Americans are taking a “startling” amount of mental-health related medications, according to a big new study by Medco Health Solutions. More than 1 in 5 Americans now takes at least one drug to treat a psychological disorder, ranging from antidepressants like Prozac to anti-anxiety drugs like Xanax. Understanding why Americans are taking more pills to treat mental illness “is the next critical goal,” says Dr. Martha Sanjatovic in a statement released by Medco. Here’s a look this growing trend, by the numbers: