary publication have not been formally disseminated by the [USDA] and should not be construed to represent any agency determination or policy.”  This disclaimer caused concern over claims that it was confusing and possibly misleading. Scientific publications are peer-reviewed (evaluated by professionals in the field for quality and accuracy) and considered completed work, not preliminary. Some among the scientific community feared the disclaimer might reduce the impact of the published research conclusions or be used to diminish findings that conflict with views of the current administration. 

While reaction towards the disclaimer change has been generally positive, some non-USDA researchers are still concerned that the latest guidelines have the potential to jeopardize scientific integrity. The new guidelines say that the USDA can request “corrections” or “changes” to research papers if they pertain to a “prominent issue,” a significant scientific advancement, or could influence trade/policy decisions. Rebecca Boehm, an economist at the Union of Concerned Scientists, stated that “removing ‘preliminary’ from the disclaimer is a step in the right direction, but there still may be unnecessary obstacles preventing agency researchers from publishing their work in peer-reviewed journals.” 

(Ben Guarino, Washington Post)

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May 14, 2019 at 4:56 pm

Science Policy Around the Web – March 12, 2019

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By Andrew Wright, BSc

Source: Pixabay

The war on ‘prediabetes’ could be a boon for pharma—but is it good medicine?

Diabetes is highly prevalent in the United States, affectingnearly 10% of the US populationand accounting for approximately 80,000 deaths every year. While the pursuit to reduce or mollify the societal and economic impact of this disease is undoubtedly necessary in a country where fully 39.8% of adults are obese, there are some who wonder if such efforts have slipped into problematic territory. 

            Similar to how the introduction of pain as a fifth vital signhelped to unintentionally spur on the devastating opioid crisis, there is fear that the expanding diagnostic criterion of prediabetes could lead to the familiar territory of unnecessary treatment. For one, the risk of prediabetic patients developing diabetes from year to year is low: just under 2% according to the Centers for Disease Control (CDC).  At the same time the methods of treatment for prediabetes, designed to prevent progression to the full disease, are not particularly effective in achieving that goal. While a 2009 study demonstrated that exercise intervention or metformin, a common drug used to treat diabetes, did prevent some prediabetic patients from transitioning to full diabetes, methodological concerns have been raised with the authors’ results. One of the major issues is that the study used high risk patients at the upper end of the prediabetic spectrum, which is significant given that the American Diabetes Association (ADA) reduced the lower threshold of what counts as prediabetes around the same time. Of these “less” prediabetic patients, many never transition to the full disease. This suggests at the very least that treating these patients, especially pharmacologically, is not necessary or beneficial.

            Despite these issues being raised, there is a worrying trend of medical professionals doing just that. While no drug has been approved to treat prediabetes, doctors are continuing to treat prediabetic patients with diabetes drugs by prescribing them off-label at the recommendation of the ADA. Not only does this include metformin, which has its own difficult side-effects, but also several medications with “black box” labels that denote severe risks. Particularly when one considers that those who progress to full diabetes will be treated with these same drugs as their condition worsens, using them prophylactically is likely overzealous.

            Finally, there have been concerns raised about financial conflicts of interest, to which the medical and pharmaceutical industry are certainly not strangers. The companies behind the most prominent diabetes drugs have gifted millions of dollars to those in positions of influence at the ADA and other medical institutions. Perhaps as a result, while international groups such as the World Health Organization (WHO) have rejected prediabetes as a condition outright, the American medical community seems to be falling in line with the diagnosis. When top-down societal changes to reduce obesity may a be more effective means to reduce diabetes according to the WHO, the over-medicalization of prediabetes could ultimately do more harm than good.

(Charles Piller, Science)

Microplastic pollution revealed ‘absolutely everywhere’ by new research

With estimates that the ocean will have more plastic than fishby weight by 2050, it should come as no surprise that global plastic pollution is becoming rapidly untenable.  It is well understood that plastic does not biodegrade, but rather breaks down into increasingly smaller pieces know as microplastics. These pieces of plastic can become so small that they can be ingested by zooplankton, one of the fundamental building blocks of the marine food chain, which means they eventually make their way to the human digestive system.  

            While the problem was previously thought to be relegated to the worst polluted waterways and places like pacific vortexes (colloquially known as the “Great Pacific Garbage Patch”), recent studies have shown that microplastic pollution is so pervasive that pieces are found in every area tested. This includes freshwater bodies in the United Kingdom, groundwater supplies in the United States, the Yangtze river, off the coast of Spain, and in tap water around the world.

