As the NHS struggles with this cost, Mr Cameron plans to improve research on living with dementia and fund a new academic centre for scientists to investigate the causes of the condition.

He also wants to encourage people to volunteer for brain scanning to help identify the signs of early onset.

We did it with cancer in the 70s. With HIV in the 80s and 90s, he will say. We fought the stigma, stepped up to the challenge and made massive in-roads into fighting these killers.

Now weve got to do the same with dementia. This is a personal priority of mine.

The number of people suffering from the condition is likely to reach a million within a decade, but only around one in four will get a correct diagnosis.

Dementia is simply a terrible disease, he will say. And it is a scandal that we as a country havent kept pace with it. The level of diagnosis, understanding and awareness of dementia is shockingly low. It is as though weve been in collective denial.

So my argument today is that weve got to treat this like the national crisis it is. We need an all-out fight-back against this disease; one that cuts across society."

Shirley Cramer, chief executive of Alzheimers Research UK, said the new money was crucial to "if we are to avert the drastic economic costs of dementia that lie in wait".

Emergency hospital admissions for dementia sufferers have risen sharply in recent years.

Experts say the increasing number of admissions is costly to the NHS and in many cases unnecessary, as well as traumatic for vulnerable patients.

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Dementia is a national crisis like HIV and cancer, says David Cameron