In a recent study it was found that as many as two-thirds of Americans with severe depression are not on medication.
Eleven percent of Americans age 12 and older are taking antidepressant medication, a slight uptick over a 2009 survey that showed 10.1 percent, according to the latest data from the National Center for Health Statistics.
However, just one-third of people with "severe depressive symptoms take antidepressant medication," said the survey, which described rates of antidepressant use by age, race, income, sex, severity and treatment time.
"Large numbers of Americans are not receiving antidepressants for their clinical depression," said Mark Olfson, professor of clinical psychiatry at Columbia University, in an interview with AFP.
"There is evidence of a mismatch between who most needs these drugs and who is getting them," said Olfson, who co-authored a 2009 study that showed rates of antidepressant use in the United States had doubled from 1996 to 2005.
Experts said the shortfall comes despite efforts to convince more primary care physicians to discuss mental health with their patients, since people see their regular doctors more frequently than they do psychiatrists.
Frequent commercials on television and in other media promoting antidepressant drugs in the United States could be leading more people to ask their doctors for such prescriptions, but not among the group that could be most helped by them.
"One of the things you see is when patients start asking for the medication they end up getting prescriptions for much less severe forms of depression," Olfson said.
"One of the things we know is that antidepressants are most effective when they are given to people with more severe rather than less severe depression."
The survey also said antidepressants are the most common prescription drug used by people age 18-44, and rates are two and half times higher in women than in men.
Nearly one-quarter (23 percent) of women age 40-59 take antidepressants, more than in any other age-sex group, said the study, funded by the US Centers for Disease Control and Prevention.
The high rate among women is not a surprise, according to Norman Sussman, professor of psychiatry and associate dean for continuing medical education at the New York University school of medicine.
"Women have a much higher rate of anxiety disorders. At any point, women are more likely than men to be amenable to taking medications," Sussman told AFP.
"Men view acknowledging that they are depressed as some sort of personal or character failure, and more often than women, men to turn to alcohol and drugs to self-medicate, whereas women are more able to talk about their symptoms and seek help and in turn receive it."
The data also showed significant racial and ethnic differences, with almost 14 percent of non-Hispanic whites taking antidepressants compared to four percent of African-Americans and three percent of Mexican-Americans.
Olfson said that even though non-whites are getting treated less often, studies have shown they are just as likely as whites to suffer from depression.
"The reasons for these differences do require more research and more study. Part of it may have to do with underlying cultural preferences," said Olfson.
Minority groups "may have different relationships with their physicians than non-Hispanic whites do," he added. "The role of the church, the role of the family and so forth, they may help to explain this."
The data was derived from 12,637 people who took part in an ongoing survey of Americans' health, known as the National Health and Nutrition Examination Surveys (NHAMES) from 2005-2008, including a household interview and a medical visit.
Previous studies have shown that antidepressant use rates in Europe are around 10 percent, while Asian countries tend to have much lower numbers of people taking doctor-prescribed antidepressants.