            The problem is not relegated to shallow water bodies either, with microplastics being found at the bottom of the Mariana Trench at levels of up to 2,200 pieces per liter of sediment. While these levels of contamination are undoubtedly perilous to wildlife, the affect they might have on humans is unclear. However, research from the National University of Singapore has demonstrated that microplastics harbor both bacteria that cause coral bleaching and those that cause gastroenteritis.  Further,  the possibility remains for chemicals contained in microplastics such as polychlorinated biphenyls (PCBs), which are carcinogenic, to cause deleterious health effects as chronic exposure leads to cumulative effects. What is clear is that without some method of reducing plastic pollution or monumental cleanup efforts, microplastics will become a troubling global burden in the years to come.

(Damian Carrington, The Guardian)

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March 12, 2019 at 4:53 pm

Science Policy Around the Web – September 15, 2017

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By: Liu-Ya Tang, PhD

20170915_Linkpost_1

source: pixabay

Public Health

A new flavor in cancer research: sugar

Sugar is an important energy source for fueling our body. However, eating too much sugar doesn’t do any good to our health. It can cause obesity or diabetes, both of which are considered risk factors for cancer. Moreover, there is evidence showing that sugar may play a direct role in cancer development/progression. Here’s why.

The first study is about how sugar protects cancer cells from attack by the immune system. The immune system is the safeguard of our body that acts by cleaning out “foreign” invaders or bad cells. When the cell becomes cancerous, it may disguise itself and escape the challenges imposed by the immune system. Dr. Carolyn Bertozzi’s group at Stanford University found that cancer cells have denser sialic acid, a type of sugar, on the cell surface than that on normal cells. This sugary coating makes cancer cells invisible to the immune system, so they can divide freely in the body. To enable the immune system to attack cancer cells, Dr. Bertozzi proposed to strip away the sugary coating by using drugs.

In addition to masking cancer cells, sugar can also directly promote their growth. Glucose, a metabolic product of sugar, is important for not only the growth of normal cells but also for that of cancer cells. One distinct phenotype of cancer cells is uncontrolled cell growth, which may require more glucose. This notion has been supported by a recent study done by Dr. Jung-whan Kim’s group at The University of Texas at Dallas. The researchers found that high levels of a protein called glucose transporter 1 (GLUT1), which is responsible for transporting glucose, is associated with lung squamous cell carcinoma (SqCC). However, they didn’t observe similar results in lung adenocarcinoma (ADC), which indicates that different cancer cells may adopt different mechanism to satisfy their energy needs. They further found that using GLUT1 inhibitor can suppress the tumor growth in a SqCC mouse model, but not the adenocarcinoma mouse model. Their findings will help the development of specific treatment plans for SqCC patients targeting GLUT1.

The American Heart Association recommended that the maximum amount of sugar consumption for women is 25 grams a day and that for man is 36 grams. However, the reality is that in 2015, on average, each American consumed more than 93 grams of sugar a day. Reducing sugar consumption and eating a balanced diet will not only help decrease the high rates of obesity in the US, but also benefit cancer prevention.

(Erin Blakemore, Washington Post and University of Texas at Dallas, ScienceDaily)

Innovative Technology

Stem cells could help Parkinson’s patients get the dopamine they need

Parkinson’s disease (PD) is a chronic degenerative disorder of the central nervous system that mainly affects movement. It is a progressive disease and PD patients can have very severe symptoms such as the inability to walk or talk. The cause of PD is the death of dopamine-producing neurons, as dopamine, a neurotransmitter, is essential for motor neurons to function properly.

Medications and surgery can help alleviate the symptoms of PD, but there is no cure for it. Recently, a study published in Nature brings hope to doctors, PD patients and their families. This study was led by Dr. Jun Takahashi, a stem-cell scientist at Kyoto University in Japan. As the loss of dopamine is the root cause of PD, to implant dopamine-producing cells to the brain of PD patients would be the most effective way to cure PD. Embryonic stem cells have the versatile ability to develop into different organs, but there are always ethical issues around this research. Dr. Takahashi’s group generated induced pluripotent stem (iPS) cells derived from both healthy people and those with PD, transformed iPS cells to dopamine-making neurons and implanted the cells into monkeys with neurodegenerative disorders. After two years, the monkeys are still alive and the disorder symptoms are greatly mitigated. Dr. Takahashi hopes to begin a clinical trial by the end of next year.

