Higher Altitude Protects Teens from Concussions

The human brain is a vulnerable thing, perched in its peanut shell on top of our walking, stumbling bodies. Humans who enjoy collision-heavy pastimes—say, tackle sports—put their brains in particular danger. And when it comes to concussions, young people are at even more risk than adults. Yet kids who play at at higher altitudes seem to be safer than their peers. The reason, hidden somewhere in the brain's squishy dynamics, might help protect kids and adults who are smashing into each other everywhere.

You don't have to travel to Denver's Mile High stadium for your body to start responding to altitude. "Relatively small changes in altitude can have significant changes upon the physiology of the body," say Gregory Myer and David Smith, both in the sports medicine department at Cincinnati Children's Hospital Medical Center. (The coauthors responded to my email jointly.)

At just 600 feet above sea level, the authors point out, oxygen in the atmosphere has already dropped from 21 percent to 20 percent. Your body notices this slight change and adjusts. One measure it takes, upon noticing there's less oxygen available than usual, is to send a little more blood to your brain. "This leads to a slight filling up of the brain space," Myer and Smith say. Your brain ends up squeezed just a tad more tightly into your head.

Wherever you are, if you get suddenly knocked on the head, your brain will ricochet around inside your skull's fluids. In actual scientific terms, it "sloshes." The delicate brain squishes and twists, and hosts of neurons fire all at once. You may black out. Afterward, you might have memory loss, confusion, nausea, dizziness, and other symptoms that can last for days or months. The looser, stretchier blood vessels in the brains of people under age 20 may explain why they're at even greater risk.

Concussions might be prevented if the skull could keep the brain from sloshing by holding onto it a little tighter—as it does at higher altitudes. To find out whether this works, Myer, Smith and their colleagues used data from the National High School Sports-Related Injury Surveillance System. Run by the University of Colorado, Denver, this study collects data on injuries from high schools across the country.

The authors looked at nearly 6,000 concussions from about 500 schools. The concussed kids were athletes in all kinds of sports, at schools ranging from sea level to 6,900 feet. When the researchers divided student athletes into those living above and below the median altitude—which was 600 feet—they saw a significant difference in concussions. Across all sports, kids at higher altitudes had a 31 percent lower risk of concussion. Among football players only, the results were essentially the same: a 30 percent lower risk at higher altitude.

It's an intriguing difference. As sports organizations and the public learn more about chronic traumatic encephalopathy (CTE) and the long-term risks for athletes with head injuries, the quest to prevent concussions is growing more urgent. High schoolers, though, don't travel to play like professional athletes do. Could some of their lower risk have to do with changes in their bodies that happen over a lifetime of living at a certain altitude? "Visiting altitude will begin creating a tighter fit the minute you arrive," Myer and Smith say. However, adjustment happens over the long term too. "Everyone is likely different in how quickly they respond [to altitude] and how protection occurs for them," the authors say. "This is why we are working to evaluate technologies that can give this same protection whether you are in Denver or Miami." They'll be looking next at adults and professional athletes to try to find answers.

One hint comes from an earlier study David Smith performed on rats. While wearing a collar that slightly squeezed their jugular veins, the rats were hit hard on the head. The collar seemed to make rats less vulnerable to concussion, apparently because more blood was in their heads, squeezing their brains more tightly and preventing sloshing. This all sounds pretty unpleasant for the rats, but Myer and Smith insist that "the technologies we are studying are no more risky than yawning or even the act of lying down."

Animals like woodpeckers and head-ramming sheep manage to protect their brains from damage, the researchers point out. So why can't we? Of course, in our case the head ramming is in the name of fun. But there might be ways to safeguard our brains, like these animals do, from the inside out.


Image: Rocky Mountain High School in Colorado, by Paul L. Dineen (via Wikimedia Commons)

David W. Smith, Gregory D. Myer, Dustin W. Currie, R. Dawn Comstock, Joseph F. Clark, & Julian E. Bailes (2013). Altitude Modulates Concussion Incidence: Implications for Optimizing Brain Compliance to Prevent Brain Injury in Athletes. Orthopaedic Journal of Sports Medicine DOI: 10.1177/2325967113511588

Laughter Is OK Medicine, Unless It Kills You

Careful with the bedside banter, doctors. Before you put on your best Patch Adams impression, you might want to consider whether your attempts at humor will ease your patient's discomfort or give him a protruding hernia.

That's the conclusion of a review paper in the Christmas issue of BMJ that asks the jolly question of whether laughter can kill. The two authors, R. E. Ferner of the University of Birmingham and J. K. Aronson of Oxford University—no JK-ing, those are his real initials—take a tongue-in-cheek approach. They even give their research question an acronym: MIRTH (Methodical Investigation of Risibility, Therapeutic and Harmful).

Ferner and Aronson scoured medical literature for studies having to do with laughter. After "excluding papers on the Caribbean sponge Prosuberites laughlini and with authors called Laughing, Laughter, Laughton, or McLaughlin," they were left with three categories of study. One had to do with the benefits of laughter, one with its dangers, and the third with medical conditions that have laughter as a symptom.

Let's hear the bad news first. Laughter, according to various researchers, can lead to syncope (fainting), arrhythmia, and cardiac rupture. In asthmatics, laughing can trigger an attack. Laughing can even cause pneumothorax, a collapsed lung. People with cataplexy, a rare condition tied to narcolepsy, may suddenly lose all their muscle strength and collapse during a fit of laughter. An especially good laugh can make a person's hernia protrude, or dislocate someone's jaw.

Among the more pedestrian dangers, breathing in sharply when you start to laugh can make you choke. Laughing in someone's face can spread germs. And, of course, there's the danger of pee coming out when you laugh, which doctors call "giggle incontinence."

The authors also gathered a list of about three dozen medical conditions that have been reported—commonly or not—to cause laughter. These include epilepsy, brain tumors, multiple sclerosis, and kuru (a disease you are unlikely to contract unless you're a practicing cannibal).

Now for the good news. Laughter may increase your pain tolerance, reduce stiffness in the walls of your arteries, and even lower your risk of a heart attack. In patients with chronic obstructive pulmonary disease (COPD), laughter can improve lung function. Fifteen minutes of laughter reportedly burns 40 calories, which fitness-wise makes it similar to a very slow walk (or, according to Fitness magazine, barbecuing.)

