Well: For Athletes, Risks From Ibuprofen Use

Phys Ed

Gretchen Reynolds on the science of fitness.

Many active people use the painkiller ibuprofen on an almost daily basis. In surveys, up to 70 percent of distance runners and other endurance athletes report that they down the pills before every workout or competition, viewing the drug as a preemptive strike against muscle soreness.

But a valuable new study joins growing evidence that ibuprofen and similar anti-inflammatory painkillers taken before a workout don’t offer any benefit and may be causing disagreeable physical damage instead, particularly to the intestines.

Studies have already shown that strenuous exercise alone commonly results in a small amount of intestinal trauma. A representative experiment published last year found that cyclists who rode hard for an hour immediately developed elevated blood levels of a marker that indicates slight gastrointestinal leakage.

Physiologically, it makes sense that exercise would affect the intestines as it does, since, during prolonged exertion, digestion becomes a luxury, said Dr. Kim van Wijck, currently a surgical resident at Orbis Medical Center in the Netherlands, who led the small study. So the blood that normally would flow to the small intestine is instead diverted to laboring muscles. Starved of blood, some of the cells lining the intestines are traumatized and start to leak.

Thankfully, the damage seems to be short-lived, Dr. van Wijck said. Her research has shown that within an hour after a cyclist finished riding, the stressed intestines returned to normal.

But the most common side-effect of ibuprofen is gastrointestinal damage. And since many athletes take the drug for pain before and after a workout, Dr. van Wijck set out to determine the combined effect of exercise and ibuprofen.

For the new study, published in the December issue of Medicine & Science in Sports & Exercise, researchers at Maastricht University in the Netherlands recruited nine healthy, active men and had them visit the university’s human performance lab four times.

During two of the visits, the men rested languorously for an hour, although before one of the visits, they swallowed 400 milligrams of ibuprofen the night before and also the morning of their trip to the lab. (Four hundred milligrams is the recommended non-prescription dosage for adults using the drug to treat headaches or other minor pain.)

During the remaining visits, the men briskly rode stationary bicycles for that same hour. Before one of those rides, though, they again took 400 milligrams of ibuprofen the night before and the morning of their workout.

At the end of each rest or ride, researchers drew blood to check whether the men’s small intestines were leaking. Dr. van Wijck found that blood levels of a protein indicating intestinal leakage were, in fact, much higher when the men combined bike riding with ibuprofen than during the other experimental conditions when they rode or took ibuprofen alone. Notably, the protein levels remained elevated several hours after exercise and ibuprofen.

The health implications of this finding are not yet clear, although they are worrying, Dr. van Wijck said. It may be that if someone uses ibuprofen before every exercise session for a year or more, she said, “intestinal integrity might be compromised.” In that case, small amounts of bacteria and digestive enzymes could leak regularly into the bloodstream.

More immediately, if less graphically, the absorption of nutrients could be compromised, especially after exercise, Dr. van Wijck said, which could affect the ability of tired muscles to resupply themselves with fuel and regenerate.

The research looks specifically at prophylactic use of ibuprofen and does not address the risks and benefits of ibuprofen after an injury occurs. Short-term use of Ibuprofen for injury is generally considered appropriate.

Meanwhile, the Dutch study is not the first to find damage from combining exercise and ibuprofen. Earlier work has shown that frequent use of the drug before and during workouts also can lead to colonic seepage. In a famous study from a few years ago, researchers found that runners at the Western States 100-Mile Endurance Run who were regular ibuprofen users had small amounts of colonic bacteria in their bloodstream.

Ironically, this bacterial incursion resulted in “higher levels of systemic inflammation,” said David C. Nieman, a professor of health and exercise science at Appalachian State University who conducted the study and is himself an ultramarathoner. In other words, the ultramarathon racers who frequently used ibuprofen, an anti-inflammatory, wound up with higher overall levels of bodily inflammation. They also reported being just as sore after the race as runners who had not taken ibuprofen.

