Terry Pratchett, the bestselling fantasy author, is suffering from a rare form of Alzheimer’s but would like it to be known that he is not dead yet.

In a statement posted on the website of his illustrator Paul Kidby, the author describes the diagnosis as “an embuggerance”.

He adds: “Frankly, I would prefer it if people kept things cheerful, because I think there’s time for at least a few more books yet.”

Pratchett, 59, is best known for his satirical Discworld novels and he has sold more than 55 million books.

Sod the Booker, this is popular

Giles Hattersley, of The Sunday Times, meets Terry Pratchett

BACKGROUND

• James Jackson meets Terry Pratchett on the set of Hogfather

• The Times review: Making Money by Terry Pratchett

• The Sunday Times review: Making Money by Terry Pratchett

• Imaginary worlds from Pullman to Pratchett

Related Internet Links

• Terry Pratchett explains why he became a writer

• Pratchett video interview: part 1 (footage courtesy of the BBC)

• Pratchett video interview: part 2 (footage courtesy of the BBC)

Related Links

• Illness that sent Iris tumbling into silence

Earlier this year, he started having problems with his hand-eye co-ordination while working on a manuscript. “It was as if I was typing wearing gloves,” he said.

Pratchett was referred to a specialist and an MRI scan revealed areas of dead tissue, suggesting that he had suffered a "mini-stroke" at some time in the past few years and that he was now living with its legacy.

In the statement, Pratchett tells his fans: “I have been diagnosed with a very rare form of early onset Alzheimer's, which lay behind this year's phantom "stroke".

“We are taking it fairly philosophically down here and possibly with a mild optimism. All other things being equal, I expect to meet most current and, as far as possible, future commitments but will discuss things with the various organisers.

Alzheimer’s is a degenerative brain disease for which there is no cure.

However, Pratchett adds: “I would just like to draw attention to everyone reading the above that this should be interpreted as, 'I am not dead'. I will, of course, be dead at some future point, as will everybody else. For me, this maybe further off than you think - it's too soon to tell.

“I know it's a very human thing to say, "Is there anything I can do?" but in this case I would only entertain offers from very high-end experts in brain chemistry.”

Pratchett was born in Beaconsfield, Buckinghamshire in 1948. His first short story The Hades Business was published in Science Fantasy magazine when he was 15 years old and his first novel The Carpet People came out in 1971.

He was a journalist and a publicity officer for the Central Electricity Generating Board before becoming a full time writer in 1987.

His most recent novel is Making Money, the 36th book in his globally acclaimed Discworld series which is set in a surreal world on the back of four elephants that stand on the shell of Great A'Tuin, the giant space turtle.

Long before JK Rowling and Phillip Pullman he straddled the divide between imaginative children’s and adult literature, writing fiction for both sets of readers. In 1989 Truckers became the first children's book to appear in British adult fiction best-seller lists while The Amazing Maurice and his Educated Rodents won the prestigious Carnegie medal for children's fiction in 2001. Pratchett was awarded an OBE in 1998 for services to British literature.

Alzheimer’s disease affects more than 400,000 Britons. It is the most common of more than 100 different types of dementia, most of which are progressive and eventually severe.

There is no cure for Alzheimer's disease or any other type of dementia.

People in the early stages of Alzheimer's disease may experience lapses of memory and have problems finding the right words. As the disease progresses they may: Become confused, experience mood swings or become more withdrawn due either to a loss of confidence or to communication problems.

As the disease progresses, people with Alzheimer's will need more support from those who care for them. Eventually they will need help with all their daily activities, the Alzheimer’s Society said.

The novelist Iris Murdoch and the politicians Harold Wilson and Ronald Reagan were among the best known sufferers.

Explore Books

• Book Extracts

• Book Reviews

• Books Group

• Audio Books

Times Recommends

• The 100 Best Books of the Decade
• The Times picks the 50 best paperbacks of 2009
• The conversation: James Ellroy