Prime Minister David Cameron and Health Secretary Jeremy Hunt have called on health ministers from member countries to attend a meeting to confront this "global challenge" in London on December 11.
Currently there are 35.6 million people worldwide living with dementia. By 2020, it is estimated that the figure will rise to nearly 70 million.
In launching the summit, Hunt said: "This is a global challenge and one which is set to intensify.
"While we continue to pursue tomorrow's cures, it is critical now more than ever to pay serious attention to what we can do to reduce the average number of years living with the condition.
"The G8 have a unique chance to come together to help people manage dementia better, lead healthier lives and deliver real improvements in care and substantial economic savings."
No new treatments since 2003
The total estimated worldwide cost of dementia was $604 billion (£386 billion) in 2010. About 70% of the costs occur in Western Europe and North America.
But nearly 60% of people with the condition live in developing countries. As their populations grow and age, the pressure on their services and budgets will increase.
Hilary Evans from Alzheimer's Research UK said: "Worryingly, there have been no new treatments for dementia since 2003 and those in existence only offer modest efficacy.
"We desperately need new treatments and interventions that can delay the onset, slow the progression and manage the symptoms of dementia.
"Only through increased research can we make progress and offer hope to people with dementia."