Chronic Traumatic Encephalopathy (CTE): An Introduction

What do we know?

  • CTE is a progressive neurodegenerative condition characterised by hyperphosphorylated tau pathology that we are finding in the brains of football players (NFL), boxers, hockey players and military veterans
  • CT’s associated with repeated mild traumatic brain injury
  • The above usually occur for an individual in their teens or early 20’s
  • Once triggered, the neuro-degeneration progresses slowly over decades to involve widespread degeneration of many structure
  • In addition to tau pathology, there is also widespread axonal injury and loss, inflammation and in most cases, TDP-43 pathology

What is CTE?

A progressive degenerative disease of the brain found in athletes (and others) with a history of repetitive brain trauma, including symptomatic concussions as well as asymptomatic subconcussive hits to the head.

John-Grimsley

In both sets of photographs, above, the brain tissue has been immunostained for tau protein, which appears as a dark brown color. Tau immunostained sections of medial temporal lobe from 3 individuals

 

Whole brain section from a 65 year old control subject showing no tau protein deposition left
Microscopic section from 65 year old control subject also shows no tau protein deposition
Whole brain section from John Grimsley showing abundant tau protein deposition in the amygdala and adjacent temporal cortex  middle
Microscopic section showing numerous tau positive neurofibrillary tangles and neurites in the amygdala
Whole brain section from a 73 year old world champion boxer with severe dementia showing very severe tau protein deposition in the amygdala and thalamus  right
Microscopic section from a 73 year old world champion boxer with severe dementia showing extremely dense tau positive neurofibrillary tangles and neurites in the amygdala

CTE Pathology

  • Neuropathological changes of CTE are distinctive and easily distinguished from other tauopathies, including Alzheimer’s Disease
  • Neuropathological features of CTE include generalised atrophy of the cerebral cortex, medial temporal lobe diencephalon, and mammillary bodies within enlarged ventricles, cavum septum pellucidum, extensive p-tau immunoreactive neurofibrillaly tangles and astrocytic tangles in the frontal and temporal cortices, limbic regions, diencephalon and brain stem nuclei, extensive degeneration of axons and white matter fibre bundles and a relative absence of amyloid-peptide deposits

Symptoms of CTE

These usually occur 8 – 10 years post repetitive mild TBI.

Emotional/Behavioural Changes:

  • Short fuse
  • Aggressive and violent behaviour
  • Erratic dangerous behaviour
  • Impulse control problems
  • Mood changes, most usually depression
  • Confusion
  • Suicidality
  • Paranoia
  • Drug and alcohol abuse

Cognitive Changes:

  • Attention and concentration
  • loss Short-term memory problems
  • Executive dysfunction i.e. poor planning, organisation, multi-tasking and judgement
  • Dementia 

Other Abnormalities Include:

  • Gait problems
  • Parkinsonism
  • Speech abnormalities