Children's books still show bias toward male protagonists, analysis finds

"Children's stories are incredibly important to a child's development," says Stella Lourenco, Emory associate professor of psychology and senior author of the study.

By Carol Clark

A major analysis of children’s books published during the last 60 years suggests that a bias persists toward male protagonists — despite an overall trend for an increasing proportion of female leads.

PLOS ONE published the results of the analysis, conducted at Emory University, and focused on books that feature a single main character. 

The bias toward male protagonists remained slight in the books overall, at a rate of 1.2 to 1 in the last decade. When broken down by variables and including all publication years, however, some larger gaps were seen. Among male authors overall, for instance, across the six decades the bias toward male protagonists occurred at a rate of 3 to 1. 

“While gender bias in children’s books appears to have declined significantly over the years, we found that bias remains,” says Stella Lourenco, Emory associate professor of psychology and senior author of the study. “We worry about what this mismatch communicates to children, particularly to girls. It’s concerning because disproportionate gender representation in children’s books may contribute to the persistence of biases in society.” 

First author of the study is Kennedy Casey, who did the work through an internship in the Lourenco lab while she was an undergraduate at Princeton University. Kylee Novick, an Emory senior in the Lourenco lab, is co-author of the paper. 

The statistical analysis included 3,280 books, aimed for audiences aged 0 to 16 years, that could be purchased online in the United States, either as hard copies or digitally. The analysis broke down the results by a range of variables, such as the target age group, categories of fiction or non-fiction, whether the protagonist is human or non-human, and by the gender of the authors. 

“We hope our data can provide insights for parents and teachers,” Lourenco says. “We also hope that publishers see our results and do what they can to encourage more equitable gender representation in children’s books.” 

Lourenco’s research focuses on spatial perception and cognition, including sex and socioeconomic differences. 

The largest known gender difference in cognition occurs in visual-spatial reasoning, including the ability to mentally rotate objects. On average, men outperform women on this task of imagining multi-dimensional objects from different points of view. 

A major meta-analysis by the Lourenco lab, however, found that men are not born with this advantage. Instead, males gain a slight advantage in mental-rotation performance during the first years of formal schooling, and this advantage slowly grows with age, tripling in size by the end of adolescence. That finding suggests that other factors besides intrinsic gender differences in spatial reasoning may be at play. 

“One of the focuses of my lab is trying to understand the mechanisms that underlie such gender differences,” Lourenco says. “That includes potential environmental influences that may affect your motivation, confidence and anxiety levels when you’re performing various tasks.”

The researchers decided to explore gender in protagonists of children’s books because a major analysis on that topic did not appear to have been conducted since 2000. 

The results showed that non-fiction books have a greater degree of gender bias for males than do fiction books. And male character bias is higher for fiction featuring non-human characters than for fiction with human characters. 

Books by male authors showed a decline over time in bias for males, but only in books targeted toward younger children. Female authors also declined in male character bias over time, even overrepresenting female characters in books targeted to older children. Female authors continued to favor male leads, however, in books with non-human protagonists. 

Many factors are likely driving the differences in these variables, Lourenco says. For instance, books featuring actual historical characters who were scientists would likely show a bias toward male protagonists, since most scientists in history have been men. 

The current analysis was limited in that it only looked at books focused on a single main character, and it did not consider how the character was depicted in the narrative. 

“As a next step, I hope we can do precise, rigorous experiments on what books children are actually reading and learn what kind of impact the gender representation in those books may have on the children’s attitudes about themselves,” Lourenco says. 

She hopes other researchers will also build off the analysis to study other remaining questions in gender representation in children’s books, including examining trends in the representation of non-binary protagonists. 

“Children’s stories are incredibly important to a child’s development,” Lourenco says. “Exposure to books is a form of enculturation, in addition to building language and reading skills. Children look to stories for inspiration and for role models.”

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How grandmothers' brains react to the sight of their grandchildren

"We're highlighting the brain functions of grandmothers that may play an important role in our social lives and development," says Minwoo Lee, an Emory graduate student and co-author of the study. "It's an important aspect of the human experience that's been largely left out of the field of neuroscience."

By Carol Clark

Many people lucky enough to have grown up with doting grandmothers know that they can burnish a child’s development in unique and valuable ways. Now, for the first time, scientists have scanned grandmothers’ brains while they’re viewing photos of their young grandchildren — providing a neural snapshot of this special, inter-generational bond. 

Proceedings of the Royal Society B published the first study to examine grandmaternal brain function, conducted by researchers at Emory University. 

“What really jumps out in the data is the activation in areas of the brain associated with emotional empathy,” says James Rilling, lead author and professor in Emory's Department of Anthropology and Department of Psychiatry and Behavioral Sciences. “That suggests that grandmothers are geared toward feeling what their grandchildren are feeling when they interact with them. If their grandchild is smiling, they’re feeling the child’s joy. And if their grandchild is crying, they’re feeling the child’s pain and distress.” 

In contrast, the study found that when grandmothers view images of their adult child, they show stronger activation in an area of the brain associated with cognitive empathy. That indicates they may be trying to cognitively understand what their adult child is thinking or feeling and why, but not as much from the emotional side. 

“Young children have likely evolved traits to be able to manipulate not just the maternal brain, but the grand maternal brain,” Rilling says. “An adult child doesn’t have the same cute ‘factor,’ so they may not illicit the same emotional response.” 

Co-authors of the study are Minwoo Lee, a PhD candidate in Emory’s Department of Anthropology, and Amber Gonzalez, a former Emory research specialist. 

"What really jumps out in the data is the activation in areas of the brain associated with emotional empathy," Rilling says.

“I can relate to this research personally because I spent a lot of time interacting with both of my grandmothers,” Lee says. “I still remember warmly the moments I had with them. They were always so welcoming and happy to see me. As a child, I didn’t really understand why.” 

It’s relatively rare, Lee adds, for scientists to study the older human brain outside of the problems of dementia or other aging disorders. 

“Here, we’re highlighting the brain functions of grandmothers that may play an important role in our social lives and development,” Lee says. “It’s an important aspect of the human experience that has been largely left out of the field of neuroscience.” 

Rilling’s lab focuses on the neural basis of human social cognition and behavior. Motherhood has been extensively studied by other neuroscientists. Rilling is a leader in researching the lesser-explored neuroscience of fatherhood. 

Grandmothers interacting with grandchildren offered new neural territory. 

“Evidence is emerging in neuroscience for a global, parental caregiving system in the brain,” Rilling says. “We wanted to see how grandmothers might fit into that pattern.” 

Humans are cooperative breeders, meaning that mothers get help caring for their offspring, although the sources of that help vary both across and within societies. 

“We often assume that fathers are the most important caregivers next to mothers, but that’s not always true,” Rilling says. “In some cases, grandmothers are the primary helper.” 

In fact, the “grandmother hypothesis” posits that the reason human females tend to live long past their reproductive years is because they provide evolutionary benefits to their offspring and grandchildren. Evidence supporting this hypothesis includes a study of the traditional Hadza people of Tanzania, where foraging by grandmothers improves the nutritional status of their grandchildren. Another study of traditional communities showed that the presence of grandmothers decreases their daughters’ interbirth intervals and increases the number of grandchildren. 

