WASHINGTON: Hillary Clinton announced Tuesday a $2 billion annual effort to cure Alzheimer's disease by 2025, calling for doubling federal spending to combat the illness.

The Democratic front-runner plans to introduce her proposal in Iowa during her last presidential campaign swing before the holidays. The funding is coupled with proposals to aid the 15 million Americans caring for those afflicted by the illness.

The proposal marks the first time a presidential candidate has made combating Alzheimer's a campaign issue, according to advocates, and is part of a larger effort by Clinton to increasing funding for health research.

"We owe it to the millions of families who stay up at night worrying about their loved ones afflicted by this terrible disease and facing the hard reality of the long goodbye to make research investments that will prevent, effectively treat and make a cure possible by 2025," Clinton said. "The best scientific minds tell us we have a real chance to make groundbreaking progress on curing this disease and relieving the pain so many families feel every day."

Five million Americans have been diagnosed with Alzheimer's, a number that's expected to increase to 15 million by 2050. The disease is the 6th leading cause of death in the United States and disproportionally impacts minorities and women. Two out of three Alzheimer's patents are women.

Clinton's plan would guarantee consistent funding so researchers can work toward advancing treatment, not only for Alzheimer's but other neurodegenerative illness including Parkinson's disease and Lewy body dementia. She would also try and ease the burden facing caregivers by expanding Medicare to cover care-planning sessions, working with the federal government include information about Medicare-covered screenings on Social Security payments and push Congress to reauthorise a federal grants programme funding local initiatives to identify, locate and protect disoriented Alzheimer's patients who wander from their homes.

Clinton will pay for her plan by closing tax loopholes, though her campaign did not specific which ones.

"Our single bottle-neck has been funding. We are budget-constrained not a knowledge-constrained field," said Alzheimer's expert Rudolph Tanzi, who discovered many of the genes leading to Alzheimer's and oversees a research centre at Massachusetts General Hospital. "Hopefully with $2b a year we can finally do the work we need to do."

Last year, the government spent $586 million on the disease. The 2016 budget signed by US President Barack Obama last week will increase federal funding to $936 million annually. Total costs may exceed $1 trillion by 2050, according to estimates.

Clinton is campaigning in Iowa Tuesday with Secretary of Agriculture Tom Vilsack.