Note: As Mike Yassa, the lead author on the study, pointed out to me, the study did not actually test whether consuming caffeine before a task enhances memory, the problem being that other confounding factors can then lead to difference in performances on the test.
The US debt is more than $20.1 trillion, the largest in the world. Here are the 3 reasons it grew so large, and how it damages U.S. economic growth. The US debt is more than $20.1 trillion, the largest in the world.
According to the OECD, general government gross debt (federal, state, and local) in the United States in the fourth quarter of 2015 was $22.5 trillion (125% of GDP); subtracting out $5.25 trillion for intergovernmental federal debt to count only federal debt held by the public gives 96% of GDP.