The U.S. National Institutes of Health is the single biggest funder of biomedical research in the world, with a current budget of $30.1 billion spread across its 27 separate institutes and centers.

At the request of Congress, in 2008 NIH began releasing to the public how much the agency spends in various research categories. I decided to pick out the top-funded disease areas to get a sense of what disorders and diseases the U.S. government is prioritizing. The red and green arrows indicate whether categories had a decrease or bump in funding from the previous year, respectively.

In the 2013 column, you'll notice that funding for almost every disease area got slashed--that's the result of sequestration, the across-the-board spending reductions that automatically took effect in March 2013. The fiscal 2015 column represents projected levels for that disease area based on President Obama's proposed 2015 budget, released in March, of $30.4 billion for the upcoming fiscal year that begins in October

A few important caveats about this chart: NIH does not expressly budget by category, so the research sections below are not mutually exclusive. What that means is that individual research projects and grants may be included in multiple categories. For example, brain disorders and neurodegenerative diseases very likely have some overlap. In addition, NIH catalogs all its research areas, including categories like clinical research, genetics, prevention and women's health; but in making this chart, I only chose to list the disease areas. Lastly, the dollar amounts represent NIH's best estimates based on individual categories' definitions.

 

The top 15 NIH-funded disease areas
Disease area	FY 2012 (millions)	FY 2013 (millions)	FY 2014 (est. in millions)	FY 2015 (est. in millions)
1. Cancer	$5,621	$5,274	$5,418	$5,418
2. Infectious diseases	$3,867	$4,887	$5,015	$5,015
3. Brain disorders	$3,968	$3,708	$3,796	$3,799
4. Rare diseases	$3,623	$3,456	$3,553	$3,553
5. Pediatric disorders	$3,612	$3,266	$3,339	$3,339
6. HIV/AIDS	$3,074	$2,898	$2,978	$3,005
7. Aging	$2,593	$2,429	$2,494	$2,494
8. Mental health	$2,287	$2,174	$2,215	$2,215
9. Cardiovascular	$2,040	$1,964	$2,015	$2,015
10. Emerging infectious diseases	$2,153	$1,804	$1,853	$1,853
11. Neurodegenerative	$1,671	$1,619	$1,662	$1,662
12. Digestive diseases	$1,719	$1,575	$1,617	$1,617
13. Heart disease	$1,278	$1,230	$1,262	$1,262
14. Lung disease	$1,286	$1,230	$1,261	$1,261
15. Hematologic diseases	$1,091	$1,020	$1,050	$1,050

Data courtesy of NIH