Repetitive head impacts in youth hockey lead to significant changes in brain 'vital signs'

Results of the latest phase of a multi-year hockey concussion study by SFU researchers, working with neuroscientists at Surrey’s Health and Technology District and the Mayo Clinic, have found significant brain “vital sign” changes in a pre-to-post season comparison across two youth player groups.

Researchers monitored the brain vital signs in 23 U.S.-based Bantam players (age 14 and under) and Junior A players (age 16-20) during pre- and post-game play. Brainwaves were measured at the rink using portable electroencephalography (EEG), which provided an objective evaluation of cognitive brain function. 

In addition to changes in auditory sensation and cognitive processing, sub-concussive changes were significantly correlated with the number of head impacts over the season across both age groups.

A sub-concussive impact is a mechanical force transmitted to the brain below the threshold for a diagnosis of an acute concussive injury. The effects of these low-magnitude impacts may not even be noticeable to the player or to observers on the sidelines.

The study builds on initial 2019 results published in Brain: A Journal of Neurology that confirmed significant brain vital sign changes shortly after concussions were diagnosed in Junior A players. 

The initial 2019 study results show that undetected impairments remained when players were cleared to return to play using current clinical concussion protocols. Notably, the initial study also reported sensitivity to sub-concussive impairments in those players who did not sustain a concussion diagnosis over the course of the season.  

The current study's latest results with the addition of younger Bantam players have been published in Brain Communications. 

New results show: 

• Significant brain vital sign changes in specific auditory sensation and cognitive processing responses for the pre-to-post season comparison across both groups. 
• Differences between the Bantam and Junior A ice hockey players showed more changes in the Junior A group.
• Importantly, the subconcussive changes were significantly correlated with the number of head impacts over the season across both age groups, and consequently showed more subconcussive changes in brain vital signs.

"Our research has shown that repetitive sub-concussive impacts triggered compounding effects in brain function changes,"  says study lead author Shaun Fickling, a recent SFU PhD biomedical engineering graduate. "This underscores the importance of shifting our thinking and understanding of concussions as a singular acute-injury model to a spectrum of head-impact exposure and effects over time." 

SFU neuroscientist and professor Ryan D'Arcy, who collaborated on the research, says: "In medicine, you can't treat what you can't measure. With breakthroughs on measurement challenges, we hope to now accelerate treatment innovations for prevention, acute care and extended care concussion management – for all people across a range of different applications."

The study was funded in part by USA Hockey and co-led by researchers at the Health and Technology District in Surrey, and the Mayo Clinic Sports Centre in Rochester, Minnesota.