Chronic traumatic encephalopathy

When we discussed concussions in class today, we talked about how repeated concussions can lead to a neurodegenerative syndrome in which the brain shows changes similar to those in Alzheimer disease. Here’s a little more info on that syndrome, in case you’re interested.

Epidemiology

So the official name of the disorder is chronic traumatic encephalopathy, or CTE, and it’s a progressive degenerative disease of the brain that occurs in people (often athletes) with a history of multiple traumatic brain injuries (usually concussions – but non-symptomatic subconcussive trauma contributes too). At this time, the only definitive way to make the diagnosis is to examine the postmortem brain (see below).

CTE has been diagnosed in professional athletes, but also in people who only played sports in high school/college, and in military veterans with a history of head trauma. Initially it was thought to be a disease that appeared later in life, but it has been diagnosed in patients as young as 17. The disease may appear within a few months after a traumatic event – but it may also begin years or even decades later.

Mechanism

Repetitive head trauma leads to degeneration of brain tissue and an accumulation of a protein called tau. This protein builds up in neurons and astrocytes in lesions called “tangles” (these look very similar to the neurofibrillary tangles we’ll talk about tomorrow in Alzheimer disease). Amyloid (another protein that is present in Alzheimer disease) is also present in many (but not all) cases. In early stages of CTE, the lesions are found in small foci in the frontal cortex. As the disease progresses, the lesions spread throughout all areas of the cortex, and eventually involve non-cortical structures like the amygdala, hippocampus, and brainstem.

Symptoms

There are a LOT of symptoms that characterize CTE. Here’s a short list:

  • impaired judgment
  • problems with impulse control
  • aggression
  • depression
  • anxiety
  • memory loss
  • confusion
  • suicidality
  • parkinsonism
  • progressive dementia

A lot of these symptoms occur in Alzheimer disease too. However, Alzheimer disease typically presents later in life (e.g. around 60s-70s), and the most prominent initial symptom is memory loss. CTE typically presents at an earlier age (e.g., 40s or younger), and the initial symptoms typically include aggression as well as problems with judgment, reasoning, and impulse control.

There are tons of good resources for more reading – here are just a couple. For more info on disease features and diagnosis, check out the FAQ page of the CTE center at Boston University. For a personal account of how CTE affects the patient and family, check out this NYT article on Daniel Te’o-Nesheim, who died of CTE at the age of 30.

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