Most strangely, one study used clowns to try to (indirectly) get women pregnant. Immediately after undergoing IVF, women were subjected to 12 to 15 minutes of entertainment by "a clown, dressed as a chef de cuisine." Among these women, 36 percent became pregnant, compared to just 20 percent in a control group.

Perhaps aspiring clowns themselves, the authors can't resist throwing in a few puns of their own: "Laughing fit to burst can cause cardiac rupture." "Perhaps surgical patients derive no advantage from being in stitches." "It remains to be seen whether...sick jokes make you ill, [or] dry wit causes dehydration." I'll give them the benefit of the doubt and assume that, knowing the potentially serious side effects of laughter, they chose to spare their audience the risk.


Image: Urban Combing (Ultrastar175g) (via Flickr)

R E Ferner, & J K Aronson (2013). Laughter and MIRTH (Methodical Investigation of Risibility, Therapeutic and Harmful): narrative synthesis. BMJ DOI: 10.1136/bmj.f7274

Snoozing on the Weekend Won't Undo Workweek Sleep Loss

Does your workweek schedule dig you into an ever-deepening hole of sleep deprivation? Do you sleep in on the weekends to try to boost yourself back out? You're in good company. But even if you feel recovered by the following week, your brainpower might be suffering.

In a survey by the National Sleep Foundation, 40 percent of respondents said they try to "catch up" on sleep during the weekend. Pennsylvania State University professor and physician Alexandros Vgontzas, along with a group of colleagues, recruited 30 subjects to study how well this catching up really works. The subjects were healthy men and women between 18 and 34 (who didn't mind the prospect of sleeping with a catheter in their arm).

For two weeks before the study, researchers made sure subjects got 7.5 to 8 hours of sleep every night. Then the subjects came into the sleep lab. The experiment began with three "baseline" nights of 8 hours' sleep. For the next five nights, their sleep was restricted to just 6 hours, mimicking a full workweek of uncomfortably early rising. Then subjects had two "recovery" nights where they were left sleeping for 10 hours.

During most days of the experiment, subjects were allowed to go home and follow their normal routine—though monitors on their wrists made sure they followed strict no-napping instructions. At night, they returned to the lab. And after each phase of the experiment, subjects spent a full 24 hours undergoing tests: researchers tracked the levels of hormones circulating in their blood and gave them cognitive tests. They also asked subjects to rate how sleepy they felt. To measure their actual sleepiness, researchers had subjects lie down to nap, recorded how long it took them to conk out, and woke them up again—six times a day.

Predictably, subjects were sleepier during their week of sleep deprivation. It took them less time to fall asleep during the day, and the easiest time for them to nap was 9:00 in the morning (as opposed to 3:00 in the afternoon during the baseline period). After their two recovery days, subjects' sleepiness returned to normal.

One hormone the scientists monitored was IL-6, a marker of inflammation in the body. They found that IL-6 increased when subjects lost sleep. This fits with what earlier studies have found, and suggests one way sleep deprivation is bad for your health. IL-6 levels dropped back to normal after the two nights of recovery sleep.

The only measurement that didn't go back to normal was performance on a test called the psychomotor vigilance task (PVT). Subjects did this test every two hours during their lab days. In it, they watched a screen for ten minutes and pressed a button every time a certain number appeared. It's a test that measures a person's ability to sustain attention; astronauts on the International Space Station do a similar test on themselves to check for fatigue.

Subjects in the sleep study did worse on the PVT after their sleep-deprived week, and continued to do poorly even after two nights of catch-up sleep. Vgontzas says he doesn't know why this is. But apparently some function in people's brains hadn't recovered fully by the end of the experiment, even though they felt well rested.

It's worth noting that because there was a 24-hour testing period after each stage of the experiment, subjects actually had a sixth night of poor sleep before their "weekend." And some champion snooze-button users can sleep well past 10 hours on their real makeup days. Still, Vgontzas's findings suggest our brains are slow to catch up after losing sleep—specifically, our ability to pay attention suffers—and we might not know when we're mentally fatigued.

Vgontzas also doesn't know what the cumulative effect might be of living this way every week. On average, he writes, we need seven hours of sleep a night. (Though if you really can't sleep any later, a nap during the day will also help you recover.)


Image: by Phae (via Flickr)

Pejovic S, Basta M, Vgontzas AN, Kritikou I, Shaffer ML, Tsaoussoglou M, Stiffler D, Stefanakis Z, Bixler EO, & Chrousos GP (2013). Effects of recovery sleep after one work week of mild sleep restriction on interleukin-6 and cortisol secretion and daytime sleepiness and performance. American journal of physiology. Endocrinology and metabolism, 305 (7) PMID: 23941878

Threat of Death Makes People Go Shopping

Nothing says "Let's hit the outlet mall" like nearly being wiped out by a rocket. A study of both Americans and terrorized Israelis suggests that certain people respond to the threat of death by going shopping. Because if it's your time to go, you may as well be wearing the latest from Forever 21.

Michigan State University marketing professor Ayalla Ruvio and her colleagues performed two studies of potential shoppers. The first took place in Israel. Questionnaires were handed out at a community center in a town just one kilometer from the Gaza Strip, during six months of daily rocket attacks there in 2007. The same surveys were distributed in a second town farther from the fighting, where residents were aware of the violence but not in direct danger. The researchers got back 139 surveys from the first group and 170 from the second.

The questionnaires were meant to ferret out a few different answers about people. Did they experience post-traumatic symptoms such as nightmares or memory loss? Did they cope with negative feelings by buying things? How often did they return from a shopping trip with items they hadn't meant to purchase? Other questions assessed how materialistic the subjects were—did they place a lot of value on owning nice things?

Israelis who were experiencing daily rocket attacks, unsurprisingly, reported more post-traumatic stress. People who felt more stress admitted to more compulsive or impulsive shopping behaviors. And both these effects (feeling stress and going shopping) were stronger in more materialistic people.

For their second study, the researchers used a group of 855 American subjects, meant to be demographically representative of the U.S. population overall. Subjects filled out an online survey that measured their materialism, shopping habits, and how much they thought about their own death, as well as other factors. Once again, for people who were more materialistic, there was a relationship between fear of death and impulse buying.

Because the more materialistic Israelis experienced more stress, the researchers think "materialism makes bad events even worse." And when materialistic people feel threatened, they buy things they don't really want (or maybe can't afford).

