Concussions Cause Brain Atrophy
There has been much data lately showing that National Football League (NFL) players who lose consciousness as a result of a concussion may be at increased risk for brain atrophy and memory impairment later in life.
“The good news is the majority of NFL players do not suffer any memory impairment or brain atrophy — this only happens in a small number,” senior author C. Munro Cullum, PhD, from the University of Texas Southwestern Medical Center, Dallas, told Medscape Medical News.
“Most individuals recover completely after a concussion, usually within days or weeks, but the potential association between concussion and later development of memory dysfunction with brain atrophy is not well understood,” Dr. Cullum said. The study was published online May 18 in JAMA Neurology.
But it’s NOT just NFL players that need to be concerned! The number of concussions experienced in high school and college sports is on the rise and the most susceptible individuals are those that have either had a more severe initial injury AND/OR those who have had repeated concussions.
A good example is football however, there can be more serious brain damage from heading the soccer ball than any other sport.
“We have a long-standing interest not only in the acute effects of concussion but what might a history of concussion do in terms of the aging brain,” the study’s author said. “Given the high interest in chronic traumatic encephalopathy (CTE) we decided to recruit retired NFL players with a history of concussion to study with neuropsychological measures their mood and memory and also do brain imaging studies in these men. This is the third paper we have published on retired NFL football players.”
In the current study, which Dr. Cullum stressed is preliminary, the researchers assessed the relationship of hippocampal volume, memory performance, and the effect of concussion in 28 retired NFL players (8 of whom had mild cognitive impairment [MCI]) and a history of concussion. These players were compared them with 21 cognitively healthy controls with no history of concussion or past football experience, as well as 6 controls with MCI but no history of concussion.
The main outcomes and measures were hippocampal volume, age, California Verbal Learning Test (CVLT) scores, and the number of grade 3 (G3) concussions.
The retired athletes ranged in age from 36 to 79 years (mean±SD, 58.1±13 years). Their education ranged from 15 to 18 years (mean, 16.5±0.9 years), and their estimated IQ ranged from 92 to 126 (mean, 111±10).
The athletes had played in the NFL from 2 to 15 years (mean, 8.9±4.2 years). Nineteen were white and nine were African American.
Concussion history was obtained by self-reports. All but 3 of the retired players experienced at least one concussion (mean, 3.85±3.47 concussions), and 17 had sustained a G3 concussion with loss of consciousness.
The 21 cognitively healthy controls had not participated in college or professional football; were matched for education and IQ; and had no history of mental illness, cognitive symptoms, or neurologic disorders. They ranged in age from 41 to 77 years (mean, 59.0±12 years), and their education ranged from 12 to 20 years (mean, 15.9±2.4 years). Two of the control participants were African American and 19 were white.
The control group with MCI were also age- and sex-matched but had no history of concussion; they were recruited from the Alzheimer’s Disease Center at UT Southwestern Medical Center. They ranged in age from 55 to 77 years (mean, 68.0±8.3 years).
CVLT Worse in Athletes
The researchers found that the athletes who had sustained a concussion but did not have cognitive impairment had normal but significantly lower CVLT scores compared with control participants (mean, 52.5± vs 60.24±7; P = .002).
The 8 former players who had a history of concussion and MCI did worse on the test, with a mean score of 37±8.62, than did the controls (P < .001) and the athletes with no memory impairment (P < .001).
No difference was found between controls with MCI and athletes with MCI on the CVLT.
The 11 retired NFL players without a G3 concussion showed similar hippocampal volumes compared with controls at all ages. However, athletes who had sustained at least 1 G3 concussion had significantly smaller bilateral hippocampal volumes compared with control participants 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).
These athletes also had a smaller right hippocampal volume compared with athletes who did not have a G3 concussion at the 40th percentile (P = .03), 60th percentile (P = .02), and 80th percentile (P = .02). Players with a history of G3 concussion were more likely to have MCI compared with those who did not, and this effect was most likely to manifest by age 63.
Of the 8 former NFL players who had MCI, 7 had a history of G3 concussion, compared with 1 without a history of G3 concussion (P = .01).
In addition, the left hippocampal volume in retired athletes with MCI and concussion was significantly smaller than in controls with MCI (P = .03). “To our knowledge, this is the first study to show an association between concussion, cognition, and anatomical structural brain changes across the age spectrum in former NFL players,” Dr. Cullum said.
Predicting Brain Damage
“Right now, we cannot predict who will develop cognitive impairment after a concussion. There is such a wide variability. That is why we also are taking blood samples from our volunteer athletes. We may be able to discover a factor in the blood that predicts who will be more vulnerable,” he said.
“For example, APOE, the cholesterol transporter, has been shown to be associated with a greater risk for Alzheimer’s disease. If you have that, and then get a head injury with loss of consciousness, or have other vascular risk factors, that might put one person at a higher risk compared to another,” Dr Cullum said.
Most individuals who sustain a concussion recover within a week, he added.
“The brain has a lot of plasticity, so we need to identify why one person can sustain multiple concussions and be fine, and why another who has only one becomes impaired, and we really do not understand that very well as yet.”
Commenting on this study for Medscape Medical News, Cyrus Raji, MD, PhD, said, “This study demonstrates that we can quantify the negative influence of concussions over the course of an NFL career on magnetic resonance imaging in the hippocampus.”
Hippocampus Damage Equals…
Dr. Raji added: “We also know that long-term damage to the hippocampus increases the risk of memory loss, cognitive decline, and Alzheimer’s. Our goal now should be to challenge ourselves as physicians to best apply the growing literature of such findings into practice so that they maximally benefit patient outcomes.”
This project was supported by the BrainHealth Institute for Athletes at the Center for Brain Health, University of Texas at Dallas, and the National Institute on Aging. Dr Cullum and Dr Raji have disclosed no relevant financial relationships.
JAMA Neurol. Published online May 18, 2015.