White matter hyperintensities may hold key to identifying long-term harm in contact sports

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A new study has found that brain scans taken during the lifetimes of athletes in contact sports, compared to changes in their brains at autopsy, showed that white matter hyperintensities—markers of injury to the brain’s white matter—were associated with neuropathological changes. The study also found that white matter hyperintensities were more common in athletes who played contact sports longer or had more head impacts during their careers. This research is published in an online issue of Neurology, the medical journal of the American Academy of Neurology (AAN).

“Our results are exciting because they show that white matter hyperintensities might capture long-term harm to the brain in people who have a history of repetitive head impacts,” said study author Michael Alosco (Boston University School of Medicine, Boston, USA). “White matter hyperintensities on MRI [magnetic resonance imaging] may indeed be an effective tool to study the effects of repetitive head impacts on the brain’s white matter while the athlete is still alive.”

The study involved 75 people who were exposed to repetitive head impacts and had reported symptoms, and all of whom had donated their brains after their death in order to advance research into the long-term effects of repetitive head impacts.

This included 67 American football players, as well as eight other athletes in contact sports like soccer and boxing, or military veterans. Of the American football players, each of whom played the sport for an average of 12 years, 16 athletes played professionally and 11 played semi-professionally.

Researchers then looked at medical records, including scans that were done while the athletes were still alive. Participants had scans taken of their brains at an average age of 62 years. The average age of the athletes at death was 67 years.

Of the participants, 64% were judged to have had dementia prior to death. This was determined by a discussion with their loved ones. Autopsies showed that 53 of them (71%) also had chronic traumatic encephalopathy (CTE)—a neurodegenerative disease associated with repetitive head impacts, including those from contact sports, that can progress to dementia.

After examining the brain scans, the study’s researchers found that, for every unit difference in white matter hyperintensity volume, the odds of having more severe small vessel disease and other indicators of white matter damage roughly doubled, and the odds of having more severe tau accumulation in the frontal lobe of the brain increased threefold. Tau protein accumulation in the brain is a biomarker for progressive brain disorders like Alzheimer’s disease and CTE.

The researchers also found that higher amounts of white matter hyperintensities were associated with more years of playing American football. And, when it came to completing daily tasks, greater amounts of white matter hyperintensities were associated with higher scores on a questionnaire about performing daily tasks that was completed by caregivers of the brain donors.

Limitations of the study included the use of MRIs obtained for clinical purposes rather than research purposes, and the fact that participants were mostly older, symptomatic, male, former American football players. “There are key limitations to the study, and we need more research to determine the unique risk factors and causes of these brain lesions in people with a history of repetitive head impacts,” Alosco added.


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