Ideally and in theory, deriving iPS cells from a patient’s own cells would allow them to avoid taking the immune-suppressing drugs that are usually necessary when introducing non-native tissues. But generating customized iPS cells is expensive and requires a couple months for propagation. A good solution, planned by Dr. Takahashi, is to establish iPS cell lines from healthy people and match them with PD patients by using immune cell biomarkers. This approach will probably be feasible as it has been successfully applied in monkeys.

In addition to Dr. Takahashi, there are other scientists conducting stem-cell research on PD. Dr. Jeanne Loring, working at Scripps Research Institute in La Jolla, California, prefers to transplant iPS-derived neurons made from a patient’s own cells. She hopes to start a clinical trial in 2019. Another stem-cell expert from the Memorial Sloan Kettering Cancer Center in New York City, Dr. Lorenz Studer, is working on a trial that will use neurons derived from embryonic stem cells. Although there are still issues in this field, all the efforts will ultimately lead to a better treatment for PD patients. (Ewen Callaway, Nature News)

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September 15, 2017 at 4:05 pm

Science Policy Around the Web – August 15, 2017

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By: Liu-Ya Tang, PhD

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Picture Source: pixabay

Public Health

Obesity and Depression, Entwined or Not?

It might seem that obesity and depression are not related since they are diseases from different parts of the body; however, health care practitioners have observed that these two diseases have a close relationship. The development of obesity and depression can be a vicious cycle, one favoring the other. Extra weight brings anxieties to obese people, which can cause poor self-image and social isolation. These are known contributors to depression. On the other hand, people experiencing depression tend to overeat and avoid exercising. According to the federal Centers for Disease Control and Prevention, about 43 percent of people with depression are obese, compared with 36.5 percent of the general population. People with obesity have a higher risk to develop depression, and vice versa, according to one 2010 study.

Both obesity and depression are chronic diseases that are hard to treat, placing a big burden on the health care system. Obesity rates in the United States are among the highest in the world. Obesity alone costs almost $150 billion per year in direct expenses, and this number is estimated to increase about $1.24 billion each year till the year 2030. The cost of treating depression is even higher, which is more than $200 billion every year. So it is urgent to find ways to treat both diseases more effectively if they are bidirecitonally comorbid.

When depression and obesity coincide, the combination of physical and mental health interventions becomes important, which has been supported by several studies. Researchers from the University of Texas-Southwestern found that patients’ depression were alleviated when they did weekly exercise sessions, which were prescribed by physicians. Another study from Duke University found that the rate of depression in obese women was decreased by 50 percent simply by helping them control their weight. The combinatorial treatment has been adopted. Dr. Sue McElroy, a psychiatrist in Mason, Ohio, screens patients for weight and BMI, and treats obesity and depression together. She tailors her prescription, as some antidepressants can cause weight gain. Her “self-taught” method was welcomed by her patients. However, this is not a general practice in treating patients with both symptoms. To benefit patients’ health and reduce cost for curing obesity and depression, the whole health care system needs a change.

(Shefali Luthra, Kaiser Health News)

 

The ACA

What do people and health-policy experts think about repealing the ACA?

Since March, the Trump administration has strived to repeal and replace the Affordable Care Act (ACA), but the Senate rejected this repeal, as 3 republican senators voted “no” last month. How do people feel about repealing the ACA? What do most people say the Trump administration should do after the Senate failed to repeal? There were two reports about it.

The first one was about a survey conducted Aug. 1-6 by the Kaiser Family Foundation, which capture the opinions of 1,211 adults. Their analysis found that a majority of people (78 percent) think that the government should make the ACA work better. Grouping this majority by Political Party ID, reveales 95 percent are Democrats, 80 percent re independents and 52 percent are Republicans. Even 51 percent of President Trump’s supporters think both parties should work together to improve the health law.