The findings don't only apply to people living in the Middle East. Events that make people fear for their lives can include car accidents, assaults, and natural disasters. Yet Ruvio puts a positive spin on the ubiquity of trauma. "This presents an opportunity for both manufacturers of impulse items and the retailers that sell these products," she writes. When a severe storm or a military crisis is brewing, she suggests stores put their high-profit-margin items up front where impulse shoppers will see them.

While retailers may be able to benefit from people's crises, shoppers themselves won't. Previous research, Ruvio writes, shows that "most materialistic individuals derive little satisfaction from their consumption activities." So much for retail therapy.


Image: by Ian Freimuth (via Flickr)

Ayalla Ruvio, Eli Somer, & Aric Rindfleisch (2013). When bad gets worse: the amplifying effect of materialism on traumatic stress and maladaptive consumption. Journal of the Academy of Marketing Science DOI: 10.1007/s11747-013-0345-6

Field Guide to Arachnophobic Entomologists

Working with bugs professionally, it turns out, does not make you immune to the jeebies. A survey by American Entomologist magazine found that arachnophobic entomologists do exist. They're not even  that hard to find, if you're willing to turn over a few rocks.

Here are the most common types of spider-fearing entomologists that have been described thus far, so you can recognize them in the field:

Bad with Numbers

The survey, performed by retired spider researcher Richard Vetter, turned up 41 working entomologists who are afraid of spiders (or at least averse to them). Fifteen agreed with the statement "Spiders are one of my worst fears."

On a list of things about spiders that might bother them, more than half of the fearful entomologists said "many legs" was an important trait. Flies or cockroaches or centipedes might be no problem, but eight legs is, apparently, crossing a line.

One forensic entomologist in the survey works with maggots, and said that she "would rather pick up a handful of maggots than have to get close enough to a spider to kill it." That's a hard statement to sympathize with, but at least her anti-legs bias is consistent.

Family Blaming

"Several respondents stated that family members tormented them with spiders," Vetter writes, perhaps contributing to the development of their fear. In survey respondents, just like in the general population, arachnophobia usually arose in childhood.

One entomologist's parents warned her at an early age—when she had the chance to hold a tarantula at an exhibit—that spiders are dangerous. She may have accepted their lesson a little too well, because her survey responses put her in the range of clinical arachnophobia. Another subject's parents tried to instill an appreciation of spiders, explaining that they're good and helpful bugs—but the message must have gotten distorted somewhere.

Siblings received some blame too. One entomologist said that when she was six, her older sister used to chase her around the house holding dead spiders in tissues. Of the preserved spider collection she manages at a museum, she says, "They still give me the jeebies."

Prone to Traumatizing Events

Some people traced their fear to an especially upsetting event. One woman had watched an egg sac hatch on her mattress, releasing baby spiders everywhere. (Her father had also teased her with a large spider when she was younger.) Today her arachnophobia is so strong she has considered therapy, but prefers to just avoid looking at pictures or passing in front of posters of spiders. One imagines this is difficult for an entomologist.

Another respondent shared a uniquely harrowing tale, though it happened well after his arachnophobia had developed. He was driving a van at night, he said, when a yellow sac spider ran across the inside of his windshield:

"It disappeared, and, in a few seconds of utter, shocking horror for me, began running over my face and into one of my nostrils. Somehow maintaining control of the vehicle, I snorted out with all my force, and dislodged it. After finding a place to park and collect my wits, I searched the van in vain for almost an hour, before giving up and getting back on the road. That was not a good day."

Totally Normal

Although "many legs" was a common reason people in the survey gave for hating spiders, even more popular answers were "way they move," "fast running" and "unexpected." (Another popular one was "they bite," even though several respondents work with bees or wasps and apparently aren't scared of stings.)

Spiders probably aren't anyone's favorite surprise. And in fact, Vetter found that arachnophobic entomologists are pretty much like any other arachnophobes. Their fears develop early on, and persist even if they're clearly irrational. Like phobic entomologists, arachnophobes in the general public may hate particular spider traits such as their unpredictability, jerky walking style, or hairiness.

Unlike garden-variety arachnophobes, though, arachnophobic entomologists happily devote their careers to other creepy-crawlies. They don't find anything gross about bugs in general—as long as those bugs have the right number of legs.


Vetter, Richard S. "Arachnophobic Entomologists: When Two More Legs Makes a Big Difference." American Entomologist Fall 2013 (171-177).

Baseball Players Make Worse and Worse Decisions as the Season Goes On

If their goal were to frustrate fans, they couldn't plan it any better. Major-league baseball players reach a low point in their decision making in September, just in time for playoffs. Across all teams, batters swing at more and more pitches they shouldn't as the season goes on.

They may just need a nap.

"Consistently getting too little sleep—even if it's just [by] one hour a night—can lead to a state of chronic sleep deprivation that can compromise performance," says Vanderbilt University neurologist Scott Kutscher. "Specifically, things like judgment and reaction time."

Judgment and reaction time are just what a baseball player needs when a ball is hurtling toward his body at 90 miles an hour: he has to decide whether to swing, then react quickly enough to actually get it done. And sleep deprivation is familiar to pro ball players, who have a packed schedule and frequently travel back and forth across the country.

To see whether baseball players suffer the effects of sleep loss as the season drags on (or skips along for six non-tedious months, depending on your inclinations), Kutscher and his colleagues looked at data from 2011 back to 2006, after the MLB cracked down on steroid use. For each team, they tracked how often players swung at pitches outside the strike zone.

Over the course of the season, the researchers saw a steady increase in how many out-of-the-strike-zone pitches players swung at. These badly judged swings went up by about six-tenths of a percent each month.

Then Kutscher and his colleagues tested that model on the data from the 2012 season. When the numbers from all the MLB teams were pooled together, the model was a tight fit. Out of 30 teams, 24 were swinging at more balls in September than in April. Kutscher presented the findings at a recent conference on sleep.

Other factors aside from sleepiness may be at work. Pitchers might be throwing better curveballs as the months pass, for example. But Kutscher says pitchers threw pretty much the same ratio of balls and strikes throughout the season; if they were improving a lot, you'd expect to see them throwing more strikes. (Not to mention that batters, too, are practicing and honing their skills during the season.)

Since the researchers looked at whole teams rather than individuals, it's also possible that a change in the roster during the season—say, the addition of less experienced players who are called up from the minors—has an effect. Kutscher doesn't think this could account for all the deterioration he witnessed, though.

