BACKGROUND: Sports-related head trauma is common but still there is no 
established laboratory test used in the diagnostics of minimal or mild traumatic 
brain injuries. Further the effects of recurrent head trauma on brain injury 
markers are unknown. The purpose of this study was to investigate the 
relationship between Olympic (amateur) boxing and cerebrospinal fluid (CSF) 
brain injury biomarkers.
METHODS: The study was designed as a prospective cohort study. Thirty Olympic 
boxers with a minimum of 45 bouts and 25 non-boxing matched controls were 
included in the study. CSF samples were collected by lumbar puncture 1-6 days 
after a bout and after a rest period for at least 14 days. The controls were 
tested once. Biomarkers for acute and chronic brain injury were analysed.
RESULTS: NFL (mean ± SD, 532±553 vs 135±51 ng/L p = 0.001), GFAP (496±238 vs 
247±147 ng/L p<0.001), T-tau (58±26 vs 49±21 ng/L p<0.025) and S-100B (0.76±0.29 
vs 0.60±0.23 ng/L p = 0.03) concentrations were significantly increased after 
boxing compared to controls. NFL (402±434 ng/L p = 0.004) and GFAP (369±113 ng/L 
p = 0.001) concentrations remained elevated after the rest period.
CONCLUSION: Increased CSF levels of T-tau, NFL, GFAP, and S-100B in >80% of the 
boxers demonstrate that both the acute and the cumulative effect of head trauma 
in Olympic boxing may induce CSF biomarker changes that suggest minor central 
nervous injuries. The lack of normalization of NFL and GFAP after the rest 
period in a subgroup of boxers may indicate ongoing degeneration. The recurrent 
head trauma in boxing may be associated with increased risk of chronic traumatic 
brain injury.