A new study finds 30 percent of U.S. veterans prescribed psychiatric medications do not have a diagnosed mental health problem.

Veterans ages 65 to 85 are most likely to be prescribed psychotropic medications without having a diagnosis, Reuters reports. This age group is also the least likely to be receiving mental health treatment.

The drugs most likely to be prescribed without a diagnosis are antidepressants; sedatives, such as alprazolam or diazepam and mood stabilizers, such as gabapentin and valproic acid.

The researchers analyzed prescription and medical records of 1.85 million veterans who filled prescriptions in 2010 for at least one psychiatric medication. They found veterans older than 65 were prescribed psychiatric drugs without a diagnosis 44 percent more often than veterans in their 40s.

“Psychiatric medications can save lives, but they can also cause harm,” said lead author Ilse Wiechers, a psychiatrist at Yale School of Medicine. “My work aims to ensure that older adults receive the right medicine for the right diagnosis in the safest way possible.”

The findings are published in the American Journal of Geriatric Psychiatry.