Concussion with Loss of Consciousness Linked to Brain Atrophy, MCI

Those with a history of G3 concussion are at increased risk of brain atrophy and MCI.

Getting your bell rung during an athletic bout is sure to have its consequences, but the connection between concussion and subsequent memory dysfunction and brain atrophy later in life remains poorly understood.

However, a study of 28 retired National Football League athletes conducted by researchers from the University of Texas Southwestern Medical Center may help shed some light on the influence of concussion on the brain and its functions.

Munro Cullum, PhD, and colleagues recruited a group of 28 former athletes (mean age = 58.1 years) with a history of concussion, 21 healthy controls with no history of concussion or past football experience, and six controls with mild cognitive impairment (MCI) but no history of concussion. Seventeen of the retired NFL players reported grade 3 (G3) concussion with loss of consciousness, and eight were diagnosed with MCI.

The preliminary results of the ongoing study showed that retired athletes with history of concussion but without MCI had normal but significantly lower California Verbal Learning Test scores than controls (mean [SD], 52.5 [8] vs 60.24 [7]; P = .002), while those with concussion history and MCI performed worse than both control groups (mean [SD], 37 [8.62]; P<.001). Older athletes with a history of at least one G3 concussion had significantly smaller bilateral hippocampal volumes compared to controls at the 40th age percentile (left, P = .04; right, P = .03), 60th percentile (left, P = .009; right, P = .01), and 80th percentile (left, P = .001; right, P = .002) and a smaller right hippocampal volume compared with athletes without a G3 concussion at the 40th percentile (P = .03), 60th percentile (P = .02), and 80th percentile (P = .02). 

Retired athletes with a history of G3 concussion were more likely to have MCI compared to those without a history of G3 concussion older than 63 years. Athletes with MCI and a history of concussion also showed significantly smaller hippocampal volume than controls with MCI (P = .03). No relationship was found between number of games played and MCI diagnosis.

“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,” the authors wrote. “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. Prospective longitudinal studies after a G3 concussion would add further insight to the mechanism of MCI development in these populations.”

The study, which is the first to demonstrate an association between concussion, cognition, and anatomical structural brain changes in former NFL athletes, began in November 2010 and is ongoing.


  1. Strain JF et al. JAMA Neurol. 2015; doi:10.1001/jamaneurol.2015.0206.