BY SARAH OWENS
Researchers have identified a protein that may eventually be used to diagnose chronic traumatic encephalopathy (CTE) in living patients. That's according to a new study published online in the journal PLOS One on September 26.
An Elusive Disease
A neurodegenerative brain disease caused by repeated hits or blows to the head, CTE has been diagnosed after death in a growing number of football, hockey, and other contact sport players. A recent study of a "brain bank" at Boston University (BU), for example, found that 110 of 111 former NFL players had CTE.
The disease is difficult to diagnose, however. Symptoms such as depression and anxiety may appear years or decades before death, but the condition can only be diagnosed during autopsy. Researchers are looking for biomarkers that can be measured by blood tests or brain imaging so patients can be diagnosed and treated while they are alive.
Measuring a Protein
Researchers at Boston University zeroed in on CCL11, a protein in the brain and spine that has been linked with age-related cognitive decline, and that has been shown to increase in response to inflammation. The researchers studied 23 deceased NFL players, whose brains had been donated to BU's CTE Center and who had been determined to have CTE based on neuropathological analysis; 50 people with Alzheimer's disease who did not have a history of head trauma; and 18 non-athletes who also had no history of head trauma, who were used as a control group.
Using a specific enzyme-linked test, the researchers measured levels of CCL11 in the participants' brains and cerebrospinal fluid samples.
Interpreting the Findings
The NFL players had significantly increased levels of CCL11 compared to both the Alzheimer's disease group and the control group. NFL players who had worse CTE, as measured by the amount of tau, a toxic protein, in their brains, had higher levels of CCL11, suggesting levels of the protein increased steadily as the disease worsened. Additionally, the researchers found a strong association between the number of years of play and CCL11 levels; the longer the athletes played, the greater their CCL11 levels were.
The findings are preliminary because the number of athletes enrolled in the study was small, the study authors said. But if the relationship between CCL11 levels and CTE is confirmed in larger studies, that would "suggest that CCL11 may be a [new] biomarker to aid in the detection of CTE and to distinguish CTE from [Alzheimer's disease]." If CTE could be diagnosed in patients while they're still alive, it may be possible to treat them.