Amateur boxing can knock out precious brain cells, Swedish researchers report.

Reporting in the September issue of the Archives of Neurology, researchers at Goteborg University analyzed the spinal fluids of 14 Swedish amateur boxers and compared them to samples from 10 healthy men.

They were looking for certain chemicals that, when found in the spinal fluid, may signal damage to brain cells.

According to the researchers, the boxers had higher levels of the chemicals seven to 10 days after their boxing match than they did three months later. This likely indicates damage to brain cells from blows to the head during the match, they said.

Compared with the healthy men, the chemical levels were significantly higher in the boxers seven to 10 days and three months after the match.

Having more than 15 hits to the head or experiencing grogginess during or after a bout was associated with significantly higher levels of the chemicals, the Swedish team noted.