And in more modern societies, evidence is accumulating that positively engaged grandmothers are associated with children having better outcomes on a range of measures, including academic, social, behavior and physical health. 

"If their grandchild is smiling, they're feeling the child's joy," Rilling says. "And if their grandchild is crying, they're feeling the child's pain and distress."

For the current study, the researchers wanted to understand the brains of healthy grandmothers and how that may relate to the benefits they provide to their families. 

The 50 participants in the study completed questionnaires about their experiences as grandmothers, providing details such as how much time they spend with their grandchildren, the activities they do together and how much affection they feel for them. They also underwent functional magnetic resonance imaging (fMRI) to measure their brain function as they viewed pictures of their grandchild, an unknown child, the same-sex parent of the grandchild, and an unknown adult. 

The results showed that, while viewing pictures of their grandchildren, most participants showed more activity in brain areas involved with emotional empathy and movement, compared to when they were viewing the other images. 

Grandmothers who more strongly activated areas involved with cognitive empathy when viewing pictures of their grandchild reported in the questionnaire that they desired greater involvement in caring for the grandchild. 

Finally, compared with results from earlier study by the Rilling lab of fathers viewing photos of their children, grandmothers more strongly activated regions involved with emotional empathy and motivation, on average, when viewing images of their grandchildren. 

“Our results add to the evidence that there does seem to be a global parenting caregiving system in the brain, and that grandmothers’ responses to their grandchildren maps onto it,” Rilling says. 

One limitation to the study, the researchers note, is that the participants skewed towards mentally and physically healthy women who are high-functioning grandmothers. 

The study opens the door to many more questions to be explored. “It would be interesting to also look at the neuroscience of grandfathers and how the brain functions of grandparents may differ across cultures,” Lee says. 

An especially gratifying aspect of the project for Rilling was personally interviewing all the participants himself. “It was fun,” he says. “I wanted to get a sense of the rewards and challenges of being a grandmother.” 

The main challenge many of them reported was trying not to interfere when they disagreed with the parents over how their grandchildren should be raised and what values should be instilled in them. 

“Many of them also said how nice it is to not be under as much time and financial pressure as they were when raising their children,” Rilling says. “They get to enjoy the experience of being a grandmother much more than they did being parents.” 

This work was supported in part by the Silvia O. Conte Center for Oxytocin and Social Cognition.

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Biological studies often misinterpret sex-based data, analysis finds

"At this moment in history, the stakes are high," says Emory neuroscientist Donna Maney, senior author of the analysis. "Misreported findings may affect health care decisions in dangerous ways."

By Carol Clark

An analysis of published studies from a range of biological specialties shows that, when data are reported by sex, critical statistical analyses are often missing and the findings are likely to be reported in misleading ways. 

The journal eLife published the analysis, done by neuroscientists at Emory University, encompassing studies from nine different biological disciplines that involved either human or animal subjects. 

“We found that when researchers report that males and females respond differently to a manipulation such as a drug treatment, 70 percent of the time the researchers have not actually compared those responses statistically at all,” says senior author Donna Maney, a professor of neuroscience in Emory’s Department of Psychology. “In other words, an alarming percentage of claims of sex differences are not backed by sufficient evidence.” 

In the articles missing the proper evidence, she adds, sex-specific effects were claimed in nearly 90 percent of the cases. In contrast, authors that tested statistically for sex-specific effects reported them only 63 percent of the time. 

‘’Our results suggest that researchers are predisposed to finding sex differences and that sex-specific effects are likely over-reported in the literature,” Maney says. 

This particular problem is common and pertains to Maney’s own previous work, she adds. “Once I realized how prevalent it is, I went back and checked my own published articles and there it was,” she says. “I myself have claimed a sex difference without comparing males and females statistically.”

Maney stresses that the problem should not be discounted just because it is common. It is becoming increasingly serious, she says, because of mounting pressure from funding agencies and journals to study both sexes, and interest from the medical community to develop sex-specific treatments. 

Maney is a behavioral neuroendocrinologist interested in how research on sex differences shapes public opinion and policy. Rigorous standards are needed, she says, to ensure that people of all genders have access to care that is appropriate for them. 

Yesenia Garcia-Sifuentes, an Emory PhD candidate in the Graduate Program in Neuroscience, is co-author of the eLife analysis. 

Better training and oversight are needed to ensure scientific rigor in research on sex differences, the authors write: “We call upon funding agencies, journal editors and our colleagues to raise the bar when it comes to testing for and reporting sex differences.” 

More studies including sex-based variables 

Historically, biomedical research has often included just one sex, usually biased toward males. In 1993, Congress wrote a policy into law to ensure that women are included in clinical studies funded by the National Institutes of Health whenever feasible, and that the studies be carried out so that it is possible to analyze whether the variables being studied affect women differently than other participants. 

In 2016, the NIH announced a policy that also requires the consideration of sex as a biological variable when feasible in basic biological studies that it funds, whether that research involves animals or humans. 

“If you’re trying to model anything relevant to a general population, you should include both sexes,” Maney explains. “There are a lot of ways that animals can vary, and sex is one of them. Leaving out half of the population makes a study less rigorous.” 

As more studies consider sex-based differences, Maney adds, it is important ensure that the methods underlying their analyses are sound. 

For the eLife analysis, Garcia-Sifuentes and Maney looked at 147 studies published in 2019 to investigate what is typically used as evidence of sex differences. The studies ranged across nine different biological disciplines and included everything from field studies on giraffes to immune responses in humans. 

The studies that were analyzed all included both males and females and separated the data by sex. Garcia-Sifuentes and Maney found that the sexes were compared, either statistically or by assertion, in 80 percent of the articles. And, within those articles, sex differences were reported in 70 percent of them and treated as a major finding in about half of those. 

Some of the studies that reported a sex difference, however, committed a statistical error. For example, if researchers found a statistically significant effect of a treatment on one sex but not the other, they typically concluded a sex difference even if the effect of the treatment was not compared statistically between males and females. 

The problem with that approach is that the statistical tests conducted on each sex can’t give “yes” or “no” answers about whether the treatment had an effect. 

“Comparing the outcome of two independent tests is like comparing a ‘maybe so’ with an ‘I don’t know’ or ‘too soon to tell,’” Maney explains. “You’re just guessing. To show actual evidence that the response to treatment differed between females and males, you need to show statistically that the effect of treatment depended on sex. That is, to claim a ‘sex-specific’ effect, you must demonstrate that the effect in one sex was statistically different from the effect in the other.” 

On the flip side, the eLife analysis also encountered strategies that could mask sex differences, such as pooling data from males and females without testing for a difference. Maney recommends reporting the size of the difference — that is, the extent to which the sexes don’t overlap — before pooling data. She provides a free online tool that lets researchers visualize their data to assess the size of the difference. 

“At this moment in history, the stakes are high,” Maney says. “Misreported findings may affect health care decisions in dangerous ways. Particularly in cases where sex-based differences may be used to determine what treatment someone gets for a particular condition, we need to proceed cautiously. We need to hold ourselves to a very high standard when it comes to scientific rigor.”

