Speaking of his own personal experience with the illness, former Bishop of Clogher, the Rt Rev Brian Hannon, recalled how a throwaway remark during a regular check-up with his own doctor two years ago changed his outlook on life.

However, the 73-year-old is successfully countering the most common cause of dementia and has called for drug treatment — Aricept — to be made readily available through the National Health Service.

Speaking to the News Letter, Mr Hannon described the moment he was diagnosed as having Alzheimer's as "absolutely horrific".

"I didn't know I had a problem at all," he said, reflecting on his doctor's appointment in November 2007.

"I was expecting a quick and happy chat until on the way out of the room I joked there is only one problem — I can't remember anybody's name.

"That was all I needed to say because within 24 hours he had me with a geriatric specialist and was able to show me exactly where I had the problem in the little memory section of my brain."

The Enniskillen man, father of The Divine Comedy singer, Neil, revealed the diagnosis was a major shock both to himself and his family.

"My first reaction was two to three months of pretty depressive behaviour. I couldn't even mention the word Alzheimer's — it just did terrible things to me," he said.

However, after coming to terms with his illness, the former clergyman made a personal decision, given his previous occupation, to spread the word.

"I decided at an early stage, I suppose partly because I was a Bishop for 25 years, to go out and tell people.

"My philosophy was 'don't disappear to the other end of the street or don't let them disappear to the other side of the street', which was inclined to happen at the early stages.

"I made sure I said to every person I met and knew that I had Alzheimer's.