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Understanding Chronic Traumatic Encephalopathy (CTE)

What you need to know about the impact of football and other contact sports

On November 9th and 10th, I had the pleasure of directing our annual Chronic Traumatic Encephalopathy Conference, jointly sponsored by Boston University and the Veterans Affairs Boston Healthcare System. It brought together clinicians, researchers, athletes, veterans, and their families to review what is currently known about how repetitive impacts to the head can lead to cognitive impairment and progressive brain disorders, such as chronic traumatic encephalopathy (CTE). Here are some of the questions answered at the conference.

Do you need to have a diagnosed concussion to develop CTE? No, the strongest risk factor for the development of CTE is repetitive hits to the head causing repetitive brain trauma, regardless of whether concussion occurred.

Is CTE a new disease? No, it has been known since at least 1928 when it was described in boxers. What is new is that it occurs more commonly than we thought in those with many different types of exposure to repetitive brain trauma, including American football players and military veterans.

What exactly is CTE? It is a progressive neurodegenerative disease that has a distinct pathology when viewed under the microscope, including abnormal accumulations of the protein tau around blood vessels in the depths of the brain’s sulci. Over time, the tau spreads to other brain regions, killing brain cells and leading to problems with mood, behavior, thinking, and memory.

Are there changes other than CTE that can develop with repetitive brain trauma? Absolutely. Damage to the white-matter tracts of the brain—the brain’s wiring—is one common change that frequently develops, and inflammation is another.

Are we fairly sure that CTE is caused by repetitive brain trauma? Yes. Research using animal models shows that either blast or impact injury can produce near identical pathologic changes. Pathological studies of humans to date have only found CTE only in individuals who were exposed to repetitive brain trauma.

What is special about Aaron Hernandez’s brain? Two features: First, never before has such severe CTE pathology been observed in someone so young. Second, the brain was obtained in extremely good condition, allowing special types of analyses to be performed. Both features will help us better understand the disorder.

Can CTE be diagnosed during life? The short answer is no. However, researchers presented novel blood, spinal fluid, and brain-imaging tests as well as clinical criteria that they hope will lead to the ability to diagnose the disease in the future. Currently available brain-imaging studies, such as magnetic resonance imaging (MRI) and positron emission tomography (PET) scans, can provide clues that CTE may be present.

Are there genetic risk factors for CTE? It turns out that the same genetic risk factor for Alzheimer’s disease—having one or two APOE e4 genes—is also a risk factor for the development of CTE. Aaron Hernandez had one APOE e4 gene. (A risk factor makes it more likely that someone will develop a certain disorder, but having the risk factor does not mean that one will definitely develop the disorder, and not having the risk factor does not mean that one will not develop the disorder.) Note that we do not recommend testing for this risk factor; at this point it is important only for research.

What should you do if you are concerned that you or a loved one has CTE? Speaking with your doctor is always the right place to start. More and more clinicians are becoming familiar with this disorder and, most importantly, there are other causes of changes in mood, behavior, thinking, and memory besides CTE that your doctor can search for.

Are there any treatments available for CTE? As with many neurological disorders, there are no specific treatments for CTE. One cannot go wrong with doing activities that have been proven to be good for brain health, such as aerobic exercise, eating a Mediterranean diet, staying socially active, and keeping a positive mental attitude. Cognitive strategies and memory aids can help to improve day-to-day function. There are also medications that may be able to help with specific symptoms, such as depression, anxiety, poor attention, and memory impairment.

What do individuals and families want from their doctors in relation to CTE? The message was clear that it is important for all clinicians to be aware of this disorder. Although there is no cure or specific treatment available for CTE, healing begins with knowledge and understanding.

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