The goal of finding a cure for dementia with 12 years is “within our grasp” the prime minister tells an international summit, as he announces that funding for dementia research in the UK is to double.

Mr Cameron told scientists and campaigners at an international dementia summit that he wants UK government investment in dementia research to double from £66m in 2015 to £122m in 2025, to be matched by increases from the commercial and charitable sectors.

The prime minister compared the fight against dementia to previous global campaigns to tackle malaria, cancer and HIV.

The challenge is huge and we are a long way from a cure, but there is hope Prime Minister David Cameron

The World Health Organisation is forecasting that the numbers of dementia sufferers will almost double every two decades.

Statistics published last week show 44 million people now have the condition, with the number set to soar to 76 million by 2030. With an ageing population, dementia is on course to become the biggest burden on healthcare systems around the world.

The health secretary, Jeremy Hunt, said the illness costs the UK £23bn and the global cost is around £600bn.

Mr Cameron said the London conference, organised by the UK as part of its G8 chairmanship, would mark the point when “the global fightback really started, not just in finding a cure for dementia, but also in preventing it, delaying it and, crucially, helping those with dementia to live well and with dignity”.

He added: “The challenge is huge and we are a long way from a cure, but there is hope.

“We meet with the conviction that human ingenuity can overcome the most daunting of challenges and we meet with the determination that we will take the fight to dementia and improve and save millions of lives.

“The aim of trying to find a cure or disease-halting therapy by 2025 by a big collective boost to research funding is within our grasp.”

The London summit is expected to agree to a package of measures on international information-sharing and collaboration in research.

Mr Cameron announced three new investments, including £200m from GlaxoSmithKline, £150m from the Medical Research Council for clinical infrastructure for dementia and genomics and £3m from Belgian pharmaceutical company UCB for its research centre in Slough.

The G8 summit comes as the Care Quality Commission announced a national review of dementia care. Inspectors will visit 150 care homes and hospitals in England to gather information on what works well and what needs improving. A national report on the issue will be published in May 2014.