The impact of contact sports on the brain
It is no longer to be proven that contact sports have an impact on our brain. A study, published in September 2025 in the journal Sports Medicine, had for example demonstrated that rugby players (at a level ranging from semi-professional to professional) had almost a 25% increased risk of developing dementia.
New research carried out on the brains of boxing and martial arts fighters, sports known for their violent blows, particularly to the head, has reinforced concerns about the impacts of contact sports on brain health.
The work, the conclusions of which will be presented at the annual meeting of the Radiological Society of North America (RSNA) scheduled from November 30 to Thursday December 4, 2025, was carried out by researchers from the University of Alabama at Birmingham and the Cleveland Clinic Nevada (USA).
The glymphatic system at the heart of the study
For this research, the authors analyzed data from a study called PABHS (Professional Athletes Brain Health Study), conducted by the Cleveland Clinic and which follows approximately 900 active fighters.
The researchers focused on a sample of 280 fighters, including 95 individuals with cognitive impairments at baseline and 20 healthy participants (without cognitive impairments), matched on demographic characteristics.
They used Along the Perivascular Space (DTI-ALPS), a non-invasive MRI method that tracks water movement in and around the spaces surrounding the channels of the glymphatic system, a recently discovered brain-cleaning network.
“The recently discovered glymphatic system is comparable to the brain's plumbing and waste disposal system,” said Dr. Dhanush Amin, lead author of the study, in comments reported by
SciTechDaily.
Removing waste from the brain is essential to maintain its proper functioning and prevent neurodegenerative diseases.
The brain's ability to eliminate waste increases…then decreases
The research team subsequently calculated the DTI-ALPS index, which makes it possible to assess the functioning of the glymphatic system, in athletes and control subjects. If this index decreases, it could mean cognitive decline or the progression of diseases such as Alzheimer's or Parkinson's.
After analyses, the researchers found that the DTI-ALPS index was higher in fighters with cognitive impairments, but that it decreased over time depending on the total number of knockouts. In athletes exposed to repeated trauma, glymphatic function significantly declined.
“We believe that the glymphatic index was initially elevated in injured athletes because, when faced with repeated head trauma, the brain initially responds by intensifying its cleaning mechanism, but this eventually becomes saturated,”
explained Dr. Amin, reports the English-speaking media.
Early detection of these changes in the glymphatic system could allow for better management of neurodegenerative risk in athletes practicing contact sports, the researchers concluded.
Source: SciTechDaily
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