Electroconvulsive Therapy: Major Depressive Episodes
Evidence for Acute-Phase Efficacy
It is generally accepted that ECT is the most rapid and effective treatment available for major depressive episodes (Weiner and Coffey 1988). The evidence supporting this conclusion is compelling and includes a sizable number of well-controlled “sham-ECT” studies. In these studies, patients were randomized to receive real ECT or sham-ECT (involving anesthesia but no electrical stimulation), thus providing for rigorous double-blind tests of efficacy (Brandon 1986). The degree of increased efficacy with ECT compared with antidepressant medication has also been considered by meta-analytic studies. Janicak et al. (1985), for example, reported that ECT was 20% more likely to induce a remission than were tricyclic antidepressants (P < .001). In many series, ECT has been associated with a remission rate of 80%-90%, with maximum response typically attained after 2-4 weeks. However, it is now apparent that such rates primarily apply to those with high prognosis for good response to ECT (see below), and that response rates for those with more moderate prognoses may be appreciably lower. In addition, there have not yet been adequate comparisons between ECT and newer antidepressant agents or combined antidepressant and mood-stabilizing medications.
Recent data suggest that ECT is as effective in severe nonmelancholic episodes as it is in episodes that meet the criteria to be classified as melancholic (Sackeim and Rush 1995). Similarly, efficacy appears to be equivalent in depressed patients with unipolar or bipolar mood disorders. Psychotic depression, particularly in the presence of mood-congruent delusions, is believed to be associated with an increased likelihood of success with ECT, compared with nonpsychotic depression (Sobin et al. 1996). However, an adequately controlled comparison of ECT with a combination of antidepressant and antipsychotic medications remains to be carried out in psychotic depression.
Another way to dichotomize major depressive episodes is by whether the episode is primary or secondary to a preexisting mental or chronic physical disorder. There is now evidence that primary depressive episodes are more likely to show full improvement with ECT than are those that are secondary, including those associated with dysthymia, anxiety disorders, and borderline personality disorder. For example, the presence of a preexisting dysthymic disorder in a patient with a major depressive episode may result in a less complete remission with ECT than would be seen in a patient with a primary major depressive episode—that is, a remission in the major depressive episode may have little or no effect on the underlying dysthymic condition.
In the past, it was believed that the presence of an antidepressant drug failure during the current episode did not influence response to ECT. Newer data, however, suggest that this assumption may not be true and that patients with medication-resistant depression have a lower remission rate with ECT (Prudic et al. 1996). The reason for this effect is unclear, but it may be that there was a higher percentage of pure treatment-refractory cases in the group of patients whose depression did not respond to medication. Alternatively, longer episodes may be associated with a relative inertia to treatment interventions of any type.
Historically, much attention has been devoted to the prediction of who will respond to ECT (Abrams 1997a). In this regard, both phenomenological and biological factors have been considered, as well as composite indices. Unfortunately, none of these efforts has met with consistent success, and one is left with the types of considerations already discussed above. Although there is a general belief that mood-congruent delusions and catatonic symptomatology are associated with a particularly good response to ECT, it is possible that these features may merely be markers for a severe episode.
Evidence for Continuation/Maintenance-Phase Efficacy
As already mentioned, a course of ECT by itself produces a remission rather than a “cure,” and continuation/maintenance therapy is nearly always indicated. For the great majority of patients receiving ECT for the treatment of a major depressive episode, continuation/maintenance therapy consists of antidepressant agents, which are continued for at least a year. However, recent evidence suggests that continuation pharmacotherapy is less effective in patients who were medication-resistant during the index episode for which they ultimately received ECT (Sackeim 1994; Sackeim et al. 1990). These results bring into question the routine use of pharmacological continuation therapy in such persons and bring to mind as an alternative an old and—until recently—nearly forgotten alternative: continuation/maintenance (C/M) ECT.
Although only a few uncontrolled reports of the use of C/M ECT appeared in the literature before the early 1980s, there have been dozens of publications on this topic since that time, consistent with other evidence of increased clinical interest in this use of ECT. This literature abounds with reports of success with C/M ECT, including 1) open trials, 2) post hoc comparisons of clinical outcome before versus after initiation of C/M ECT, and 3) outcome comparisons of compliance and noncompliance in C/M ECT treatment regimens. Although a randomized controlled trial remains to be completed, most experts believe that existing data are sufficient to argue for consideration of C/M ECT in situations in which there is a history of refractoriness to, intolerance to, or noncompliance with continuation or maintenance antidepressant medication trials. Given the very difficult problem of otherwise managing such patients, it is likely that, at present, C/M ECT is underutilized.
Specific indications for continuation ECT are 1) history of recurrent episodes responsive to ECT and either 2) ineffectiveness of or intolerance to prophylactic pharmacotherapy or 3) patient preference (American Psychiatric Association Committee on ECT 2000). It may be worth noting that in many such cases, patients will receive less total ECT than they would have had they not undergone continuation ECT (because relapse often requires an entire new course of ECT). Maintenance ECT (i.e., an extension of prophylactic ECT beyond 6 months) is indicated either when the patient’s history suggests a high risk of delayed relapse or when acute evidence of decompensation occurs during attempts to stretch out the interval between treatments during the continuation phase (asee Case 3).
Revision date: July 9, 2011
Last revised: by David A. Scott, M.D.