Cognitive effects of intravenous Ketamine in treatment-resistant depression: A systematic review.
Psychological medicine May 8, 2026 Lou-Anne Chavigny, Véronique Desbeaumes Jodoin, Nicolas Garel et al.
A systematic review of 21 studies involving approximately 900–1,180 participants with treatment-resistant depression found that low-dose intravenous ketamine preserves and enhances certain cognitive functions. Improvements were frequently observed in processing speed and working memory, while attention remained stable or modestly improved. Results for verbal and visual memory varied across studies. Executive control, especially inhibitory performance on Stroop tasks, improved in several trials. No cognitive worsening was reported. Two studies directly examined cognition in relation to suicidal behaviors, suggesting that procognitive effects, particularly in executive control, may mediate ketamine's antisuicidal action. Standardized longitudinal studies are needed to clarify durability and clinical significance.