Experts in the field of traumatic brain injury research agree that the solution to the NFL’s concussion epidemic lies in the area of the brain known as the hippocampus. A recent study conducted at the University of Texas Southwestern Medical Center in Dallas has found that retired NFL players with a history of concussion that resulted in unconsciousness have a higher risk for suffering brain atrophy associated with memory storage and impaired memory performance as they get older.

"Our findings suggest that a remote history of concussion with loss of consciousness is associated with both later-in-life decreases in hippocampal volume and memory performance in retired NFL players," Dr. Munro Cullum, a neuropsychologist at the UT Southwestern Medical Center, said in a statement.

Cullum and his colleagues recruited 55 study participants, including 28 retired NFL players, a control group of 21 cognitively healthy adults with no athletic experience or a history of concussion, and six participants with mild cognitive impairment (MCI), but no history of concussion. Only one retired NFL player had been diagnosed with MCI, but had no history of a grade 3 (G3) concussion with loss of consciousness.

Among the 28 retired NFL players, eight had been diagnosed with MCI and had a history of concussion. Seventeen had also reported a G3 concussion with loss of consciousness. Researchers used a test of verbal memory to examine the relationship between memory performance and hippocampal volume. Results showed no relationship between THE number of games played and risk for MCI. Every player over the age of 63 with a history of a G3 concussion had been diagnosed with MCI.

Retired NFL players with a history of concussion but no MCI had normal scores on verbal memory tests, while players with a history of concussion and MCI recorded lower scores on memory tests compared to both the control group and players with no MCI. Retired athletes who suffered at least one G3 concussion with loss of consciousness had smaller right and left hippocampal volumes compared to both the control group and retired athletes without a G3 concussion.

“Our findings further show that a history of G3 concussion in athletes with MCI was associated with greater hippocampal volume loss compared with control participants with MCI,” Cullum added. “Prospective longitudinal studies after a G3 concussion would add further insight to the mechanism of MCI development in these populations.”

Damage to the hippocampus — measured by hippocampal volume — is often indicated as a potential risk factor for neurological disorders. For example, recent studies have linked reductions in hippocampal volume to increased risk for chronic traumatic encephalopathy (CTE), depression, and epilepsy. The future of concussion research hopes to focus on the hippocampus’s relationship with emotions and memory function.

Source: Strain J, Womack K, Cullum M, et al. Imaging Correlates of Memory and Concussion History in Retired National Football League Athletes. JAMA Neurology. 2015.