Bestselling fantasy author Pratchett reveals Alzheimer's diagnosis

Bestselling British author Terry Pratchett, creator of the monumentally successful Discworld series, has revealed that he has been diagnosed with a rare form of early onset Alzheimer's disease.

The 59-year-old writer made the announcement Tuesday through a web posting to fans on the website of illustrator Paul Kidby, who has worked on many of Pratchett's Discworld titles.

"I would have liked to keep this one quiet for a little while, but because of upcoming conventions and, of course, the need to keep my publishers informed, it seems to me unfair to withhold the news," Pratchett wrote in a message titled "An Embuggerance."

"We are taking it fairly philosophically down here and possibly with a mild optimism," he wrote.