"I am hesitant to argue that fatigue is 100% of the story," Kutscher says. "But we have findings that are consistent with what we know about fatigue and chronic sleep loss."

Pro ball players, and other athletes, might see their performance improve if they could avoid sleep deprivation. So stop shouting at that guy on your screen who just struck out—he needs to go home and get some rest.


Image: Ed Gaillard (via Flickr)

Google Promises We'll Feel Better in the Summer

Shakespeare wasn't kidding about the "winter of our discontent." In the colder and darker months, people do more internet searches for mental health terms, from anxiety and ADHD all the way to suicide. Search patterns also promise that like a refreshed browser window, better times are due to arrive soon.

John Ayers, of the Center for Behavioral Epidemiology and Community Health in San Diego, and other researchers dove into Google Trends to explore whether certain searches vary by season. "Seasonal affective disorder is one of the most studied phenomena in mental health," Ayers says, "with many individuals suffering mood changes from summer to winter due to changes in solar intensity." He wanted to find out whether any other mental health complaints changed with the seasons, as some studies had hinted.

Since Google Trends breaks down searches by category, the researchers started in the "mental health" section. Looking at all mental health searches in the United States between 2006 and 2011, they saw a consistent cycle with peaks in the winter and troughs in the summer. (If you do this search yourself, you'll see that there's also a dip around the December holidays—but the curve reliably bottoms out in July of each year.)

The team did some statistical smoothing and found that mental health searches overall were about 14% higher in the winter than in the summer. To confirm that the difference was due to the season, they ran the same analysis on data from Australia. Searches cycled in the same way—about 11%  higher in winter than summer—but the peaks in the southern-hemisphere country were almost exactly 6 months out of sync with the United States.

When the scientists broke down searches by specific symptoms or illnesses, the seasonal cycle remained—and in some cases got much stronger. "We were very surprised" to see this, Ayers says. Searches including the terms ADHD, anxiety, bipolar, depression, anorexia or bulimia, OCD, schizophrenia, and suicide all rose in the winter and fell in the summer.

One of the most dramatically cycling search terms was schizophrenia, at 37% higher in the winter. Eating disorder terms varied just as strongly. (The smallest seasonal difference was for anxiety, which was just 7% higher in the winter in the United States, and 15% in Australia.)

Some of this seasonality might be due to the schedule of the school year, Ayers points out. Referrals for kids with ADHD and eating disorders may come from their schools.

Other explanations involve winter itself. The effect of shorter days on our circadian rhythms and hormone levels might be a factor, the authors write, as in seasonal affective disorder. They speculate that a lack of vitamin D (which we make using sunlight) in the winter might contribute. Even omega 3 fatty acids might matter: we consume less of them in winter, and omega 3 deficiency has been linked to some mental illnesses.

There's also the question of what we're doing all season. People hunkered indoors during the colder months may have fewer chances for socializing, which is "a well-known health emollient," the authors write. The same goes for physical activity.

"There is a lot more we need to learn about mental health and seasonality," Ayers says. "For instance, is there a universal mechanism that impacts our mental health?"

Of course, sometimes our malaise isn't about the season.

Whatever portion of mental health is predictable, though, doctors would love to know about it and use that information to help.

This study doesn't reveal much about low-income or elderly populations who aren't online. And knowing what people are searching for isn't exactly the same as knowing what symptoms they're experiencing. "We are actively working to address these limitations," Ayers says. Working with Google.org, the charitable branch of Google, he hopes to develop systems similar to Google Flu Trends that can track a population's mental health.

"Intuition suggests that these results are reflective of an important link between the seasons and mental health," Ayers says. For now, we have the reassurance of computer algorithms that skies will be clearer soon.


Ayers, J., Althouse, B., Allem, J., Rosenquist, J., & Ford, D. (2013). Seasonality in Seeking Mental Health Information on Google American Journal of Preventive Medicine, 44 (5), 520-525 DOI: 10.1016/j.amepre.2013.01.012

Image: Skaneateles, NY, by me.

Aging Makes People Colon-Close-Parenthesis

Getting older is not a recipe for crotchetiness. Although those two cranky Muppets will always be up in their balcony, Americans in general don't become less happy with age. If anything, they get happier.

The trajectory of people's happiness over a lifetime is tricky to study, because in a given year you're capturing not only your subject's age but also the current events. You need to follow a large group of people over many years, and you need them to be all different ages when the study starts.

Angelina Sutin and her colleagues at the National Institute of Aging in Maryland had just such a dataset to work with. Called the Baltimore Longitudinal Study of Aging (BLSA), this project has been running for more than five decades and has gathered data on people born everywhere between 1885 and 1980. These subjects have answered questions about their happiness on many occasions—some as many as 19 times—throughout their lives.

Want to find your own happiness score? Answer the following questions on a scale from 0 to 3, where 0 is "rarely or never" and 3 is "most or all of the time." In the past week of your life, how frequent were these feelings?

     I enjoyed life

     I felt I was just as good as other people

     I felt hopeful about the future

     I was happy

Summing the four numbers will give you your well-being score. If you were in the BLSA, that score would be your data point for today.

When the researchers put all 2,267 subjects together and looked at how their happiness changed with age, they got a decidedly downward slope. A frowny face, if you will.

age = : ( 

It looked like aging made people less happy. But then the researchers tried a different tactic. Instead of lumping all their subjects together, they grouped them by when they were born. That frown turned upside down:

age = : \

Within each birth year, the results now looked like a somewhat more optimistic "meh?" face. Every group's well-being slightly (but significantly) improved with age.

The first set of results had sloped downward because people who were born earlier reached lower endpoints of well-being. In the graph, you can see that someone born in 1905 or 1925 is likely to reach a 9 or a 10 later in life; someone born in the 1960s might make it nearly to 12 (a perfect score).

Sutin thinks this could have to do with the biggest national frowny-face of all: the Great Depression. People who lived through this time, she writes, may have felt lasting psychological effects. Although their well-being still improved as they aged, the cloud of the Depression may have lingered.

(Sutin notes also that younger and older adults, according to previous studies, treat this set of well-being questions and the 0-to-3 scale similarly. This suggests the results aren't just happiness inflation—say, younger people reporting a 12 for the same feelings that older people would rate a 10.)

