UCLA has released a new study of brain damages caused by concussions. The current study this spring involves retired football players, but UCLA says the next phase of its ongoing study will involve military veterans.

There’s an interesting new twist on this research, though. The degenerative brain condition known as chronic traumatic encephalopathy (CTE) can only be diagnosed after death during an autopsy to reveal abnormal tangles of a protein called tau in sections of the brain that control mood, cognition and motor function.

However, scientists are now using PET scans (positron emission tomography) to look for the tau tangles in the brains of living athletes.

And they’re finding that there are some remarkable differences in the brains of retired NFL players who have suffered concussions that set them apart from the scans of healthy people and from those with Alzheimer’s disease.

Using FDDNP, a chemical marker that binds to tau tangles and amyloid beta plaques, researchers found that the former athletes had four stages of tau deposits that could signify early to advanced levels of CTE.

“These different stages reflected by the brain marker may give us more insight into how CTE develops and allow us to track the disease over time,” said Dr. Vladimir Kepe, one of the study’s authors and a research pharmacologist at the Geffen School of Medicine.

Participants also underwent MRI scans and neuropsychological testing to determine whether they had symptoms consistent with CTE, Alzheimer’s dementia, or normal aging.

“We found that the imaging pattern in people with suspected CTE differs significantly from healthy volunteers and from those with Alzheimer’s dementia,” said Dr. Julian Bailes, an author of the study and director of the Brain Injury Research Institute at NorthShore University HealthSystem in Evanston, Ill. “These results suggest that this brain scan may also be helpful as a test to differentiate trauma-related cognitive issues from those caused by Alzheimer’s disease.”

Compared with healthy people and those with Alzheimer’s the former athletes had higher levels of FDDNP in the amygdala and subcorticol regions of the brain, areas that control learning, memory, behavior, and emotions.

On the other hand, people with Alzheimer’s had higher levels of FDDNP in the cerebral cortex, which controls memory, thinking, attention and other cognitive abilities.

Researchers say that more expanded studies will help them understand better how different types of head injuries may contribute to chronic brain disorders. This could help doctors and scientists to test treatments that could delay the progression of the disease before significant brain damage occurs.