CSF-Biomarkers in Olympic boxing: Diagnosis and effects of repetitive head trauma
Neselius S., Brisby H., Theodorsson A., Blennow K., Zetterberg H,, Marcusson J. PLoS ONE. 2012; 7(4): 1-8.
It has been shown that there are deleterious acute and long-term effects (e.g., chronic traumatic brain injury) in the brain among boxing athletes. Currently, there are no objective measures sensitive enough to diagnosis a concussion or monitor the long-term effects from head impacts (e.g., neurofibrillary tangles, amyloid plaques). Therefore the purpose of this study was to evaluate the relation between cerebral spinal fluid biomarkers (an objective measure that marks the state of a biological process) and boxing exposure in elite Olympic boxers. The study included 30 Olympic boxers with a history of at least 45 bouts (only 26 boxers had complete data due to drop outs) and 25 healthy family or friend controls (non-boxers) matched on age. All participants filled out a questionnaire about medical history as well as any current head and neck signs and symptoms, medication, education, occupation, concussion history, as well as alcohol and drug usage. In addition the boxers reported data about their boxing career (e.g., number of knock outs, referee stoppages, record). With this information a boxing expert with no CSF biomarker knowledge graded the boxers into 1 of 5 boxing exposure categories, where 1 was a boxer with low risk to receive a head blow according to their reported skill and a boxing exposure category 5 was a boxer with the highest risk of receiving a blow to the head. After that, all of the participants had a neurological examination (e.g., concussion signs and symptoms, coordination, gait, cranial nerves, neurological status), magnetic resonance imaging (MRI), neuropsychological testing (e.g., long and short memory, mental speed, recollection), and finally a lumbar puncture. Lumbar punctures were collected twice for boxers (within 6 days of a bout and at least 14 days after a bout). The cerebral spinal fluid biomarkers included S-100b, T-tau, neurofilament light (NFL, and glial fibrillary acidic protein (GFAP). The control subjects had 1 lumbar puncture. No difference were found between boxers and controls within their medical and social history. Only 1 boxer had current concussion signs and symptoms listed on the questionnaire. Both, boxers and control groups had no symptoms of concussion on their neurological exam, MRI, or neuropsychological examination. Boxers had significantly elevated concentrations of GFAP and NFL at both acute and long-term tests compared to controls. T-tau and S-100b were also significantly elevated in boxers compared to control but only during the acute test period.
Repetitive head trauma in boxing may be associated with increased risk of chronic traumatic brain injury. Analysis of biomarkers can assist in understanding the pathology associated, at a molecular level, with concussions. Furthermore, some biomarkers may be sensitive enough to detect subclinical brain responses to repetitive head impacts and could possibly be used to predict the risk of the patient having a prolong recovery or long-term effects. In this role, biomarkers may be able to prevent-long term effects if they can be eventually used to improve return to play guidelines. This data demonstrates that even though traditional objective and subjective data showed no concussion, the boxers had higher concentrations of the NFL, GFAP, S100-b, and T-tau biomarkers within 6 days of a bout, which indicates axonal and neuronal damage. Furthermore, the elevated NFL and GFAP, even after at least 14 days of no head impact exposures, may suggest ongoing degenerative changes. In addition, this suggests that boxers may need longer time off between bouts. Biomarkers may be used to evaluate recovery and useful in specific return to play guidelines, however, lumbar puncture is an evasive procedure. It would be interesting to see if these biomarkers are also elevated in the blood, which would be much easier to collect. Do you believe biomarkers would be a good tool in concussion diagnosis, return to play, and following long term recovery?
Written by: Jane McDevitt MS, ATC, CSCS
Reviewed by: Jeffrey Driban
Neselius, S., Brisby, H., Theodorsson, A., Blennow, K., Zetterberg, H., & Marcusson, J. (2012). CSF-Biomarkers in Olympic Boxing: Diagnosis and Effects of Repetitive Head Trauma PLoS ONE, 7 (4) DOI: 10.1371/journal.pone.0033606