Individual Interventions Improve Classroom Environment

Interventions targeted at individual students can improve the classroom environment and trigger a second wave of benefits for all classmates, new research shows. The findings, published in Psychological Science, a journal of the Association for Psychological Science, indicate that sharing a classroom with greater numbers of students who participate in a brief intervention can boost all students’ grades over and above the initial benefits of the intervention.

“Our results suggest that the whole effect of an intervention is more than the sum of its individual effects,” explains psychological scientist Joseph Powers of Stanford University, lead author on the study. “As a field, we’ve often focused on understanding and changing individual psychological processes, but these findings show that changing individual psychology can trigger important second-order effects with measurable benefits for everyone in the environment.”

To examine the potential emergent effects of educational interventions, Powers and colleagues analyzed data from two previous intervention studies conducted with 7th graders. Both studies involved a values affirmation exercise aimed at diminishing the threat of negative stereotypes related to African American students’ academic abilities.

The first study took place in 45 classrooms at the beginning of the school year. Participating students received a writing prompt from their teachers, who were not aware of the research hypothesis. The prompt instructed some students to write about their most important values, such as friends or artistic ability; these students were in the intervention group. Other students, assigned to the control group, received a prompt instructing them to write about their least important values. After about 15 minutes of writing, the students placed their responses in envelopes, which were collected by their teachers.

On average, about half of the students in each classroom participated in the study. Importantly, the students believed that the exercise was a typical writing assignment for class.

Previous research by members of this team found that writing about their most important values at the beginning of the year helped insulate students from negative stereotypes about their racial groups and thereby boosted the grades of African American students but not those of White students, as the researchers had predicted.

The new analyses by Powers and colleagues showed that individual student grades also improved just from being in classrooms with a greater proportion of African Americans who received the intervention. The results showed that the intervention effects didn’t just “spill over” to untreated students – rather, the classroom environment improved, and the improved environment benefited everyone in it.  For example, White students who saw no direct effects from the intervention still benefitted from the improved classroom environment, and African American students who directly benefited from the initial intervention also received a second wave of benefits from the improved classroom environment.

Intriguingly, the boost appeared to be especially strong for low-performing students of all races. The data indicate that adding just two African American students to the intervention group in a typical classroom improved the classroom environment enough that low-performing students’ grades increased, on average, by a third of a letter grade from a C to a C+.

The second study, conducted with a separate group of 7th graders in 15 different classrooms, confirmed these findings. And further analyses revealed that the classroom improvement effect was not influenced by various individual- and classroom-level factors, including student race, student intervention condition, and teacher team, in either study.

The researchers were surprised by the strength of these emergent effects, which were as large as or even larger than the direct effects that triggered them:

“It really makes you wonder how often we underestimate the full impact of social interventions,” says Powers.

Powers and colleagues plan on exploring these effects further to investigate the mechanisms that drive these emergent effects and the conditions that may limit them. They posit that the intervention may lead to strong indirect effects by strengthening classroom norms of cooperation, order, and growth in ways that benefit all students in the class.

Study co-authors include Jonathan Cook of Pennsylvania State University, Valerie Purdie-Vaughns of Columbia University, Julio Garcia of Stanford University, Nancy Apfel of Yale University, and Geoffrey L. Cohen of Stanford University.

This research was primarily funded by grants from the National Science Foundation (Research and Evaluation on Education in Science and Engineering division Award ID 0723909), the Spencer Foundation (Award 200800068), the William T. Grant Foundation, and the Russell Sage Foundation (Award 87-08-02). Additional support was provided by the Nellie Mae Education Foundation and the Institute for Social and Policy Studies of Yale University.

“Fat but Fit” Not Ok

A new study, published in the International Journal of Epidemiology [1], has dismissed the concept of ‘fat but fit’. In contrast, the results from the new study suggest that the protective effects of high fitness against early death are reduced in obese people.

Although the detrimental effects of low aerobic fitness have been well documented, this research has largely been performed in older populations. Few studies have investigated the direct link between aerobic fitness and health in younger populations. This study by academics in Sweden followed 1,317,713 men for a median average of 29 years to examine the association between aerobic fitness and death later in life, as well as how obesity affected these results. The subjects’ aerobic fitness was tested by asking them to cycle until they had to stop due to fatigue.