Animal studies have also shown that ibuprofen hampers the ability of muscles to rebuild themselves after exercise. So why do so many athletes continue enthusiastically to swallow large and frequent doses of ibuprofen and related anti-inflammatory painkillers, including aspirin, before and during exercise?

“The idea is just entrenched in the athletic community that ibuprofen will help you to train better and harder,” Dr. Nieman said. “But that belief is simply not true. There is no scientifically valid reason to use ibuprofen before exercise and many reasons to avoid it.”

Dr. van Wijck agrees. “We do not yet know what the long-term consequences are” of regularly mixing exercise and ibuprofen, she said. But it is clear that “ibuprofen consumption by athletes is not harmless and should be strongly discouraged.”

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Storm Hits Hiring in November; Service Sector Expands

NEW YORK (Reuters) - Private-sector hiring took a hit in November due to the impact of storm Sandy that ravaged consumers and businesses in the northeastern United States, but the huge services sector continued to expand albeit at a modest pace.

The ADP National Employment Report, which is closely watched as it comes two days ahead of the government's monthly employment report, showed that the private sector added 118,000 jobs during the month, below expectations for a gain of 125,000.

The report largely confirmed economists' forecast for a weak reading in the Labor Department payrolls report on Friday. Economists expect the economy added 93,000 jobs in November, down from 171,000 the month before, according to a Reuters poll.

"It's close to what the market was expecting. If Friday's employment report from the U.S. Labor Department comes in similar to this, that would be a good outcome," said Terry Sheehan, economic analyst at Stone and McCarthy Research Associates in Princeton, New Jersey.

A separate report on the U.S. services sector showed a similar dip in hiring during the month. But forward-looking indicators pointed to faster growth as a rise in new orders and business activity helped offset a slowdown in employment and prices.

The Institute for Supply Management said its services index rose to 54.7 last month from 54.2 the month before, with 50 being the divide between growth and contraction. The reading topped economists' forecasts for growth of 53.5, according to a Reuters survey.

"The much larger service side of the U.S. economy remains relatively healthy," said Joseph Trevisani, chief market strategist at Worldwide Markets, Woodcliff Lake, New Jersey.

"It has so far avoided the contraction in manufacturing, but worse is probably coming in the first quarter of next year as the economy continues to slow."

A separate report on Monday showed that the manufacturing sector contracted after two months of growth.

U.S. stocks were little changed after the data but drifted lower by midmorning. The S&P 500 index, a broad measure of U.S. stocks, traded down 0.4 percent at 1,401.74 points.

Also on Wednesday, a report showed new orders received by U.S. factories unexpectedly rose in October as demand for motor vehicles and a range of other goods offset a slump in defense and civilian aircraft orders, a hopeful sign for the manufacturing sector.

That chimed with another report showing U.S. nonfarm productivity increased at a much faster clip than initially thought in the third quarter as businesses held the line on hiring even as output surged, with unit labor costs falling at their fastest pace in almost a year.

Mark Zandi, chief economist of Moody's Analytics, who helps compile the ADP report, said underlying jobs growth was closer to 150,000 in November after discounting the impact of the storm as well as seasonal jobs brought forward at the start of the holiday season.

"Abstracting from the storm, the job market turned in a good performance during the month," he said. "Superstorm Sandy wreaked havoc on the job market in November, slicing an estimated 86,000 jobs from payrolls."

Zandi said he was seeing little indication that budget negotiations in Washington aimed at averting the so-called "fiscal cliff," a series of automatic tax hikes and spending cuts due in 2013, were having a significant impact of hiring.

"I don't sense that businesses have pulled back on their hiring or increased their layoffs as a result of the angst surrounding the fiscal issues," said Zandi.

The current impasse over the fiscal cliff, which could impact the economy to the tune of $600 billion next year, has been blamed for fueling uncertainty and causing corporate managers to delay business decisions.

(Reporting By Edward Krudy; Editing by Clive McKeef and Chizu Nomiyama)

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A Utah craftsman races illness to finish a vintage carousel

PETERSBORO, Utah — By any measure, Vean Woodbrey looms large.

