'Blast Wind' Linked to Chronic Brain Injuries in Military (5/16/2012)

'Blast Wind' Linked to Chronic Brain Injuries in Military

Force created by an explosion causes similar effects as repeated concussions in athletes, study finds.
WEDNESDAY, May 16 (HealthDay News) -- The same type of brain damage seen in athletes who suffer repeated concussions also occurs in soldiers exposed to large blasts, new research indicates.

In the study, researchers at Boston University and the Veterans Affairs Boston Healthcare System analyzed brain tissue from four U.S. military personnel who were known to have been close to explosions.

The results, published online May 16 in Science Translational Medicine, showed that exposure to a single blast -- equivalent to the force from a typical improvised explosive device (IED) -- results in chronic traumatic encephalopathy and long-term brain impairments associated with the condition.

Chronic traumatic encephalopathy, a progressive brain disorder that can only be diagnosed after death, has been reported in athletes with multiple concussions. Chronic traumatic encephalopathy and traumatic brain injury share common features, including psychiatric symptoms and long-term memory and learning problems.

Traumatic brain injury can occur in people exposed to blasts and may affect about 20 percent of the 2.3 million U.S. military personnel deployed in Iraq and Afghanistan since 2001, according to the researchers.

The investigators also concluded that the blast wind, not the shock wave, from an IED explosion leads to traumatic brain injury and long-term consequences such as chronic traumatic encephalopathy.

Explosions lead to dramatic changes in pressure in the air around the blast. In addition to injuries caused by debris and shrapnel, the blast forces themselves can lead to devastating injuries.

A shock wave occurs right after an explosion, when the air around the explosion becomes overpressurized; a blast wind follows the shock wave, when the air around the explosion gets sucked back in to fill the void created by the blast. A blast wind can reach a velocity of up to 330 miles per hour.

"The force of the blast wind causes the head to move so forcefully that it can result in damage to the brain," study co-leader Dr. Lee Goldstein, an associate professor at Boston University School of Medicine and Boston University College of Engineering, said in a university news release.

The researchers also found that immobilizing the head during blast exposure can prevent the learning and memory deficits associated with chronic traumatic encephalopathy.

"Our study provides compelling evidence that blast TBI [traumatic brain injury] and CTE [chronic traumatic encephalopathy] are structural brain disorders that can emerge as a result of brain injury on the battlefield or playing field," Goldstein said. "Now that we have identified the mechanism responsible for CTE, we can work on developing ways to prevent it so that we can protect athletes and our military service personnel."


Source: http://www.womenshealt.gov/new/news/headlines/664751.cfm/

Clues to 'Slacker' Behavior Found in Brain, Study Says (5/2/2012)

Clues to 'Slacker' Behavior Found in Brain, Study Says

Levels of the chemical dopamine in key regions of the brain may influence motivation.

WEDNESDAY, May 2 (HealthDay News) -- Chemistry in three areas of the brain may influence your motivation levels, a new, small study says.

Along with providing new information about how the brain works, this study could prove important in finding ways to treat depression, schizophrenia, attention-deficit disorder and other types of mental illness linked with decreased motivation, Vanderbilt University researchers said.

The researchers monitored brain activity in 25 volunteers, aged 18 to 29, as they performed a task designed to assess their willingness to work for a cash reward.

The results showed that "go-getters" who were willing to work hard for a reward had higher release of the neurotransmitter dopamine in areas of the brain known to play an important role in reward and motivation -- the striatum and ventromedial prefrontal cortex.

But "slackers" -- those who were less willing to work hard for a reward -- had higher levels of dopamine in a brain area involved in emotion and risk perception, known as the anterior insula. Dopamine's role in this area of the brain surprised the researchers.

"Past studies in rats have shown that dopamine is crucial for reward motivation, but this study provides new information about how dopamine determines individual differences in the behavior of human reward-seekers," study author Michael Treadway, a post-doctoral student, said in a university news release.

The study appears in the May 2 issue of the Journal of Neuroscience.

"At this point, we don't have any data proving that this 20-minute snippet of behavior corresponds to an individual's long-term achievement, but if it does measure a trait variable such as an individual's willingness to expend effort to obtain long-term goals, it will be extremely valuable," co-author David Zald, a professor of psychology, said in the news release.

Further research is needed to determine whether differences in dopamine levels play a role in the lower levels of motivation seen in people with certain types of mental illness.


