A new study says Alzheimer's disease is almost as lethal as heart disease and cancer.

Alzheimer's is currently considered the sixth leading cause of death in the United States. However, researchers at Rush University found that Alzheimer's may be responsible for the deaths of more than 500,000 people per year, which would make it the third leading killer behind heart disease and cancer. Experts say the problem in calculating the numbers is that medical examiners usually only list the immediate cause of death, which leads to underreported numbers for Alzheimer's-related fatalities.

Advocates say there needs to be more funding for Alzheimer's research, and are hopeful that the recent study could mean some big changes in the amount of money that's put into research for finding a cure.

Researchers say they need $2 billion for the next decade to really make a difference in the prevention and treatment of Alzheimer's.

In 2013, $524 million went to research.