Thursday, August 22, 2013

Chronic Traumatic Encephalopathy (CTE) Found in Living Athletes

"Chronic traumatic encephalopathy, or CTE, is a brain disease that closely resembles dementia, which is usually diagnosed late in life. It manifests as dark tangles in the brain and spinal cord that may alter functioning in regions that control sexual impulses, emotion, even breathing. Forensic pathologist Dr. Bennet Omalu said that among players he has examined, CTE is associated with loss of cognitive functioning, loss of language, uncontrollable depression and suicidal tendencies."
An insidious, microscopic protein that has been found in the brain tissue of professional football players after death may now be detectable in living people by scanning their brains.

Researchers say they found tau protein in the brains of five living retired National Football League players with varying levels of cognitive and emotional problems.

Using a scan called positron emission tomography, or PET -- typically used to measure nascent Alzheimer's disease -- researchers injected the players with a radioactive marker that travels through the body, crosses the blood-brain barrier and latches on to tau.

Then, the NFL retirees had their brains scanned.

"It's definite, we found it, it's there," said Dr. Julian Bailes, co-director of the NorthShore Neurological Institute in Evanston, Illinois, and co-author of a new study that identified the tau. "It was there consistently and in all the right places."

"It was identical to what's seen in a condition called chronic traumatic encephalopathy, CTE, that has only been diagnosed at autopsy," said Dr. Gary Small, professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA and lead author of the study, published Tuesday in the American Journal of Geriatric Psychiatry.

Tau is significant because it has been found -- posthumously -- in the brains of dozens of former NFL players, including Junior Seau, Dave Duerson, Ray Easterling, Terry Long, Shane Dronett and Mike Webster. All committed suicide and were later diagnosed with a disease called chronic traumatic encephalopathy.

What has stymied researchers for years is that tau can only be uncovered after death. Finding it in living players is considered by many researchers to be the "holy grail" of concussion research, according to Bailes.

"After a while it gets old and not so fulfilling to take the brain out when (an athlete) is dead," said Bailes, a neurosurgeon and director of the Brain Injury Research Institute, which focuses on the study of traumatic brain injuries and their prevention. "At that point there is no solution, no answer."

"This is a very exciting but preliminary study," said Robert Stern, co-founder of the Center for the Study of Traumatic Encephalopathy at the Boston University School of Medicine. "The researchers did what so many of us have been wanting to do for the last couple of years.

"The problem is that the type of PET scan they used is really not specific to what we're looking at with chronic traumatic encephalopathy."

The marker used in the PET scan -- the one that binds to tau -- is called FDDNP. The problem with using that marker, said Stern, is that it is not specific enough. It binds not just to tau, but also to another protein called beta amyloid, which is commonly seen in Alzheimer's disease patients.

"In CTE, only tau is found in abundance," said Stern, an Alzheimer's expert. "What researchers saw was parts of the brain lighting up and showing abnormal findings. ... But we don't know if what is lighting up is tau alone, or beta amyloid, or both."

It's the location of the protein that is important, Small said. In Alzheimer's disease, tau is typically found in the outer part of the brain, called the cortex.

"It's different from Alzheimer's," said Small, director of the UCLA Longevity Center, adding that he found tau in deeper structures of the brain.

"The patterns of the scans are identical to what's seen at autopsy in other people (with CTE)," like Seau, Duerson and Easterling, he said. "And we know at autopsy it's primarily tau."

When tau lodges into those deep brain structures -- for example, the amygdala, which is associated with rage and other emotions, or the hippocampus, a seat of memory -- it causes major disruptions to those areas.

That disruption may be related to depression, memory problems and suicidal behavior common in cases of CTE studied thus far -- not just in retired NFL players, but in athletes in other sports and members of the military.

The hope among the study's authors is that a diagnostic brain scan might one day detect burgeoning CTE in all sorts of people who suffer concussions.

Building on the research -- expanding the study population -- is what Small and Bailes are working on now. In the meantime, they are optimistic about their findings.

"Right now, the (FDDNP) PET scan is the only method that we know of that can measure tau protein in living people," said Small. "It's not the perfect holy grail ... but for now it seems to be showing us what we're looking for."

More information:
» New study shows people with CTE were more likely to express the APOE gene, which is associated with slower recovery and worse cognition after traumatic brain injury; it's also associated with later development of Alzheimer's disease.
» NFLPA, Harvard University study long-term health of players with $100 million deal
» NIH found CTE in 34 of 35 deceased NFL players whose brains were donated
» NFL and 4,500 Former Players Settle Concussion-Related Lawsuit for $765 Million

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