Ketamine augmentation rapidly improves depression scores in inpatients with treatment-resistant bipolar depression

Objective: To study the clinical effect of a single ketamine infusion, 0.5mg/kg body weight, in bipolar depressive patients receiving mood-stabilising drugs, not improving on antidepressants. Previously, in such patients, we had found a correlation between clinical efficacy, serum brain-derived neurotrophic factor and vitamin B12 levels and a rapid improvement in neurocognitive performance. Methods: The study included 53 patients (13 men, 40 women), aged 22-81 years, receiving >= 1 mood-stabilising medications of the first and/or second generation. Pre-infusion depression intensity on the Hamilton Depression Rating Scale (HDRS) was 23.4 +/- 4.6 points and the assumed criterion for response was a reduction of >= 50% in the HDRS score after 7 days. Results: Twenty-seven subjects (51%) met a criterion for response, more frequently males (77%) than females (43%). Responders did not differ from non-responders as to age, illness onset, duration of depressive episode, type of bipolar illness, family history of psychiatric illness, personal/family history of alcoholism or using lithium, quetiapine or a combination of these mood stabilisers. Conclusions: The results confirm a rapid antidepressant effect of ketamine infusion in a considerable proportion of those patients with bipolar depression receiving mood-stabilising drugs. Apart from male gender, no other clinical factors were predictors of response.