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.
(Source: Debt to the Penny, U.S. Treasury. Debt FAQ, U.S. Treasury.) America's debt is the largest in the world for a single country. It runs neck and neck with that of the European Union, an economic union of 28 countries. For more, see Sovereign Debt Rankings. The debt is greater than what America produces in a whole year. This high debt-to-GDP ratio tells investors that the country might have problems repaying the loans. That's a new and worrying occurrence for the United States. In 1988, the debt was only half of America's economic output.