Antidepressant effects of ketamine and ECT: A pilot comparison.

Background: To compare the antidepressant effects and cognitive adverse effects of intravenous ketamine infusion and Electro-convulsive therapy (ECT) in persons with severe depressive episodes.

Methods: This assessor-blinded randomized control trial included 25 patients (either sex; 18-65 years) meeting ICD-10 criteria for severe depression (bipolar or unipolar). Patients received either ECT (n = 13) or intravenous infusions of ketamine hydrochloride (0.5 mg/kg over 45 min; n = 12) for six alternate day sessions over a period of two weeks. Severity of depression was assessed at baseline and on every alternate day of intervention using the Hamilton Depression Rating Scale (HDRS) and self-reported Beck Depression Inventory (BDI).

Results: Baseline socio-demographic and clinical variables including HDRS (ECT: 25.15±6.58; Ketamine: 23.33±4.05, p = 0.418) and BDI (ECT: 37.07±6.58; Ketamine: 33.33±9.29; p = 0.254) were comparable. Repeated-measures analysis of variance revealed that ECT patients showed significantly greater reduction in HDRS (group*time interaction effect; F = 4.79; p<0.001) and BDI scores (group*time interaction effect; F = 3.83; p<0.01). ECT patients had higher response rate than ketamine patients [HDRS: ECT- 13/13(100%) vs ketamine- 8/12 (66.70%); p = 0.04]. This was true for remission as well [ECT- 12/13(92.30%) vs ketamine- 6/12(50%), p = 0.030; both HDRS and BDI]. Performance on Digit Symbol Substitution Test (as part of the Battery for ECT-Related Cognitive Deficits scale) significantly improved in ketamine patients (p = 0.02) while that in ECT patients worsened non significantly (p = 0.30).

Limitations: Relatively small sample size; higher proportion of dropouts in the Ketamine arm.

Conclusion: This study favoured ECT over ketamine for a better efficacy over six treatment sessions in severe depression. The results need to be replicated in larger studies.

Trial Registration: CTRI/2019/09/021184.