Soccer heading associated with white matter microstructure and cognitive abnormalities
Lipton ML., Kim N., Zimmerman ME., Kim M., Stewart WF., Branch CA. Radiology. 2013; ahead of print
Take Home Message: Heading was associated with abnormal white-matter microstructure and poorer neurocognitive performance. History of concussion was not associated with altered structure.
Long-term cognitive impairments following repeated sport-related head injury is a major concern. However, the role of subconcussive impacts from soccer heading as an additional mechanism of cumulative brain injury has not been well examined. If repetitive heading causes adverse effects on the brain there could be additional rules put in place to prevent long-term consequences. Therefore, the purpose of this study was to investigate the association of soccer heading with evidence of traumatic brain injury. Twenty-eight male and 9 female amateur soccer players completed the Einstein Heading Questionnaire. The Einstein Heading Questionnaire was used to estimate heading during the prior 12 months as well as ascertain participants’ demographics and lifetime concussion history. Then a licensed neuropsychologist conducted a neuropsychological assessment to measure psychomotor speed, attention, executive function, and memory. Finally, whole-brain magnetic resonance imaging was performed. Using the data taken from the Einstein Heading Questionnaire the authors determined that the number of headings ranged from 32 to 5400 times during the previous year. To assess the relationship of heading and participant characteristics researchers separated the participants into 3 exposure groups: nine participants were in the low-heading group (£ 276 headings a year), 19 participants were classified in the medium-heading group (277 to 1095 headings per year), and nine were placed into the high-heading group (³ 1096 headings per year). Higher levels of heading were associated with more months of playing per year. There was no difference in groups with respect to age, years of education, or concussion history. Imaging revealed an association between heading and amount of white matter microstructure damage within 3 locations of the temporal-occipital region with a threshold value from 885 to 1550 headings per year. There was also an association between heading and memory function with a threshold of approximately 1800 headings per year. There were no other significant relationships found between imaging and cognitive measures.
This study suggests a relationship between the number of self-reported headings with abnormal white matter microstructure and poorer neurocognitive performance on a memory test. Interestingly, there were no relationships associated with previous concussion. Additionally, there were estimated heading thresholds (885-1550 headings associated with abnormal white matter microstructure; 1800 headings associated with memory impairments). It has been proposed that athletes can recover from a concussion given enough time. This study suggests that brain tissue is injured with sub-concussive impacts and that the white matter is unable to repair itself beyond a certain level of heading exposure. There are some notable limitations within this study. For example the heading exposure was self-reported, and there was no consideration for site of impact, velocity, or other individual heading characteristics.
Questions for Discussion: Do you think placing rules on heading count limits would help prevent concussions? How would this be monitored? Do you think youth athletes are more at risk?
Written by: Jane McDevitt PhD, ATC, CSCS
Reviewed by: Stephen Thomas