A brain injury specialist has established a link between early-onset dementia and playing rugby, as well as other high-injury sports.
Dr Willie Stewart told BBC Radio Scotland of research he had undertaken with a former rugby player, where he examined tissue sections and discovered abnormal proteins usually associated with head injuries and dementia.
He said high-impact sports such as American football, ice hockey and rugby were beginning to lead to problems later in life normally suffered by former boxers.
The former player was found to have higher levels of the protein than a retired amateur boxer who has dementia pugilistica, also known as punch-drunk syndrome.
Symptoms such as poor memory and speech, and co-ordination and personality problems will usually appear about 15 years after the boxer's career starts. But until recently it had been thought to affect only boxers who suffered repeated concussion.
Dr Stewart said the percentage of rugby players affected was likely to be lower than in sports where concussion is common, but was a concern.
"What we're finding with people who've survived head injuries is that their brain shows changes down the microscope that look very much like what you would see in people with dementia, so similar abnormalities in people with Alzheimer's disease."
Dr Stewart, of the Southern General Hospital in Glasgow, said players and organisers should take better precautions.