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 December 15, 2015, the U.S. is $18.8 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. Deficits are common: in the last half century, the federal government has run a deficit in 45 out of 50 years.