On a Saturday night in February 2018, 31-year- old British boxer Scott Westgarth spoke of his love of the sport as he emerged triumphant from his match against Dec Spelman in Doncaster, England.

Hours later he collapsed in his locker room and was rushed to hospital, where he tragically died of head injuries sustained during the fight.

Then in July this year came two more boxing fatalities within a few days of each other. Both the Russian boxer Maxim Dadashev, 28, and 23-year-old Argentinian fighter Hugo Alfredo Santillan died from brain injuries, prompting fresh calls for drastic changes in the sport.

Boxers know they take a risk every time they enter the ring. Success is measured by the number of blows to the head delivered to your opponent, and has therefore long been controversial among campaigners.

Brain injury charity Headway has even called for it to be banned on several occasions. But while we often hear about what can go wrong inside the ring, boxing has a hidden danger less talked about.

American pathologist Dr Harrison Martland first described a group of boxers as being “punch drunk” in 1928.

His research paper gave a name to the phenomenon of boxers with a history of repetitive head trauma developing neurological symptoms.

Today punch drunk syndrome is better known as Chronic Traumatic Encephalopathy (CTE), the degenerative brain disease increasingly linked with rugby, football and injuries sustained in military service.

CTE, currently only diagnosed after death through brain tissue analysis, has been confirmed in more than 50 former boxers, according to the Concussion Legacy Foundation in America, using data from the VA-BU-CLF Brain Bank in Boston.

“To put it simply, the more head impacts somebody gets, the greater the risk,” says neurologist Dr Charles Bernick, from his office at the Lou Ruvo Centre for Brain Health, in the self-proclaimed fight capital of the world, Las Vegas.

“It’s just that boxing is probably the sport that gets the largest number of head impacts, because that’s the whole goal.”

In 2011 Bernick and fellow researchers at the Ruvo Centre, which specialises in research and care of neurodegenerative diseases, launched the Professional Athletes Brain Health Study (PABHS).

It is now the largest longitudinal research project into the effects of repetitive impacts to the brain in a group of professional combatants.

The study currently has over 800 participants, at various stages in their careers; from active fighters at different levels to retired athletes of varying lengths of time – and others who are transitioning between the two.

“CTE is a neurodegenerative disease, it’s in the same category as other disorders such as Alzheimer’s and Parkinson’s, but although we’ve known about it for almost 100 years, nobody really understood it.”

Symptoms of CTE don’t generally begin to appear until years after the head impacts.

So while a boxer may seem to have walked away from a fight unscathed, the signs of long-term brain damage could show up in later life.

Former British Gold Olympian boxer Audley Harrison has spoken recently about the long-term impact his career has had, as he battles permanent brain damage, sight and balance problems and behavioural issues, such as mood swings.

Early symptoms affect the individual’s mood and behaviour, but as the disease progresses, some may experience memory loss, confusion, impaired judgment, and eventually progressive dementia.

From two experts at Boston University, Dr Ann McKee and Dr Robert Stern, we know that CTE can take two forms.

Some with CTE initially present with behavioural symptoms, usually in their late 20s or 30s, while others first show signs of cognitive problems, typically beginning in their 40s and 50s. What we don’t know is why it affects some people and not others.

“We thought this was a condition that we needed to learn more about, and being in Las Vegas, we had the means to do it,” says Bernick.

With his team, he set out to find out how CTE evolves, what the risk factors are and why only some boxers go on to develop the disease.

“We started working with key players, with the Nevada Athletic Commission (NAC) and some of the main organisations and top boxing promoters, to begin recruiting fighters, alongside a controlled group of non-fighters.

“We’ve been following these people on a yearly basis over that time, to try to really understand what happens.”

The open-ended study was set to last for at least 10 years, but as the decade draws to a close it looks likely to continue for as long as the funding is in place. Eight years in, it has made some stand-out findings.

While symptoms may not show up for many years after an athlete has left the ring, according to the research, in some cases, changes in certain areas of the brain can be detected by MRI methods within just a year of being exposed to repetitive head injuries.

These changes correlate with a decline in performance on tests of cognitive function, such as memory and thinking tasks.

The effects also differed between active and former fighters, with some evidence to suggest the disease actually progresses more quickly once a boxer retires.

And changes were also influenced by an individual’s genetic make-up, in older, former athletes.