The second report said that a coalition of liberal and conservative health-policy leaders is making suggestions for how to strengthen the existing ACA law, aligned with a favorable view in the public. The nine group members are from think tanks, universities and advocacy groups, who can be influential in health-policy formation of the government. The coalition was founded when it appeared that the Republican-controlled Congress would pass a repeal of the ACA without a replacement plan. It took the group eight months to come up with a five-point set of principles. It says that the government should continue providing subsidies to insurers that extend plans to 7 million lower-income customers and strong incentives for Americans to carry health insurance. The latter will help the cost of expensive care be shared by a stable insurance pool with healthy customers. They also urge the government to bring health plans to about two dozen counties, which would be left providerless in the ACA marketplace for 2018. The group said they intend to present their idea to Republican and Democratic lawmakers. “We are trying to model bipartisanship so incremental steps can be taken,” said by Ron Pollack, chairman emeritus of the liberal consumer-health lobby Families USA.

To prevent the potential collapse of health insurance market, the Senate is planning a bipartisan hearing on health care in September. In the House, a group of around 40 Republicans and Democrats known as the Problem Solvers Caucus aims to making urgent fixes to the ACA law. On September 27th, insurers will sign contracts with the federal government over what insurance plans to sell on the marketplace for 2018, which pushes Congress to come up with a solution before then.

(Phil Galewitz, Kaiser Health News, and Amy Goldstein, The Washington Post)

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August 15, 2017 at 6:27 pm

Science Policy Around the Web – March 14, 2017

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By: Liz Spehalski, PhD

Affordable Care Act

ACA Replacement Bill Released by House

Last Monday, House Republicans released their plan to repeal and replace former President Obama’s Patient Protection and Affordable Care Act (ACA), also known as Obamacare. The American Health Care Act (AHCA), a more conservative vision for the nation’s health care system, was created as a collaboration between the White House and the Senate Republicans. The Republican Party has been critical of the ACA because of the large role that it created for the federal government in health care, such as the need for the IRS to verify eligible people for financial help and federally mandating the public to have health insurance.

The AHCA will maintain some of the popular features of the ACA, such as allowing young adults to stay on their parent’s health care plans until the age of 26, banning lifetime coverage caps, and maintaining the ban on discrimination against people with pre-existing conditions. It also temporarily maintains the expansion of Medicaid to cover millions of low income Americans through January 1, 2020.

Instead of the individual mandate, a fine penalizing Americans for failing to have health insurance, the new bill would try to encourage people to sustain coverage by allowing insurers to impose a 30 % fine to those who have a gap between plans. The AHCA also changes the structure of tax credits given to those who want to buy insurance. Under the ACA, people who earn less than 200 percent of the poverty line get the highest subsidies. The Republican plan would instead give tax credits based mostly on age. The AHCA will also cut off federal funds to Planned Parenthood through Medicaid and other government programs for one year.

While Republicans did not offer any estimate of how much their plan would cost, or how many people would gain or lose insurance coverage, the Congressional Budget Office released its estimate yesterday, raising concerns. Two key House committees swiftly approved the bill, but uncertainty surrounds how this bill will fare in Congress, as some conservatives are concerned that it does not go far enough to remove government from health care, while others are concerned about their constituents losing coverage due to the loss of Medicaid expansion. No Democrats are expected to support the bill. (

Obesity

Fewer Overweight Americans Trying to Lose Weight

A study published in the Journal of the American Medical Association this week found that the percentage of Americans trying to lose weight is declining. In 1990, when researchers asked overweight Americans if they were trying to lose weight, 56% responded yes, while that number decreased to 49% in 2014. Researchers analyzed US government health surveys from 1988 through 2014 which involved in-person physical exams and health- related questions including whether the participants had tried to lose weight within the last year. The study included over 27,000 adults ages 20-59, and weight status was determined using body mass index (BMI).

The explanation behind this trend seems to be the shift in public perception over dieting and overweight people. “Socially accepted normal body weight is shifting toward heavier weight. As more people around us are getting heavier, we simply believe we are fine, and no need to do anything with it,” said lead author Dr. Jian Zhang, a public health researcher at Georgia Southern University. The authors of the study also discuss other possible reasons for this data, such as primary care physicians not discussing weight issues with their patients.

