Sports-related concussions and mild traumatic brain injuries have grabbed headlines in recent months, as the long-term damage they can cause becomes increasingly evident among both current and former athletes. The Centers for Disease Control and Prevention estimates that millions of these injuries occur each year.
Despite the devastating consequences of traumatic brain injury and the large number of athletes playing contact sports who are at risk, no method has been developed for early detection or tracking of the brain pathology associated with these injuries.
Now, for the first time, UCLA researchers have used a brain-imaging tool to identify the abnormal tau proteins associated with this type of repetitive injury in five retired National Football League players who are still living. Previously, confirmation of the presence of this protein, which is also associated with Alzheimer's disease, could only be established by an autopsy.
The preliminary findings of the small study are reported Jan. 22 in the online issue of the American Journal of Geriatric Psychiatry, the official journal of the American Association for Geriatric Psychiatry.
Previous reports and studies have shown that professional athletes in contact sports who are exposed to repetitive mild traumatic brain injuries may develop ongoing impairment such as chronic traumatic encephalopathy (CTE), a degenerative condition caused by a build up of tau protein. CTE has been associated with memory loss, confusion, progressive dementia, depression, suicidal behavior, personality changes, abnormal gait and tremors.
"Early detection of tau proteins may help us to understand what is happening sooner in the brains of these injured athletes," said lead study author Dr. Gary Small, UCLA's Parlow-Solomon Professor on Aging and a professor of psychiatry and biobehavioral sciences at the
Semel Institute for Neuroscience and Human Behavior at UCLA. "Our findings may also guide us in developing strategies and interventions to protect those with early symptoms, rather than try to repair damage once it becomes extensive."
Small notes that larger follow-up studies are needed to determine the impact and usefulness of detecting these tau proteins early, but given the large number of people at risk for mild traumatic brain injury — not only athletes but military personnel, auto accident victims and others — a means of testing what is happening in the brain during the early stages could potentially have a considerable impact on public health.
For the study, the researchers recruited five retired NFL players who were 45 years of age or older. Each had a history of one or more concussions and some were experiencing cognitive or mood symptoms. The players represented a range of positions, including linebacker, quarterback, guard, center and defensive lineman.
"I hope that my participation in these kinds of studies will lead to a better understanding of the consequences of repeated head injury and new standards to protect players from sports concussions," said Wayne Clark, a player in the study who had normal cognitive function.
For the study, the UCLA scientists used a brain-imaging tool they had developed previously for assessing neurological changes associated with Alzheimer's disease. They employed a chemical marker they created called FDDNP, which binds to deposits of amyloid beta "plaques" and neurofibrillary tau "tangles" — the hallmarks of Alzheimer's — which they then viewed using a positron emission tomography (PET) scan, providing a "window into the brain." With this method, researchers are able to pinpoint where in the brain these abnormal proteins accumulate.
After the players received intravenous injections of FDDNP, researchers performed PET brain scans on them and compared the scans to those of healthy men of comparable age, education, body mass index and family history of dementia.
The scientists found that compared to the healthy men, the NFL players had elevated levels of FDDNP in the amygdala and subcortical regions of the brain. These regions control learning, memory, behavior, emotions, and other mental and physical functions. Those players who had experienced a greater number of concussions were found to have higher FDDNP levels.
"The FDDNP binding patterns in the players' scans were consistent with the tau deposit patterns that have been observed at autopsy in CTE cases," said study author Dr. Jorge R. Barrio, a professor of molecular and medical pharmacology at the David Geffen School of Medicine at UCLA.