Football hits the brain hard

Playing football is hard on a player’s body. The sport can take a toll on the brain, too, according to a new study. It found a difference in the hippocampus, a part of the brain important for making memories. The hippocampus was smaller in college football players than in other men.

Researchers found the difference in hippocampus size was even more dramatic among football players who had been diagnosed with a concussion. A concussion is a blow to the head that may leave a person unconscious.

“This is one of the first papers to draw a direct link from concussion to specific tissue changes,” Dennis Molfese told Science News. A neuroscientist at the University of Nebraska-Lincoln, Molfese did not work on the new study.

The hippocampus helps turn short-term memories into long-term memories. Scientists study this region because some sports injuries result in memory problems. However, many previous studies have focused on adults that are middle-aged or older, says Patrick Bellgowan. He’s a psychologist at the Laureate Institute for Brain Research in Tulsa, Okla., and the University of Tulsa.

In this new study, Bellgowan and his colleagues used MRI, or magnetic resonance imaging, to scan the brains of participants. The technique allowed them to measure the hippocampus in 50 college football players. About half the football players had been diagnosed with a concussion in the past. The researchers did the same in 25 male volunteers of the same age. The volunteers hadn’t played football or soccer. (Concussions occur among players of both sports.)

MRI scans revealed big differences in hippocampus size. Those differences were especially large among the players who’d had a concussion. On average, these players had hippocampi that measured just three-quarters as large as those of the non-players.

The scans showed that the 25 football players who had never suffered concussions also had smaller hippocampi. Their hippocampi were about five-sixths the volume of those of the men who didn’t play football or soccer. The researchers also found that having more years of football experience was associated with slower reaction time on tests. The findings appeared May 14 in the Journal of the American Medical Association.

Bellgowan told Science News he didn’t expect to see brain differences of this kind between nonplayers and players who hadn’t had concussions.

“It was a bit of a surprise,” he said, to find that hippocampi were smaller in both groups of football players.

Bellgowan suggested those players may have suffered head injuries. It’s just that their injuries weren’t severe enough to be called concussions. But over time, those smaller knocks still add up, he told Science News. Together, they may cause brain changes.

Scientists still don’t know why the hippocampus would shrink. One theory suggests that the body’s response to the blows suffered in contact sports causes inflammation. That may lead cells in the hippocampus to become excited and die.

“That’s the operating thesis,” Bellgowan said. However, there’s no evidence as of yet to back it up.

Power Words

concussion  Temporary unconsciousness, or headache, dizziness or forgetfulness due to a severe blow to the head.

hippocampus   (plural: hippocampi) A seahorse-shaped region of the brain. It is thought to be important to emotion, memory and the involuntary nervous system.

magnetic resonance imaging (MRI)  An imaging technique to visualize soft, internal organs, like the brain, muscles, heart and cancerous tumors. MRI uses strong magnetic fields to record the activity of individual atoms. 

neuroscience  Science that deals with the structure or function of the brain and other parts of the nervous system. Researchers in this field are known as neuroscientists.

psychology  The study of the human mind, especially in relation to actions and behavior. Scientists and mental-health professionals who work in this field are known as psychologists.