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.
Total America $57 Trillion debt shown at the top of this page can be broken down into two parts. This data graphic is of External U.S. Debt, meaning sum total of all debt owed to foreign entities. From $6.4 trillion of external debt in 2003 to $14.4 trillion in 2010 - 125% increase in 7 years of $8 trillion.