Sir Terry Pratchett on living with Alzheimer's disease
11 December 2013 Last updated at 11:16 GMT
The best-selling author, Sir Terry Pratchett, was first diagnosed with Alzheimer's disease in 2007.
Since then he has donated more than half a million pounds to help fund research.
Now six years later, Sir Terry, who supports the Alzheimer's Society, says that not enough has been done to tackle dementia.
BBC Breakfast's Charlie Stayt went to meet him to find out what life is like living with the condition, and whether Wednesday's international summit of health ministers could make a difference.