Dressed in denim bib overalls, he stands 6 feet 4, weighs 275 pounds and wears size 16 shoes. His children — all 16 of them — jokingly call him Sasquatch because of the cartoonish spread of his footprint. So do many of his 70 grandchildren and great-grandkids.

And then there is the 7-foot-tall wooden giraffe he's carving inside his home workshop in this farming town near the Idaho border. He runs a gnarled hand along the figure's neck, wiping off the sawdust that covers everything like an early season snow.

"It's simple, but there's a certain beauty to it," Woodbrey, 69, said. "The best part is that it came straight out of my imagination."

Woodbrey is an aging craftsman on a mission to finish an amusement-park-sized carousel for his grandchildren and other other youth in this Mormon community before his declining health finally fails him.

As he painstakingly crafts a menagerie of 22 animals — horses, a panda, a zebra, a lion, a tiger, a camel, an elephant and the giraffe — Woodbrey knows time is running out. He has already battled prostate and bone cancer, both of which have slowed his once-loping gait. He also suffers from a neuropathy that numbs the toes in both feet, making him teeter like a child's top in its final throes of movement. To keep his balance in his shop, he holds onto his animals and various saws and sanders.

Every morning, he slowly scales the ramp onto his second-floor workshop to create his imaginary world out of scavenged lumber. Each day is one more sunrise wrung out of a life as a father, community leader, coach and scoutmaster.

"I've got to get this carousel done," he said. "There's this sense of urgency, but I'm inching my way there."

There have been delays: Once he stapled three fingers together with a nail gun. Then he took a fall and broke five toes on one foot. He's already burned through two drills.

He shakes his head. The illness has made him see things so clearly. The doctors say the bone cancer is 85% licked, but that either could return at any time. "When you have cancer, you take an inventory of what you've done, but there's so many things you still want to do," Woodbrey said. "Every day, my wife knows exactly where I am — up in the wood shop with my animals. I'm a man on a time clock."

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Woodbrey's fondness for carousels dates to his boyhood in San Diego, where his father took the family's four children to a local amusement park. "My dad would buy one ticket he said would go to the eldest — and that was him," he said. "But he'd grab so many brass rings he'd win free tickets so we could all ride."

When the family moved to Salt Lake City, Woodbrey collected soda bottles to redeem for the money to ride the carousel at a local park. If he was lucky, he'd make enough to buy a drink or an ice cream cone.

Years later, after Woodbrey married his wife, Tonya, and they started raising their 16 kids, he took a job at nearby Hill Air Force Base where, for 40 years, he repaired F-4 fighter jets and, later, Minuteman missile systems. At home, he began making wooden dollhouses for his eight daughters and toys for his eight sons.

At age 58, he was struck with prostate cancer. As he lay in the hospital, one of his kids bought him a copy of a magazine dedicated to carousels. Once again, he was hooked — checking each new issue for trends, seeing which old carousels were up for sale.

Eight years later, Woodbrey was treated for a golf-ball-sized tumor in his skull. After weeks of radiation treatments, weary and depressed, he asked his wife, "What am I going to do?"

"She responded: 'Go do whatever you want. Just don't give up.'"

Woodbrey retired from his job at the base and began scouting a carousel to refurbish. He finally found the 7-ton shell of a 1930s Allan Herschell ride — its animals long ago sold off as antiques by the previous owner — for sale in Montana for $5,000

Woodbrey got the contraption home and set to work. One day, he called his eight sons and eight sons-in-law over to the house for a meal. But first the men were instructed to hoist the carousel's 16-foot center pole aloft into the sky and set it into place. They worked together, grunting and sweating, like Amish barn builders. "I told them nobody could eat until we were done," Woodbrey recalled.

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NASA's Giant New Rocket Goes Supersonic (In a Wind Tunnel)

NASA has a big new rocket in the works, one designed to carry astronauts beyond earth orbit for the first time since the Saturn V took us to the moon. The Space Launch System will, among other things, make a trip to an asteroid, but before it can do that it must make a few trips to the wind tunnel.

