Changes in blood miRNAs in football players may be biomarkers representing brain injury

This is the first study of its kind in professional football players, and the findings show that repeated headers and accidental head strikes can lead to changes in blood patterns that are linked to specific brain signaling pathways

Study leader Dr Stian Bahr Sandmo said: "This was an exploratory study with a relatively small sample size, however, building on our study, future discoveries may ultimately lead to a potentially dangerous impact on repeated head impacts.

Publishing their findings in the journal Brain Injury, the researchers wrote: "To our knowledge, this is the first study to explore the effects of different head impacts on circulating miRNAs in football.

Football involves active headers as well as the risk of accidental head blows, which expose players to constant head blows over a period of time

A key hurdle in assessing potential brain injury from head impact is the lack of objective diagnostic and prognostic biomarkers, the team goes on to say

In contrast, the researchers previously suggested that several miRNAs in the blood may be altered by mTBI, which may help determine the severity of brain injury and provide prognostic information

However, the team noted, "Although previous studies have identified candidate miRNAs as biomarkers for mTBI, including in sports-specific settings, the impact of football-related heads on miRNAs remains largely unexplored

In their newly published study, the multidisciplinary team of researchers wanted to uncover whether head impacts during football matches alter levels of microRNAs that reflect short-term effects on the brain

Blood samples were taken from 89 professional football players at rest

The microRNAs highlighted by their data were subsequently validated to identify microRNAs that were consistently deregulated

When specifically considering accidental head injuries, the study identified eight dysregulated microRNAs that were not affected by high-intensity exercise

Interestingly, the findings highlight microRNA changes that are specific to each scenario

"It is interesting to find no overlap between repeated head impacts and accidental head impacts in our study," the researchers added

The findings also explain several shared pathways under different conditions, the researchers report

Limitations of the study include the relatively small sample size and the use of direct observation and video analysis to assess head impact exposure, making it impossible to quantify the extent of biomechanical effects across conditions

Nonetheless, the team said, "Overall, these findings do add further evidence of how microRNAs can be used as biomarkers of brain injury

While previous studies have shown a link between repeated head impacts and potential signs of neuroinflammation, they said, "Ultimately, it is unknown how our findings might translate into specific changes in brain structure, function and metabolism.

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" One possible explanation is that the repetitive head has the potential to trigger a neuroinflammatory response in neural tissue
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Exploring the relationship between TFG-β, fluid biomarkers, and clinical outcomes may be the subject of future research
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