"Right now our diagnoses for these disorders is often fuzzy and based on subjective self-report of symptoms," Zald said. "Imagine how valuable it would be if we had an objective test that could tell whether a patient was suffering from a deficit or abnormality in an underlying neural system. With objective measures we could treat the underlying conditions instead of the symptoms."

Source: http://www.womenshealt.gov/new/news/headlines/664313.cfm/

Dental X-Rays May Be Linked to Benign Brain Tumors (4/10/2012)

Dental X-Rays May Be Linked to Benign Brain Tumors

Study found increased risk, but connection was not conclusive.

By Randy DotingaHealthDay Reporter
TUESDAY, April 10 (HealthDay News) -- People who underwent frequent dental X-rays in the past, before radiation doses were lowered, may be at greater risk of a usually benign form of tumor in the lining of the brain, a new study suggests.

The research doesn't definitely link dental X-rays to the tumors, which affect about 1 percent of people. It's also possible that dental X-rays, which are now given at a lower radiation dose, have nothing to do with the tumors.

Still, the study suggests that dental X-rays could be a risk factor for the tumors, called meningiomas, said study author Dr. Elizabeth Claus, a neurosurgeon at Brigham & Women's Hospital in Boston and a professor of epidemiology at Yale University School of Medicine. The findings suggest that patients should talk to their dentists about the possible dangers of X-rays and be aware of national recommendations regarding their use, she said.

"I do not get the feeling that people are aware of those guidelines," she said. "Many people are having them every six months or every year when the American Dental Association is saying once every two to three years." (That's the recommendation for the patient who's never had a cavity or only a small number of fillings and isn't at increased risk for a cavity.)

Meningiomas affect the lining of the brain and the spinal cord. More than 90 percent are classified as benign, not malignant. But in some cases they can grow to the size of a baseball and disrupt the brain's functioning, leading to vision problems, headaches, hearing and memory loss, and seizures.

Neurosurgeons often try to remove them in the most severe cases.

"They cause problems as soon as they achieve a certain size, because there is no room in the skull to accommodate growth. Any growth that is more than a couple centimeters can result in symptoms," explained Dr. Isabelle Germano, director of the Comprehensive Brain Tumor Program at Mount Sinai School of Medicine in New York City.

Radiation is linked to various types of tumors, including meningiomas. In the new study, researchers sought to determine whether dental X-rays are connected to meningiomas that affect the lining of the brain specifically.

The researchers examined a group of more than 1,400 patients aged 20 to 79 who were treated for the tumors between 2006 and 2011, and compared them to 1,350 similar people who did not develop the tumors. The average age in both groups was about 57.

Those with tumors were more than twice as likely as the others to report having more frequent bitewing X-rays (at any time) and panorex X-rays (especially at a young age).

Bitewing X-rays allow views of the back teeth; patients bite onto a tab during the X-rays. Panorex X-rays show the whole area in and around the mouth from below the nose to the chin.

The design of the study didn't allow the researchers to specify the level of increased risk of a tumor that a person who's had dental X-rays would conceivably face. It does appear, however, that the raised risk would remain low, Claus said.

Overall, more than 92 percent of people in the study reported having had at least one bitewing X-ray.

Dr. Matthew Messina, a Cleveland dentist and spokesman for the American Dental Association, said one weakness of the study is that people's memories about their X-rays are fuzzy. "It's difficult to pin this down," he said, especially without dental records.

Messina added that the amount of radiation in dental X-rays has gone down significantly over the years, thanks to factors such as the improved speed of X-ray film and the advent of digital X-rays.

The study was also observational in nature, meaning it can show an association but not cause-and-effect.

So what should patients do?

Adult patients and parents of child patients should talk to their dentists about X-rays, Germano said. "It's always important to discuss what the X-ray is for and what the advantage is. It's not a good idea to assume that X-rays are a benign procedure," she said.

Messina agreed. "It's always good for patients to talk to their dentists about why they're getting X-rays and what is being done to shield the patient."

Overall, dentists are trying to balance the possible dangers of radiation and the usefulness of X-rays, he said. "We take dental X-rays because we're trying to make sure the person is healthy or trying to diagnose what's wrong with them."

The study appears in the April issue of the journal Cancer.

Source: http://www.womenshealt.gov/new/news/headlines/663600.cfm/