Amateur Boxers at Risk of Brain Despite Headgear

MÖLNDAL, Sweden, Sept 11 -- Amateur boxers risk becoming "punch drunk" just like professional fighters despite shorter fights and protective headgear, according to researchers here.

A large body of evidence already shows that pro boxers run the risk of dementia pugilistica, said Henrik Zetterberg, M.D., Ph.D., of the Sahlgrenska University Hospital here.

However, "to our knowledge, no study has examined the short-term effects of amateur boxing on the brain in direct connection to a bout," Dr. Zetterberg and colleagues said in the September issue of the Archives of Neurology.

Some have argued that amateur boxers suffer less repetitive head trauma, making them less at risk for the syndrome. Amateur bouts are shorter than professional fights, and the amateurs must wear protective headgear, the researchers noted.

The current study included 14 Swedish amateur boxers (11 men and three women; average age 22). They underwent a lumbar puncture seven to 10 days after a fight and again after a three-month rest from boxing. Cerebrospinal fluid was analyzed for markers of brain injury, and the results were compared with cerebrospinal fluid from 10 healthy male non-athletic controls.

The study found increased levels of two markers of neuronal and axonal injury after a fight, neurofilament light protein (NFL) (845 ng/L versus 208 ng/L; P=.008) and total tau protein (T-tau) (449 ng/L versus 306 ng/L; P=.006).

The study also found increased levels of glial fibrillary acidic protein (GFAP), a marker of astroglial injury, after a fight (541 ng/L versus 405 ng/L; P=.003).

Levels of neurofilament light protein and glial fibrillary acidic protein were also significantly elevated compared with the control subjects. After three months of rest from boxing, glial fibrillary acidic protein returned to levels that were not significantly higher than the controls. However, neurofilament light protein levels remained elevated (208 ng/L in the boxers after rest versus than 125 ng/L or less in the controls; P=.001).

Levels of all three proteins were also higher in boxers who had taken 15 or more blows to the head during a fight compared with those who had taken fewer:

• Neurofilament light protein (1,490 ng/L versus 200 ng/L; P=.002)
• Total tau protein (551 ng/L versus 346 ng/L; P=.02)
• Glial fibrillary acidic protein ( (650 ng/L versus 431 ng/L; P=.02).

"The current study contributes new information about brain injury risks in amateur boxing," authors said. "Data suggest that participation in an amateur boxing bout is directly associated with neuronal and astroglial damage, as reflected by the increase in NFL, T-tau, and GFAP concentrations in cerebrospinal fluid."

"The findings that the increase in these cerebrospinal fluid biomarkers is most pronounced in boxers who receive many hits or high-impact hits to the head and that the cerebrospinal fluid levels show normalization after three months of rest from boxing indicate that the changes are directly related to brain trauma inflicted by hits to the head," they added.

"The molecular changes detected are likely to be even more pronounced in professional boxers and in boxers who have received a knockout punch," they said.

"If verified in longitudinal studies with extensive follow-up regarding the clinical outcome, analysis of cerebrospinal fluid may provide a scientific basis for medical counseling of athletes after boxing or head injury," they concluded.