Evaluation of Early Ketamine Effects on Belief-Updating Biases in Patients With Treatment-Resistant Depression

Key Points

Question  What are the effects of ketamine on belief updating in patients with treatment-resistant depression (TRD)?

Findings  This case-control study in patients with TRD showed that belief updating became more optimistically biased as soon as 4 hours after a first ketamine infusion. This early cognitive effect of ketamine was formalized by stronger asymmetrical reinforcement learning and mediated at 1 week of treatment the clinical antidepressant effect.

Meaning  These findings provide new perspectives for the understanding of the cognitive effects of fast-acting antidepressants that potentially can be leveraged to promote sustained clinical improvement and treatment responsiveness.