The psychiatric study everyone's talking about this month is "Randomized trial of ketamine masked by surgical anesthesia in patients with depression".
Ketamine is a dissociative drug - it produces weird drug effects like feelings of bodylessness and ego death. Recent research suggests it's a powerful antidepressant. Usually we would try to run placebo-controlled trials. But it's hard to run a placebo controlled trial of a dissociative. Either you feel bodylessness and ego death (in which case you know you're getting the real drug) or you don't (in which case you know you're in the placebo group). Sometimes researchers try to use an "active placebo" like midazolam - a drug that makes you feel weird and floaty. But weird and floaty feels different from bodyless and ego-dead.
https://www.astralcodexten.com/p/does-anaesthesia-prove-ketamine-placebo