Men in the highest fifth of aerobic fitness had a 48 per cent lower risk of death from any cause compared with those in the lowest fifth. Stronger associations were observed for deaths related to suicide and abuse of alcohol and narcotics. Unexpectedly, the authors noted a strong association between low aerobic fitness and also deaths related to trauma. Co-author Peter Nordström has no explanation for this finding: “We could only speculate, but genetic factors could have influenced these associations given that aerobic fitness is under strong genetic control.”

The study also evaluated the concept that ‘fat but fit is ok’. Men of a normal weight, regardless of their fitness level, were at lower risk of death compared to obese individuals in the highest quarter of aerobic fitness. Nevertheless, the relative benefits of high fitness may still be greater in obese people. However, in this study the beneficial effect of high aerobic fitness was actually reduced with increased obesity, and in those with extreme obesity there was no significant effect at all.

With the limitation that the study cohort included only men, and relative early deaths, this data does not support the notion that ‘fat but fit’ is a benign condition.

Home Births: No Increase Risk of Complications

For women with low-risk pregnancies who plan to give birth at home with the help of a midwife, there is no increased risk of harm to the baby, compared with a planned hospital visit, according to new research in CMAJ (Canadian Medical Association Journal).

The study compared 11 493 planned home births and 11 493 planned hospital births in Ontario, Canada’s largest province, over 3 years to determine the risk of stillbirth, neonatal death or serious events among low-risk women. They included both first-time mothers (35%) and women who had previously given birth (65%).

“Among women who intended to birth at home with midwives in Ontario, the risk of stillbirth, neonatal death or serious neonatal morbidity was low and did not differ from midwifery clients who chose hospital birth,” writes Dr. Eileen Hutton, Department of Obstetrics and Gynecology and the Midwifery Education Program, McMaster University, Hamilton, Ontario, with coauthors.

In Ontario, about 10% of births are attended by midwives, and about 20% of these are at home.

In the study group, about 75% of the women who planned to give birth at home were able to, and about 97% of those who planned to give birth in hospital had their babies there. For the planned home birth cohort, 8% needed emergency medical services, as did 1.7% in the planned hospital group. Women in the hospital group were more likely to have interventions such as labour augmentation, assisted vaginal births or cesarean deliveries. The incidence of stillbirth or neonatal death was 1.15 per every 1000 births in the planned home birth group compared with 0.94 per 1000 in the planned hospital birth group.

“Compared with women who planned to birth in hospital, women who planned to birth at home underwent fewer obstetrical interventions, were more likely to have a spontaneous vaginal birth and were more likely to be exclusively breastfeeding at 3 and 10 days after delivery,” write the authors.

“As more women choose home birth and as the midwifery profession grows in Ontario, it will be interesting to see whether the lower intervention rates that have been consistently observed to date among women who plan home births are sustained.”

Ban on Tanning Bed Use By Under 18

The U.S. Food and Drug Administration (FDA) has proposed a ban on tanning bed use by those under 18. In 2013, a law was enacted in New Jersey banning those under the age of 17 from using tanning beds. Jerod L. Stapleton, PhD, is a behavioral scientist at Rutgers Cancer Institute of New Jersey and assistant professor of medicine at Rutgers Robert Wood Johnson Medical School, whose research aims to understand why young people frequently engage in indoor tanning.  He shares some insight into the concern by medical professionals about the risks of this practice – especially by teens and young adults.

Q:  The FDA also proposed that adults sign a waiver indicating they understand the risks associated with using a tanning bed.  Is the risk the same for adults and teens?

A: The artificial ultraviolet radiation emitted from tanning beds can cause the type of skin damage that can become skin cancer.  This type of damage occurs for anyone who uses a tanning bed regardless of their age.

Q:  What is the concern with people under 18 in particular in using tanning beds?

A: Many scientific studies show the risk of skin cancer from using tanning beds is greater among people who start using tanning beds at a younger age and report longer periods of prolonged use.  Young women are the most likely group to become prolonged users of tanning beds and many first engage in indoor tanning as teenagers.  The steady rise in melanoma rates among young adult females in the United States and in several European countries is a particularly concerning reason to enact additional restrictions related to indoor tanning.

Q:  What is the significance of the FDA proposed ban in light of existing and ongoing indoor tanning laws?

