The man mountain centre-half, who spent three years at Hillsborough after a storied spell at Everton, is famed as one of the club’s most iconic leaders having played 129 league matches between 1982 and 1985.
Liverpool-born Lyons achieved promotion to the First Division with Wednesday in the 1983/84 season under Howard WIlkinson and is widely regarded as one of the best players never to have represented England, though he did collect two England ‘B’ caps.
Speaking a day after the PFA launched an initiative to learn the full extent of the dementia problem in English football, with the players' union calling for families to come forward, Lyons’ daughter Francesca confirmed Lyons’ condition to The Telegraph.
The 70-year-old is living out in Australia, where he ended his career in management back in 2011.
“He forgets people and short-term stuff,” Francesca said. “I first noticed when people would come up to him and he didn't remember who they were.
“He has been living in Australia where my brother Michael is doing a brilliant job helping him. At the beginning, I wondered if it was just a case of having been away.
“Then I became aware of the issue in football. He says it’s from heading the ball but he remembers everything from years back - football matches and scores.
“He had scans and the professor said it was repeated heading of the ball. They can see brain damage from the impact.
“He’s still a big, strong, fit man. He still likes to call himself an athlete and has his sense of humour, his memory is just not the best. He’s got a lovely life out there but I’m concerned about the future.”
Lyons doesn’t appear to have any regrets looking back on a career that also saw him play for Grimsby Town and Canadian side Novia Scotia Clippers before moving into management abroad, twice with the Bahrain national team and with three Australian sides.
“I loved heading the ball, I’d go up for all the corners,” he said.
“I do obviously think the more you headed the ball, the more likely you were to forget things. And some opposition teams used to soak the ball on purpose.
“When you headed it, it was thud, thud, thud. I used to get quite a few stitches in the face through heading. My memory has not been fantastic over the years.
“I think, ‘what did I do then?’ but I just get through OK. I don't worry at all about it. To me, it was part of the job.”
Lyons is the latest high-profile former player to have come forward with the reality of a battle with dementia.
Legendary players such as Denis Law and Sir Bobby Charlton are living with the disease, which also affected the final years of the life of former Wednesday manager Jack Charlton, who died in 2020.
Light has been shined on the issue of brain injuries in former footballers in no small part due to the work of charity set up by the family of former West Brom icon Jeff Astle, who died from dementia aged just 59 in 2002.