Aside from increasing economic prosperity in the United States, there are plenty of other reasons people may have felt happier in more recent decades. Sutin cites increased life expectancy, decreased infant mortality, better nutrition, less disease, and more women in the workplace as possible factors. The twentieth century also saw faster travel, the invention of the Internet, and the eradication in America of both the polio virus and gelatin-based entrées. There's a lot to be happy about.

Now that Sutin has found that the average American seems to have an upward trajectory of well-being, she's interested in people's individual paths: what makes one person's happiness increase more or less (or decrease) over time?

In this study, subjects who were white had higher well-being scores on average, as did those with more education. Sutin hopes to pick apart the social, economic, and health factors that affect how happiness changes with age. When everyone can feel as :) as they want, we'll really be living in the future.

Sutin, A., Terracciano, A., Milaneschi, Y., An, Y., Ferrucci, L., & Zonderman, A. (2013). The Effect of Birth Cohort on Well-Being: The Legacy of Economic Hard Times Psychological Science DOI: 10.1177/0956797612459658

Image: a 102-year-old woman, by Uppy Chatterjee (Flickr)

Why You Itch When Others Scratch

Itching is contagious, and not only when one party has the chicken pox. The mere sight of a stranger scratching can be enough to trigger an itch in your own flesh. If you're especially prone to contagious itchiness, psychologists say, it's not because you relate well to other people—you're just neurotic.

The researchers who delved into the science of contagious itching thought it might be similar to another famously spreadable phenomenon: yawning. Previous studies found that a person's likelihood of catching someone else's yawns is linked to empathy. It's easier to trigger contagious yawning in people who are good at understanding others' states of mind.

To explore contagious itching, psychologist Henning Holle at the University of Hull, UK, and his colleagues subjected 51 volunteers to videos of people scratching themselves. Each person watched a series of videos with changing variables: some showed a man scratching himself and others showed a woman; the model scratched 5 different body parts (upper or lower left or right arm, or the middle of the chest); and in control videos the model simply tapped the body part in question.

After each video, subjects rated how itchy they felt. Since the experiment was being filmed, researchers could also see how often their subjects scratched themselves, whether they realized they were doing it or not.

The results showed that itching is highly contagious, the authors report this week in PNAS. People reported feeling itchier after the scratching videos than the tapping videos, and most subjects scratched themselves at some point during the experiment. It's normal to feel itchy when you see someone else scratching. But the degree of itchiness varies from person to person.

To find out what makes someone especially vulnerable, the researchers gave subjects a group of standard personality tests. "We expected to find contagious itching to be associated with empathy," Holle says. A questionnaire that measured empathy, though, turned up no connection.

But the researchers did find a correlation between their subjects' contagious itching and their neuroticism. As defined by psychologists, neuroticism is someone's tendency toward worry and insecurity. Holle and his colleagues measured this and other personality traits using a test called the Big Five personality inventory. (The other four traits in this test are openness, conscientiousness, extraversion, and agreeableness. Worried you're a worrier? You can take a version of the test here.)

Making a study of itching and scratching even less physically comfortable, 18 of the subjects watched the videos while inside an fMRI scanner. They weren't allowed to scratch themselves, since that motion might interfere with the machine. But when they saw scratching videos, the activated areas in their brains matched a previously observed group of regions called the "itch matrix."

Among other areas, this brain network included the premotor cortex (involved in planning and carrying out motions) and the primary somatosensory cortex (headquarters for our sense of touch). Also active was the anterior insula, an area the authors say may be crucial to our feeling of sharing another person's pain.

When asked how itchy this research had made him personally, Holle declined to comment.


Holle, H., Warne, K., Seth, A., Critchley, H., & Ward, J. (2012). Neural basis of contagious itch and why some people are more prone to it Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1216160109

Image: Holle et al.

Caffeine Helps Us Recognize Positive Words

Does anyone still say "full of beans"? The phrase is supposed to describe someone who's upbeat and energetic. Maybe we can revive the expression by attaching it specifically to coffee beans, as in, "I just had a double-shot cappuccino and boy, oh boy am I full of beans!"

Caffeine lovers know the feeling of finishing a well-timed cup of coffee or tea: positive, alert, ready to go. (And maybe ready to go to the bathroom.) New research suggests that our brains also process language differently after having caffeine. We're quicker and more accurate at recognizing words—but only if those words have positive connotations.

Lars Kuchinke and Vanessa Lux, researchers at Ruhr University Bochum in Germany, studied the effect of caffeine on a word recognition challenge. To start, they recruited 66 subjects with a range of personal caffeine habits.

Leading up to the experiment, subjects abstained from coffee (and nicotine and alcohol) for at least 12 hours. Thirty minutes before the experiment started, each subject took a pill that contained either sugar or 200 mg of caffeine. That's the equivalent of 2 to 3 standard cups of coffee, or a bit less than 1 tall coffee at Starbucks. Subjects didn't know which pill they'd taken.

Then subjects sat facing a screen with their chins on a chin rest. While they focused on a spot in the center of the screen, words flashed briefly on one side or the other. Half the time, these were emotionally positive, negative, or neutral German words. The other half the time, they were nonsense words that looked similar to German ones. Subjects pressed a button indicating whether the word they'd just seen was real or not.

On the whole, people performed better on this task when the words flashed in front of their right eyes. This was expected, based on previous experiments and the fact that the right eye connects to the left hemisphere, the brain's language headquarters. What was more interesting was that on left-hemisphere trials, people who had taken a caffeine pill were significantly better at recognizing positive words than neutral or negative ones.

The researchers think the effect is down to dopamine. In addition to waking you up and making you quicker and more accurate at cognitive tasks, caffeine increases the activity of dopamine, a signaling molecule in the brain. (This may also be why caffeine drinkers say it improves their mood.)

Previous studies found that the brain is a little better at recognizing positive words (and happy faces) in general. Adding caffeine—and therefore dopamine—exaggerated this effect. Kuchinke and Lux think this is because dopamine interacts with the brain's language centers to make us quicker at processing positive words. They haven't yet studied how caffeine affects our understanding of outdated idioms.


