Tommy Smith, the renowned Liverpool hard man, died on April 12.

He was 74. He had been diagnosed with Alzheimer's disease in 2014.

Ten days later another European champion, Celtic and Scotland's Billy McNeill died. He was 79. He had spent the last years of his life battling dementia.

Given their status as defenders and powerful headers of the ball, it is natural to speculate that they may have died with chronic traumatic encephalopathy (CTE).

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While contact sports such as boxing, American football and rugby are seen as the most at-risk sports, football is also dealing with neurodegenerative issues.

The