Frank Bruno is undergoing brain scans amid concerns of a "slow decline".
The 62-year-old former heavyweight champion - who won 40 of his 45 fights in the 1980s and 1990s - is being studied by doctors, who are trying to determine if the blows to the head he sustained during his 14-year career have caused long-term damage.
Speaking in new documentary 'Four Kings', Frank's daughter Rachel said: "We have learned recently that his brain might be on a slow decline.
"They are just doing scans and tests at the moment. With the impact of his career and constant knocks to the head, it’s obviously probably not helped.
"We don’t know how fast his brain is going to decline. It’s sad but we’re a strong family and we want to cherish these moments."
Despite the concerns, Frank couldn't be happier with how his life has panned out.
He said: "I fulfilled my dream.
"I won the world championship. I’ve got some beautiful kids. What more do you need?"
And he has subsequently insisted his health is "fine".
He shared a statement online which read: "I confirm my health is fine.
"I am doing speaking events every week and audiences who see and hear me up and down the country will testify to that.
"People are booking me all the time, in fact the diary is looking good."
And an insider close to the former boxer insisted the checks are a routine process for any retired fighter and Frank is currently the healthiest he has been in "years".
A source told The Sun newspaper: "Frank’s in a great place at the moment and feeling fitter and healthier than he has in years.
"Each week he will be at three or four events talking about his career and working.
"All retired boxers have regular checks, and Frank is no different."
Frank retired from the ring in 1996 and was diagnosed with bipolar disorder that same year. Since his diagnosis he has been sectioned in a psychiatric hospital four times.
