Wednesday, February 29, 2012

Marriage: A powerful heart drug in short supply

Getting married can have consequences for the health of your heart, years later.

By Carol Clark

Married adults who undergo heart surgery are more than three times more likely to survive the next three months than single people who have the same surgery, a new study finds.

“That’s a dramatic difference in survival rates for single people, during the most critical post-operative recovery period,” says Ellen Idler, a sociologist at Emory University and lead author of the study. “We found that marriage boosted survival whether the patient was a man or a woman.”

The Journal of Health and Social Behavior is publishing the results, which were co-authored by David Boulifard and Richard Contrada, both from Rutgers University. The study was funded by the National Institute on Aging.

While the most striking difference in outcomes occurred during the first three months, the study showed that the strong protective effect of marriage continues for up to five years following coronary artery bypass surgery. Overall, the hazard of mortality is nearly twice as great for unmarried as it is for married patients about to undergo the surgery.

During the 1960s, 72 percent of all adults over the age of 18 were married. Today, only 51 percent of them are, a record low.

“The findings underscore the important role of spouses as caregivers during health crises,” Idler says. “And husbands were apparently just as good at caregiving as wives.”

Tying the knot has been associated with longer life since 1858, when William Farr observed that marriage protected against early mortality in France. The evidence keeps accumulating that the widowed, never married and divorced have higher risks of mortality. Much of the research, however, has looked broadly across populations during an entire lifespan, or relies only on medical records.

“We wanted to zero in on a particular window of time: A major health crisis,” Idler says, “and we wanted to add the in-person element of patient interviews, in addition to the full record of their medical history and hospitalization.”

The major study involved more than 500 patients undergoing either emergency or elective coronary bypass surgery. All of the study subjects were interviewed prior to surgery. Data on survival status of the patients were obtained from the National Death Index.

While the data are inconclusive for what caused the striking difference in the three-month survival rate, the interviews provided some possible clues.

“The married patients had a more positive outlook going into the surgery, compared with the single patients,” Idler says. “When asked whether they would be able to manage the pain and discomfort, or their worries about the surgery, those who had spouses were more likely to say, yes.”

Patients who survived more than three months were nearly 70 percent more likely to die during the next five years if they were single. An analysis of the data showed that smoking history accounted for the lower survival rates in the single patients over this longer term.

“The lower likelihood that married persons were smokers suggests that spousal control over smoking behavior produces long-term health benefits,” Idler says.

When it comes to healing hearts, marriage may be powerful medicine, but it’s in increasingly short supply, Idler says, which does not bode well for aging baby boomers.

Barely half of U.S. adults are currently married, the lowest percentage ever, according to the Pew Research Center.

Photos by iStockphoto.com.

Related:
Are hugs the new drugs?
The science of love
Baby boomers raise mid-life suicide rate

Friday, February 24, 2012

An evolutionary view of depression



From Woodruff Health Sciences Center

A growing body of research is showing that one of the causes of depression may be inflammation, says Andrew Miller, professor of psychiatry and behavioral sciences at Emory. Whenever the body is attacked by a pathogen, the immune system becomes activated. That causes inflammation, a process that releases protein molecules known as cytokines.

“These cytokines can actually get into the brain and start to interact with all the things that we know are important to the development of depression,” Miller says.

Depression is such a common human affliction that it seems almost hard-wired into our brains. Miller and colleagues have proposed that perhaps depression is an evolutionary byproduct of our ability to fight infection. You can read their paper in Molecular Psychiatry.



The reason depression is staying in the gene pool at such a high rate may be that depression is helping us deal with the microbial world, Miller says. “It’s helping us deal with pathogens, as opposed to dealing with other people.”

The researchers looked at genes that are associated with depression one by one, and found that almost every single one of those genes was related to the ability to fight infections.

The behaviors associated with depression, social withdrawal and loss of interest in the external world, help conserve the energy needed to fight infection and heal a wound, Miller says.

Stress can lead to inflammation and ultimately to depression. In acute cases, stress can be a beneficial response, since it ramps up the immune system to help deal with a wound or infection. Chronic stress, however, causes a constant release of cytokines that get into the brain and may cause chronic depression, Miller says.

Related:
Are depressed people too clean?
What aphids can teach us about immunity

Tuesday, February 21, 2012

Monkeys, mankind and morality


Watch a video, above, of primatologist Frans de Waal's TedxPeachtree talk on "Morality without Religion."

Monkeys and mankind have a lot in common when it comes to moral outrage over inequities, and the need to reconcile the conflicts that arise from these differences. On his Cosmic Log, Alan Boyle writes a great summary of a talk on this topic by Emory primatologist Frans de Waal at the recent meeting of the American Association for the Advancement of Science. Among the nuggets he gathered:

"Different primate species express signs of reconciliation in different ways. For example, stumptail monkeys make up by inspecting each other's rear ends, without ever looking each other in the eye. In contrast, chimps and other apes (including us hairless apes) 'need eye contact' when they reconcile their differences, de Waal said."

Read the whole article on the Cosmic Log.

Related:
Are hugs the new drugs?
Hugs go way back in evolution

Thursday, February 16, 2012

Fruit flies use alcohol as a drug to kill parasites



By Carol Clark

Fruit flies infected with a blood-borne parasite consume alcohol to self-medicate, a behavior that greatly increases their survival rate, an Emory University study finds.

“We believe our results are the first to show that alcohol consumption can have a protective effect against infectious disease, and in particular against blood-borne parasites,” says Todd Schlenke, the evolutionary geneticist who led the research.

