Friday, November 21, 2014

Athletes' testosterone surges not tied to winning, study finds

Kathleen Casto, number 1931 in the center, shown competing in cross country as an undergraduate in North Carolina. She is now a graduate student in psychology at Emory, studying the hormonal correlates of competition in women.

By Carol Clark

A higher surge of testosterone in competition, the so-called “winner effect,” is not actually related to winning, suggests a new study of intercollegiate cross country runners.

The International Journal of Exercise Science published the research, led by David Edwards, a professor of psychology at Emory University, and his graduate student Kathleen Casto.

“Many people in the scientific literature and in popular culture link testosterone increases to winning,” Casto says. “In this study, however, we found an increase in testosterone during a race regardless of the athletes’ finish time. In fact, one of the runners with the highest increases in testosterone finished with one of the slowest times.”

The study, which analyzed saliva samples of participants, also showed that testosterone levels rise in athletes during the warm-up period. “It’s surprising that not only does competition itself, irrespective of outcome, substantially increase testosterone, but also that testosterone begins to increase before the competition even begins, long before status of winner or loser are determined,” Casto says.

Cross country is "an intense experience."
Casto was a Division I cross country runner as an undergraduate at the University of North Carolina, Wilmington. She majored in psychology and chemistry and became interested in the hormonal correlates of competition in women. She applied as a graduate student in psychology at Edwards’ lab when she learned about his work.

Edwards has been collecting data since 1999 on hormone levels of Emory sports teams that have volunteered to participate. The research has primarily involved women athletes. Edwards’ lab also developed a questionnaire to measure the status of an athlete. Members of the team rate the leadership ability of other individuals on the team, to provide a combined rating score for each of the participating athletes.

Many of the labs’ previous studies involved sports such as volleyball and soccer that require team coordination, intermittent physical exertion and only overall team outcomes of win or loss. Casto wanted to investigate how hormones relate to individual performance outcomes in cross country racing.

Cross country racing is both a team and individual sport. Teams are evaluated through a points-scoring system, but runners are also judged on their individual times, clearly ranking their success in an event.

“Cross country running is a unique sport. It’s associated with a drive to compete and perseverance against pain over a relatively long period of time,” Casto says. “It’s an intense experience.”

Participants in the study were consenting members of the 2010 and 2011 Emory varsity men’s and women’s cross country teams. Each participant provided three saliva samples: One before warming up (to serve as a baseline), one after warming up, and a third immediately after crossing the finish line.

Testosterone went up from the baseline for both men and women during the warm-up, while levels of cortisol – a hormone related to stress – did not.

At the end of the race, both men and women participants showed the expected increases in cortisol and surges in testosterone. Neither hormone, however, was related to finish time.

This research follows on the heels of a 2013 study of women athletes in a variety of sports by Edwards and Casto, published in Hormones and Behavior. They found that, provided levels of the stress hormone cortisol were low, the higher a woman’s testosterone, the higher her status with teammates.

The body uses cortisol for vital functions like metabolizing glucose. “Over short periods, an increase in cortisol can be a good thing, but over long periods of chronic stress, it is maladaptive,” Casto says. “Among groups of women athletes, achieving status may require a delicate balance between stress and the actions or behaviors carried out as a team leader.”

Higher baseline levels of testosterone have been linked to long-term strength and power, such as higher status positions in companies.

“Although short-term surges of testosterone in competition have been associated with winning, they may instead be indicators of a psychological strength for competition, the drive to win,” Casto says.

Photos courtesy Kathleen Casto.

Tuesday, November 18, 2014

Climate change will slow China's reduction in infectious diseases

Shanghai depends on water from the Huangpu River, which is connected to the heavily polluted Tai Lake. Photo by Jakub Halun.

From Woodruff Health Sciences Center

China has made significant progress increasing access to tap water and sanitation services, and has sharply reduced the burden of waterborne and water-related infectious diseases over the past two decades. Climate change, however will blunt China’s efforts at further reducing these diseases, finds a study in the latest edition of Nature Climate Change.

By 2030, changes to the global climate could delay China’s progress reducing diarrheal and vector-borne diseases by up to seven years, the study shows. That is, even as China continues to invest in water and sanitation infrastructure, and experience rapid urbanization and social development, the benefits of these advances will be slowed in the presence of climate change.

The study, led by Justin Remais, associate professor of environmental health at Emory’s Rollins School of Public Health, provides the first estimates of the burden of disease due to unsafe water, sanitation and hygiene in a rapidly developing society that is subjected to a changing climate.

“Our results demonstrate how climate change can lead to a significant health burden, even in settings where the total burden of disease is falling owing to social and economic development,” says Remais. “Delays in development are especially concerning for China, which is investing heavily in improving health even as the impact of those investments is being countered by the effect of climate change.” 

Read more.

Creating an atmosphere for change

Friday, November 7, 2014

Interstellar: Starting over on a new 'Earth'

The movie Interstellar opens in theaters at a time when Earth is facing major losses of biodiversity and ecosystems, says David Lynn, an Emory professor of biomolecular chemistry.