The rocket’s first mission beyond earth orbit isn’t expected until 2017, assuming the program doesn’t fall off a fiscal cliff. Right now, NASA engineers are busy finalizing the design of the launch vehicle, testing a 10-foot model in the agency’s transonic tunnel in Langley, Virginia.

“The test includes the largest integrated vehicle model to be tested in a wind tunnel for SLS,” says John Blevins, SLS Lead Engineer for Aerodynamics and Acoustics. “It will simulate the environment of transonic flight that the SLS rocket will navigate during its flight.”

The model will be exposed to speeds up to Mach 1.2. There are 360 pressure transducers spread across the surface of the model, and data is acquired at a rate of thirteen thousand scans per second, according to NASA. The information gleaned from the wind tunnel tests will provide insight into the structural forces the SLS will endure during launch and acceleration from subsonic to supersonic flight.

The first mission will see the SLS launch the Orion spacecraft into lunar orbit as an initial check of the system. It will be an unmanned flight, but NASA hopes to fly astronauts around the moon by 2021 and expand the flight envelope of its new generation of space vehicles.

The Orion capsule has endured numerous kinds of testing in recent years, but it hit a bit of a speed bump recently when small cracks were found in the capsule slated for flight in 2017. The three hairline cracks, each less then two inches long, are located on the bottom of the vehicle. This capsule is expected to be used for a test flight to earth orbit atop a Delta IV rocket in 2014, three years before the SLS will launch an Orion into lunar orbit.

The cracks did not penetrate the aluminum skin of the Orion spacecraft. NASA says a simple fix will distribute the stress across the location where the cracks occurred according to the Denver Post.

“For this flight, since its unmanned, we can fix it and fly it” Orion program manager Mark Geyer told the newspaper. “When we build the one we’re actually going to put people on, we’ll make sure to fix this design.”

With NASA handing off the job of delivering astronauts and cargo to low earth orbit over to commercial companies like SpaceX and Orbital Sciences, the manned space program at the agency is focusing on exploration a bit deeper into space. Orion will be able to carry a four person crew on mission lasting up to 210 days. In addition to possible missions to an asteroid, Orion is also being designed for trips to the moon and Mars. For all trips the capsule would just be part of the space vehicle needed as was the case with the Apollo capsules which used a command module and lunar module for the missions.

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Howard Stern signs on for more “America’s Got Talent”

LOS ANGELES (Reuters) – Shock jock Howard Stern will return as a judge for his second season on NBC‘s summer talent show “America’s Got Talent,” the broadcaster said on Monday, although the high-priced radio host appears to have done little to improve the show’s ratings.

NBC hoped Stern, 58, known for this sexually explicit radio interviews, would attract bigger audiences, but the finale in September was watched by a record low of under 11 million viewers, according to ratings data.

“Howard Stern’s towering presence and opinions on last season’s show as a new judge made a dramatic impact and added a sharper edge to the fascinating developments on stage,” Paul Telegdy, president of alternative programming at NBC, said in a statement.

The show, which also features celebrity judges Sharon Osbourne and Howie Mandel, remained the top-rated summer series among adults aged 18-49, the demographic most coveted by advertisers.

NBC attributed the overall 2012 audience decline partly to an earlier start that pitted “Got Talent” against end-of-season original programming in May.

The network is still searching for a replacement for Osbourne, who has quit in a dispute with NBC over their decision to drop her son Jack from another reality show.

Unlike popular singing competitions “The Voice,” “The X Factor” and “American Idol,” “America’s Got Talent” is open to dancers, comics, dancers and other performers. It is produced by “The X Factor” creator and judge Simon Cowell.

Stern is noted for his say-anything and do-anything radio program but he toned down his act when he started appearing as a judge on the show.

(Reporting by Eric Kelsey; Editing by Jill Serjeant)

TV News Headlines – Yahoo! News

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Well: New Meaning and Drive in Life After Cancer

When people hear the words “You have cancer,” life is suddenly divided into distinct parts. There was their life before cancer, and then there is life after cancer.

