FANS have been left heartbroken after shocking footage emerged of veteran fighter Nam Phan's speech deteriorating over the years.
Phan is a retired MMA fighter and professional boxer who started competing in 2001.
The American retired from MMA in 2017 - after stints with the UFC - but he continued to fight in boxing and Muay Thai bouts afterwards.
A video has circulated on social media which shows a clear deterioration in Phan's speech throughout his career.
It is likely to have been caused by years of sparring and fighting in the ring and cage.
His speech goes from being clear and easy to understand to slurred and slow - leaving fans devastated.
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One said: "This actually hurts to watch."
Another added: "Rough man. Nam is an OG."
One commented: "Damn man this was a sad watch."
Another said: "Hard to watch."
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What is CTE?
CTE, or chronic traumatic encephalopathy, refers to a brain degeneration caused by frequent head traumas
Other elements may play a role, including genetics, but exact factors are yet to be discovered, as reported by the .
CTE is only diagnosed through an autopsy of the brain and is known to be a rather rare disease.
It is most commonly found in athletes, including football players and fighters.
Some symptoms of CTE include memory loss, confusion, impaired judgment, depression, anxiety, suicidal thoughts, and progressive dementia.
These signs can begin to appear after years or even decades after the last brain trauma.
It is possible Phan, 41, is suffering from the effects of the fatal brain disease chronic traumatic encephalopathy (CTE).
CTE is a degenerative brain disorder which has strong links to repeated head trauma and can only be diagnosed after death.
It can cause dementia, personality changes and depression - with sadly no cure or treatment.
Former UFC star Julie Kedzie, 43, last year revealed plans to donate her brain for post-mortem research.
Kedzie told : "It seems a very normal thing to do.
"I've been hit in the head a lot so we might as well see what is in there and get some good out of it for data.
"If there is a way that I can still keep pushing in this field [of mixed martial arts] and advancing the cause of women, then yeah."