“It may be that fruit flies are uniquely adapted to using alcohol as medicine,” he adds, “but our data raise an important question: Could other organisms, perhaps even humans, control blood-borne parasites through high doses of alcohol?”

Current Biology is publishing the study, co-authored by Emory graduate student Neil Milan and undergraduate student Balint Kacsoh.

The results add to the growing body of evidence that some animals know how to use toxic substances found in nature as medicine.

A vicious, co-evolutionary battle is constantly ongoing between the common fruit fly, above, and tiny, parasitoid wasps that lay their eggs in the larvae of fruit flies. Photo by Andre Karwath/Wikipedia Commons.

Drosophila melanogaster, the common fruit fly that swirls around browning bananas in your kitchen, is an important biological model system. The Schlenke lab uses D. melanogaster to study how immune systems adapt to pathogens.

The fly larvae eat the rot, or fungi and bacteria, that grows on overripe, fermenting fruit. “They’re essentially living in booze,” Schlenke says. “The amount of alcohol in their natural habitat can range from 5 to 15 percent. Imagine if everything that you ate and drank all day long was 5-percent alcohol. We wouldn’t be able to live like that, but fruit flies are really good at detoxifying alcohol.”

Tiny, endoparasitoid wasps are major killers of fruit flies. The wasps inject their eggs inside the fruit fly larvae, along with venom that aims to suppress their hosts’ immune response. If the venom is effective enough, the wasp egg hatches, and the wasp larva begins to eat the fruit fly larva from the inside out. Eventually, an adult wasp emerges from the remains of the fruit fly pupa.

Adult wasps are about to emerge from fruit fly pupae, above, after eating the fruit fly larvae from the inside out. Photo by Todd Schlenke.

Some fruit flies, however, can overcome the effects of wasp venom and mount an immune response against wasp eggs. The blood cells in these fly larvae swarm over the wasp eggs and release nasty chemicals to kill them, allowing the fruit fly larvae to grow into adults.

“A constant co-evolutionary battle is going on between the immune systems of the flies and the venoms of the wasps,” Schlenke says. “Any new mechanism of defense that protects flies from wasps will tend to spread through fly populations by natural selection.”

Schlenke wondered if the fruit flies could be tapping the toxic effects of alcohol in their natural habitat to fight off wasps.

To test the theory, the researchers used a bisected petri dish filled with the yeast that fruit flies are normally fed in a lab environment. The yeast on one side of the dish was mixed with 6 percent alcohol, while the yeast on the other side remained alcohol-free. The researchers then released fruit fly larvae into the dish, allowing them to freely move to either side.

After 24 hours, 80 percent of the fruit fly larvae that were infected with wasps were on the alcohol side of the dish, while only 30 percent of the non-infected fruit fly larvae were on the alcohol side.


If fruit flies infected with wasps tap the alcohol in rotting fruit, it raises their blood-alcohol levels and their survival rates. The alcohol doesn't just kill the wasps, it essentially liquifies them. Photo by Carol Clark.

“The strength of the result was surprising,” Schlenke says. “The infected fruit flies really do seem to purposely consume alcohol, and the alcohol consumption correlates to much higher survival rates.”

Infected fruit flies that consumed alcohol beat out the wasps in about 60 percent of the cases, compared to a 0 percent survival rate for fruit fly controls that fed on plain yeast.

“The wasps aren’t as good as the flies at handling alcohol,” Schlenke says.

A developing wasp knocked out within an alcohol-consuming fly larva dies in a particularly horrible way, he adds. “The wasp’s internal organs disperse and appear to be ejected out of its anus. It’s an unusual phenotype that we haven’t seen in our wasps before,” Schlenke says.

The lab repeated the experiment using another species of wasp that specializes in laying its eggs in D. melanogaster, rather than the generalist wasp used previously. Again, 80 percent of the infected flies wound up on the alcohol side of the dish, while only 30 percent of the uninfected flies did. But the alcohol diet was far less effective against the specialist wasps, killing them in only 10 percent of the cases.

“You would expect this kind of result,” Schlenke says, “since the generalist wasp species can attack plenty of other flies, but the specialist wasps are under strong pressure to adapt to the alcohol-infused habitat of D. melanogaster.”

The researchers hope that their data will lead to more studies of how alcohol may control pathogens in other organisms, including humans.

“Although many studies in humans have shown decreased immune function in chronic consumers of alcohol, little attempt has been made to assay any beneficial effect of acute or moderate alcohol use on parasite mortality or overall host fitness following infection,” Schlenke says.

Related:
Monarch butterflies use drugs
What aphids can teach us about immunity
Farming ants reveal evolution secrets

Wednesday, February 15, 2012

When music and molecules converge


Mark Gresham reviews Emory's recent music-and-science performance of "Creation of the World" for ArtsCriticATL.com:

"In the beginning was the Sound. The big bang. From that event more than 13 billion years ago, science tells us, the universe rapidly expanded and cooled enough that its white noise of energy could change into subatomic particles. Those particles later joined to form atoms, and those atoms combined to form molecules, eventually leading to the emergence of life. Biochemists are researching what harmonious chemical conditions might have led to the emergence of life.

"Science isn’t the only field to speculate about the origins of the universe and of life. Explorations of the relationship of music to the fundamental nature of the cosmos go far back in history, from the teachings of Pythagoras and the ancient Chinese “yellow bell,” which served as a foundation of not just music but of all physical measurements, to the medieval European concept of musica universalis, the 'music of the spheres.'"

Read the whole article at ArtsCriticATL.com.

Related:
Teaching evolution enters new era
A new twist on an ancient story
A geologist paints Darwin