We knew for a long time that boxers get it. We more recently learned that soccer players get it from heading the ball. There has now been detected an abnormally high proportion of rugby players.
"At the last count, in 2014, there were 1,339 people in the UK between the ages of 30 and 44 who had been diagnosed with dementia – or 0.01% of the 13 million in that age group, or one in every 9,500. The startling news that 11 former professional rugby players from that demographic have been diagnosed with the condition presents rugby with a reality it has dared not face until now.
Even if the 11 (eight of whom are joining a new legal action) turn out to be the only ones, which is next to inconceivable given we know of another 90 with likely symptoms – and this before those players had gone public, this before some have even reached middle age – they represent nearly 1% of the roughly 1,500 players from that age group who played professionally in England and Wales in the 15 years after rugby union went open. Assuming the incidence rate derived from the 2014 Dementia UK report has remained constant, the chances of that same wider population of 13m returning 10 or more cases from a sample of 1,500 are a shade under one in 10 trillion. For 11 or more, the chances are so small that a regular spreadsheet cannot cope and defaults to a probability of zero."
https://www.theguardian.com/sport/2...ia-presents-sport-with-reality-dared-not-face
"At the last count, in 2014, there were 1,339 people in the UK between the ages of 30 and 44 who had been diagnosed with dementia – or 0.01% of the 13 million in that age group, or one in every 9,500. The startling news that 11 former professional rugby players from that demographic have been diagnosed with the condition presents rugby with a reality it has dared not face until now.
Even if the 11 (eight of whom are joining a new legal action) turn out to be the only ones, which is next to inconceivable given we know of another 90 with likely symptoms – and this before those players had gone public, this before some have even reached middle age – they represent nearly 1% of the roughly 1,500 players from that age group who played professionally in England and Wales in the 15 years after rugby union went open. Assuming the incidence rate derived from the 2014 Dementia UK report has remained constant, the chances of that same wider population of 13m returning 10 or more cases from a sample of 1,500 are a shade under one in 10 trillion. For 11 or more, the chances are so small that a regular spreadsheet cannot cope and defaults to a probability of zero."
https://www.theguardian.com/sport/2...ia-presents-sport-with-reality-dared-not-face