A: State-level laws that restrict or ban access to indoor tanning beds widely vary across the country.  Some states have no restrictions on indoor tanning or instead of bans rely on parental consent laws, which studies suggest may not be effective in preventing minors from using indoor tanning beds.  An FDA ban would provide necessary protection for all U.S. minors from harmful tanning beds and would represent a significant public health improvement.

Q:  Your research examines why young people engage in this practice.  What are some of your findings?

A: In my research with young women who regularly engage in indoor tanning, it’s clear that being tan is a fundamentally important part of being an attractive person.  As a result, these young women think about tanning a lot and are unhappy with their appearance around others when they are not tan. In addition, it’s interesting to see indoor tanning is often a social experience, as many young women go to the salon with a group of friends.  For these tanners, the benefits of tanning outweigh the health risks.

Q:  Are there any effective ways to encourage people to stop using indoor tanning beds?

A: Tanners may be reluctant to stop if being tan is an important part of their identity or if tanning is part of their relationships with friends.  I recently tested an internet-based intervention designed to encourage women to reconsider the importance they placed on tanning in light of the harmful effects and to consider alternative ways to achieve some of the benefits of indoor tanning.  We found encouraging results, as women who viewed the intervention reported less tanning behavior compared to a group who did not receive the intervention.

The U.S. Food and Drug Administration (FDA) has proposed a ban on tanning bed use by those under 18. In 2013, a law was enacted in New Jersey banning those under the age of 17 from using tanning beds. Jerod L. Stapleton, PhD, is a behavioral scientist at Rutgers Cancer Institute of New Jersey and assistant professor of medicine at Rutgers Robert Wood Johnson Medical School, whose research aims to understand why young people frequently engage in indoor tanning.  He shares some insight into the concern by medical professionals about the risks of this practice – especially by teens and young adults.

Q:  The FDA also proposed that adults sign a waiver indicating they understand the risks associated with using a tanning bed.  Is the risk the same for adults and teens?

A: The artificial ultraviolet radiation emitted from tanning beds can cause the type of skin damage that can become skin cancer.  This type of damage occurs for anyone who uses a tanning bed regardless of their age.

Q:  What is the concern with people under 18 in particular in using tanning beds?

A: Many scientific studies show the risk of skin cancer from using tanning beds is greater among people who start using tanning beds at a younger age and report longer periods of prolonged use.  Young women are the most likely group to become prolonged users of tanning beds and many first engage in indoor tanning as teenagers.  The steady rise in melanoma rates among young adult females in the United States and in several European countries is a particularly concerning reason to enact additional restrictions related to indoor tanning.

Q:  What is the significance of the FDA proposed ban in light of existing and ongoing indoor tanning laws?

A: State-level laws that restrict or ban access to indoor tanning beds widely vary across the country.  Some states have no restrictions on indoor tanning or instead of bans rely on parental consent laws, which studies suggest may not be effective in preventing minors from using indoor tanning beds.  An FDA ban would provide necessary protection for all U.S. minors from harmful tanning beds and would represent a significant public health improvement.

Q:  Your research examines why young people engage in this practice.  What are some of your findings?

A: In my research with young women who regularly engage in indoor tanning, it’s clear that being tan is a fundamentally important part of being an attractive person.  As a result, these young women think about tanning a lot and are unhappy with their appearance around others when they are not tan. In addition, it’s interesting to see indoor tanning is often a social experience, as many young women go to the salon with a group of friends.  For these tanners, the benefits of tanning outweigh the health risks.

Q:  Are there any effective ways to encourage people to stop using indoor tanning beds?

A: Tanners may be reluctant to stop if being tan is an important part of their identity or if tanning is part of their relationships with friends.  I recently tested an internet-based intervention designed to encourage women to reconsider the importance they placed on tanning in light of the harmful effects and to consider alternative ways to achieve some of the benefits of indoor tanning.  We found encouraging results, as women who viewed the intervention reported less tanning behavior compared to a group who did not receive the intervention.

Excess Body Fat Harms Bone Growth

Studies have shown that obese children tend to have more muscle, but recent University of Georgia research on the muscle and bone relationship shows that excess body fat may compromise other functions in their bodies, such as bone growth.

In a literature review, lead author Joseph Kindler studied how muscle can influence different characteristics of bone geometry and strength in children. The review was published in the journal Current Opinion in Endocrinology, Diabetes and Obesity.