The number of people in that second category continues to grow. In June, the National Cancer Institute reported that an estimated 13.7 million living Americans are cancer survivors, and the number will increase to almost 18 million over the next decade. More than half are younger than 70.

A new book, “Picture Your Life After Cancer,” (American Cancer Society) focuses on the living that goes on after a cancer diagnosis. It’s based on a multimedia project by The New York Times that asked readers to submit photos and their personal stories. So far, nearly 1,500 people have shared their experiences — the good, the bad, the challenging and the inspirational — creating a dramatic photo essay of the varied lives people live in the years after diagnosis.

For Susan Schwalb, a 68-year-old artist from Manhattan, a diagnosis of early-stage breast cancer at the age of 62 led to a lumpectomy, followed by a mastectomy and then failed reconstruction surgery. She discovered that cancer was not only a physical challenge but a mental one as well, and she turned to friends and support groups to cope with the emotional strain. When she saw the “Picture Your Life” project, she submitted a photo of herself wearing a paint-splattered artist’s apron.

“What cancer made me do in my own professional life is to pedal faster,” Ms. Schwalb said in an interview. “I’ve encountered some people who decide to enjoy life, retire, work in a garden. I decided I had to have more of what I wanted in life, and I better move fast because maybe I don’t have the long life I imagined I would have.”

Indeed, a common theme of the “Picture Your Life” project is that cancer spurs people to take long-delayed trips, seek out adventure and spend time with their families. Photos of mountain climbs, a ride on a camel, scuba diving excursions and bicycle trips are now part of the online collage.

Dr. David Posner, associate program director of pulmonary medicine at Lenox Hill Hospital in Manhattan, says a diagnosis of metastatic colon cancer at the age of 47 has helped him relate to his own patients with cancer. The past decade has included nine operations, six recurrences and three rounds of chemotherapy, but Dr. Posner said he never missed more than three weeks of work.

“My salvation has been my family and my work,” he said. “When I was at work I wasn’t thinking about myself, and it was very therapeutic. I see my share of cancer patients, and I motivate them and they motivate me.”

Dr. Posner said he decided to be part of “Picture Your Life” because he wants to get the word out that a cancer diagnosis — even a dire one like his — doesn’t have to define your life.

“I think about someone asking me, ‘So how was your last decade — was it wasted or was it a life filled with a lot of happiness and joy?’ ” he said. “The cancer thing was a pain, but for the most part I’ve had a pretty good time.”

The “Picture Your Life” collage includes photo after photo of survivors with their pets. Sandra Elliott, 59, of Claremont, Calif., submitted a picture of herself with her two golden retrievers, Buddy and Molly. They were just puppies when she received a diagnosis of Stage 2 breast cancer in 2003. During her recovery from surgery and chemotherapy treatments, she took the dogs to romp on the Pomona College campus, near her home, and one day a professional photographer snapped the picture.

“No matter how bad I felt that day, no matter how many chemo treatments or doctors appointments, those two little puppies with these big black eyes would look at me with their tails wagging as if to say, ‘It’s time. It’s time. It’s time to go out!’  ” Ms. Elliott recalled.

“I felt so physically horrible, and I’d look at them and the pure joy on their faces and in their bodies for just being out in nature and being able to smell the air, smell the trees, chase a squirrel — that sheer in-the-moment love of life they showed me really lifted my spirit on a daily basis.”

Ms. Elliott still lives with chronic pain as a result of nerve damage from her cancer treatment, and she can relate to others in the “Picture Your Life” project who worry that their cancer will recur or that they’ll never feel completely normal again. But she says a stronger theme runs through all the pictures and stories.

“We have all been forced to find the joy in the smallest things,” she said. “I’m sitting here looking at a geranium about to bloom. These things are out there — we just have to be reminded to look at them. And cancer is a big reminder.”