Though the decline of 7% may seem low, this number could represent up to seven million Americans, as more than two thirds of adults are considered to be overweight or obese, according to recent NIH statistics. Scientists say this is concerning because obesity increases the risk of a host of diseases such as heart disease, diabetes, cancer, liver disease, osteoarthritis, and stroke. However, “There’s a possible good news story in this,” says Janet Tomiyama, a psychologist at UCLA who studies eating behavior and weight stigma. “We’re not going to shame people into health,” Tomiyama says, “a lot of research shows that having a healthy body image is what leads to better health outcomes. Maybe people are taking the focus off the number on the scale, and going more towards focusing on their health.” The CDC’s current  obesity prevention efforts focus on policy and environmental strategies that target the affordability of healthy eating and active living, noting that fad diets can be unhealthy and tend to fail over the long term. (Allison Aubrey, NPR)

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March 14, 2017 at 10:00 am

Science Policy Around the Web – February 21, 2017

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By: Rachel Smallwood, PhD

Obesity

Should We Treat Obesity Like a Contagious Disease?

Researchers are modeling obesity from a public health perspective as a contagious disease. There are many factors associated with obesity, including genetics, low levels of physical activity, and high caloric intake. An earlier study examined the effects of different social factors on an individual’s risk of being obese; it found that people with obese friends and family were at an increased risk for obesity, and this trend was influenced by how close the relationships were.

In this model of the prevalence of obesity, the researchers included a factor to represent obesity as a “social contagion”, reflecting those previous findings and indicating a potential increased risk and increased prevalence due to transmission from one person to another. This mechanism is assumed to be related to people adopting the behaviors of those close to them; notably, activity levels and type and quantity of food consumed. The model predicts obesity rates in populations with terms associated with the genetic contribution to obesity, the mother’s non-genetic contribution to her offspring, and the prevalence of obesity. Essentially, the more obese individuals there are in a society, the more likely it is for someone to know and interact with an obese person.

The models indicate that obesity prevalence plateaus around 35-40% without an intervention. The model is still fairly primitive, but the researchers hope that in future it could provide insight into the effects of potential interventions. For example, is it better to target an intervention to individuals who are already obese, or should the reach of the intervention be more broad and target the population as a whole? When the models reach a level of complexity comparable to the existing factors for obesity, they can be a powerful tool in preventing and addressing the epidemic. (Kelly Servick, Science Magazine)

Autism

Brain Scans Spot Early Signs of Autism in High-Risk Babies

A study recently published in Nature showed that alterations in brain development in children who go on to be diagnosed with autism precede behavioral symptoms. High-risk infants’ brains were scanned with MRI at 6, 12, and 24 months. It was determined that the infants who were subsequently diagnosed with autism had a faster rate of brain volume growth between 12 and 24 months. Additionally, between 6 and 12 months, these infants had a faster rate of growth in the surface area of folds on the brain, called the cortical surface.

Taking these findings, the research team used a machine learning approach called a deep-learning neural network to make a model to predict whether an infant would be diagnosed with autism based on their MRIs from 6 and 12 months. This model was tested in a larger set of infants, and the model correctly predicted 30 out of 37 infants who went on to be diagnosed (true positives), and it incorrectly predicted that 4 infants would be diagnosed with autism out of the 142 who were not later diagnosed (false positives). These results are much more robust than behavior-based predictions from this same age range.

More work needs to be done to replicate the results in a larger sample. Additionally, all of the participants were high-risk infants, meaning they had a sibling who was diagnosed with autism, so the results are not necessarily generalizable to the rest of the population. Further studies need to be done in the general population to determine if these same patterns are observable, but that would require an even larger sample due to the lower risk. However, the early detection of symptoms and prediction of diagnosis are potentially valuable tools, especially considering another recent publication showed that early intervention in children with autism affects the severity of symptoms years down the road. (Ewen Callaway, Nature News)

Science Funding

Ebola Funding Surge Hides Falling Investment in Other Neglected Diseases

Funding totals from 2015 reveal a trending decrease in funding for neglected diseases, excluding Ebola and other viral hemorrhagic fevers. Neglected diseases are diseases that primarily affect developing companies, thus providing little incentive for private research and development by commercial entities; the other diseases include malaria, tuberculosis, and HIV/AIDS. Given the recent surge of funding for Ebola research, the analysis firm, Policy Cures Research, decided to separate it from the other neglected diseases in its analysis to observe funding patterns independent from the epidemic that dominated the news and international concerns. Funding was tracked from private, public, and philanthropic sources.

