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.
As of January 8, 2015, the U.S. is $18.1 trillion in debt. The national debt-aka the federal debt-is the total of all the past years' budget deficits, minus what the government has paid off with budget surpluses.