Most Americans who screen positive for depression don’t receive treatment, while most who do receive treatment don’t actually have the condition. These are among the findings of a new study published in JAMA Internal Medicine.

“Over the last several years there has been an increase in prescription of antidepressants,” said Mark Olfson, a professor of psychiatry at the Columbia University Medical Center and lead author of the study. “In that context, many people assumed that undertreatment of depression is no longer a common problem.”

But Olfson found the opposite to be true after analyzing data from surveys that included questionnaires to screen for depression. Of the 46,417 adults surveyed, 8 percent answered in ways that suggested they had depression, but only 29 percent of those who seemed to need help received any treatment for it.

“The findings highlight that there are continuing challenges in aligning depression care with patient needs,” he said.

Adults in the lowest-income group were five times as likely to have signs of depression as were those in the highest-income group. But they were also less likely to receive treatment.

Among the people who received treatment for depression, only 30 percent had screened positive for depression and 22 percent had serious psychological distress. (Patients with serious psychological distress have more-severe symptoms of depression than do those with mild depression, and the condition typically requires treatment beyond antidepressants.) Those with either less serious or no depression were more likely than those with signs of depression to receive antidepressants. That’s a problem of overprescription, Olfson said, because studies have shown that anti­depressants are no more effective for mild depression than a placebo.

“Being a little less aggressive in medication in mild depression would be beneficial,” he said. “There are simpler forms of psychological interventions that can be adapted for primary care.” For example, patients can be given counseling, exercise and yoga.

The researchers concluded that those with serious psychological distress were more likely to be treated by psychiatrists than by general medical professionals, although this trend was not seen in older patients, African Americans, the uninsured or those with less education.

“Some when they have depression don’t believe they require treatment or that they could benefit from treatment,” Olfson said. “People are visiting doctors, but the attention is to current, pressing medical problems.”

Olfson found that most people with untreated depression make at least one visit annually to a primary-care doctor. If depression screening and mental health services were integrated into primary care, he said, there would be better access to assistance and awareness about the illness.

“If you give them a referral to a mental health clinic, they simply won’t go if they don’t think they have a mental health disorder,” he said. “By embedding the services within primary care, it becomes more accessible and less stigmatized.”

Benjamin Cook, the director of the Health Equity Research Lab at Harvard Medical School, agrees, but he said increasing access for minorities would require professionals who speak their languages and understand what types of treatment they are open to.

For example, said Cook, who was not involved in the study, “African Americans and Latinos prefer anti­depressants less than whites.” That might be an underlying reason “not to go for mental health treatment, why they might not stay at treatment for as long.”

This integration of services would also benefit patients who receive antidepressants when they don’t need to.

Olfson said many primary-care doctors expressed frustrations in finding mental health professionals, particularly in small towns and rural areas, so prescribing antidepressants might become their only option when they don’t have other resources. If there were a mental health professional right in the clinic, patients might get services that a primary-care doctor cannot offer, such as counseling and psychotherapy.

“Depression really is a serious condition, and we’re finding that so many Americans aren’t receiving care,” he said. “I hope that [this study] brings attention to this situation.”