A single intravenous infusion of ketamine produced greater improvement in depression severity 24 hours later than the active placebo midazolam in patients with treatment-resistant major depression. In a randomized controlled trial of 73 participants, the ketamine group scored 7.95 points lower on the Montgomery-Åsberg Depression Rating Scale than the midazolam group. Response rates were 64% for ketamine and 28% for midazolam, with an odds ratio of 2.18 favoring ketamine. The findings support NMDA receptor modulation as a mechanism for rapid improvement in severe, chronic depression, though more information on durability and safety is needed before clinical use.
Over eleven million U.S. Veterans are 65 or older, and nearly 20% of that group experiences clinically significant depression. Existing medications often work poorly for late-life depression, especially when it is treatment-resistant. Ketamine offers a potentially rapid-acting option, but few studies have tested it in older adults. This ongoing trial uses an adaptive randomization design to compare the safety, tolerability, efficacy, and durability of three different low doses of intravenous ketamine against a single dose of an active placebo (midazolam) in older depressed veterans. As the study proceeds, Bayesian adaptive randomization shifts the odds of assignment toward the more promising dose conditions.