A new scientific study which looked at the brains of high-profile footballers from yesteryear marks another step towards understanding the causes of dementia in former athletes, according to a former England football captain.

A team from the University of Glasgow, working with the University of Pennsylvania, has been looking at the role of a condition known as chronic traumatic encephalopathy (CTE) in former footballers and rugby players who had dementia.

Alan Shearer, who has campaigned for research into this issue, described the work by researchers in Glasgow as “incredibly important”.

CTE is a progressive brain condition that is thought to be caused by repeated blows to the head and episodes of concussion, and it has been associated with contact sports.

There is a growing belief that footballers, especially those who played the game in earlier years when balls were heavier, especially when wet, have a greater risk of developing dementia. 

The disease has affected a number of former Scottish stars of the game, including the former Celtic captain Billy McNeill and his fellow Lisbon Lion Stevie Chalmers, who both passed away following long battles with dementia last month.   

Dundee United legend Frank Kopel is another high-profile victim of dementia. Kopel, who was part of Manchester United’s European Cup-winning squad in 1968, was a defender for Dundee United in the 70s and 80s. 

He was 59 when he was diagnosed with early-onset dementia and died aged 65 in 2014.

Other footballers who have gone on to develop dementia include former Celtic striker Chris Sutton’s father Mike Sutton and former England player Jeff Astle.

Former Scotland manager Ally MacLeod, who played for teams including Wolves, Blackburn and Ayr United, died in February 2004, aged 72, after spending nearly 10 years battling Alzheimer’s disease.

The scientists analysed 11 brains from former athletes with a history of dementia – seven footballers and four rugby players – and found that signs of CTE were present in around three-quarters of the cases.

In many cases, however, researchers also noted other complex and mixed degenerative brain pathologies existing alongside CTE.

As a result, the significance of the CTE in dementia patients remains “uncertain”, the researchers said.

The report concluded: “In the majority, CTE-NC (neuropathologic change consistent with CTE) appears as a co-morbidity rather than the primary, dementia causing pathology.

“As such, we suggest that while CTE-NC might be common in former athletes with dementia, in many cases its clinical significance remains uncertain.”

The study is said to be the largest of its kind to date, and experts said it demonstrates the importance of brain donations in scientific research.

Dr Willie Stewart, honorary clinical associate professor at the University of Glasgow’s institute of neuroscience and psychology, said: “Our findings suggest that, while CTE is prevalent in a high number of the patients we studied, in many cases it is not the primary pathology driving the dementia.

“In other words, while head injury-associated degenerative brain disease is important in these patients, the reality of dementia in former footballers and rugby players is that the disease is more than just CTE, and more complex.”

He added: “This work demonstrates the incredible importance of research brain donation to support such detailed examination of the pathology of dementia, and we are incredibly grateful to all the families who have supported our studies in this way.”

Shearer has previously spoken of his own fears for his health after becoming aware of the possibility of a link between heading the ball and future ill-health.

He said: “This is incredibly important work by Dr Stewart and his team in Glasgow.

“Finally, we are beginning to see some progress towards understanding dementia in former footballers and I look forward to hearing more from these studies.”

The study has been published in the journal Acta Neuropathologica.