McDermott, 69, announced on Liverpool’s official website that he was in the early stages of Lewy Body dementia following hospital tests.
“I’ve got to get on with it and I will. It’s the way I’ve been brought up. Nothing has come to me easily,” McDermott said on www.liverpoolfc.com.
“I’m not frightened of taking it on and also, as we’ve seen, there are a lot of former players in a worse state than me.
“Battling is second nature. The worst thing was, until my condition was diagnosed you don’t know what’s going on.
“The number of ex-players being diagnosed with dementia or Alzheimer’s is frightening.”
McDermott’s announcement comes only two days after Manchester United and Scotland great Denis Law revealed he was suffering from dementia.
McDermott made 329 appearances and scored 81 goals for Liverpool between 1974 and 1982, helping the Reds to four league titles and three European Cup victories as well as UEFA Cup success and two League Cup crowns.
The former England international later had spells working as assistant manager at Newcastle, alongside the likes of Kevin Keegan Kenny Dalglish, Graeme Souness, Glenn Roeder and Sam Allardyce, as well as with Huddersfield and Birmingham.
McDermott was at Anfield on Saturday to watch Liverpool’s Premier League win over Burnley.
“I’ve been looking forward to going down to Anfield and seeing the lads, people I have known for years and having a good craic with them,” said McDermott. “Thankfully there are games coming up regularly now which I can go to.”
Liverpool have pledged to give McDermott all the support he and his family might need.
“Everybody at Liverpool Football Club sends their love and best wishes to Terry and his family and the club will offer any and all support,” a club statement read.