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Supreme Court keeps California in suspense on gay marriage

By Jessica Garrison, Los Angeles Times

December 3, 2012, 7:27 a.m.

The U.S. Supreme Court did not address the California gay-marriage case on Monday morning. The next time they can consider it is on Friday.

The case against Proposition 8, the 2008 ballot initiative that banned gay marriage in California, had been discussed by justices last Friday, but was not on the list of cases the court said it would review.

Many speculated that the court might have decided not to take the case, which would let an appeals court ruling on the matter stand. The 9th Circuit Court of Appeals found earlier this year that Proposition 8 was unconstitutional, clearing the way for same-sex marriage in California unless the Supreme Court decides to get involved.

But the matter will remain in suspense for a while longer. The court could continue to discuss the case at conferences this year and early next year in advance of possibly hearing the case in June. They could also hold the matter over for the fall. 

Gay-marriage activists expressed disappointment that there was no news Monday.

"We understand that it is a complex case, and if they need another week to reach the right decision, we're fine with that," said Adam Umhoefer, executive director of the American Foundation for Equal Rights, which is fighting to overturn Proposition 8.

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Induction Charging Comes to Public Transit

Say goodbye to catenary wires. Utah State University has unveiled an electric bus that charges through induction, topping off its batteries whenever it stops to pick up passengers.

Designed by USU’s Wireless Power Transfer team and the Utah Science Technology and Research initiative’s Advanced Transportation Institute, the prototype Aggie Bus is already on the road. It uses the same wireless charging principle as an electric toothbrush or a wireless smartphone charger, except optimized for a massive public-transit vehicle.

As in all modern inductive-charging setups, a transformer is “split” between the bus and a charge plate under the bus stop. When the bus drives over the charging plate, current flows with no physical contact required. Engineers at USU designed their system so that the Aggie Bus can be misaligned up to 6 inches from the charge plate and still get 25kW of power and 90 percent efficiency from the power grid to the battery.

Because of the fixed routes they run and frequent stops they make, induction charging is ideal for buses. Instead of charging up a massive battery overnight before a route, the Aggie Bus features a smaller battery setup that recharges every time the bus reaches a predetermined stop. The smaller batteries free up interior space, reduce downtime and lower battery costs — although induction plates must be added to bus stops.

Though the Aggie Bus is a working prototype, USU is working with Wireless Advanced Vehicle Electrification (WAVE) — a company spun-out from USU — in order to bring a commercialized bus to market. In mid-2013, WAVE and the Utah Transit Authority are planning to unveil a 40-foot induction-charged transit bus on the USU campus that’s capable of taking a 50kW charge. The project was funded by USU, who will purchase the bus, and a $2.7 million grant from the Federal Transit Administration.

Charging a bus through induction may be a new idea in the U.S., but bus routes with similar wireless charging systems have been in place in Torino, Italy, since 2003 and Utrecht, the Netherlands, since 2010. Ideally, induction charging would be used in city centers to replace noisy, smoky diesel buses. It would also work on already electrified routes, allowing cities to take down unsightly hanging catenary wires.

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Led Zeppelin will Reunite – for “Letterman” interview

LOS ANGELES (TheWrap.com) – The surviving members of Led Zeppelin will make a rare appearance together on “Late Show With David Letterman” on December 3, CBS said Friday.

Jimmy Page, Robert Plant and John Paul Jones will drop in on the late-night show for an interview – which isn’t quite the reunion that Zep fans have been patiently waiting for, but it might have to do. With the exception of a one-off tribute concert for Atlantic Records founder Ahmet Ertegun at London’s O2 Arena in 2007 – which was released as the DVD “Celebration Day” in October – Jones has largely been estranged from Page and Plant since the group’s 1980 breakup following drummer John Bonham‘s death.

The “Late Show” appearance won’t be the only time that Letterman hangs out with the rock legends – the group, along with Letterman, will be lauded at the 35th Annual Kennedy Center Honors in Washington, D.C., which will take place December 2 and air December 26 on CBS.

