Poll: Should heading be banned in youth football?

The findings, from a study of 14 former players, suggest a possible link between playing football and developing such conditions later in life, researchers said.

The results provide a platform for a "pressing research question" on whether dementia is more common in footballers than the general population, Dr Helen Ling, lead author of the UCL Queen Square Brain Bank study said.

Chronic traumatic encephalopathy (CTE) can cause dementia and, like Alzheimer's disease, is characterised by a build-up of abnormal tau protein in the brain.

The rate of CTE detected in the brains of the players was greater than the 12% average found in a previous study which looked at brains from the general population.

The results show more research is urgently needed to assess risks faced by players and allow measures to be put in place to protect footballers from long-term damage, Professor Huw Morris of UCL Institute of Neurology said.

"We do not yet know exactly what causes CTE in footballers or how significant the risk is," said Prof Morris.

"Major head injuries in football are more commonly caused by player collisions rather than heading the ball.

"The average footballer heads the ball thousands of times throughout their career, but this seldom causes noticeable neurological symptoms."

He added: "Of course, any kind of physical activity will be associated with health risks and benefits and it is well-established that playing sports can significantly improve physical and mental health."

The players involved in the study, 12 of whom eventually died of advanced dementia, all began playing football and heading the ball when they were children or teenagers and continued for an average of 26 years.

They were all referred to the Old Age Psychiatry Service in Swansea, Wales between 1980 and 2010.

Consultant psychiatrist Dr Don Williams, who ran the study from the Swansea service, said he was motivated to do so after being approached by a man whose footballer father had been diagnosed with dementia, and who wanted to know if headers could be the cause.

He said: "As a result I looked out for men with dementia and a significant history of playing soccer, followed them up and where possible arranged for post-mortem studies to be carried out.

"The results suggest that heading the ball over many years, a form of repetitive sub-concussive head injury, can result in the development of CTE and dementia.

"Thus the original suggestion has been shown to be of merit and worthy of further investigation."

Dr Ling said the research is important, but cautioned more is needed for definitive results.

"Previous studies have shown that the risk of Alzheimer's disease is increased in people with previous head injuries.

"On the other hand, the risk of dementia is also increased with age and we don't know if these footballers would have developed Alzheimer's disease anyway if they hadn't played football.

"The most pressing research question is therefore to find out if dementia is more common in footballers than in the normal population."

Velicia Bachtiar, chief scientific officer at the UK-based not-for-profit The Drake Foundation, which funded the research, said it "highlights the need for future work to improve our understanding of sports-related head injuries and their long-term implications".