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Can Mental Disorders Predict Physical Illnesses?

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The phrase “mind-body connection” is so overused it sounds like a cliché, yet there’s a significant body of research that shows mental and physical health are in fact deeply intertwined. Despite that, healthcare systems are still slow to integrate mental and physical healthcare in order to provide better patient care. To address this, Swiss psychologists set out to study instances in which specific mental health disorders are followed or accompanied by physical disorders in adolescents. The goal was to determine a causal relationship between them, and if possible, to predict certain physical illnesses by the presence of a mental disorder.

What they found were small—but definite—associations between certain mental and physical disorders. In their paper, published in PLOS One, the authors write, “The most substantial associations with physical diseases preceding mental disorders included those between heart diseases and anxiety disorders, epilepsy and eating disorders, and heart diseases and any mental disorder.”

“To have proof of causality, you have to experimentally manipulate people being physically or mentally sick, which isn’t ethical,” Gunther Meinlschmidt, co-lead author of the study and a professor of psychology at University of Basel, Switzerland tells mental_floss. Since that wasn’t possible, he and the research team, led by Marion Tegethoff, analyzed data from a large co-morbidity survey of 6483 U.S. teenagers, aged 13 to 18.

Using statistical models, they first looked at whether mental disorders predicted physical disease. Indeed, arthritis and digestive disorders were more common after depression in adolescents, while skin disorders seem to follow anxiety disorders. Next, they reversed the variables, to see if physical disease was a better predictor of mental disorders. But those results were statistically very small, suggesting that the physical disorders either follow the mental disorders, or arise at the same time.

More research with larger sample sizes still needs to be done, including recruiting subjects who have both a physical and mental condition. Meinlschmidt plans to “try to understand if someone was treated, say, for epilepsy—does it effect [their] eating disorder?” This will help the team isolate strict causality, he says. However, “With this work, we go beyond mere associations toward these temporal or chronological associations. One indicator increases the confidence that something causal might be going on.”

This research is a necessary first step that “stresses the importance of integrative health care to have close collaboration with a system for treating people with mental disorders and physical illness,” Meinlschmidt says. Up to now, these “two separate worlds are not really working closely together.” His ultimate goal is “to dig deeper into potential mechanisms for developing new interventions." He hopes his research will bring more integration to two systems and help doctors create more integrated ways of treating a person’s health.

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People Listen (and Remember) Better With Their Right Ears, Study Finds
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If you’re having trouble hearing in a noisy situation, you might want to turn your head. New research finds that people of all ages depend more on their right ear than their left, and remember information better if it comes through their right ear. The findings were presented at the annual meeting of the Acoustical Society of America in New Orleans on December 6.

Kids’ ears work differently than adults' do. Previous studies have found that children's auditory systems can’t separate and process information coming through both of their ears at the same time, and rely more on the auditory pathway coming from the right. This reliance on the right ear tends to decrease when kids reach their teens, but the findings suggest that in certain situations, right-ear dominance persists long into adulthood.

To study how we process information through both our ears, Auburn University audiologists brought 41 adult subjects (between the ages of 19 and 28) into the lab to complete dichotic listening tests, which involve listening to different auditory inputs in each ear. They were either supposed to pay attention only to the words, sentences, or numbers they heard in one ear while ignoring the other, or they were asked to repeat all the words they heard in both ears. In this case, the researchers slowly upped the number of items the test subjects were asked to remember during each hearing test.

Instructions for the audio test read 'Repeat back only the numbers you hear in the right ear.'
Sacchinelli, Weaver, Wilson and Cannon - Auburn University

They found that the harder the memory tests got, the more performance varied between the ears. While both ears performed equally when people were asked to remember only four or so words, when the number got higher, the difference between their abilities became more apparent. When asked to only focus on information coming through their right ear, people’s performance on the memory task increased by an average of 8 percent. For some people, the result was even more dramatic—one person performed 40 percent better while listening with only their right ear.

"Conventional research shows that right-ear advantage diminishes around age 13, but our results indicate this is related to the demand of the task,” one of the researchers, assistant professor Aurora Weaver, explained in a press release. In other words, when the going gets tough, the right ear steps up.

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Pigeons Are Secretly Brilliant Birds That Understand Space and Time, Study Finds
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Of all the birds in the world, the pigeon draws the most ire. Despite their reputation as brainless “rats with wings,” though, they’re actually pretty brilliant (and beautiful) animals. A new study adds more evidence that the family of birds known as pigeons are some of the smartest birds around, as Quartz alerts us.

In addition to being able to distinguish English vocabulary from nonsense words, spot cancer, and tell a Monet from a Picasso, pigeons can understand abstract concepts like space and time, according to the new study published in Current Biology. Their brains just do it in a slightly different way than humans’ do.

Researchers at the University of Iowa set up an experiment where they showed pigeons a computer screen featuring a static horizontal line. The birds were supposed to evaluate the length of the line (either 6 centimeters or 24 centimeters) or the amount of time they saw it (either 2 or 8 seconds). The birds perceived "the longer lines to have longer duration, and lines longer in duration to also be longer in length," according to a press release. This suggests that the concepts are processed in the same region of the brain—as they are in the brains of humans and other primates.

But that abstract thinking doesn’t occur in the same way in bird brains as it does in ours. In humans, perceiving space and time is linked to a region of the brain called the parietal cortex, which the pigeon brains lack entirely. So their brains have to have some other way of processing the concepts.

The study didn’t determine how, exactly, pigeons achieve this cognitive feat, but it’s clear that some other aspect of the central nervous system must be controlling it. That also opens up the possibility that other non-mammal animals can perceive space and time, too, expanding how we think of other animals’ cognitive capabilities.

[h/t Quartz]

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