Oct. 12, 2010 -- A small study of high school football players suggests that players who endure multiple impacts to the head may experience brain impairment, even in the absence of a diagnosed concussion.

Researchers led by Thomas Talavage, PhD, of Purdue University in West Lafayette, Ind., and colleagues identified 11 male high school football players, ages 15 to 19, who were either diagnosed by a doctor as having a concussion, withstood a high number of hits to the head during practice or games, or withstood an unusually hard impact. Among those 11 players, three were diagnosed with concussions during football season, and eight had no documented concussions.

The players wore the appropriate safety gear throughout the season, including helmets equipped with sensors so that the researchers could record and analyze impact data. The impact data were then compared with brain-imaging scans and cognitive tests performed by each player before, during, and after football season. Talavage and his team also video-recorded the athletes while they played on the field.

Four of the eight players who appeared to be uninjured, meaning they did not have a diagnosed concussion, showed significant changes in brain function, such as memory. These players had endured multiple hits to the top front of the head, near the dorsolateral prefrontal cortex. This is an area of the brain critical for planning and organization. The three players who were diagnosed with concussions also showed changes in brain function and memory.

The researchers found that these changes in cognitive function persisted at the end of the season.  According to Talavage, new preliminary data show that the players might recover before the start of the next season, but additional research is need to determine the extent of recovery.

The findings are published online in the Journal of Neurotrauma.
How Brain Damage Occurs

"Our key finding is a previously undiscovered category of cognitive impairment," says Talavage, associate professor of biomedical engineering and electrical and computer engineering and co-director of the Purdue MRI Facility.

When a person is hit in the head, the brain bounces back and forth in the skull, the researchers explain, which can lead to damaged brain cells and even damage to surrounding tissue. Such an impact can break nerve fibers called axons or connective cell tissue called synapses. This, in turn, could interfere with proper brain cell signaling.

The study results come just weeks after authorities reported that a 21-year-old Pennsylvania college football player who had committed suicide also suffered brain damage. The young player was diagnosed by Boston University researchers with chronic traumatic encephalopathy, often seen in boxers and National Football League players who have suffered repeated head trauma.

The Purdue researchers say their findings raise the question of how many hits it takes to cause brain impairment. This information could help lead to improvements in safety guidelines and more sophisticated safety gear for players.