For this particular review, researchers were interested in looking at the geometry of bones—the measures of size and strength of the bone—particularly for children and adolescents. Kindler pulled together previously published findings to give an up-to-date look at how muscle influences bone geometry and bone strength during youth. The role of fat in these relationships was also investigated.

Based on the research they gathered, muscle was a strong contributor to bone growth throughout childhood and adolescence. However, this relationship may differ in children with greater body fat.

“It’s a common understanding that, in children, muscle is a very strong determinant of how bone is going to grow,” said Kindler, a doctoral candidate at UGA’s College of Family and Consumer Sciences’ department of foods and nutrition. “Obese children will tend to have more muscle, so we would suspect that they would also have larger, stronger bones.”

What researchers found during the review was less clear.

The excess fat that accompanies obesity can be deposited within the muscle. There is emerging evidence that suggests this fat within the muscle may have an effect on how the bone grows, according to the review. Understanding how excess fat, specifically that within the muscle, can influence the muscle and bone relationship in children is still under investigation, but there is clearly a connection, Kindler said.
“It’s an emerging area of research,” he said.

Kindler typically studies the different ways to measure bone—bone geometry being less studied than the commonly reported bone density. With bone geometry, researchers are able to determine the spatial distribution of the bone and how tightly packed an individual’s bone mineral content is in his or her body.

These bone geometric features can tell researchers just how strong a bone is.

“These were the skeletal characteristics we were looking for in this review, particularly in children,” Kindler said.

In the study, they also identified where gaps in research still remain.
“This paper summarizes the literature that’s been published. We know that muscle is such an important contributor to bone development,” Kindler said. “But it also shows that our understanding of how fat influences these relationships is still unclear.”

The authors hope to use the review to identify and fill holes in these research gaps, particularly understanding these problems in children.

“One of our major goals is to understand how obesity-related conditions, like the progression of Type 2 diabetes, can influence muscle and bone growth in children,” Kindler said.

Because of the potential harmful connection between body fat and bone growth, Kindler recommends that children strive to live a healthy lifestyle through proper diet and physical activity.

Additional study co-authors are Richard Lewis, a professor of foods and nutrition at UGA’s College of Family and Consumer Sciences, and Mark Hamrick, a professor of cellular biology and anatomy at Georgia Regents University.

The study, “Skeletal muscle and pediatric bone development,” is available online at http://www.ncbi.nlm.nih.gov/pubmed/26414082.

Virtual Reality Helps Avoid Road Hazards for Child-Pedestrians

“Look both ways before you cross the street” may be sage advice, but it is also apparently necessary for children as old as 13, according to a new study by BGU researchers, who have pinpointed many of the behaviors that lead to child-pedestrians being hit by cars.

Traffic accidents are one of the most common sources of injuries and fatalities for children on foot around the world. In Israel, automobiles cause 20 percent of child deaths.

The study, published in the online journal Safety Science (Elsevier), was conducted at the BGU Virtual Environment Simulation Laboratory, one of the world’s most sophisticated traffic research facilities, which enables researchers to measure pedestrian reactions to virtual reality scenarios.

“While we already knew that children were less able than adults to recognize road crossing hazards, our goal was to pinpoint which behaviors might lead to accidents and develop training to correct them,” explains Anat Meir, Ph.D., a lecturer in the BGU Department of Industrial Engineering and Management.

The study examined experienced-based hazard perception differences among child-pedestrians and relative to experienced adults. Overall, the experimental design included groups of seven to nine-year-olds, nine to 10-year-olds, 10 to 13-year-olds, and experienced adult pedestrians. The study simulated 18 prototypical streets in Israel and used an eye-tracking device to study how 46 adults and children evaluated when it was safe to cross. Participants’ eye movements were recorded to identify areas or objects of interest and unique behaviors.

“As predicted, we found that child-pedestrians age seven to 10 had the most difficulty in identifying when it was safe to cross and recognizing hazards caused by parked vehicles or curvature in the road that restricts field of view,” Dr. Meir explains.

Older children did not perform much better and lingered on the curb for an excessive amount of time, which indicates that they are less able to distinguish between safe and hazardous situations than adults. In interviews, the children did not express an understanding of how crossing safety could be impacted by factors such as car speed and field of vision.

