The study by Hatta and his coworkers included 67 older hospitalized patients. Half received a melatonin agonist called ramelteon nightly and half received a placebo. Only three percent of the subjects getting ramelteon developed delirium, whereas 32 percent of placebo subjects did--a significant difference.
"This is an interesting study despite the small size of the sample," Gary Kennedy, M.D., a professor of psychiatry at Albert Einstein College of Medicine and director of the Division of Geriatric Psychiatry at Montefiore Medical Center, said in an interview. "It reinforces the novel theory that melatonin is involved in the genesis of delirium and would explain in part why older adults are more likely to develop delirium. The potential of ramelteon to reduce the risk of delirium is especially appealing because of its low adverse reactions, unlike antipsychotics that are so often used when delirious behavior threatens the patient's well-being."
Ramelteon has been approved by the U.S. Food and Drug Administration to treat insomnia.
More information about diagnosing and treating delirium can be found in American Psychiatric Publishing's new Clinical Manual of Geriatric Psychiatry.
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