Alzheimer’s – Another Consequence of Concussions?

by Wellness Editor – MH

You might have noticed that concussions seem to be in the news more and more frequently. There is good reason for this increased media attention; according to the Centers for Disease Control and Prevention, Americans suffer 1.7 million traumatic brain injuries (TBIs) each year. Of this figure, approximately three-fourths are either concussions or mild types of brain injuries. In addition to their immediate impact on the body, research has linked concussions to long-term problems like depression and memory loss. Perhaps most alarmingly, new evidence suggests that that a correlation exists between concussions and a higher risk of Alzheimer’s disease.

How Alzheimer’s Develops

Alzheimer’s disease is a chronic condition that steadily erodes a patient’s cognitive abilities. As the disease progresses, patients encounter increasingly worse problems with short and long-term memory, basic reasoning and overall behavior. In its latter stages, Alzheimer’s renders the patient completely dependent on the daily assistance of caregivers.

The exact causes of Alzheimer’s have yet to be conclusively determined. However, it is suspected that the blame might largely lie with substances called plaques. Plaques are abnormal clumps of proteins that develop between the brain’s nerve cells, having the possible effect of interfering with cell-to-cell communications. Furthermore, the presence of these proteins might also prompt a hostile reaction by the immune system, causing inflammation to occur within the brain. Doctors refer to these proteins as beta-amyloids.

Concussions and Brain Plaque

Given the strong possibility that concussions can cause compromise the long-term health of the brain, it would seem worthwhile to investigate the relationship between this injury and Alzheimer’s risk. Researchers as the Rochester, Minnesota based Mayo Clinic did just that, releasing their findings on the matter in December 2013.

For their study, the Mayo team examined the brains of 589 volunteers, all of whom were aged 70 or older. Nearly a quarter (141 out of 589) of these seniors exhibited signs of mild cognitive impairment. Mild cognitive impairment (MCI) is a condition involving difficulties related to memory, judgment and speaking. It is not unusual for MCI to act as a precursor to the onset of Alzheimer’s disease; compared with those without this disorder, older adults with MCI are more likely to develop Alzheimer’s at some point in the future.

Another area of great interest to the Mayo researchers concerned prior head injuries. Specifically, all subjects were asked if they had suffered a concussion or other type of head trauma that resulted in loss of consciousness. Interestingly enough, MCI did not significantly impact how the subjects answered this question; 18 percent of those with this disorder responded “yes,” as did 17 percent of seniors without cognitive problems.

When reviewing their sets of brain scans, the study’s authors noticed a striking trend among their group of subjects. Among the participants with MCI, those who had suffered head trauma had had 18 percent more plaque than those with no such injury history. Furthermore, the scans of seniors without MCI symptoms revealed no evidence of abnormal plaque buildup. In this particular group, previous concussions or head injuries had no discernable impact on brain plaque.

In summation, the study found higher levels of brain plague in those who had both MCI and a history of head trauma. All other groups did not exhibit the increased amounts of beta-amyloids often associated with Alzheimer’s.

A Doubled Risk?

A study released in 2011 likewise found that concussions can lead to dementia later in life (Alzheimer’s is a form of dementia). A collaborative effort between San Francisco VA Medical Center (SFVAMC) and University of California, San Francisco (UCSF), this report included data from over 280,000 military veterans.  All of these individuals were over the age of 55, and had previously received treatment from the US Department of Veterans affairs.

When reviewing their slate of medical records, the research teams found that 15 percent of vets who sustained TBIs later developed dementia. In contrast, dementia was much less prevalent among those who had not suffered a TBI; only 7 percent of the veterans in this group were diagnosed with dementia by 2007. The researchers presented their report to an audience at the 2011 Alzheimer’s Association International Conference on Alzheimer’s Disease, which was held in Paris, France.

Regardless of what type of TBI the veterans suffered, the end result was the same; concussions, skull fractures and various intra-cranial injuries all were found to greatly increase the risk of dementia diagnosis. Though the study could not provide a conclusive answer to explain its findings, it did offer a possible explanation for this relationship.     Attached to the brain’s nerve cells are long fibers known as axons, which are tasked with transmitting electrical impulses to other cells in the body. According to the authors of the report, axons can swell in size after the brain experiences a TBI. In turn, clusters of beta-amyloid proteins may develop around these swollen axons, possibly leading to the debilitating symptoms of Alzheimer’s.

The research mentioned in the preceding sections makes a strong case for a concussion-Alzheimer’s connection. This prospect of an increased risk of Alzheimer’s, along with the other health risks posed by concussions, highlights the need to take reasonable precautions against sustaining this type of injury.

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