A leading cause of disability, depression rates are increasing in the U.S. and under-treatment is widespread, especially among certain groups including men, the poor, the elderly and ethnic minorities, finds a new study in General Hospital Psychiatry.

The study provides "useful data for and policy makers" as it may lead to better identification of depressed patients needing care, said lead author Saranrat Wittayanukorn, a doctoral student in the department of health outcomes research and policy at Auburn University's Harrison School of Pharmacy.

The researchers used data from 13,320 U.S. adults over 18. These adults answered a nine-question survey widely used to diagnose depression. In the sample, 24.1 percent were depressed, with 36.6 of the depressed group having moderate-to-severe depression. Overall, 70 percent of in the study had received no whatsoever.

The study highlighted specific demographic factors associated with having depression, including being obese, poor, female, having certain chronic illnesses, such as arthritis and asthma, and lacking health insurance.

It also brought to light that influenced the chances that a depressed patient would receive treatment. Among people with moderate to severe depression, for whom current guidelines recommend the use of antidepressants, those who were female, white and young were most likely to receive treatment. Having certain other illness, such as arthritis or hypertension, and having had a prior hospitalization also increased the odds of treatment. Participants who were male, Mexican- or African-American, and older than 80 were identified as being at special risk for receiving no treatment.

"This elegant, nationally representative study highlights the remarkably low rate of any for those in the most need," said Bradley Gaynes, M.D., MPH, professor of psychiatry at the University of North Carolina School of Medicine. For the most severely , only half received any treatment and only 1 in 7 had received any antidepressants in the prior year. "This severely depressed group is the one for whom the benefits of treatment, especially medication, are most clearly established," noted Gaynes. The study also showed, added Gaynes, that for patients with moderate or moderate-to-, only 1 in 5 received any treatment and only 1 in 4 received medication.

Greater societal awareness of the widespread problem of untreated depression and of the special vulnerability of certain groups is much needed, said Gaynes. It's important information, he said, "for patients, who may avoid discussing depression due to stigma, for clinicians who may not discuss because doing so cuts into the time they have to address other conditions, and for payers, who may question the need to cover its care."

Journal information: General Hospital Psychiatry