A NEW study revealed that long-term blood-brain barrier (BBB) disruption was associated with cognitive decline in retired athletes exposed to repeated head trauma.
Repetitive head impacts in collision and combat sports have long been linked to neurodegenerative conditions such as chronic traumatic encephalopathy (CTE). However, the biological mechanisms underlying these long-term effects have remained unclear. The latest findings provided evidence that BBB disruption may play a central role in this process, persisting years after athletes have retired.
Blood Brain Barrier Disruption and Long-Term Brain Health
The BBB disruption observed in this study was detected using dynamic contrast-enhanced MRI in 47 retired athletes. Researchers found that leakage across the BBB remained evident long after exposure to head impacts had ceased.
Importantly, athletes with greater BBB disruption showed worse cognitive performance compared with those with less leakage and with control participants. A distinct subgroup with extensive disruption also demonstrated reduced brain volumes, suggesting structural as well as functional consequences.
Notably, self-reported concussion history and symptom burden did not reliably predict BBB disruption, indicating that traditional clinical assessments may underestimate underlying neurological damage.
Inflammation and Cognitive Decline After Head Trauma
Further analysis revealed that BBB disruption was closely linked to systemic inflammation. Athletes with greater leakage had higher proportions of circulating monocytes and evidence of complement system dysregulation, a key component of immune response.
Gene expression analysis identified altered complement-related pathways, including receptors such as C5AR1, ITGAM, ITGB2 and CD59. Postmortem brain tissue from individuals with confirmed CTE showed deposition of the membrane attack complex around cerebral blood vessels, supporting a role for immune-mediated vascular injury.
These findings suggest that persistent inflammation and vascular dysfunction may contribute to ongoing neurodegeneration following repeated head trauma.
Despite the relatively small sample size, the study provided important mechanistic insights linking BBB disruption to cognitive decline. Larger longitudinal studies will be needed to confirm causality and determine whether targeting inflammation or vascular integrity could reduce long-term neurological risk in athletes.
Overall, the research highlighted BBB disruption as a potential biomarker and therapeutic target in CTE, offering a new direction for monitoring and managing the lasting effects of sports-related head injury.
Reference
Greene C et al. Blood-brain barrier disruption, traumatic encephalopathy, and cognitive decline in retired athletes. Sci Transl Med. 2026; DOI:10.1126/scitranslmed.adu6037.
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