Sir Terry Pratchett told the BBC that life since diagnosis had been 'busy'
Two years after being diagnosed with Alzheimer's, Sir Terry Pratchett has appeared on the BBC's The One Show talking about the disease's effects.
He said: "The difficulty is that I've never been 61 before so I don't know how you're supposed to feel."
Sir Terry is patron of Cambridgeshire-based Alzheimer's Research Trust.
His television appearance coincided with the Trust's new advertising campaign which aims to raise awareness of the 820,000 UK dementia-sufferers.
Since being diagnosed by specialists at Addenbrooke's Hospital in December 2007, Sir Terry Pratchett summed up his life, saying: "It's been busy."
'I feel good'
"People ask me how I am," he continued. "And I say 'well I've got it but it's not that much of a problem for me to be honest'.
"I'm speaking as a rich man who can afford not to have to drive myself and that sort of thing, and I can talk to my computer and actually get it to understand me most of the time, and for an author that's the most important thing.
"And I've been doing lots of work for various campaigns... and I feel good."
Now aged 61, he said that he was not really able to say whether he was feeling the effects of Alzheimer's - he has a rare form of the disease, posterior cortical atrophy - or whether changes in his behaviour could simply be part of the ageing process.
"What I always say is the baby-boomers conspire to believe that they're not getting older, so they say 'well everybody loses their car keys; everybody goes upstairs to find something and forgets why they went up there', so I don't know whether what I'm feeling is the disease or normality."
He said that he tried to remain upbeat as much as possible, and laughed as he said: "I wear a heavy leather jacket and the nice thing about a heavy leather jacket is that it has a shape. It falls into a shape and it's easy to put on.
"I don't put my trousers on upside down or things like that and I can get myself dressed - but I'm always aware of this little problem that I'm overcoming.
"You work around as much as you can. You'll never see me go into a revolving door..." He laughed again and added: "But it would be fun!"
In March 2008, Sir Terry Pratchett pledged $1m to the Alzheimer's Research Trust, and became a patron of the organisation in May that same year.
The Trust has recently launched a UK-wide television campaign to increase awareness and funding of research into the disease.
Two adverts are being shown; one featuring a scientist researching the disease in order to discover new treatments, and the other an emotional appeal from a woman who describes how she lost her husband two years ago - her husband sits next to her staring vacantly into space, physically alive yet no longer aware of who or where he is.
A memory wall project was also launched in Cambridge by the Alzheimer's Research Trust. It features precious memories from well-known names including Sir Terry, Gordon Brown and Sir Michael Parkinson.
The wall is part of a campaign called Memory Matters and will be taken all across the UK, where members of the public will be invited to add their own memories.