WASHINGTON (AFP) - Democratic White House frontrunner Hillary Clinton on Tuesday (Dec 22) unveiled a plan to battle Alzheimer's, saying she would more than double federal funding for research and treatment of the disease.

Fighting Alzheimer's, a form of dementia which affects five million Americans and currently has no cure, is a steadily growing effort in the United States.

Congress recently increased the federal research budget by US$350 million (S$491 million), on top of the US$586 million that the National Institutes of Health spent this past year.

But Clinton proposed raising that budget to US$2 billion per year until 2025.

"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 good-bye to make research investments that will prevent, effectively treat and make a cure possible by 2025," she said in a statement.

The Clinton campaign notes that some two-thirds of Alzheimer's patients are women, and that prevalence in elderly African-Americans is twice as high as in elderly whites.

Investment is vital, Clinton said, because the disease is already costing US$200 billion per year in the United States and that figure will only grow with the country's ageing population.

"Our main bottleneck in this field has been funding," Rudolph Tanzi, a neurology professor at Harvard Medical School and chair of the Cure Alzheimer's Fund Research Consortium, told reporters on a call arranged by the Clinton campaign.

"We are a budget-constrained, not a knowledge-constrained field," he said.