Terry Pratchett has revealed in a letter on the website of artist Paul Kidby that he is suffering from a rare form of early Alzheimer’s disease.

Pratchett is probably most famous for his Discworld series, where a parallel world, carried by 4 huge elephants standing on an enormous turtle named Great A’Tuin, has more than a passing resemblance to our own world.

In his announcement letter he proves he hasn’t lost his sense of humor:

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.

He still has a couple of books in him, and I look forward to them with more anticipation than ever before. God bless, Terry.