Bernick says: “In some individuals you can track change over time, in certain areas of the brain, and it seemed to differ between active and retired fighters. Once they retire, there’s a subset of people that have this progressive process which may affect different areas of the brain. This is really interesting stuff as we try to develop ways to identify who might be at risk of CTE.”

The study has also discovered blood markers – certain proteins released from injured brain fibres which leak out of the brain and can be measured in the blood.

They could be used to identify brain injury and follow recovery, and changes in MRI imaging that may be able to track an injury.

It is hoped this will lead them to identifying the “breaking point” – the point at which repeated head trauma begins to cause cognitive problems for a boxer, and could lead to serious brain conditions such as CTE.

Researchers are also exploring how changes in behaviour correlate with brain imaging changes. Behavioural issues are common in the early stages of CTE, with symptoms including impulse control problems, aggression, paranoia and depression.

In April 2019, Bernick and co published a paper linking symptoms of depression in some athletes to structural brain changes associated with CTE; but the pathologist is eager to state it as “cause and effect”.

“Depression is complicated, because there’s the issue of what happens in the brain and the issue of other surrounding factors, such as family history, life circumstances, drug and alcohol use, which makes it difficult to tease out how much is really from the head impact.

“The prevalence of depression in our group was the same as the general population of men at that age, but in those who have depression there was a correlation with smaller regional volumes in certain areas of the brain.

“It suggests that there is a relationship between what’s changing in the brain and the manifestation of depression and other behavioural changes.”

There is also preliminary evidence to suggest that symptoms of depression could even appear before noticeable cognitive changes in someone with CTE.

Far from banning boxing, however, researchers hope that the findings will help to guide new practices to improve brain health in the sport and ultimately, make it safer.

“There is no question that there is great value in boxing. It’s an outlet, and there’s a clear societal benefit to these sports.

“It’s just a matter of how we make them safe.

“In the US, even though the main risk of fighting is to the brain, there is no requirement for any brain tests, except for an MRI scan. “Looking at the risk factors, whether it’s genetic, environmental or lifestyle, might help to protect an athlete as they play these sports.”

Few boxers have spoken publicly about CTE, perhaps for fear of giving the sport a bad name.

Yet, those in the industry have been right behind the study from the beginning, says Bernick, particularly representatives of the NAC, which provides the athletes for the study.

“The first goal of the NAC is to advocate and protect the safety of unarmed combatants,” says Dr Timothy Trainor, consulting physician to the NAC.

“When we partnered with the Ruvo Centre years ago, it was the vision of both the NAC and the Ruvo Centre to see if we could make meaningful progress in the diagnosis and treatment of CTE and brain injury. Anything we can do to promote the safety of an inherently risky sport is our first objective.

“The NAC has stressed the importance of this study to all of our licensed unarmed combatants, including boxers, mixed martial artists and kickboxers, and we are hoping the data gleaned from the study can better help us protect the athletes from harm, both short and long term.”

As a result of the study, the NAC is now looking into ways to actively protect its fighters, and identify potential problems sooner.

“We have learned that we need to focus more on functional studies as opposed to static anatomy tests like MRI/MRA,” says Trainor.

“Certainly, the study is pointing us in other directions that need further study. “One specific test that we have looked at extensively is the ‘C-3 Test’, a cognitive function test performed on an iPad.

“We have tried to implement this in our jurisdiction, however, the logistics of conducting such a test have proved insurmountable.

“We are continuing to try to find tests that will not be logistically prohibitive to the athletes.”

But, he adds: “Just the fact that the studies are being performed has raised the awareness of brain health to the fighters, trainers, and all involved in these sports.”

Things in the boxing ring are certainly changing. Fighters are reportedly sparring less and choosing their opponents more carefully.

In a 1973 study by British pathologist John Corsellis, the boxers participating were exposed to between 300 and 700 bouts over the course of their careers, in addition to sparring and other training.

Today a professional boxer would rarely see upwards of 50 fights before retirement.

But as far as Bernick is concerned, this in no way means athletes today don’t run a substantial risk of suffering a neurological hangover from their careers.

“What we’ve learned from 40 to 50 years ago may not be exactly what the risk is for modern day fighters,” he says.

“But we know that the more exposure you have to head trauma, the higher the risk of CTE.”

Thankfully, many in the boxing world appear to be waking up to dangers of the sport and taking research evidence on board.

Bernick would like to see such recognition in other sports too.

“If all sports took some responsibility for the long-term health of these athletes, not just when they are playing, I think it would be a real step forward for safety in sports.”