BRAIN experts have warned against making simplistic links between sporting head injuries and dementia.

More than 60 leading international neuroscientists have stressed they still know little about a condition called chronic traumatic encephalopathy or CTE.

That has not stopped a spree of articles in both the popular and academic press linking frequent concussions among boxers, footballers or rugby players with the disease.

Some former sporting stars have sought to blame their dementia on injuries sustained in their sporting careers. Former Celtic player Billy McPhail back in 1999 claimed heading a heavy ball contributed to his Alzheimers.

Then a coroner decided that an English footballer, Jeff Astle, died because if brain damage received in his youth heading heavy balls.

One of the doctors who investigated Mr Astle was Willie Stewart, consultant neuropathologist and honorary clinical associate professor Glasgow University. He was one of the experts signing a letter to The Lancet Neurology urging caution on the scale of CTE - or even its symptoms.

He said: “In recent years there has been a worrying trend to imply that the causes, diagnosis and prevalence of CTE are fully understood, or at least that data to date leave little doubt.”

“The truth is we know very little about CTE, certainly not enough to be able to estimate with any certainty how many people might be affected, or what the various symptoms might be. Much more research effort is required before we can confidently say we understand this condition.”

Although CTE is often discussed, experts in their joint letter said there was only preliminary agreement on how to recognise this disease, and no agreement on how to assess its severity.

There is also no clear understanding of the link between CTE pathology and any specific symptoms, they said.

Douglas Smith, of the University of Pennsylvania, added: “Current reporting on the possible consequences of CTE without acknowledging the many unknowns and uncertainties can do real harm.

“In particular, individuals with potentially treatable conditions might make decisions on their future based on a misguided understanding that their symptoms are the inevitable consequence of a brain disease that will lead to dementia.”