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.

But the current study is drawing some skepticism, doubts that likely will not ebb until future research examines a larger study group.

"Sometimes I wish (study authors) would hang on and wait until they have a more meaningful sample size," said Kevin Guskiewicz, a concussion expert and director of the Center for the Study of Retired Athletes at the University of North Carolina at Chapel Hill. "I think that then people would be less skeptical of the findings."

Still, Guzkiewicz is encouraged by the study results.

"Unfortunately we tend to identify these (CTE) cases when they're already on the slippery slope toward dementia and it's too late to do anything," said Guskiewicz. "I'm all for trying to build on studies like this."

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."