While humanity is challenged to find out what’s happening to Earth and how to make adjustments, we have also begun to realize that billions of Earth-like planets likely exist in habitable zones around the stars of our galaxy.

“In as little as 10 years, we could know whether we’re alone in the universe, whether there are other living systems,” Lynn says. “That’s an exciting prospect. It’s not clear necessarily that we’ll find out that there is intelligent life or not. That may be a lower probability, but that’s also possible.”

Much of the science in Interstellar is not accurate, and its vision of the future may not come true. And yet, it is still an important film, Lynn says, since its themes resonate today, during a critical time in our history.

Chemists boldly go in search of 'little green molecules'
Prometheus: Seeding wonder and science

Tuesday, November 4, 2014

Having a Y chromosome doesn't affect women's response to sexual images, brain study shows

The study provides "further evidence that we need to revamp our thinking about what we mean by 'man' and 'woman,'" says psychologist Kim Wallen.

By Carol Clark

Women born with a rare condition that gives them a Y chromosome don’t only look like women physically, they also have the same brain responses to visual sexual stimuli, a new study shows.

The journal Hormones and Behavior published the results of the first brain imaging study of women with complete androgen insensitivity, or CAIS, led by psychologists at Emory.

“Our findings clearly rule out a direct effect of the Y chromosome in producing masculine patterns of response,” says Kim Wallen, an Emory professor of psychology and behavioral neuroendocrinology. “It’s further evidence that we need to revamp our thinking about what we mean by ‘man’ and ‘woman.’”

Wallen conducted the research with Stephan Hamann, Emory professor of psychology, and graduate students in their labs. Researchers from Pennsylvania State University and Indiana University also contributed to the study.

The Y chromosome was identified as the sex-determining chromosome in 1905. Females normally have an XX chromosome pair and males have an XY chromosome pair.

By the 1920s, biochemists also began intensively studying androgens and estrogens, chemical substances commonly referred to as “sex hormones.” During pregnancy, the presence of a Y chromosome leads the fetus to produce testes. The testes then secrete androgens that stimulate the formation of a penis, scrotum and other male characteristics.

Women with CAIS are born with an XY chromosome pair. Because of the Y chromosome, the women have testes that remain hidden within their groins but they lack neural receptors for androgens so they cannot respond to the androgens that their testes produce. They can, however, respond to the estrogens that their testes produce so they develop physically as women and undergo a feminizing puberty. Since they do not have ovaries or a uterus and do not menstruate they cannot have children.

“Women with CAIS have androgen floating around in their brains but no receptors for it to connect to,” Wallen says. “Essentially, they have this default female pattern and it’s as though they were never exposed to androgen at all.”

Wallen and Hamann are focused on teasing out neural differences between men and women. In a 2004 study, they used functional magnetic resonance imaging (fMRI) to study the neural activity of typical men and typical women while they were viewing photos of people engaged in sexual activity.

The patterns were distinctively clear, Hamann says. “Men showed a lot more activity than women in two areas of the brain – the amygdala, which is involved in emotion and motivation, and the hypothalamus which is involved in regulations of hormones and possibly sexual behavior.”

For the most recent study, the researchers repeated the experiment while also including 13 women with CAIS in addition to women without CAIS and men.

“We didn’t find any difference between the neural responses of women with CAIS and typical women, although they were both very different from those of the men in the study,” Hamann says. “This result supports the theory that androgen is the key to a masculine response. And it further confirms that women with CAIS are typical women psychologically, as well as their physical phenotype, despite having a Y chromosome.”

A limitation of the study is that it did not measure environmental effects on women with CAIS. “These women look the same as other women,” Wallen explains. “They’re reared as girls and they’re treated as girls, so their whole developmental experience is feminized. We can’t rule out that experience as a factor in their brain responses.”

The findings may have broader applications in cognition and health. “Anything that we can learn about sex differences in the brain,” Wallen says, “may help answer important questions such as why autism is more common in males and depression more common in females.”

Intersex: A lesson in biology, identity and culture

Images: Thinkstock

Monday, November 3, 2014

Creepy crawlies and the science of fear

Tarantulas don't eat people and even try to avoid them. So chill out.

Why are we afraid of spiders, snakes and roaches? WXIA reporter Julie Wolfe explores that question through a new exhibit at the Fernbank Museum of Natural History called "Goose Bumps! The Science of Fear." Below is an excerpt from a report by Wolfe:

"It was my nightmare inside a glass box: A dozen cockroaches hissing and wiggling and waiting to crawl up my nose. Okay, maybe not that last part.

"When Emory Assistant Psychology Professor Seth Norrholm suggested I slip my hand into a box that may lead to that creepy, crawly nightmare, I hesitated. It's a response that was programmed into me stretching back to my caveman ancestors.

"All fears can fit into three categories: Innate fears, learned fears and preparatory fear.

"'An innate fear is something that you're born with, and it's a survival instinct type of fear,' Norrholm explained. Fear of animals and insects fall into that category. Among the most common fears: Spiders, cockroaches and snakes."

Watch a video of her report on the WXIA web site.

The psychology of screams
Psychologists closing in on claustrophobia
How fear skews our spatial perception
The anatomy of fear and memory formation