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Into the heart of brightness: An ethnobotanist's memoir celebrates a life in science

"We have barely scratched the surface of the medicinal value of plants," says Emory ethnobotanist Cassandra Quave, shown in the field in South Georgia.

Cassandra Quave's story is like a tropical forest: Varied, colorful, bursting with life and and laced with hidden pathways that must be constantly cleared to move along them. Her new memoir guides readers through a world of plants and the people entwined with them. The story is sometimes dark but mostly uplifting, lit up by her personal revelations and scientific discoveries.

"The Plant Hunter: A Scientist's Quest for Nature's Next Medicines" was recently published by Viking. 

"I was inspired to write the book because people have found my work interesting," says Quave, associate professor in Emory's Center for the Study of Human Health and the School of Medicine. "It's a chance to tell the larger story of my life, bringing together all of the different parts of it."

Read more here.

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Youth views on climate crisis take world stage

Emory students and alumni are raising diverse voices on equity during the United Nations Conference of the Parties on Climate Change (COP26) now underway in Glasgow. This year, Emory is not sending an in-person student delegation, due to the pandemic and related concerns, says Eri Saikawa, associate professor of environmental sciences, who normally leads students at COP. Instead, the 17 undergraduate and six graduate students in Saikawa's "Climate and Society" class are contributing virtually by hosting virtual seminars for COP's Zero Emissions Solutions Conference. They are also producing a series of Emory Climate Talks seminars and AmpliFIRE podcasts, also aimed at bringing in diverse viewpoints to discuss key issues at COP.

Read the full story here.

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A new way to measure tech complexity

As humans evolved our brains became bigger and our technology became more complex. While brains can be compared by size and other concrete measures of form and physiology, quantifying technological complexity has proven more challenging. 

“Although we know that some human technologies have grown more complex and sophisticated with time, we actually don’t know exactly what we mean when we say that because we haven’t had a good way to measure that complexity,” says Dietrich Stout, associate professor of anthropology at Emory University. “Is a straight razor more, or less complex, than a baseball bat? Are Polynesian fishing nets more, or less, complicated than lassoes used by reindeer herders in Lapland?” 

Now, Stout and colleagues have developed the first computational method to measure fluid human actions to try to answer such questions. Scientific Reports published their method, based on the making and use of different types of Stone Age tools.

Read more about the research.

Left-wing authoritarians share key psychological traits with far right, Emory study finds

"Having clarity about the appeal of authoritarianism may be relevant to help better understand what's going on in the political landscape today," says Thomas Costello, an Emory graduate student of psychology and first author of the study.

By Carol Clark

People with extreme political views that favor authoritarianism — whether they are on the far left or the far right — have surprisingly similar behaviors and psychological characteristics, a new study finds. 

The Journal of Personality and Social Psychology published the research by psychologists at Emory University — the first comprehensive look at left-wing authoritarianism. 

“We took the long history of research into right-wing authoritarianism and used insights from that to develop a conceptional framework and measures to test for authoritarianism in the political left,” says Thomas Costello, an Emory PhD student of psychology and first author of the study. “We found that in terms of their psychological characteristics and their actual behaviors, left-wing authoritarians are extremely similar to authoritarians on the right.” 

Right-wing authoritarians tend to aggressively back the established hierarchy, while left-wing authoritarians tend to aggressively oppose it. They are almost like mirror images of one another that both share a common psychological core, the researchers conclude. 

“Authoritarians have a predisposition for liking sameness and opposing differences among people in their environment,” Costello says. “They are submissive to people they perceive as authority figures, they are dominant and aggressive towards people they disagree with, and they are careful to obey what they consider the norms for their respective groups.” 

At its core, authoritarianism is likely about power, Costello adds. 

“It’s a mistake to think of authoritarianism as a right-wing concept, as some researchers have in the past,” he says. “We found that ideology becomes secondary. Psychologically speaking, you’re an authoritarian first, and an ideologue only as it serves the power structure that you support.” 

Predicting political violence 

Another key finding is that authoritarianism from both ends of the spectrum is predictive of personal involvement in political violence. While left-wing authoritarianism predicts for political violence against the system in power, right-wing authoritarianism predicts for political violence in support of the system in power. 

Respondents to an online questionnaire who scored at the highest end of a one-to-seven scale for authoritarianism were two to three times more likely to report having engaged in political violence during the past five years. 

The good news is that both extreme authoritarianism and a tendency toward political violence appear relatively rare, Costello adds. Out of a sample size of 1,000 respondents, drawn from the online research tool Prolific and matched to the demographics of the U.S. population for age, race and sex, only 12 reported having engaged in political violence, and they all scored high for authoritarianism. 

“It’s clear that the loudest and most politically engaged segments of society have a big effect on our national discourse,” Costello says. “But there’s a big difference between criticizing those with opposing views and being willing to use violent force against people who disagree with you as a means of changing the status quo.” 

While an individual reporting that they had performed an act of violence was rare, nearly a third of respondents agreed with the statement that they wouldn’t mind if a politician that diametrically opposed their own political views was assassinated. “The higher a respondent ranked on the scale for either left-wing or right-wing authoritarianism, the more likely they were to agree with this statement,” Costello says. 

Understanding left-wing authoritarianism 

The psychological study of authoritarianism goes back to the 1930s, as social scientists tried to understand the psychological processes that made people more inclined to support the rise of fascism in Europe. The resulting Fascism Scale, developed to measure the strength of individuals’ support for far-right ideology, helped spawn the field of political psychology. 

The topic especially intrigued Costello, who plans a career in political psychology. He joined Emory to work with Emory psychologist Scott Lilienfeld — a leader in research at the interface of psychology, politics and the polarization of society — who passed away last year. Lilienfeld is senior author of the current paper. 

“As I began investigating the topic of authoritarianism, I found it puzzling that psychology researchers had almost exclusively looked at the concept from the perspective of the far right,” Costello says. “That makes it’s difficult to truly understand the psychology of authoritarianism and the conditions that can lead to its spread in a society.” 

For the current paper, the researchers developed a conceptual framework for left-wing authoritarianism, created measures for it, and then refined these measures after testing their validity through a series of studies across five community samples. 

In addition to the striking similarities between the two political extremes, the research also highlighted a key difference between the two: Left-wing authoritarians were more likely to perceive the world as a dangerous place and experience intense emotions and a sense of uncontrollability in response to stress. Right-wing authoritarians were more cognitively rigid, less open to new experiences, and less likely to believe in science. 

The research does not delineate the prevalence of authoritarianism in society. Like any other personality trait, authoritarianism lies on a spectrum with only a few at the extreme top-end of the scale, Costello says. 

“Our work should not be used as a political cudgel,” he stresses. “Instead it should be used as a piece of information to help us understand the pull of extremism and intolerance. Having clarity about the appeal of authoritarianism may be relevant to help better understand what’s going on in the political landscape today.” 

Co-authors of the paper include Shauna Bowes, an Emory graduate student of psychology; Irwin Waldman, Emory professor of psychology; Arber Tasimi, Emory assistant professor of psychology; and Sean Stevens, from New York University’s Department of Business and Society and the Foundation for Individual Rights in Education. The work was funded in part by the Institute for Humane Studies at George Mason University.

