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 death of Smith, who was a towering aerial player most famous for a goal in a European Cup final against Borussia Monchengladbach, will be seen by many as further evidence that heading the ball is inherently dangerous.

An investigation into the fates of the members of England's World Cup-winning squad of 1966 revealed four had confirmed dementia - Martin Peters, Nobby Stiles, Ray Wilson and Jack Charlton - though the number is understood to be even higher.

The most famous case of CTE and football was that of West Bromwich Albion striker Jeff Astle, who was diagnosed with Alzheimer's at the age of 54 and died in 2002 at 59. It was later revealed he had CTE. The coroner ruled he had died of "industrial disease" due to heading footballs.

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In a cruel twist of fate, he was taught the art of heading by the great England striker Tommy Lawton, who also died of dementia.

Concerns are so great in the footballing community about the link between heading and CTE that Alan Shearer, one of England's greatest strikers, fronted a widely admired documentary Dementia, Football and Me , that confronted the idea that years upon years of heading balls in matches and training could do irreversible damage to hundreds of players.

FILE - In this May 25, 1967 file photo Celtic soccer team captain Billy McNeill holds aloft the European Cup after it was presented by Portugal's President Americo Tomaz. Photo / AP
FILE - In this May 25, 1967 file photo Celtic soccer team captain Billy McNeill holds aloft the European Cup after it was presented by Portugal's President Americo Tomaz. Photo / AP

Today's footballers are blessed by the fact that balls are now water resistant and much lighter than those used in the past. That is not enough for some scientists, however, who say that no kids under the age of 12 should be heading a ball as their brain cells are still developing and their neck muscles are too weak.

These arguments will be examined in a three-part series - "It's all in my head" - starting tomorrow.

Sam Wilkinson, who runs a youth football academy in Hamilton, says the risks are mitigated by several factors, including weight and age-specific ball sizes.

Most notably, however, he says the reduction of team and field sizes in kids football means the ball is rarely in the air.

"It's a much more ground-based sport now," Wilkinson said.

In terms of training, he said it would be rare for coaches at youth level to do any "volume" header training.

"From what I've seen, it just doesn't happen now," he said, "and I'd be concerned if I heard about it."

Melville United coach Sam Wilkinson. Photo / Marc McMullan.
Melville United coach Sam Wilkinson. Photo / Marc McMullan.