About 700,000 in the UK have dementia
The predicted rise in dementia over the next two decades could destroy the NHS, say top scientists in an open letter.
An ageing population means the burden of dementia on the UK will double to £35bn-a-year within 20 years.
They told Health Secretary Alan Johnson that more should be spent researching new treatments for Alzheimer's disease.
The 11 specialists claimed only 3% of the annual NHS research budget was aimed at dementia. But the government said it was looking to improve care.
The open letter to Mr Johnson says that the NHS "may well be unsustainable" as the number of people with dementia increases.
They wrote: "As the NHS turns 60, the question isn't whether it will last a further 60 years, but if it can survive the next 20.
"The government must greatly increase dementia research now."
The signatories included Professor Simon Lovestone, from King's College London, Professor Nick Fox, from University College London, and Professor John Mayer, from Nottingham University.
Rebecca Wood, the chief executive of the Alzheimer's Research Trust, said that a quarter of the Department of Health's £700m research and development money was spent on cancer research, more than six times the figure received by dementia researchers.
"If underinvestment persists, the economic consequences arising from dementia care costs will be catastrophic."
A spokesman for the King's Fund, whose recent report predicted the doubling of costs for dementia care, said: "There is no cure for dementia.
"Unless there is a major breakthrough in drugs to arrest the course of this illness, there will be a great need for extra care and support, some of it quite intense."
But a Department of Health spokesman said that the first ever "National Dementia Strategy", which the government is currently working on, would improve early diagnosis, treatment and care.
She said that "significant funding" had already been made in dementia research, with the department investing £20m over five years from 2006 in a national research network on dementia and other neurodegenerative diseases.