“These results can serve as a tool to construct a hazard perception training intervention for youngsters,” Meir says. “Moreover, the differences that emerged between the various age groups reinforce that child-pedestrians cannot be trained as a group, but rather the training needs to be adjusted to the level of experience the child has gained.”

More effective training based on Meir’s research may already be working. She recently conducted another study on hazard detection training of seven to nine-year-olds, and then compared their performance to untrained children. The children who had undergone training faired significantly better, approaching the skills of an adult pedestrian.

Other researchers involved in the study include Prof. Tal Oron-Gilad and Dr. Yisrael Parmet of the Ben-Gurion University of the Negev Department of Industrial Engineering and Management.

‘Pill Mill’ Crackdown Dramatically Reduced Drugs Overdose Deaths

A crackdown on Florida’s “pill mills” – clinics dispensing large quantities of prescription painkillers often for cash-only and without proper medical examinations – appears to have dramatically reduced the number of overdose deaths in the state from these drugs and may have also led to a drop in heroin overdose deaths, new research suggests.

The Johns Hopkins Bloomberg School of Public Health researchers, publishing their findings in the American Journal of Public Health, say an estimated 1,029 fewer people in Florida lost their lives to prescription painkiller overdoses over a 34-month period than would have had the state not taken aim at pill mills. Florida passed new laws in 2010 and 2011 establishing oversight over pain clinics and restricting the dispensing of opioids there, while major drug law enforcement initiatives arrested and prosecuted those operating them.

The researchers also found substantially fewer deaths in Florida from overdoses involving either prescription painkillers or heroin during 2011 and 2012, a finding that calls into question claims that reducing prescription painkiller diversion will increase overall heroin use. Rates of prescription painkiller addiction are at historic highs and a portion of those abusing these medications have switched to heroin, which can be cheaper and, in some cases, easier to obtain. Other research has found that four out of five new heroin users first used prescription painkillers. What could be happening in Florida, they say, is that with less access to prescription painkillers, fewer people may be developing an addiction, which in turn may prevent people from later transitioning to heroin.

“Florida’s focus on these pill mills seems to have been an effective way to reduce overdose deaths in the state,” says study leader Alene Kennedy-Hendricks, PhD, an assistant scientist in the Bloomberg School’s Department of Health Policy and Management. “An added benefit of Florida’s increased oversight of unethical businesses and providers dispensing large quantities of narcotics may be that they may have prevented new cases of heroin addiction from developing as well. Other states should consider restrictions on pill mills as one potential way to reduce prescription painkiller overdose deaths.”

In 2010, of the top 100 physicians purchasing the most oxycodone in the United States, 90 were in Florida. Much of the dispensing was done in cash-only pill mills where standard medical practices were rarely followed.

For the study, Kennedy-Hendricks and her colleagues compared Florida, before and after the implementation of pill mill laws, with North Carolina, a state with similar trends of prescription painkiller overdose death rates before 2010 and with no new restrictions on pill mills during the study period. They analyzed data on 11,721 Florida deaths and 3,787 North Carolina deaths between 2003 and 2012 in which an opioid (either a prescription painkiller or heroin) was identified as the primary cause of death.

They examined changes in trends in death rates in North Carolina and pre-2010 trends in Florida to predict how many deaths were likely to have occurred in Florida had there not been this effort to rein in pill mills. Over the nearly three years, they estimated that 1,029 lives were saved in Florida, and the number of estimated lives saved grew dramatically each year as new measures were instituted to reduce pill mill operations in the state. From March 2010 until December of that year, the prescription painkiller overdose death rate in Florida was 7.4 percent lower than would have been expected absent Florida’s interventions, 20.1 percent lower in 2011 and 34.5 percent lower in 2012.

Heroin overdose mortality rates rose in each state at the beginning of 2011, but North Carolina’s rate of heroin overdose deaths increased much more rapidly than Florida’s rates. North Carolina’s rate continued to rise, increasing four-fold from early 2011 to late 2012. In contrast, Florida’s rate of increase in heroin overdose mortality rates during this period was substantially lower.

Previous research has also found that since 2010, Florida has seen substantial reductions in oxycodone-prescribing physicians, opioid prescribing and the diversion of prescription painkillers to people for whom they are not prescribed.

