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Scientists Have Found a Possible Cause of Severe PMS

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There’s no two ways about it: premenstrual syndrome (PMS) is awful. But for people with severe PMS (also known as premenstrual dysphoric disorder, or PMDD), “awful” is an understatement. Now scientists at the National Institutes of Health say they may have found the root of the problem: abnormal gene expression. They published their findings in the journal Molecular Psychiatry.

Experiencing PMDD symptoms is like having the volume turned up on the emotional elements of regular PMS. These extreme bouts of depression, anger, and anxiety can be so deep and persistent that they interfere with work or school, home, or relationships.

PMDD is not common; scientists estimate that it affects 2 to 5 percent of people who menstruate. But for those who have it, it can be disabling, and it sure would be nice to know what’s causing it.

Previous studies in the '90s concluded that people with PMDD appear to be hypersensitive to ordinary, menstrual-related fluctuations in steroid hormones like estrogen and progesterone. They still couldn’t tell us where this hypersensitivity came from, but they kept looking.

Fast-forward to 2015. Technology has advanced in ways that would have blown our minds 20 years ago. Behavioral endocrinologist Peter Schmidt, who led the earlier studies, teamed up with experts in neurogenetics and psychiatry to try a new approach.

They recruited 67 women between the ages of 18 and 48. Some of these women had been diagnosed with PMDD, while others said they had no trouble with severe PMS. One subgroup of participants with PMDD were given drugs that turned off their production of estrogen and progesterone. Their symptoms abated. When the researchers stopped the treatment, the women’s symptoms returned. These changes supported the theory that even normal changes in hormone levels could trigger big emotional changes for women with the condition. In other words, PMDD is quite literally PMS on steroids.

Next, the researchers extracted cell samples from 48 participants (24 with PMDD and 24 without) and sequenced their genetic code, looking for differences. They found them, all right: A large group of genes called the ESC/E(Z) complex was working overtime in women with PMDD. This makes a lot of sense, the researchers say, as the role of the ESC/E(Z) complex is to tell our genes how to respond to changes in our internal and external environment. Hypersensitivity there could definitely cause dramatic overreaction to hormonal changes.

The authors say these findings strike at the myth of the fragile, overly emotional woman. “This is a big moment for women’s health,” co-author and neurogeneticist David Goldman said in a statement. "It establishes that women with PMDD have an intrinsic difference in their molecular apparatus for response to sex hormones—not just emotional behaviors they should be able to voluntarily control.”

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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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