A single infusion of ketamine, compared to midazolam as an active placebo, did not reduce suicidal ideation scores on the Beck Scale for Suicidal Ideation at 24 hours in patients with mood and anxiety disorders who were at elevated risk for suicidal behavior. A significant difference favoring ketamine emerged at 48 hours, but the effect was no longer significant by the end of 7 days. The intervention was well tolerated with no dropouts during the primary assessment period. The findings support the safety and tolerability of ketamine for suicidal ideation but larger studies are needed.
A single low dose of ketamine increases brain activity in the right caudate when people with treatment-resistant depression view happy faces, reversing a baseline deficit compared with healthy volunteers. Twenty patients with treatment-resistant depression not taking other antidepressants underwent fMRI before and 24 hours after receiving intravenous ketamine (0.5 mg per kg of body weight). Twenty matched healthy controls were scanned once. Before ketamine, depressed patients showed reduced neural responses to happy faces in the right caudate. After ketamine, responses to happy faces increased in a similar region. Greater connectivity of the right caudate during positive emotion perception was linked to greater improvement in depression severity. No effects were seen for sad faces.