Ketamine Effective in ECT-Resistant Depression

In an abstract presented at the Society of Biological Psychiatry meeting in May, Lobna Ibrahim and Carlos Zarate of the National Institute of Mental Health reported that intravenous infusions of ketamine were effective in a majority of patients with highly treatment-resistant depression, i.e. even those who had been unresponsive to a course of electroconvulsive therapy. Editor’s note: Few treatments have been explored for this subgroup of highly treatment-resistant patients, although some have been referred for experimental protocols with intracranial deep brain stimulation (DBS) and others have been successfully treated by Mark George and colleagues at the Medical University of South Carolina with very high intensity rTMS over the left prefrontal cortex (at 130% of motor threshold, 10 Hz stimulation). Further study is needed to determine what follow-up procedures can be used to sustain an acute response to ketamine, rTMS, or ECT for the long term. Prudic, Sackeim and colleagues have reported that 40% of patients with a good response to three times a week ECT relapsed within a month of completing that course of treatment. This loss of effect occurred even when ECT was continued more intermittently, suggesting that other therapeutic options need to be developed for this rapidly relapsing subgroup. Most of the data suggest that if patients fail to respond to a drug treatment regimen prior to ECT and then respond to ECT, a different or an increased intensity of the earlier drug regimen is required in order to sustain their response. Nonresponse to a drug treatment regimen prior to ECT predicts nonresponse to the same regimen following ECT. Since there are now numerous drugs for the primary and auxiliary treatment of depression, research should focus on determining optimal treatment algorithms for patients, both those who are responsive to ECT and those who are not. Having a potential treatment such as intravenous ketamine that is rapidly effective for ECT nonresponders is a good start. However, at the present time it is not clear how the acute onset antidepressant effects of intravenous ketamine may be sustained for the long term. Since intravenous ketamine also exerts positive effects on acute suicidal ideation, it is likely that IV ketamine will develop into an emergency room procedure for patients in suicidal crisis.