Disentangling the association of depression on the anti-fatigue effects of ketamine.

•In patients with treatment-resistant depression, ketamine does not have a unique effect on fatigue outside of its general antidepressant effects.•The anti-fatigue effects of ketamine were mostly accounted for by the changes in amotivation and depressed mood scores.•The anti-fatigue effects of ketamine should be assessed by fatigue-specific measures other than the National Institutes of Health - Brief Fatigue Inventory.