Money will go into researching cures and treatments. Around 800,000 people current suffer from dementia in the UK, at a cost to the economy of around £23bn, and the figure is set to rise above the 1 million mark in the next decade.
In a speech, the Prime Minister will call dementia awareness “shocking low”, adding, “Dementia is simply a terrible disease. And it is a scandal that we as a country haven't kept pace with it.
"One of the greatest challenges of our time is what I'd call the quiet crisis, one that steals lives and tears at the hearts of families, but that relative to its impact is hardly acknowledged.
"We did it with cancer in the 70s. With HIV in the 80s and 90s. We fought the stigma, stepped up to the challenge and made massive in-roads into fighting these killers. Now we've got to do the same with dementia. This is a personal priority of mine, and it's got an ambition to match.”
Funding for research topped £26m in 2010, but this figure will rise to £66m by 2015.
Jeremy Hughes, chief executive of the Alzheimer's Society, told the BBC, "Doubling funding for research, tackling diagnosis and calling for a radical shift in the way we talk, think and act on dementia will help to transform lives.”