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Emora, the chatbot who cares for you

"We believe that Emora represents a groundbreaking moment for conversational artificial intelligence," says Jinho Choi, Emory associate professor of computer science.

A team of six Emory computer science students are helping to usher in a new era in artificial intelligence. They’ve developed a chatbot capable of making logical inferences that aims to hold deeper, more nuanced conversations with humans than have previously been possible. They’ve christened their chatbot “Emora,” because it sounds like a feminine version of “Emory” and is similar to a Hebrew word for an eloquent sage. 

The team is now refining their new approach to conversational AI — a logic-based framework for dialogue management that can be scaled to conduct real-life conversations. Their longer-term goal is to use Emora to assist first-year college students, helping them to navigate a new way of life, deal with day-to-day issues and guide them to proper human contacts and other resources when needed.

Eventually, they hope to further refine their chatbot — developed during the era of COVID-19 with the philosophy “Emora cares for you” — to assist people dealing with social isolation and other issues, including anxiety and depression. 

 

The Emory team is headed by graduate students Sarah Finch and James Finch, along with faculty advisor Jinho Choi, associate professor in the Department of Computer Sciences. The team also includes graduate student Han He and undergraduates Sophy Huang, Daniil Huryn and Mack Hutsell. All the students are members of Choi’s Natural Language Processing Research Laboratory.

Read more.

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Diverse landcover boosts yields for major U.S. crops, study finds

"Landscape diversification appears to be an important piece for boosting our resilience to climate change, both as a country and at the farm scale," says Emily Burchfield, assistant professor of environmental sciences. 

By Carol Clark

Monoculture — or specializing in a single crop, covering larger fields, that can be harvested with bigger machines on a simplified landscape — is widely assumed to boost a farm’s production capacity. A major study encompassing the mainland United States, however, suggests that the opposite is true. 

Nature Food published the research. 

“We found that in more diverse systems, corn and wheat yields can be up to 10 percent higher,” says Emily Burchfield, assistant professor in Emory University’s Department of Environmental Sciences and co-author of the study. “And if you combine high diversity of landcover with more complex landscape configurations, corn and wheat yields increase by more than 20 percent.” 

 

Burchfield’s research combines spatial-temporal, social and environmental data to understand the future of food and water security in the United States and the consequences of a changing climate. She shares authorship of the Nature Food paper with Katherine Nelson, from the Department of Geography and Geospatial Sciences at Kansas State University. 

The research has major implications for helping farmers adapt to climate change. “Farming is already one of the toughest jobs on the planet,” Burchfield says. “And many people’s lives depend on a cropping system that likely won’t be sustainable 30 years from now. Landscape diversification appears to be an important piece for boosting our resilience to climate change, both as a country and at the farm scale, in terms of extreme weather events.” 

Agriculture has radically transformed Earth’s landscape, the authors note. Globally, agriculture encompasses a third of all ice-free land. In the United States, agriculture covers more than half of the land area, more than two-thirds of which is cultivated with the commodity crops of corn, wheat or soy. 

It’s well-established that diverse landscapes are associated with healthier ecosystems, benefiting pollination, water retention and soil quality — environmental factors that are also important to agriculture. Small, field-scale trials have suggested that adding diversity and complexity to landscapes, such as hedgerows or a strip of natural habitat within a field, may also benefit crop yields. 

For the current paper, the researchers examined how such diversity and complexity affects crop yields from a large-scale, national perspective. They drew from publicly accessible data, including the U.S. Department of Agriculture’s CropScape Data Layer, daily weather data from the PRISM Climate Group, and soil and landscape properties from the Natural Commodity Crop Productive Index. They integrated the data into an analytical computer model of crops and crop yields for 3,100 U.S. counties, covering the entire contiguous United States, for the period 2008 to 2018. 

They then used this model to test the impacts of diversity and complexity of landscapes on the yields of the major U.S. food crops of corn, wheat and soy. The researchers controlled for factors such as weather, soil quality, water access and market fluctuations. 

The results showed that increased landcover diversity is associated with increases for corn and wheat of more than 10 percent — an effect similar to the impact of seasonal rainfall and soil suitability. And landscape configurations that are both moderately complex and also highly diverse are associated with yield increases of more than 20 percent for corn and wheat. 

The researchers are now digging into how landscape diversity and complexity could best be applied at a regional scale. 

“The United States is huge and there can be no one-size fits all strategy,” Burchfield says. “We plan to zoom into different regions and look at the barriers and bridges to diversification for each region. We hope that our work can provide data-driven evidence to help farmers diversify their landscapes in intentional ways to boost their livelihoods and their resilience to climate change, while also supporting the resilience of ecosystems.” 

The research was funded in part by the U.S. Department of Agriculture National Institute of Food and Agriculture.

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EPA funds project to measure environmental contaminants, exposures in West Atlanta

The research project grew out of a 2018 discovery of high lead levels in the soil of some residences in West Atlanta by Eri Saikawa (above), associate professor in the Department of Environmental Sciences, and former student Sam Peters, who received a PhD from Rollins School of Public Health.

By Carol Clark

The Environmental Protection Agency awarded Emory University researchers $1.35 million to work with members of the West Atlanta community to better understand any potential risks in the area for exposures among children to lead and heavy metals and metalloids, along with other environmental contaminants. 

“This award helps researchers at Emory University develop approaches to advance research that will help protect our children,” says John Blevins, the EPA’s acting region four administrator. “This EPA-funded research will further our understanding of children’s chemical exposures and potential strategies to reduce their impact on children’s health.” 

“A key part of this project is strong engagement with the community,” says Eri Saikawa, associate professor in Emory’s Department of Environmental Sciences, who is the lead contact and co-principal investigator on the grant. She notes that the researchers will hold regular meetings with residents to learn their needs and concerns before testing for environmental contamination and exposures, and to communicate findings as the project proceeds. 

“We want to make sure that community members are not just subjects of the research but are involved in ways that help them benefit from the science,” Saikawa says. “Ultimately, we want to raise awareness of the community members and provide them with educational materials specific to their needs to help lower the risks of their families being exposed to toxicants. We also hope our data will help in the development of holistic regulatory frameworks to prevent exposures to environmental contaminants in underserved communities around the country.” 

Dana Barr, professor of environmental health in Emory’s Rollins School of Public Health, is co-principal investigator on the grant. Ziad Kazzi, associate professor in Emory Medical School’s Department of Emergency Medicine and an expert in medical toxicology, is a co-investigator. 

Historic Westside Gardens, made up of residents of the area, is a community partner for the project.

“This project is unique and important,” says Barr, who co-directs Rollins’ Laboratory for Exposure Assessment and Development in Environmental Research Lab (LEADER). “We’re not just analyzing environmental samples for toxicants, we’re also testing children for potential exposures and evaluating possible mitigation strategies. Our results will provide up-to-date information that is critical for the EPA to better regulate and mitigate the ongoing issue of environmental contaminants in urban areas.” 

“Good communication with our community partners is vital,” adds Kazzi. “As a physician specialized in toxicology, my main responsibility will be to answer any medical questions that may arise from community members and discuss their health concerns. We will also explain the science of environmental toxicants and help put our findings into context.” 

