For severely depressed inpatients aged 18–85, electroconvulsive therapy (ECT) led to remission in 63% of patients, while ketamine infusions led to remission in 46%, a statistically significant difference. Both treatments required a median of six sessions to achieve remission. ECT caused more serious and long-lasting side effects, including persisting amnesia, whereas ketamine caused more treatment-emergent adverse events leading to dropouts. Among those who remitted, about two-thirds in each group relapsed within 12 months, with no significant difference between treatments. Ketamine, though less effective than ECT, appears to be a safe and useful option for treating unipolar depression.
Electroconvulsive therapy (ECT) and racemic ketamine are both effective treatments for severe major depressive disorder, but they target different patient populations. Systematic reviews show higher remission rates with ECT than with ketamine. However, ketamine acts rapidly and causes less cognitive side effects, making it valuable for outpatients or when ECT is unavailable. ECT induces transient cognitive impairments, while ketamine commonly causes dissociative symptoms. Older patients and those with psychotic symptoms respond better to ECT, whereas younger patients with longer episode duration may benefit similarly from ketamine. Although biological variables and brain imaging hold promise as biomarkers, their clinical use remains limited. The review advocates integrating clinical predictors with patient characteristics to personalize treatment.