Interesting study. However, I would argue that the study introduces an additional confound (anesthesia) rather than removing a confound (in order to isolate the effectiveness of ketamine).
I think it's also very probable that the trip is indeed part of the therapeutic effects of ketamine therapies.
On top of just the anesthesia confounding variable there's also the fact they were all getting surgery so improvements might have come from getting over the stress of whatever procedures they were having done.
My main worry is this will be waved around by people as an argument against the therapy without understanding what they were actually testing which is if you need to experience the trip for ketamine to have an antidepressant effect or if the effect is more principally neurochemical. The article has hints of this and at the bottom the authors also say that's mainly what they were looking to test here.
On top of just the anesthesia confounding variable there's also the fact they were all getting surgery so improvements might have come from getting over the stress of whatever procedures they were having done.
My main worry is this will be waved around by people as an argument against the therapy without understanding what they were actually testing which is if you need to experience the trip for ketamine to have an antidepressant effect or if the effect is more principally neurochemical. The article has hints of this and at the bottom the authors also say that's mainly what they were looking to test here.