Concussions May Increase Risk of Alzheimer’s Disease


brainplaqueThe links between head trauma and degenerative brain disorders has been increasingly in the spotlight with the issues of professional athletes. A 2012 study concluded that retired National Football League players were 4 times more likely to die from diseases such as ALS (amyotrophic lateral sclerosis, or Lou Gehrig’s disease) and Alzheimer’s. Repeated concussions were believed to play a significant role in the 2012 study, but the concussion history was insufficient to provide any conclusions.

Outside the world of sports, a separate association was recently made between concussions and Alzheimer’s disease. In a study to be published in the upcoming print issue of Neurology, researchers at the Mayo Clinic studied almost 600 residents of Olmsted County, Minnesota that were at least 70 years old. Almost 25% of the study participants had mild cognitive impairment, defined as problems with thinking and memory skills. The research team analyzed build-up of beta-amyloid plaques—pieces of proteins that are more prevalent in Alzheimer’s patients which disrupt the normal function of nerve cells in the brain. The ability to interview living patients and perform brain scans on them is a step forward; previous studies had to rely on post-mortem analysis.

The team discovered that within the group of study participants who had reported concussions, brain scans of those with memory problems showed an 18% higher amount of plaques than those who did not have any cognitive impairment. While this suggests a link, it doesn’t prove any causal relationship—and may point toward other contributing factors. Of those reporting any brain injury, the percentages of those with cognitive impairments and those without were similar (approximately 17% each).

The overall development mechanism of the damaging plaques is likely more complex. Perhaps a cumulative effect is as important, or even more important, than the severity of any individual trauma. In this study, loss of consciousness was considered the threshold for having a concussion history. It could be that less severe trauma, with or without cumulative effects, could lead to Alzheimer’s development.

The higher incidence in NFL players is consistent with this—although NFL players certainly deal with both a higher number and greater severity of concussions than the average person. Without a means to quantify the trauma, it’s extremely difficult to determine a threshold value. Even so, this study suggests that concussions are a likely risk factor in the development of Alzheimer’s disease.

Should you take pre-emptive action? With respect to head trauma, you should take the same preventive actions whether you are at risk for Alzheimer’s or not. Take common sense precautions such as wearing helmets while riding bicycles or motorcycles, and using automobile seat belts.

It’s possible that some day a mechanism for head trauma and future development of beta-amyloid plaques will be discovered and understood, and if so, that drugs may be developed to prevent their growth. In the meantime, the best steps for Alzheimer’s prevention is unrelated to head trauma. By controlling your blood pressure and cholesterol levels, and maintaining a good diet and exercise regimen, you can reduce factors already known to contribute to Alzheimer’s disease.
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