Music News Headlines – Yahoo! News

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Study Bolsters Link Between Routine Hits to Head and Long-Term Brain Disease

The growing evidence of a link between head trauma and long-term, degenerative brain disease was amplified in an extensive study of athletes, military veterans and others who absorbed repeated hits to the head, according to new findings published in the scientific journal Brain.

The study, which included brain samples taken posthumously from 85 people who had histories of repeated mild traumatic brain injury, added to the mounting body of research revealing the possible consequences of routine hits to the head in sports like football and hockey. The possibility that such mild head trauma could result in long-term cognitive impairment has come to vex sports officials, team doctors, athletes and parents in recent years.

Of the group of 85 people, 80 percent (68 men) — nearly all of whom played sports — showed evidence of chronic traumatic encephalopathy, or C.T.E., a degenerative and incurable disease whose symptoms can include memory loss, depression and dementia.

Among the group found to have C.T.E., 50 were football players, including 33 who played in the N.F.L. Among them were stars like Dave Duerson, Cookie Gilchrist and John Mackey. Many of the players were linemen and running backs, positions that tend to have more contact with opponents.

Six high school football players, nine college football players, seven pro boxers and four N.H.L. players, including Derek Boogaard, the former hockey enforcer who died from an accidental overdose of alcohol and painkillers, also showed signs of C.T.E. The study also included 21 veterans, most of whom were also athletes, who showed signs of C.T.E.

The study was conducted by investigators at the Boston University Center for the Study of Traumatic Encephalopathy and the Veterans Affairs Boston Healthcare System, in collaboration with the Sports Legacy Institute. It took four years to complete, included subjects 17 to 98 years old, and more than doubled the number of documented cases of C.T.E. The investigators also created a four-tiered system to classify degrees of C.T.E., hoping it would help doctors treat patients.

The volume of cases in the study “allows us to see the disease at all stages of severity and how it starts and spreads in the brain, which gives us an idea of the mechanism of the injury,” said Ann McKee, the main author of the study, who is a professor of neurology and pathology at Boston University School of Medicine and works at the V.A. Boston.

Those categorized as having Stage 1 of the disease had headaches and loss of attention and concentration, while those with Stage 2 also had depression, explosive behavior and short-term memory loss. Those with Stage 3 of C.T.E., including Duerson, a former All-Pro defensive back for the Chicago Bears who killed himself last year, had cognitive impairment and trouble with executive functions like planning and organizing. Those with Stage 4 had dementia, difficulty finding words and aggression.

Despite the breadth of the findings, the study, like others before it, did not prove definitively that head injuries sustained on the field caused C.T.E. To do that, doctors would need to identify the disease in living patients by using imaging equipment, blood tests or other techniques. Researchers have not been able to determine why some athletes who performed in the same conditions did not develop C.T.E.

The study also did not demonstrate what percentage of professional football players were likely to develop C.T.E. To do that, investigators would need to study the brains of players who do not develop C.T.E., and those are difficult to acquire because families of former players who do not exhibit symptoms are less likely to donate their brains to science.

“It’s a gambler’s game to try to predict what percentage of the population has this,” said Chris Nowinski, a co-author of the study and a co-director of the Center for the Study of Traumatic Encephalopathy at Boston University School of Medicine. “Many of the families donated the brains of their loved ones because they were symptomatic. Still, this is probably more widespread than we think.”

Researchers expected the details in the study to dispel doubts about the likelihood that many years of head trauma can lead to C.T.E. The growing connections between head trauma and contact sports, though, have led some nervous parents and coaches to assume that any concussion could lead to long-term impairment. Some doctors say that oversimplifies matters. Rather, the total amount of head trauma, including smaller subconcussive hits, as well as how they were treated, must be considered when evaluating whether an athlete is more at risk of developing a disease like C.T.E.

“All concussions are not created equal,” said Robert Cantu, a co-author of the study and a co-director of the encephalopathy center. “Parents have become paranoid about concussions and connecting the dots with C.T.E., and that’s wrong. The dots are really about total head trauma.”

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