Emory research led to EPA investigation 

The health hazards of human exposures to heavy metals and metalloids — such as lead, cadmium, chromium and arsenic — are a globally recognized problem, and yet these hazards persist in many urban areas of the United States. Such contamination can accumulate through emissions from industry and power plants, the former use of lead in paint and gasoline, and through fertilizer, sewage sludge and pesticides. 

The community-based research project grew out of a 2018 discovery by Emory scientists of high lead levels in the soil of some residences of West Atlanta. Also known as the Westside, West Atlanta has a high poverty rate and is largely African American. Saikawa and Sam Peters, a PhD student at Rollins School of Public Health who has since graduated, were working with community members of Historic Westside Gardens to test their soil. 

The discovery of lead in some samples, along with deposits of slag — a waste byproduct of smelting and steel-making processes — led to a major EPA investigation and designation of parts of the area as a Superfund site. The EPA investigation now encompasses more than 2,000 properties. 

Issues of environmental justice 

Lead is a neurotoxicant that is especially harmful to children. Residents within the EPA investigation site, whose soil is found to be above the EPA threshold of 400 parts per million, are now able to have their soil removed and replaced for free, funded by Superfund appropriations. 

“This is an environmental justice issue,” Saikawa says. “Racial and class disparities for heavy metal and metalloid exposures are substantial, with African-Americans and the poor and the disenfranchised bearing the greatest risk.” 

Lead-exposure related cognitive impairments, she adds, are estimated to cost more than $50 billion annually in lost U.S. economic productivity. 

Expanded testing for harmful toxicants 

The new research project, funded by $1.35 million from the EPA’s Science to Achieve Results (STAR) program, will involve areas of the Westside outside of the current EPA investigation site. The research team plans to test the homes and yards of willing participants not just for heavy metals and metalloids but a total of 40 other organic and inorganic environmental toxicants. 

Young children may ingest significant quantities of soil and dust because they often play on the ground and put their hands and other objects into their mouths that can have dust or soil on them. Soil and dust ingestion can be a major route of exposure to chemicals such as lead, mercury, polychlorinated biphenyls (PCBs) and asbestos. 

The three-year project will also consider exposure pathways in addition to soil, such as household dust and paint. The team will seek to recruit 100 households to participate in environmental sampling. In addition, the team will seek parental permissions for 140 children ages six months to six years for biological samples of saliva, urine and blood, to test for exposures. 

Saikawa’s interdisciplinary research encompasses environmental health, atmospheric chemistry and environmental policy. She and her lab members will focus on recruiting participants, conducting surveys with community members, and gathering environmental samples of soil, household dust and paint chips. Her team will analyze these samples for heavy metals and metalloids, as well as modeling exposures from these various pathways. 

Barr’s lab will primarily focus on analyses of the biological and other environmental samples for a broader range of potential organic and inorganic toxicants. 

Kazzi, who specializes in the clinical assessment and management of toxicologic exposures, will help address health and medical concerns that may arise from the community. 

Emory is one of seven institutions across the United States that recently received STAR grants to help improve children’s health. The EPA’s STAR Program supports scientific research that advances EPA’s mission to protect human health and the environment. It is a competitive, peer-reviewed, extramural research program that provides access to the nation’s best scientists and engineers in academic and other nonprofit research institutions. 

“It is our duty to protect the health of those most vulnerable among us, including our children,” says Wayne Cascio, acting assistant administrator in EPA’s Office of Research and Development. “The researchers receiving these awards will improve our understanding of how children are exposed to chemicals, which will inform future actions to reduce these exposures and better protect their health.”

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Emory soil analysis leads to EPA site investigation

Emory team makes finals in Amazon's Alexa Prize for artificial intelligence

The Emory team is led by faculty advisor Jinho Choi (center) and graduate students James Finch (left) and Sarah Finch.

A team of six Emory computer science students made it to the final round for Amazon’s Alexa Prize Socialbot Grand Challenge, a global competition among universities to create a chatbot that advances the field of artificial intelligence. The winner of the 2021 Alexa Prize will be announced in mid-August. At stake is a $500,000 first prize. In addition, $1 million in research funds will be awarded to the winning team if it meets the “grand challenge” criteria, including the ability of its chatbot to engage the judges in conversation for at least 20 minutes. 

 

In addition to Emory, the finalists are Czech Technical University, Prague; SUNY at Buffalo, New York; Stanford University and the University of California Santa Cruz. 

 

The Emory team is headed by graduate students Sarah Finch and James Finch, along with faculty advisor Jinho Choi, assistant professor in the Department of Computer Sciences. Last year, the trio headed a team of 14 Emory students that took first place, winning $500,000 for their chatbot named Emora. They chose the name because it sounds like a feminine version of “Emory” and is similar to a Hebrew word for an eloquent sage. 

This year, they are turning up the heat with an even more advanced version of Emora and new team members, including graduate student Han He and undergraduates Sophy Huang, Daniil Huryn and Mack Hutsell. All the students are members of Choi’s Natural Language Processing Research Laboratory. 

“I’m extremely proud to have such a talented team of students,” Choi says. “It’s a group of strongly motivated people with the right combination of diverse skills coming together at the right time. They’re working on changing the paradigm for conversational artificial intelligence.” 

“We’re using some established technology but taking a groundbreaking approach in how we combine and execute dialogue management so a computer can make logical inferences while conversing with a human,” adds Sarah Finch. “Ultimately, we’re making Emora even more flexible in how she can interact with people.”

Read the full story.

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Emory students win Amazon's 2020 Alexa Prize 

Using big data to zero in on a mosquito menace

"The ultimate goal is to give public health officials the power to do more effective and efficient mosquito control — even before an epidemic beings," says Gonzalo Vazquez-Prokopec, right, shown with public health technicians in Merida, Mexico.

Scientists from Emory University are leading a new strategy in humanity’s long-running war with the mosquito, using big data to target one species of this tiny disease vector. They have studied the behavior of the Aedes aegypti mosquito, pinpointing where it hangs out in homes. They are mapping cases over time of viral infections that this species can transmit when it bites a human — including dengue fever, Zika, chikungunya and yellow fever. They are zeroing in on high-risk neighborhoods for outbreaks of these diseases in sprawling urban areas of the tropics. 

“We’re working on some of the boldest and biggest changes in decades for the surveillance and control of this mosquito,” says Gonzalo Vazquez-Prokopec, associate professor in Emory's Department of Environmental Sciences. 

 

The National Institutes of Health’s Division of Microbiology and Infectious Diseases awarded Vazquez-Prokopec a $6.5 million grant to lead a consortium in a randomized clinical trial in Merida, Mexico, as part of the quest to reduce Aedes-borne viral infections. The trial is testing a novel intervention that previous Emory research finds promising: Indoor residual spraying of insecticide, targeted to the places in homes where this mosquito tends to rest. 

 

Read the full story here. 