“This study underscores that the sharp rise in prescription opioid overdose deaths has become a public health epidemic that is driven, in part, by major criminal enterprises,” says co-author Daniel Webster, ScD, MPH, a professor of health policy and management at the Bloomberg School. “Our new study demonstrates that the right laws and strategic enforcement can prevent addiction and save many lives.”

Expanding distribution of naloxone (a drug that can reverse the effects of an overdose) and implementing evidence-based, medication-assisted treatment programs for opioid use disorders may also reduce overdose deaths, the researchers say.

“Opioid overdose deaths and Florida’s crackdown on pill mills” was written by Alene Kennedy-Hendricks, PhD; Matthew Richey, PhD; Emma E. “Beth” McGinty, PhD, MS; Elizabeth A. Stuart, PhD; Colleen L. Barry, PhD, MPP; and Daniel W. Webster, ScD, MPH.

This study was funded by an unrestricted research grant from AIG Inc.

Vitamin A and Colon Cancer

A leading cause of cancer deaths worldwide, colon cancer is famously resistant to treatment. There are many reasons for this, but one has to do with a group of persisting cancer cells in the colon that cause relapses. Conventional therapies against them are mostly ineffective. EPFL scientists have now identified a biological mechanism that can be exploited to counteract colon cancer relapses. The approach activates a protein that is lost in the persisting cancer cells. The researchers were able to reactivate it using vitamin A, thus eliminating the cancer cells and preventing metastasis. The study is published in Cancer Cell, and introduces a new way to treat colon cancer.

When a colon-cancer patient receives treatment, e.g. chemotherapy, most of the cancer cells die off. But the genetic mutations that caused the cancer in the first place can survive in a specific group of cells of the colon. These are actually stem cells, meaning that they are premature cells waiting to grow into full-blown, normal cells of the colon. After cancer treatment ends, the surviving stem cells, still containing the cancerous mutations, can reappear and cause a relapse.

The lab of Joerg Huelsken at EPFL studied how differentiated colon cells come from stem cells in the gut. Using an array of different techniques, the team looked at cells, mouse models and samples from human patients.

Proteins and signaling pathways

The study focused on a protein called HOXA5, which belongs to a family of proteins that regulate the development of the fetus. These proteins are made during early development and work together to make sure that every tissue is correctly identified and that the fetus’s body and limbs are patterned properly. In the adult body, proteins like HOXA5 regulate the body’s stem cells to maintain both the identity and function of different tissues. Huelsken’s team found that in the gut, HOXA5 plays a major role in restricting the number of stem cells, as well as the cells that make them.

Like all proteins, HOXA5 originates from a specific gene. The study showed that the cancerous stem cells of the colon use a biological mechanism that blocks it. This mechanism is called a “signaling pathway” because it involves a domino of molecules, each activating the next one down the line. The purpose of a signaling pathway is to transmit biological information from one part of the cell to another, e.g. from the outer membrane all the way to the nucleus. By blocking the HOXA5 gene, the cancerous stem cells of the colon can grow uncontrollably and spread, causing relapses and metastasis.

Retinoids: a way to fight back

The researchers looked for ways to reverse the blocking of HOXA5. The answer came from vitamin A. This small chemical structure is called a retinoid, and it has been known to induce differentiation of stem cells in the skin. The EPFL scientists found that retinoids can re-activate HOXA5. In mice that had colon cancer, the treatment with retinoids blocked tumor progression and normalized the tissue. By turning the gene for HOXA5 back on, this treatment eliminated cancer stem cells and prevented metastasis in the live animals. The researchers got similar results with samples from actual patients.

The new study suggests that patients that may profit from this well-tolerated treatment can be identified based on their expression pattern for the HOXA5 gene. Retinoid differentiation therapy could be significantly effective against colon cancer, not only for treatment of existing disease but also as a preventive measure in high-risk patients.

One-Size Fits All Vaccine Strategy Not Effective

In the face of a flu epidemic, a one-size fits all vaccine strategy won’t be effective, a York University study has found. Instead, strategies need to change significantly depending on the characteristics of each region in Canada and how easily the particular flu strain spreads.

“The window of time around the onset of the epidemic is going to be vastly different between a remote population and an urban one, and this is something public health needs to pay attention to when developing vaccine strategies,” says York U researcher and study lead Seyed Moghadas. “Different populations require different vaccination policies to minimize the impact of the disease.”

The study, published today in the journal Scientific Reports by Nature, looked at which strategies produce the lowest number of infections and lead to the least number of hospitalizations.

