Preventing Alzheimer's: Can Concussions Cause Dementia?

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What Is a Concussion?

According to the Centers for Disease Control and Prevention, "a concussion is a type of traumatic brain injury, or TBI, caused by a bump, blow, or jolt to the head that can change the way your brain normally works. Concussions can also occur from a fall or a blow to the body that causes the head and brain to move quickly back and forth" (Quoted form the Centers for Disease Control and Prevention).

What's the Difference between a Concussion and Traumatic Brain Injury?

Essentially, a concussion where a loss of consciousness is experienced, even for seconds or minutes, is considered a mild traumatic brain injury.

Is There a Connection between Concussions and the Risk of Dementia?

Severe traumatic brain injuries (where the person experiences an extended loss of consciousness or inability to remember) have been correlated with a greater risk of the development of dementia, but what about mild traumatic brain injuries such as concussions?

One study outlined in PLOS One found that there was indeed a higher risk for dementia in mild traumatic brain injuries. Researchers reviewed the records of more than 90,000 people and found that even after adjusting for other risk factors, those who experienced a mild brain injury were more likely to develop dementia.

    What Does Research Say about Sports and Concussions?

    According to Bostonia, a newsletter published by Boston University, professional football players have a 19 times greater chance of developing chronic traumatic encephalopathy (CTE). CTE is a chronic neurological condition with symptoms that “include confusion, memory loss, impaired judgment, paranoid and aggressive behavior, depression, and dementia” (Bostonia)

    Other studies have concluded that boxers and hockey players also have increased rates of dementia related to CTE.

    However, not all studies agree on the risks of concussions. One study outlined in Neurology tracked the number of hits received by football players by placing a device inside the helmet of players for a season. Researchers then measured cognitive performance at the end of the season. The good news in this study was that short-term brain functioning did not decline related to small impacts. There has been a fair amount of media coverage on proper concussion identification and care lately.

    Interestingly, another study involving 92 former professional football players found that approximately 11 percent presented signs of mild cognitive impairment or dementia; however, the researchers did not find any increased chance of dementia for those who played high-risk positions when compared to those who played in low-risk positions. Furthermore, they did not find a correlation between a higher likelihood of dementia and a longer career in professional football.

    The Risk of Repeated Head Injuries

    People who have suffered multiple concussions do appear to be at a greater risk for developing dementia, according to U.S. Alzheimer’s. They note that falls, car accidents and sports injuries are common causes of brain injury.

    Do Concussions Increase the Risk of Mild Cognitive Impairment?

    Neurology recently published a study on head trauma and compared the amount of amyloid protein deposits in the brains of people with mild cognitive impairment and in individuals who were evaluated to be cognitively intact. The buildup of amyloid protein deposits in the brain is one of the hallmarks of Alzheimer's disease. The researchers found that among cognitively intact people, there was no difference in the levels of amyloid protein deposits in the brain, regardless of if the participant reported a history or head trauma or not. However, among participants with mild cognitive impairment, those with previous head trauma displayed a higher level of amyloid protein deposits in the brain than those without a history of head trauma. In this study, "head trauma" was defined as losing consciousness or memory even momentarily after a head injury. The authors concluded that trauma such as concussions does appear to increase the risk of mild cognitive impairment, which often but not always progresses to Alzheimer's disease.

    Sources:

    Alzheimer’s.gov. Alzheimer's Symptoms. Accessed February 26, 2014. http://www.alzheimers.gov/symptoms.html

    Bostonia. Boston University. Brain Injury Association of America. Mild brain injury and concussion. Accessed February 20, 2014. http://www.biausa.org/mild-brain-injury.htm#Concussion

    British Journal of Sports Medicine. 2014 Jan;48(2):159-61. Heading in football, long-term cognitive decline and dementia: evidence from screening retired professional footballers. http://www.ncbi.nlm.nih.gov/pubmed/24026299

    Centers for Disease Control and Prevention. What Are the Potential Effects of TBI? September 25, 2012. http://www.cdc.gov/TraumaticBrainInjury/outcomes.html

    Centers for Disease Control and Prevention. Severe Traumatic Brain Injury. September 21, 2012. http://www.cdc.gov/TraumaticBrainInjury/severe.html

    Deutsches Arzteblatt International. Boxing-acute complications and late sequelae: from concussion to dementia. Accessed October 13, 2012. http://www.ncbi.nlm.nih.gov/pubmed/21173899

    Neurology - Volume 78, Issue 22 (May 2012). Effects of repeated mild head impacts in contact sports: Adding it up. http://www.neurology.org/content/78/22/e140.full?sid=78830a01-cea3-48ff-8c6c-237f0ae8ae4f

    Neurology. December 26, 2013. Head trauma and in vivo measures of amyloid and neurodegeneration in a population-based study. http://www.neurology.org/content/early/2013/12/26/01.wnl.0000438229.56094.54.abstract?sid=bdfac23c-33d7-4f54-9f06-886295b7ab83

    PLoS One. 2013 May 1;8(5):e62422. Increased risk of dementia in patients with mild traumatic brain injury: a nationwide cohort study. http://www.ncbi.nlm.nih.gov/pubmed/23658727

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