Antidepressant use in America increased almost 400 percent over the last 20 years, according to a new report by the Centers for Disease Control and Prevention.

The CDC found that every one in ten Americans take some kind of antidepressant drug.

It also noted that roughly one in 25 adolescents in America were also taking the drugs.

The report, based on surveys and screenings of 12,000 Americans from 2005 to 2008, shows that 11 percent of Americans aged 12 and over are taking an antidepressant.

The researchers said only one-third of people in the study with symptoms of depression were taking medication.

The finding suggests that "there's a lot of people who are seriously ill who aren't getting treated," said Laura Pratt, who led the research.

The study also found:

• Nearly a quarter of American women aged 40 to 59 take antidepressants, more than in any other group.
• Primary care doctors continue to prescribe antidepressants without consulting a therapist.
• Less than a third of those taking antidepressants report seeing a therapist within the past year.
• Antidepressants are the third most common prescription drug in the U.S.