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Contact tracing, with indoor spraying, can curb dengue outbreak

Mapping dengue hot spots pinpoints risks for Zika and chikungunya

A female Aedes aegypti mosquito takes a blood meal from a human. "The ultimate goal is to give public health officials the power to harness big data and do more effective and efficient mosquito control — even before an epidemic begins," says Emory disease ecologist Gonzalo Vazquez-Prokopec. (Photo by James Gathany / CDC).

By Carol Clark

Data from nine cities in Mexico confirms that identifying dengue fever “hot spots” can provide a predictive map for future outbreaks of Zika and chikungunya. All three of these viral diseases are spread by the Aedes aegypti mosquito. 

Lancet Planetary Health published the research, led by Gonzalo Vazquez-Prokopec, associate professor in Emory University’s Department of Environmental Sciences. The study provides a risk-stratification method to more effectively guide the control of diseases spread by Aedes aegypti. 

“Our results can help public health officials to do targeted, proactive interventions for emerging Aedes-borne diseases,” Vazquez-Prokopec says. “We’re providing them with statistical frameworks in the form of maps to guide their actions.” 

The study encompassed data for 2008 through 2020 from cities in southern Mexico with a high burden of dengue fever cases during that period, along with cases of the more recently emerged diseases of Zika and chikungunya. The cities included Acapulco, Merida, Veracruz, Cancun, Tapachula, Villahermosa, Campeche, Iguala and Coatzacoalcos. 

The results found a 62 percent overlap of hot spots for dengue and Zika and 53 percent overlap for cases of dengue and chikungunya. In addition, dengue hot spots between 2008 and 2016 were significantly associated with dengue hotspots detected between 2017 and 2020 in five of the nine cities. 

The work builds on a previous study of the spatial-temporal overlap of the three diseases, focused on Merida, a city of one million located in the Yucatan Peninsula. That study showed that nearly half of Merida’s dengue cases from 2008 to 2015 were clustered in 27 percent of the city. These dengue hot spots contained 75 percent of the first chikungunya cases reported during the outbreak of that disease in 2015 and 100 percent of the first Zika cases reported during the Zika outbreak of 2016. 

“In this latest paper, we’ve expanded our analysis in scope and geography and shown that the findings are consistent across these nine cities of different sizes and in different regions,” Vazquez-Prokopec says. “We’ve confirmed that dengue, Zika and chikungunya outbreaks tend to concentrate in small areas of a city, and that these hot spots are predictive of where future cases will concentrate.” 

Mosquito control efforts generally involve outdoor spraying that covers broad swaths of a city, but the Aedes aegypti mosquito has adapted to live inside houses. Work by Vazquez-Prokopec and collaborators has shown that the best way to control these mosquitos and the diseases they spread is by spraying a long-lasting pesticide indoors — on the ceilings, along the bases of walls, and in other areas of homes where the mosquitos tend to cluster. This approach — known as targeted indoor residual spraying — is too expensive and time-consuming to apply across a city. 

The statistical framework in the current paper, however, allows public health officials to concentrate their efforts on previous hot spots for Aedes-borne diseases to better control — and even prevent — outbreaks. 

“The ultimate goal is to give public health officials the power to harness big data and do more effective and efficient mosquito control — even before an epidemic begins,” Vazquez-Prokopec says. 

Vazquez-Prokopec is currently leading a consortium in a randomized clinical trial in Merida to test targeted indoor residual spraying as an intervention against Aedes-borne diseases. The five-year trial, launched in 2020, is funded by a $6.5 million grant from the National Institutes of Health. 

Dengue fever is sometimes called “break-bone fever” due to the excruciating pain that is among its symptoms. More than one third of the world’s population lives in areas at high risk for infection with the dengue virus, a leading cause of illness and death in the tropics and subtropics. Dengue is endemic through most of Mexico, where between 75,000 and 355,000 cases occur annually, translating into an economic cost of between about U.S. $150 million and $257 million annually. 

Chikungunya is rarely fatal but the symptoms can be severe and debilitating. Zika can cause symptoms similar to those of dengue and chikungunya, such as joint pains and fever. While Zika tends to be less debilitating, or even asymptomatic, if a pregnant woman contracts the virus it can have a catastrophic impact on her unborn child, including severe brain defects. 

Co-authors of the Lancet Planetary Health paper include researchers from Mexico’s Ministry of Health; the Autonomous University of the Yucatan; the Autonomous University of Nuevo Leon; Yucatan Health Services; the Mexican Society of Public Health; the National Institute of Public Health in Cuernavaca; the Undersecretary of Prevention and Health Promotion in Mexico City; the Pan American Health Organization; and the U.S. Centers for Disease Control and Prevention. 

The work was funded by USAID, the U.S. Centers for Disease Control and Prevention, the Canadian Institute of Public Health, the state of Yucatan, the National Institutes of Health and Emory University.

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Zeroing in on a mosquito menace

Contact tracing, with indoor spraying, can curb dengue outbreak

Genetic risks for nicotine dependence span a range of traits and diseases

"Genetic studies may help reduce some of the stigma society has against substance use disorders, while also making treatment more accessible," says Victoria Risner, first author of the new study on nicotine dependence, who did the work as an Emory undergraduate.

By Carol Clark 

Some people casually smoke cigarettes for a while and then stop without a problem, while others develop long-term, several packs-per-day habits. A complex mix of environmental, behavioral and genetic factors appear to raise this risk for nicotine dependence. 

Studies of groups of twins suggest that 40 to 70 percent of the risk factors are heritable. Until recently, however, studies have only explained about 1 percent of the observed variation in liability to nicotine dependence, using a genetic score based on how many cigarettes a person smokes per day. 

A study led by psychologists at Emory University offers a new model for examining this genetic risk. It leveraged genome wide association studies for a range of different traits and disorders correlated with nicotine dependence and explained 3.6 percent of the variation in nicotine dependence. 

The journal Nicotine & Tobacco Research published the finding. 

Higher polygenetic scores for a risk for schizophrenia, depression, neuroticism, self-reported risk-taking, a high body mass index, alcohol use disorder, along with a higher number of cigarettes smoked per day were all indicators of a higher risk for nicotine dependence, the study found. And polygenetic scores associated with higher education attainment lowered the risk for nicotine dependence, the results showed. 

“If you look at the joint effect of all of these characteristics, our model accounts for nearly 4 percent of the variation in nicotine dependence, or nearly four times as much as what we learn when relying solely on a genetic index for the number of cigarettes someone smokes daily,” says Rohan Palmer, senior author of the study and assistant professor in Emory’s Department of Psychology, where he heads the Behavioral Genetics of Addiction Laboratory. 

“What we’re finding,” Palmer adds, “is that to better leverage genetic information, we need to go beyond individual human traits and disorders and think about how risk for different behaviors and traits are interrelated. This broader approach can give us a much better measure for whether someone is at risk for a mental disorder, such as nicotine dependence.” 

Rohan Palmer heads the Department of Psychology's Behavioral Genetics of Addiction Laboratory that is developing new methods to better understand what makes people vulnerable to substance use disorders.

“All of the traits and diseases we looked at are polygenic, involving multiple genes,” adds Victoria Risner, first author of the study, who did the work as an Emory undergraduate majoring in neuroscience and behavioral biology. “That means that millions of genetic variants likely go into a complete picture for all of the heritable risks for nicotine dependence.” 

The researchers hope that others will build on their multi-trait, polygenetic model and continue to boost the understanding of the risk for such complex disorders. “The more we learn, the closer we can get to one day having a genetic test that clinicians can use to inform their assessment of someone’s risk for nicotine dependence,” Palmer says. 

Although the hazards of smoking are well established, about 14 percent of Americans report daily use of tobacco. Around 500,000 people die each year in the United States from smoking or exposure to smoke, and another 16 million live with serious illnesses caused by tobacco use, including cancer, cardiovascular disease and pulmonary disease. While the toxic chemicals produced during smoking and vaping are what cause harmful health effects, it’s the addictive component of nicotine that hooks people on these habits. 

Risner worked on the current paper for her honors thesis. “Nicotine dependence was interesting to me because the vaping scene was just arriving while I was an undergraduate,” she says. “I saw some of my own friends who were into vaping quickly becoming dependent on it, while some others who were using the same products didn’t. I was curious about the genetic underpinnings of this difference.” 

The project leveraged genome-wide association studies for a range of traits and disorders. The researchers then looked for matching variants in genetic data from a national representative sample of Americans diagnosed with nicotine dependence. The results showed how polygenetic scores for the different traits and disorders either raised or lowered the risk for that dependence. The number of cigarettes smoked per day, self-perceived risk-taking and educational attainment were the most robust predictors. 

The multi-variant, polygenetic model offers a road map for future studies. A clearer picture of heritability for nicotine dependence, for instance, may be gained by adding more risk associations to the model (such as nicotine metabolism) and clusters of polygenic traits (such as anxiety along with neuroticism). 

“As we continue to zero in on who is most at risk for becoming nicotine dependent, and what inter-related factors, whether genetic or environmental, may raise their risk, that could help determine what intervention might work best for an individual,” Palmer says. 

“Just a few decades ago, it was not well understood that nicotine dependence could have a genetic component,” Risner says. “Genetic studies may help reduce some of the stigma society has against substance use disorders, while also making treatment more accessible.” 

Risner graduated from Emory in 2019 and is now in medical school at the University of North Carolina, Chapel Hill. This summer, she’s applying the coding and analytical skills she learned at Emory to conduct research into genetic factors that may raise the risk for pre-term births. 

Emory co-authors of the Nicotine & Tobacco Research article include graduate student Lauren Bertin; post-doctoral fellow Chelsie Benca-Bachman; and Alicia Smith, associate professor in the School of Medicine. Additional authors include researchers from the University of Helsinki; Brown University; the Providence VA Medical Center; the Jackson Laboratory in Bar Harbor, Maine; Purdue University; and the University of Colorado at Boulder. 

The work on the Nicotine & Tobacco Research article was funded by the National Institute on Drug Abuse and the Academy of Finland.

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New molecule found in chestnut leaves disarms dangerous staph bacteria

"We're laying the groundwork for new strategies to fight bacterial infections at the clinical level," says Emory ethnobotanist Cassandra Quave, shown gathering samples of chestnut leaves in Italy. "We urgently need these new strategies."

By Carol Clark

Scientists isolated a molecule, extracted from the leaves of the European chestnut tree, with the power to neutralize dangerous, drug-resistant staph bacteria. Frontiers in Pharmacology published the finding, led by scientists at Emory University. 

The researchers dubbed the molecule Castaneroxy A, after the genus of the European chestnut, Castanea. The use of chestnut leaves in traditional folk remedies in rural Italy inspired the research. 

“We were able to isolate this molecule, new to science, that occurs only in very tiny quantities in the chestnut leaves,” says Cassandra Quave, senior author of the paper and associate professor in Emory’s Center for the Study of Human Health and the School of Medicine’s Department of Dermatology. “We also showed how it disarms Methicillin-resistant Staphylococcus aureus by knocking out the bacteria’s ability to produce toxins.” 

Methicillin-resistant Staphylococcus aureus (MRSA) causes infections that are difficult to treat due to its resistance to antibiotics. It is one of the most serious infectious disease concerns worldwide, labeled as a “serious threat” by the Centers for the Disease Control and Prevention. In the United States alone, nearly 3 million antibiotic-resistant infections occur each year, killing more than 35,000 people. 

Antibiotics work by killing staph bacteria, which can lead to greater resistance among those few bacteria that survive, spawning “super bugs.” The Quave lab has identified compounds from the Brazilian peppertree, in addition to the European chestnut tree, that simply neutralize the harmful effects of MRSA, allowing cells and tissue to naturally heal from an infection without boosting resistance. 

“We’re trying to fill the pipeline for antimicrobial drug discovery with compounds that work differently from traditional antibiotics,” Quave says. “We urgently need these new strategies.” She notes that antimicrobial infections kill an estimated 700,000 globally each year, and that number is expected to grow exponentially if new methods of treatment are not found. 

First author of the Frontiers in Pharmacology paper is Akram Salam, who did the research as a PhD student in the Quave lab through Emory’s Molecular Systems and Pharmacology Graduate Program.

The European chestnut, also known as the sweet chestnut, is native to Southern Europe and Asia Minor.

Quave is a medical ethnobotanist, researching traditional plant remedies to find promising leads for new drugs. Although many major drugs are plant-based, from aspirin (the bark of the willow tree) to Taxol (the bark of the Pacific yew tree), Quave is one of the few ethnobotanists with a focus on antibiotic resistance.

The story behind the current paper began more than a decade ago, when Quave and her colleagues researched written reports and conducted hundreds of field interviews among people in rural southern Italy. That pointed them to the European, or sweet, chestnut tree, native to Southern Europe and Asia Minor. “In Italian traditional medicine, a compress of the boiled leaves is applied to the skin to treat burns, rashes and infected wounds,” Quave says. 

Quave took specimens back to her lab for analysis. By 2015, her lab published the finding that an extract from the leaves disarms even the hyper-virulent MRSA strains capable of causing serious infections in healthy athletes. Experiments also showed the extract did not disturb normal, healthy bacteria on skin cells. 

Finally, the researchers demonstrated how the extract works, by inhibiting the ability of MRSA bacteria to communicate with one another, a process known as quorum sensing. MRSA uses this sensing signaling system to make toxins and ramp up its virulence. 

For the current paper, the researchers wanted to isolate these active ingredients from the plant extract. The process is painstaking when done manually, because plant extracts typically contain hundreds of different chemicals. Each chemical must be separated out and then tested for efficacy. Large scale fraction collectors, coupled to high-performance liquid chromatographic systems, automate this separation process, but they can cost tens of thousands of dollars and did not have all the features the Quave lab needed. 

Marco Caputo, a research specialist in the lab, solved the problem. Using a software device from a child’s toy, the LEGO MINDSTORMS robot creator, a few LEGO bricks, and some components from a hardware store, Caputo built an automated liquid separator customized to the lab’s needs for $500. The lab members dubbed the invention the LEGO MINDSTORMS Fraction Collector. They published instructions for how to build it in a journal so that other researchers can tap the simple, but effective, technology. 

The lab's homemade fraction collector.

