NEW ORLEANS – How long does it take before the cumulative effect of repeated blows to the head result in significant cognitive changes? Preliminary results from a longitudinal study of boxers and mixed martial arts fighters suggest that it takes maybe a dozen years – but that anatomical changes begin showing up in half that time.
The results so far in 109 fighters suggest that "if you wait for people to get symptomatic, the disease has possibly progressed a fair amount," said Dr. Charles Bernick, lead investigator of the study and associate medical director of the Cleveland Clinic’s Lou Ruvo Center for Brain Health in Las Vegas.
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Preliminary results from a longitudinal study of boxers and mixed martial arts fighters suggest that it takes about a dozen years for repeated blows to the head have an impact on cognition.
Clinicians may need to be assessing fighters sooner for potential damage, he said at the annual meeting of the American Academy of Neurology. Although it is not yet known, perhaps rest periods or even stopping fighting altogether might halt the neurodegenerative process.
Dr. Bernick and his colleagues at the center aim to enroll 600 people in the Professional Fighters Brain Health Study by the time funding runs out 4 years from now. Because it is longitudinal, it has a running enrollment. Those already enrolled will be continually followed.
"The real payoff will be following these guys over time and looking at the trajectories," Dr. Bernick said in an interview. The investigators are conducting volumetric brain MRI and computerized cognitive testing. Participants also are tested for mood disorders and impulsivity, and they also undergo speech analysis as well, said Dr. Bernick.
The researchers obtain fighting history, including years of fighting and fights per year, from self-reports and published records. The study will also examine biomarkers, genetic profiles, and serum proteins that might be markers of damage, he said.
Dr. Charles N. Bernick
In the preliminary analysis, the investigators divided the fighters into three groups based on median years of fighting: less than 6 years, 6-12 years, and greater than 12 years. The relationship between exposure variables, brain volumetrics, and cognitive results were examined by correlational analysis.
The 32 fighters who fought 6 years or more had lower hippocampal and thalamic volumes. But cognitive changes – measured in lower scores on memory tests and processing speed – were found only in the 39 fighters who had fought more than 12 years. The relationships remained even after adjusting for the effect of age.
The ongoing study is funded by the Lincy Foundation. Dr. Bernick reported having no financial disclosures.