Kuchinke, L., & Lux, V. (2012). Caffeine Improves Left Hemisphere Processing of Positive Words PLoS ONE, 7 (11) DOI: 10.1371/journal.pone.0048487

Image: Dan Barbus (Flickr)

Math-Phobes Experience Arithmetic like Bodily Pain

If subtraction makes you sweat, division gives you diarrhea, and the Pythagorean theorem inspires panic attacks, you might be afflicted with math anxiety. Others may not always be sympathetic to your fear of tipping in restaurants without your cell phone. Brain scans, though, show that people like you suffer from more than just nerves. In people who are highly anxious about math, the threat of doing arithmetic activates the same brain areas as a punch in the stomach.

Researchers at the University of Chicago's Human Performance Lab study how humans think and what makes us succeed—or not—under pressure. Anxiety has been found to heighten our awareness of our bodies and make us more sensitive to pain. So Ian Lyons and Sian Bielock wondered whether feelings of anxiety might have a direct connection to pain centers in the brain.

For their anxious guinea pigs, Lyons and Bielock used humans with "high math anxiety." They measured math anxiety using a survey in which subjects rated how anxious they'd feel in various scenarios, including "walking to math class" and "being given a set of addition problems to solve on paper." From their potential subjects, the authors selected 14 people who scored especially high on this test and 14 others who scored especially low. Subjects were also tested for general anxiety (to make sure their math fears weren't part of an allover nervous disposition) and working memory (to ensure that their problem-solving capacity was normal).

Then all the subjects solved a series of math and word questions while inside an fMRI scanner. For the math questions, subjects saw equations like (3 * 5) – 4 = 11 and had to decide whether they were true or false. Some of the equations involved larger numbers to make them harder. For the word questions, subjects saw sets of letters such as yrestym and had to decide whether they spelled a real English word backward.

Subjects with high math anxiety struggled with the harder arithmetic problems more than subjects with low math anxiety did. And in the high-math-anxiety subjects, math problems lit up brain regions involved in sensing pain. Specifically, pain in the gut.

These brain areas, the dorso-posterior insula and mid-cingulate cortex, "are active during the experience of visceral pain—for example, a stomachache or a gut punch," says Ian Lyons. "These areas are also involved in detection of threat to the body." So while people with a lot of math anxiety may not feel bodily pain when facing a math test, their brains seem to interpret each arithmetic problem like a physical threat.

Earlier research found that those same brain areas were activated when people experienced social rejection, Lyons says. Our brains apparently view getting ditched by our friends, or (for some of us) solving for x, like being kicked in the liver.

But what was most surprising about the results, Lyons says, was the timing of that kick-in-the-gut reaction. It happened not when subjects were actually facing those dreaded arithmetic problems, but a few seconds before.

Subjects saw a yellow circle or a blue square, indicating whether a math or word question was coming their way. When they saw the shape and started anticipating a math problem, high-anxiety subjects' pain centers lit up. But once they actually started working on the problem, those brain centers retreated again.

"This underscores the fact that anxiety is very much about the psychological interpretation of an event or phenomenon, and not so much about the event itself," Lyons says. He and Bielock write that once people focus on solving an equation or other problem, they may not have the mental resources left over to keep feeling anxious. To stop the pain of anticipation, serious math-phobes—and perhaps the rest of us too—should just do it already.


Lyons, I., & Beilock, S. (2012). When Math Hurts: Math Anxiety Predicts Pain Network Activation in Anticipation of Doing Math PLoS ONE, 7 (10) DOI: 10.1371/journal.pone.0048076

Image: Shurik_13 (Flickr)

In Adolescence, Fears Are Harder to Forget

When it comes to fear, unlearning is as crucial as learning. Our growing brains learn to be afraid of scalding pans, oncoming traffic, and our parents calling us by our full names. But if we can't unlearn a fearful reaction, we may live our whole lives paralyzed by dentists' offices or barking chihuahuas. The ease of this unlearning may depend on our age: new research suggests that in both mice and humans, fears are hardest to dislodge in adolescence.

People suffering from PTSD or phobias are often un-taught their fears through "exposure therapy." By repeatedly facing the things that scare them while in a safe, controlled environment, they dilute the strength of the fearful association. This washing away of old associations is a classic psychological trick called extinction. But it doesn't always work.

Researchers at Cornell and New York University, reporting this week in PNAS, used human volunteers and mouse "volunteers" to assess how easy fear extinction is at different stages of development.

The mice were 23, 29, or 70 days old—representing childhood, adolescence, and adulthood. On the first day of the study, mice were put into a box where they repeatedly heard a long tone that was followed by an electric shock from the floor. A day later, the mice found themselves in a different box where they again heard the threatening tones, but received no shocks to the paws. These sessions went on for four days.

On the first day after their fearful experience in the shock chamber, mice demonstrated fear by freezing whenever they heard the tone. By the fourth day of their "therapy," this reaction was much weaker in both young and adult mice. But adolescent mice still reacted almost as fearfully as they had on the first day.

Human subjects were also split into groups based on their age: 30 kids (age 5-11), 28 adolescents (age 12-17), and 25 adults (age 18-28). On the first day, all the subjects completed a task that involved pressing computer keys while watching colored squares go by on a screen. Really, they were being taught to associate one color of square with a very loud and unpleasant noise that was sometimes blasted into their headphones.

On the second day, subjects again saw a sequence of colored squares, but this time were spared the loud noises. Meanwhile, researchers monitored their subjects' skin conductance. (This isn't exactly a measure of fear, but of general "arousal" or excitement. Or, really, sweatiness. It's the same factor measured in a lie detector test.)

Children and adults showed lower skin conductance, meaning they were less on edge, as the experiment went on and they learned not to expect loud noises anymore. But adolescents remained on edge, barely lessening their learned response to the colored squares.

To find out in more detail what was happening in the brains of their mouse subjects, the researchers dove right in. (Human volunteers were allowed to keep their brains.) They focused on an area of the prefrontal cortex that was already known to be involved in fear extinction, called the vmPFC (short for ventromedial prefrontal cortex, which is neuroscience-speak for "smack in the middle of the forehead").

Author B.J. Casey says that for the first time, her study showed that this brain region's role in fear extinction happens at the level of the connections between neurons. In young mice or adult mice, slices of fear-extinguished brains had more-active neurons in a subsection of this brain region, compared to slices of fearful brains. But adolescent brains all looked the same, whether they had undergone the fear-extinction training or not. The diminished activity in adolescent neurons, Casey says, matches adolescents' diminished ability to unlearn a fearful reaction. This region of the adolescent mouse brain—not unlike some adolescents—is relatively inactive and set in its ways.

