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Heather Anderson was a top Australian football player and died last November aged 28. She is the first former elite athlete to be diagnosed with CTE.
Heather Anderson retired from professional sports at the age of 23 because of a shoulder injury.
Will Russell / Getty
Australian football is a full contact sport. As in rugby, it is allowed to pull the opponent to the ground, and there are also violent collisions between the players. Some therefore wear head and mouth protection, but this is not mandatory. Australian football is the most popular sport, especially in the south of the country.