The Quave lab first separated out a group of molecules from the plant extract, cycloartane triterpenoids, and showed for the first time that this group actively blocks the virulence of MRSA. The researchers then dove deeper, separating out the single, most active molecule from this group, now known as Castaneroxy A. 

“Our homemade piece of equipment really helped accelerate the pace of our discovery,” Quave says. “We were able to isolate this molecule and derive pure crystals of it, even though it only makes up a mere .0019 percent of the chestnut leaves.” 

Tests on mouse skin infected with MRSA, conducted in the lab of co-author Alexander Horswill at the University of Colorado, confirmed the molecule’s efficacy at shutting down MRSA’s virulence, enabling the skin to heal more rapidly. 

Co-author John Bacsa, director of Emory Department of Chemistry’s X-ray Crystallography Center, characterized the crystal shape of Castaneroxy A. Understanding the three-dimensional configuration of the crystal is important for future studies to refine and optimize the molecule as a potential therapeutic.

“We’re laying the groundwork for new strategies to fight bacterial infections at the clinical level,” Quave says. “Instead of being overly concerned about treating the pathogen, we’re focusing on ways to better treat the patient. Our goal is not to kill the microbes but to find ways to weaken them so that the immune system or antibiotics are better able to clear out an infection.” 

Emory co-authors of the paper also include graduate students Caitlin Risener and Lewis Marquez; post-doctoral fellow Gina Porras; and former staff scientist James Lyles. Additional authors from the University of Colorado are Young-Saeng Cho and Morgan Brown. 

The work was funded by the National Center for Complementary and Integrative Health, Emory’s Department of Dermatology, the National Institute of Allergy and Infectious Diseases and the National Institute of General Medical Sciences.

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Chestnut leaves yield extract that disarms deadly bacteria

Study shows adaptive brain response to stress, and its absence in people with depression

"Learning more about how acute stress and chronic stress affect the brain may help in the development of treatment targets for depression," says Jessica Cooper, first author of the study and a post-doctoral fellow in Emory's Department of Psychology.

By Carol Clark

A new study identifies a novel biomarker indicating resilience to chronic stress. This biomarker is largely absent in people suffering from major depressive disorder, and this absence is further associated with pessimism in daily life, the study finds. 

Nature Communications published the research by scientists at Emory University. 

The researchers used brain imaging to identify differences in the neurotransmitter glutamate within the medial prefrontal cortex before and after study participants underwent stressful tasks. They then followed the participants for four weeks, using a survey protocol to regularly assess how participants rated their expected and experienced outcomes for daily activities. 

“To our knowledge, this is the first work to show that glutamate in the human medial prefrontal cortex shows an adaptive habituation to a new stressful experience if someone has recently experienced a lot of stress,” says Michael Treadway, senior author of the study and professor in Emory’s Department of Psychology and Department of Psychiatry and Behavioral Science. “Importantly, this habituation is significantly altered in patients with depression. We believe this may be one of the first biological signals of its kind to be identified in relation to stress and people who are clinically depressed.” 

“Learning more about how acute stress and chronic stress affect the brain may help in the identification of treatment targets for depression,” adds Jessica Cooper, first author of the study and a post-doctoral fellow in Treadway’s Translational Research in Affective Disorders Laboratory. 

The lab focuses on understanding the molecular and circuit-level mechanisms of psychiatric symptoms related to mood disorders, anxiety and decision-making. 

It’s long been known that stress is a major risk factor for depression, one of the most common and debilitating of mental illnesses. “In many ways, depression is a stress-linked disorder,” Treadway says. “It’s estimated that 80 percent of first-time depressive episodes are preceded by significant, chronic life stress.” 

Around 16 to 20 percent of the U.S. population will meet the criteria for a major depressive disorder during their lifetimes. Experts are predicting rates of depression to climb even further in the wake of the ongoing COVID-19 pandemic. During the pandemic, about four in 10 adults in the United States have reported symptoms of anxiety or depressive disorder, up from one in 10 who reported them in 2019, according to the Kaiser Family Foundation. 

“The pandemic has created more isolation for many people, while also increasing the amount of severe stressors and existential threats they experience,” Treadway says. “That combination puts a lot of people at high risk for becoming depressed.” 

Although the link between stress and depression is clearly established, the mechanisms underlying this relationship are not. Experiments with rodents have shown an association between the response of glutamate — the major excitatory neurotransmitter in the mammalian brain — and stress. The role of glutamate in humans with depression, however, has been less clear. 

The 88 participants in the current study included people without a mental health disorder and unmedicated patients diagnosed with a major depressive disorder. Participants were surveyed about perceived recent stress in their lives before they underwent experiments using a brain scanning technique known as magnetic resonance spectroscopy. 

While in the scanner, participants were required to alternate between performing two tasks that served as acute stressors: Putting their hand up to the wrist in ice water and counting down from the number 2,043 by steps of 17 while someone evaluated their accuracy. 

Brain scans before and after the acute stressor measured glutamate in the medial prefrontal cortex, an area of the brain involved with thinking about one’s state and forming expectations. Previous research has also found that this brain area is involved in regulating adaptive responses to stress. 

Participants submitted saliva samples while in the scanner, allowing the researchers to confirm that the tasks elicited a stress response by measuring the amount of the stress hormone cortisol in the sample. 

In healthy individuals, the brain scans revealed that glutamate change in response to stress in the medial prefrontal cortex was predicted by individual levels of recent perceived stress. Healthy participants with lower levels of stress showed increased glutamate in response to acute stress, while healthy participants with higher levels of stress showed a reduced glutamate response to acute stress. This adaptive response was comparatively absent in the patients diagnosed with depression. 

“The decrease in the glutamate response over time appears to be a signal, or a marker, of a healthy adaptation to stress,” Treadway says. “And if the levels remain high that appears to be a signal for maladaptive responses to stress.” 

The initial result was strong for the adaptation in healthy participants, but was in a modest sample size, so the researchers decided to see if they could replicate it. “Not only did we get a replication, it was an unusually strong replication,” Treadway says. 

The experiment also included a group of healthy controls who underwent scanning before and after performing tasks. Rather than stressful tasks, however, the controls were asked to place a hand into warm water or to simply count out loud consecutively. Their glutamate levels were not associated with perceived stress and they did not show a salivary cortisol response. 

To expand their findings, the researchers followed participants for four weeks after scanning. Every other day, the participants reported on their expected and experienced outcomes for activities in their daily lives. The results showed that glutamate changes that were higher than expected based on an individual’s level of perceived stress predicted an increased pessimistic outlook — a hallmark for depression. 

“We were able to show how a neural response to stress is meaningfully related to what people experience in their daily lives,” Cooper says. “We now have a large, rich data set that gives us a tangible lead to build upon as we further investigate how stress contributes to depression.” 

Emory co-authors of the study include former and current graduate students from the Treadway lab Victoria Lawlor, Shabnam Hossein and Andrew Teer; as well as current and former research assistants Makiah Nuutinen, Brittany DeVries, Daniel Cole, Chelsea Leonard and Emma Hahn. Additional authors include researchers from UCLA, the University of Arkansas, Princeton and McLean Hospital/Harvard Medical School. 

The work was supported by the National Institutes of Mental Health.

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