“Studies such as this, that combine big data and computer simulations, have the potential to inform evidence-based decision-making in public health,” said Marek Laskowski, a York U researcher involved in the study.

The research found that the different age demographics of remote and urban populations have a significant impact on the outcome of vaccinations. Many remote areas of the country have a higher percentage of children, who are key transmitters of the virus, compared with urban centres, which generally have fewer children, but more young and middle-aged adults.

The research looked at how the different areas responded when the flu vaccine was given in either a single dose or two doses before, during and after the start of the epidemic.
The study found that for most strategies the attack rates of the virus in the urban population was lowest for children under five, but in the remote population, adults older than 50 had the lowest attack rates. But those attack rates varied depending on when and how the vaccinations were given.

There is a window of time before and after the onset of an epidemic when the choice of vaccination strategy could significantly affect the outcome, said Moghadas.

Demographic variables could play an important role in determining which strategy to use.

“In all strategies for a highly transmissible virus, delivering the vaccine after the start of the epidemic had no or minimal effect,” he said. Even with the usual seasonal flu virus, if the vaccine was given after the virus has started to spread, it has little effect on who and how many people get sick.

Early vaccination leads to the best outcomes from both a public health and socioeconomic perspective, he said. It reduces the rates of infection, hospitalization and death, along with stress on the healthcare system.

The research is significant especially in light of new technologies that promise quicker production of flu vaccines, unlike the current egg-based technology which takes four to six months.

“In the case of epidemic emergencies, that’s actually a very long process. A time line of six months for vaccine production means it is basically the end of the epidemic by the time we get the vaccine,” said Moghadas.

As new technology allows for faster vaccines, strategies to distribute them quickly need to be in place and those strategies will depend on the makeup of each region.

Study: Limited Access of Food Leads to Increase Food Intake

Rats with restricted feeding schedules learn to eat more, helped by the “hunger hormone” ghrelin, according to new research from the University of Southern California.

The insights, to be published in the journal eLife, could be valuable for helping the researchers develop new effective weight-loss therapies.

“We are looking deep into the higher order functions of the brain to unpick not just which hormones are important for controlling our impulses but exactly how the signals and connections work,” says lead author Scott Kanoski from the USC Dornsife College of Letters, Arts and Sciences.

In the current study by Kanoski, Ted Hsu and colleagues, once the rats learn they have limited access to food, they are able to increase their food intake until it doubles. Over several days, meal times were restricted to a daily four-hour window, followed by 20 hours with no food. The hormone ghrelin allows the rats to reduce their feeling of fullness, so they are gradually able to eat more.

“This is an adaptive response to limited food access, but one that is no longer relevant in the Western world, where instead we need to find new ways to help us fight some of the feeding responses we have to external cues and circadian patterns,” says Kanoski.

The current study provides a rare insight into the way ghrelin communicates with the central nervous system to control how much food is consumed. The hippocampus, a region of the brain that controls memory and motivation, is understood to be linked to the way that anticipation of food can increase intake.

The system uncovered here is that ghrelin communicates with neurons from the hippocampus to stimulate appetite and allow a large amount of food to be eaten in a limited amount of time. These neurons then communicate with another part of the brain, the hypothalamus, to produce the molecule orexin, which further promotes hyperphagia, or excessive eating.

In previous research, Kanoski and colleagues found that ghrelin signals to the hippocampus to increase rats’ food intake in response to a visual signal they have learned to associate with an imminent meal. The human equivalent might be a fast-food billboard sign or vending machine that triggers a cascade of signals that can be hard to resist. So, as well as increasing the ability of circadian cues to influence feeding behaviour, as in the current study, ghrelin can increase the ability of external cues to increase food consumption.

Ghrelin has also been found to increase the rate at which nutrients pass through the body, something that is best to happen slowly in order to feel fuller for longer. Understanding this system as a whole is important for finding ways to thwart it.

The team are now experimenting with ways to reduce ghrelin’s effect by genetically suppressing the activity of the ghrelin receptor in the hippocampus. This in turn disrupts the neurochemical signals that can facilitate the consumption of large quantities of food.

“Over a third of Americans are obese and another third are overweight, so we feel we have an obligation to help identify new ways to reduce the burden on society and on our healthcare systems,” says Kanoski.