Effects of Ketamine Versus Midazolam on Neurocognition at 24 Hours in Depressed Patients With Suicidal Ideation.

Objective: Subanesthetic ketamine rapidly reduces depressive symptoms and suicidal ideation in some depressed patients. Its effects on neurocognitive functioning in such individuals with significant suicidal ideation is not well understood, even though certain neurocognitive deficits are associated with suicide behavior beyond clinical symptoms.Methods: In this study, depressed patients with clinically significant suicidal ideation (n = 78) underwent neuropsychological testing before and 1 day after double-blind treatment with intravenous ketamine (n = 39) or midazolam (n = 39). A subgroup randomized to midazolam whose ideation did not remit after initial infusion received open ketamine and additional neurocognitive testing a day after this treatment. The primary outcome was change in performance on this neurocognitive battery. The study was conducted between November 2012 and January 2017.Results: Blinded ketamine produced rapid improvement in suicidal ideation and mood in comparison to midazolam, as we had reported previously. Ketamine, relative to midazolam, was also associated with specific improvement in reaction time (Choice RT) and interference processing/cognitive control (computerized Stroop task)-the latter a measure that has been associated with past suicide attempt in depression. In midazolam nonremitters later treated with open ketamine and retested, reaction time and interference processing/cognitive control also improved relative to both of their prior assessments. Neurocognitive improvement, however, was not correlated with changes in depression, suicidal thinking, or general mood.Conclusions: Overall, ketamine was found to have a positive therapeutic effect on neurocognition 1 day after treatment on at least 1 measure associated with suicidal behavior in the context of depression. Results suggest additional independent therapeutic effects for ketamine in the treatment of depressed patients at risk for suicidal behavior.Trial Registration: ClinicalTrials.gov identifier: NCT01700829.