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.
The U.S. debt is the sum of all outstanding debt owed by the Federal Government. It's greater than $19 trillion and is tracked by the national debt clock. America's debt is the largest in the world for a single country. It runs neck and neck with that of the European Union, which is an economic union of 28 countries. For more, see Sovereign Debt Rankings.