Media playback is unsupported on your device

Dementia: Terry Pratchett 'angry' with government

11 December 2013 Last updated at 01:18 GMT

The UK will aim to double funding for dementia research by 2025 from the 2015 target of £66m, David Cameron says.

The prime minister made the announcement ahead of the dementia summit being held in London as part of Britain's presidency of the G8.

Sir Terry Pratchett was diagnosed with Alzheimer's disease in 2007. He told Newsnight's Jeremy Paxman he is often angry with the government on the issue of dementia funding.