Pratchett diagnosis stuns fans

Terry Pratchett, author of the Discworld fantasy series, announced that he has been diagnosed with early onset Alzheimer's.

Pratchett said he will continue to write Discworld novels (to date there are more than 40). In a statement released on the website of Paul Kidby, Discworld's illustrator, Pratchett set a tone of acceptance and optimism: "Frankly, I would prefer it if people kept things cheerful, because I think there's time for at least a few more books yet :o)."

Pratchett is 59.