A new study shows repeated blows to the head cause an increase of chemicals in the fluid that circulates around the brain and spinal cord. These chemicals are markers for brain and nerve cell injury. The rise of these chemicals of the brain may also help explain what is commonly known as "punch drunk" syndrome, with symptoms of long-term neurological damage.
Researchers studied a group of amateur boxers and found those who had recently suffered repeated blows to the head during a recent boxing match had higher-than-normal levels of certain chemicals in their cerebrospinal fluid (fluid that circulates around the spinal cord and brain). These chemicals, known as neurofilament light protein and total tau, have also been shown to be increased in some neurologic disorders with damage of brain neurons and cells.
Researchers say about 20 percent of professional boxers develop chronic traumatic brain injury as a result of years of repeated blows to the head during their careers in the ring. But little is known about the brain injury risks faced by amateur boxers who must wear protective headgear and compete in shorter bouts.
In the study, published in the Archives of Neurology, researchers examined the cerebrospinal fluid of 14 amateur boxers within seven to 10 days after a boxing match and again three months later after the boxers had rested from boxing. Cerebrospinal fluid from 10 healthy, nonathletic adults was also analyzed for comparison.
The results showed that after a boxing match, the boxers had higher average levels of the brain chemicals neurofilament light protein and total tau than they did after three months with no boxing. These chemicals are used as markers of brain injury and damage to nerve cells of the brain.
In addition, they also had elevated levels of another protein, called glial fibrillary acidic protein, which indicates damage to a specialized type of brain cell. An increase in this protein has also been found in people who have experienced severe brain injury.
The study showed levels of all three of these chemicals were significantly higher in boxers who had sustained more than 15 blows to the head or experienced grogginess after the bout compared with those who had 15 or fewer hits to the head and no grogginess.
Compared with the nonboxers, researchers found the boxers had higher levels of two of the three chemicals (neurofilament light protein and glial fibrillary acidic protein) immediately after a bout. Three months later, the boxers still had higher levels of neurofilament light protein than the control group.
Researcher Henrick Zetterberg, M.D., Ph.D., of Goteborg University in Sweden, and colleagues say the findings provide scientific evidence to support the development of chronic symptoms also known as "punch drunk syndrome" in professional boxers. They say if long-term studies confirm these results, analysis of spinal fluid "may provide a scientific basis for medical counseling of athletes after boxing or head injury."
SOURCES: Zetterberg, H. Archives of Neurology, September 2006; Vol. 63: pp. 1277-1280. News release, American Medical Association.
By Jennifer Warner
Reviewed by Louise Chang