The world's largest study of dementia was launched by British Prime Minister David Cameron on Thursday as part of a drive to speed up the search for treatments.
"The truth is that dementia now stands alongside cancer as one of the greatest enemies of humanity," Cameron told a London summit on dementia, a range of conditions causing mental decline that affect 40 million people globally.
The new study will collect the medical and lifestyle data of two million volunteers in Britain aged over 50, using cognitive studies, brain imaging and genetics to shed light on causes and possible treatments for dementia, the most common form of which is Alzheimer's disease.
The information collected is expected to help scientists identify those most at risk of developing dementia and pinpoint causes and risk factors for disease.
"We need to join up the dots and create a big, bold global push to beat this," Cameron said, saying that regulations should be eased to allow new drugs to be tested earlier.
"It will take years of work but we have shown with other diseases that we can make progress and we will do so again."
Cameron criticised a "market failure" that meant global spending on dementia was five times smaller than investment into cancer research, meaning only three drugs had been released to market in 15 years.
He called on governments to create incentives for research into dementia, which cost the global economy $604 billion in 2010, according to Alzheimer's Disease International.
Britain used its 2013 presidency of the G8 to call an international summit on dementia, at which experts set a goal to find a cure by 2025.
The British government is to put forward proposals to extend the length that drug companies can hold patents to incentivise research, and is increasing its funding for dementia research to £66 million ($113 million, 82 million euros) in 2015, up from £28 million in 2009.
The event also launched a £100 million project by the Alzheimer's Research UK campaign, which includes opening a stem cell research centre and a network of drug research units in universities.