Casey says her group's research might help explain teenage emotions in general. "Our findings are consistent with exaggerated emotional reactivity during adolescence in humans and rodents," she says, as well as "diminished ability to regulate these emotions."

In all mammals, adolescence—whether it happens at 29 days or 16 years—is a time to learn what threats you're facing and how to live independently. Holding on to learned fears more stubbornly might be helpful for an adolescent in evolutionary terms. But if the trait makes it harder for teens to get past crippling phobias and anxieties, therapists may need to learn a different way to talk to teenage patients and their stubbornly fearful brains.

Siobhan S. Pattwell, Stéphanie Duhoux, Catherine A. Hartley, David C. Johnson, Deqiang Jing, Mark D. Elliott, Erika J. Ruberry, Alisa Powers, Natasha Mehta, Rui R. Yang, Fatima Soliman, Charles E. Glatt, B. J. Casey, Ipe Ninan, & Francis S. Lee (2012). Altered fear learning across development in both mouse and human. PNAS : 10.1073/pnas.1206834109

Image: Drew Herron/Flickr

Sex Makes Everything Less Disgusting

Our biological drive to do it conflicts pretty directly with our biological drive not to get involved with other people's bodily fluids. How do we ignore the obvious grossness of sex for long enough to propagate the species? Maybe, researchers say, by turning off our disgust reflex whenever we get turned on.

Earlier studies have asked this question in a variety of ways. For example, by asking men to "self-stimulate" and then quizzing them on what sex acts or partners they'd be open to. Or by showing men erotic slideshows and then having them stick their hands into cold pea soup or buckets of condoms. Psychology researchers Charmaine Borg and Peter J. de Jong at the University of Groningen in the Netherlands—perhaps feeling less pessimistic than others about their ability to arouse a group of female subjects—decided to study the question in women instead.

The researchers gathered 90 female university students. Rather than just answering questions about distasteful things, these subjects were going to be challenged with some actual gross tasks to see how many they would do.

But first the researchers had to turn their subjects on. Well, a third of them, anyway. One group of women watched a film described as "female friendly erotica." A second group watched a movie that was meant to be non-sexually arousing—that is, heart-pounding but not steamy. These women saw footage of sky diving and mountain climbing. The third group saw a movie about a train ride, meant to not cause any feelings at all. The movies had been previously tested with a separate group to make sure they elicited the right emotions.

As the women watched their steamy, exciting, or boring movies, they were periodically interrupted by an experimenter who showed up and gave them disgusting tasks to do. There were a total of 16 challenges, ranging from picking up apparently soiled toilet paper to sticking a needle in a cow eye. The subjects didn't have to go through with any task they didn't want to, but they did have to rate how disgusting they found each one.

Out of the 16 gross-out tasks, 5 were classified as sex-related. These included touching some "used" condoms, handling "used" women's underwear, and reading aloud a sexual phrase about, um, a dog. (The researchers made liberal use of Halloween-style tools and props, including blood-colored ink, fake feces, coconut milk in the underwear, and one plastic bug. And one real worm, which they rereleased outside when the study was over.)

The groups who watched the train movie and the sky-diving movie didn't differ in their willingness to do the gross tasks, or in how disgusting they rated those tasks. But the women who watched the erotic film rated the sex-related tasks as significantly less disgusting than the other groups. They seemed to find the rest of the tasks less gross too, though the result wasn't quite significant. And overall, the erotica group completed more challenges of both kinds. The turned-on subjects completed 85% of the non-sexy tasks, for example, compared to about 66% in the other two groups.

Charmaine Borg says she was surprised to see that sexual arousal, but not general arousal (the sky-diving kind), "makes us approach stimuli that are in general so disgusting." The way subjects perceived disgusting things seemed to change when they were sexually aroused.

The study focused on a small group of young, heterosexual, dysfunction-free women. It was limited to one method of turning those subjects on (the erotic film) and an odd handful of gross, somewhat sex-related tasks. And the study relied on subjects' own ratings of their arousal and repulsion. But if it proves to be generally true that sexual arousal squelches disgust, it would explain how we manage to reproduce despite our usual instincts—which presumably evolved to keep us safe from disease-carrying stuff.

Borg is more interested, though, in women whose bodies don't let them have sex. She wonders if sexual disorders such as dyspareunia (painful intercourse) or vaginismus (involuntary clenching of the muscles around the vagina, making intercourse difficult or impossible) are rooted in problems overcoming disgust.

"Studies from our lab with women afflicted with vaginismus have shown that they experience disgust responses towards erotic stimulation," Borg says. "Sex-related stimuli appeared to elicit disgust rather than arousal." Since our usual response to disgust is to keep far away from what's causing it, she says the problem could be self-perpetuating as women start avoiding sex altogether.

Borg says her results so far are "very exciting." By carrying on her experiments in the condom-filled, fake-blood-soaked laboratory, she helps to hope women overcome their difficulties and get down to whatever business they want.


Charmaine Borg, & Peter J. de Jong (2012). Feelings of Disgust and Disgust-Induced Avoidance Weaken following Induced Sexual Arousal in Women. PLOS ONE : 10.1371/journal.pone.0044111

Image: Feggy Art/Flickr (Related note: I cannot BELIEVE I lived this long without knowing that England has both a name for making horrible faces—"gurning"—and competitions for it.)

Having a Water Bottle for a Mom Not Ideal

In the wild, young rhesus macaques can reasonably expect not to have their mothers replaced by kitchen props. The monkeys depend on their moms to nurse them and tote them through tree branches while they're small, just like other primates. But a laboratory experiment in Maryland took these babies from their mothers and had them raised alone or in groups of their peers. The monkeys' strange infancies had physical and mental effects that lasted into adulthood.

At the National Institute of Child Health and Human Development (part of the National Institutes of Health), rhesus macaques born between 2002 and 2007 were randomly assigned to one of three groups. The lucky first group got to stay with their mothers, who kept their young close by while living in a large cage with other monkeys.

The rest of the young monkeys were taken from their mothers and reared by humans in a nursery for their first five weeks of life. Then, if they were in the second experimental group, they were put into a cage with three other monkeys of the same age. The four peers were left to "raise" each other, Lord of the Flies style.

