BY REBECCA HISCOTT
Left image shows a normal brain scan; middle image shows a suspected CTE subject and right image shows an Alzheimer's case. More red and yellow colors demonstrate more abnormal brain proteins (tau and amyloid). Image: PNAS/David Geffen School of Medicine at UCLA.
In the past few years, national media attention has revolved around several high-profile cases of athletes who committed suicide and were later found to have chronic traumatic encephalopathy (CTE), a degenerative brain disease that appears in people with a history of repeated traumatic brain injury (TBI). It is believed to cause progressive cognitive and behavioral changes such as memory loss, confusion, dementia, suicidal behavior, depression, personality changes, and even physical symptoms like tremors or an abnormal gait.
Currently, the only way to diagnose the disease is after a patient’s death, when doctors can perform an autopsy to look for an accumulation of tau protein—which is also observed in people with Alzheimer’s—in regions of the brain that control mood, cognition, and motor function. In living patients, doctors may suspect CTE based on cognitive, behavioral, and motor changes, combined with a history of TBI.
Now, researchers at the University of California, Los Angeles, have found a way to detect possible signs of this devastating condition in the brains of living people.
PET Scans Reveal Protein Pattern
For the study, published in the Proceedings of the National Academy of Sciences, 14 former NFL players suspected to have CTE based on their cognitive and behavioral symptoms received positron emission tomography (PET) scans using a special chemical tracer that allowed the researchers to track how tau protein was spread throughout their brains. The researchers administered the same PET scans to 24 people with Alzheimer’s disease and 28 healthy people.
All of the former football players had similar patterns of tau deposits throughout their brains, concentrated mainly in the subcortical region and the amygdala—areas that govern learning, memory, behavior, and emotions. This pattern appeared consistent with that of tau accumulation observed in people with an autopsy-confirmed diagnosis of CTE, the researchers said.
The brains of the Alzheimer’s patients had a different pattern of tau accumulation—one that involved areas of the cerebral cortex, which governs cognitive abilities like memory, thinking, and attention.
“We found that the imaging pattern in people with suspected CTE differs significantly from healthy volunteers and those with Alzheimer’s,” said study author Julian E. Bailes, MD, director of the Brain Injury Research Institute and chairman of neurology at NorthShore Neurological Institute in Evanston, IL, in a news release.
The Way Forward
The findings are very preliminary, and Dr. Bailes and his colleagues cautioned that the observed tau accumulations do not definitively prove that the 14 retired NFL players have CTE. Larger studies conducted at multiple centers throughout the country will be needed to test this technology and validate the findings, they said. Involving patients who have experienced other types of brain injury, such as veterans with blast-induced TBI, will also be crucial.
But Dr. Bailes said the findings do suggest that PET scans may be helpful for differentiating trauma-related cognitive issues from those caused by Alzheimer’s disease. And, he added, the results could ultimately help doctors diagnose the condition and even test possible treatments.
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