The funding for Ebola research has primarily gone to development of a vaccine, and over a third of the funds were provided by industry. For the other diseases, the decline in overall funding is mostly represented by a decline in funding from public entities, primarily comprised of the governments of large, developed countries. Those countries accounted for 97% of the research funding for neglected diseases in 2015, so any significant change in that funding category would affect the overall funding amounts. However, there was also a slight decline in philanthropic funding. When including Ebola with the others, funding of neglected diseases was actually at its highest in the past ten years. It is not known whether money was funneled from the other diseases to Ebola research, or if this decline is indicative of less research spending in general. (Erin Ross, Nature News)

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February 21, 2017 at 10:03 am

Science Policy Around the Web – December 02, 2016

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By: Liu-Ya Tang, PhD

Source: pixabay

Public Health

Childhood Bullying and Adult Overweight

Bullying is, without a doubt, a big problem in U.S. schools, as “40% to 80% of school-age children experience bullying at some point during their school careers” according to the American Psychological Association. What influence will bullying have on child development? Bullying can not only affect mental health, but also have a lasting effect on a person’s physical health. A recent study finds that bullied children were more likely to be overweight than non-bullied children at age 18.

Scientists studied a cohort of twins from 2,232 children who were followed to age 18. Bullying victimization was reported by mothers and children during primary school and early secondary school. At ages 10, 12 and 18, they collected data for indicators of overweight. To index genetic and fetal liability to overweight, co-twin body mass and birth weight were also used. They found that the association between childhood bullying victimization and being overweight at age 18 was influenced by the chronicity of exposure, as children bullied in both primary school and secondary school showed the highest risk of being overweight. They also measured whether childhood psychosocial risk factors (socioeconomic disadvantage and food insecurity) contributed to a higher risk of being overweight at age 18. To their surprise, the result showed that the elevated risk of bullied children becoming overweight is independent of their psychosocial risk.

The researchers further dug into the mechanisms of why childhood bullying puts kids at high risk for being overweight as a young adult. One possible reason is the allostatic load theory prediction, which states that “more chronic exposure to psychosocial stress is associated with the greatest metabolic abnormalities”. This theory has been supported by a study, in which they found that children being bullied may eat more due to impaired inhibitory control over feeding linked to prefrontal cortex abnormalities. In addition to explanations from the biological aspect, social mechanisms may also need to be taken into account. Bullied children may avoid participating in group sporting activities to reduce the risks of victimization from peers. It is important for school, clinical practice and public health agencies to identify the mechanisms and develop anti-bullying interventions, which could support bullied children to have a healthy life later and help reduce the large public health burden due to overweight. (Jessie R. Baldwin et al., Psychosomatic Medicine)

Climate Change

Will Climatic Warming Affect Soil Respiration?

It is estimated that nine times more carbon dioxide (CO2) is released from soils to atmosphere via soil respiration annually when compared with anthropogenic emissions. This efflux of carbon from soils is attributed to both plant root respiration and microbial respiration. Rising temperatures are expected to increase rates of soil respiration, which potentially provides a positive feedback to climatic warming. However, there were discrepancies in the observations from recent years, so the interaction between soil respiration and climate warming remains uncertain in climate projections.

To understand the complex relationship between soil respiration and temperature, 43 researchers from the United States and Europe conducted a global synthesis of 27 experimental warming studies spanning nine biomes, which results in >3,800 observations. There are numerous interesting findings. With the exception of boreal forest and desert, they didn’t observe significant differences in the temperature sensitivity of soil respiration between warmed or control treatments within other biomes (temperate forest, northern shrubland, southern shrubland, grassland and temperate agriculture). This finding suggests that acclimation of soil communities to warmer conditions is likely to have a greater impact for soil carbon dynamics in boreal forest and desert systems, while climatic warming will have little effect on other biomes. They also investigated the relationship between soil moisture, respiration rate and temperature, and found that the magnitude of the respiration response to warming decreased linearly with the degree of soil drying across the entire dataset.

Interestingly, they found a universal decline in the temperature sensitivity of respiration at soil temperature >25°C for non-desert biomes, while deserts have a higher temperature threshold at 55°C for reduced respiration. The significant difference in soil respiration in response to temperature could be due to a number of factors, such as different plant and microbial communities in the desert compared with other biomes, or abiotic decomposition as a major component of litter decomposition in deserts. Compared with lower latitudes, higher-latitude sites more often experience soil temperature <25°C, where soil respiration rates correlate positively with temperature. So higher attitudes will be more responsive to warmer temperatures. This study helps project future shifts for different geographic regions with the climatic warming. (Joanna C. Carey et al., PNAS)

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December 2, 2016 at 11:51 pm