The final group of monkeys, after being nursed by humans for five weeks, spent two hours a day in these same peer cages. During the remaining 22 hours, they lived alone in a cage with a "surrogate mother." The name is a bit of an insult to primate intelligence, though, since researchers describe this object as "effectively a terry cloth-covered hot water bottle hanging from the top of the cage."

By the end of their first year of life, all the juvenile monkeys had been moved from their experimental cages into one social group. Now the researchers, led by Gabriella Conti at the University of Chicago, began to collect data on the monkeys' health. Over the years of the study, they watched 231 rhesus macaques grow up in this bizarre daycare system. Even though the monkeys all ended up living together, their disparate childhoods left a mark.

The first clear effect was illness. Male monkeys that had been raised by a "surrogate" got sick nearly twice as often as mother-raised or peer-raised monkeys, even though by this time in their lives they all shared the same living conditions. Nearly every surrogate-raised male monkey had an illness at some point during the study.

Female monkeys that had been raised by peers, rather than by a real or fake mother, were more likely to have wounds and bald patches once they were living in the large group. Since these females displayed more aggressive behavior, the researchers think they may have been starting fights with the other monkeys. Their aggression may have goaded other monkeys into biting them and pulling their hair out.

And across all the groups taken away from their mothers—male and female, peer-raised and surrogate-raised—monkeys were more likely to have repetitive habits called stereotypies. In the zoo, a stereotypy such as pacing or swimming in circles suggests that an animal is in distress. In humans, stereotypies can be a symptom of autism. Habits displayed by the rhesus monkeys in this study included "digit sucking (the most frequent behavior), pacing, head tossing, self-grasping, saluting, spinning, rocking, circling, and swinging."

Some of the difference between monkeys raised by their mothers and the rest could be due to breastfeeding, Conti points out. But the increased illness in male monkeys was limited to the surrogate-mom group; the peer-raised monkeys, despite also missing out on breastfeeding, didn't have extra illnesses. And although all motherless monkey groups showed an increase in stereotypy, the effect was greatest in surrogate-raised males. This suggests that even if formula feeding causes some of the health effects seen here, it can't account for all of them.

The not-shocking conclusion is that monkeys need their moms to develop normally. Being raised parentless seems to make them less able to cope with infections or social stressors later in life. It's something to consider for research centers or zoos raising animals without their mothers. Even if the young have been orphaned or abandoned, there may be ways for human keepers to mitigate the damage.

Conti is an economist, though, and she's more interested in another primate: humans. She compares the rhesus research to studies of human children raised without either of their parents. These studies have found mental and physical health effects in children in Romanian orphanages, for example, or Israeli kibbutzim (where kids were raised communally). As smart and independent as we are, we're still primates who need someone to haul us through the tree branches when we're young.


Gabriella Conti, Christopher Hansman, James J. Heckman, Matthew F. X. Novak, Angela Ruggiero, & Stephen J. Suomi (2012). Primate evidence on the late health effects of early-life adversity PNAS : 10.1073/pnas.1205340109


Image: Baby Japanese macaque by Nemo's great uncle/Flickr

Memory-Improving Gene Tied to PTSD

A superior visual memory is the best friend of artists and competitive card memorizers. But to people who've lived through traumatic events, it might be the enemy.

Researchers in Switzerland and Germany guessed that people with a better memory might be more susceptible to post-traumatic stress disorder, their minds clinging stubbornly to horrific events in the past. But studying the memories of people living with a mental illness is difficult, since the disorder itself might affect their memory. So when the researchers went on a hunt for genes that are linked to both memory and PTSD, they began in a healthy population.

A group of more than 700 Swiss young adults, free of any mental illness, participated in the first part of the study. They viewed several dozen pictures that were meant to elicit either a positive emotional response, a negative emotional response, or a neutral one. After being distracted for 10 minutes, they were given a surprise quiz on how many of the pictures they could recall.

The subjects's DNA underwent testing too. The researchers checked 2,005 individual spots in each person's genes called SNPs (pronounced "snips"). These are bits of DNA that vary across a population, such that some people might have a T nucleotide where others have a G, for example. All of the 2,005 SNPs the researchers checked had to do with certain multitasking molecules called protein kinases that seem to be involved in memory formation.

Out of the 2,005 gene variants in this haystack, one needle emerged: a bit of DNA that was significantly linked to subjects' performance on the memory test. There are two versions (or alleles) of the gene in question, which makes a molecule called PKC alpha. People with one of these alleles--an A rather than a G--remembered more of the pictures they'd seen. Although researchers were especially interested in their subjects' recall of emotionally negative pictures, the effect seemed to extend to positive and neutral ones as well.

Brain scans showed a difference inside the heads of these high-performing memorizers. Subjects with A alleles had more activity in parts of the prefrontal cortex while looking at the negative images. These same regions, the authors say, have been linked to emotional memory storage in other studies.

Now that the researchers had found a gene of interest, they could study it in some actual traumatized people. They turned to a group of 347 Rwandan refugees who fled their country during the civil war. After being interviewed thoroughly, 134 of the refugees were found to meet criteria for post-traumatic stress disorder. Rwandans who had the better-memory gene variant from the first part of the study were more likely to be in the PTSD group. They were also more likely to have the symptom of reliving a traumatic memory over and and over.

Among the healthy Swiss population, the better-memory A allele was more common than the worse-memory G allele. But among the Rwandan refugees, the opposite was true: The better-memory gene variant was the rare one. If it were more common, PTSD symptoms might have been even more frequent among the displaced Rwandans.

The genetics of mental illness are tricky to untangle, and what merits a diagnosis in one culture might  be normal in another. Studies such as this one, though, could reveal who's most at risk for certain symptoms. And if scientists can figure out how exactly the genes in question are acting in the brain, we might see new drugs that can treat some of these symptoms--or prevent people's memories from turning against them in the first place.


de Quervain, D., Kolassa, I., Ackermann, S., Aerni, A., Boesiger, P., Demougin, P., Elbert, T., Ertl, V., Gschwind, L., Hadziselimovic, N., Hanser, E., Heck, A., Hieber, P., Huynh, K., Klarhofer, M., Luechinger, R., Rasch, B., Scheffler, K., Spalek, K., Stippich, C., Vogler, C., Vukojevic, V., Stetak, A., & Papassotiropoulos, A. (2012). PKC  is genetically linked to memory capacity in healthy subjects and to risk for posttraumatic stress disorder in genocide survivors Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1200857109


Image: Virginia Guard Public Affairs/Flickr