Clinical efficacy and cognitive side effects of bifrontal versus right unilateral electroconvulsive therapy (ECT): A short-term randomised controlled trial in pharmaco-resistant major depression

Abstract

Background

In most studies right unilateral electroconvulsive therapy (ECT) has been shown to cause fewer cognitive side effects but less antidepressant efficacy compared with bi(fronto)temporal ECT at certain intensities.

Aims

To compare the short-term efficacy and side effects of right unilateral ECT and bifrontal ECT.

Methods

In a double-blind randomised controlled clinical trial, 92 patients diagnosed with pharmaco-resistant major depression received either six right unilateral ECT treatments (250% stimulus intensity of titrated threshold) or six bifrontal ECT (150% of threshold) treatments over a 3-week period. Concomitant psychotropic medications were continued during ECT treatments. The severity of depression and cognitive status was assessed prior to the first ECT and one day after the sixth ECT using the 21-item Hamilton Depression Rating Scale and the modified Mini Mental State Examination.

Results

Eight patients did not complete the course of the study due to minor side effects or withdrawal of consent. The mean Hamilton Depression score decreased from 27 to 17 points in both groups of 46 patients, resulting in 12 responders (primary endpoint defined as a decrease > 50%) in each patient group (95% confidence interval for the odds ratio from 0.35 to 2.8). There was no reduction in the modified Mini Mental State score (mean score 86 of 100 points).

Conclusions

Both bifrontal and right unilateral electrode placements in ECT were reasonably safe and moderately efficacious in reducing symptoms of pharmaco-resistant major depression.

Introduction

Electroconvulsive therapy (ECT) is the most effective treatment for severe major depression (Geddes et al., 2003, Kho et al., 2003). ECT is regarded as the treatment of choice for pharmaco-resistant major depression with suicidal intentions and psychotic features by different national psychiatric associations (Folkerts et al., 1996, APA, 2001, Geddes et al., 2003, Bundesärztekammer, 2003).

In Germany, right unilateral (RUL) ECT with a moderate intensity of 250% (Sackeim et al., 1987, Sackeim et al., 1993) of the titrated threshold is the standard therapy (Folkerts et al., 1996). Over the past decade, bifrontal ECT (Letemendia et al., 1993, Bailine et al., 2000, Ranjkesh et al., 2005) was thought to combine the high efficacy of bifrontotemporal ECT (Lawson et al., 1990) with the improved cognitive profile of RUL ECT (Lawson et al., 1990, Sackeim et al., 1993). However, over the past few years, it has been reported that bifrontal ECT has no superiority compared with higher dose RUL ECT for eight depressed patients (Heikman et al., 2002). However, in the four controlled, randomised trials of bifrontal ECT (Letemendia et al., 1993, Bailine et al., 2000, Heikman et al., 2002, Ranjkesh et al., 2005) the total number of patients treated is less than 70, although several thousand patients were treated by bifrontal ECT in the United States.

In Germany, many hospitals combine ECT with concurrent antidepressants (AD), antipsychotics and lithium, as they hope to boost ECT effects (Baghai et al., 2006) and prevent early relapse after a successful ECT series by continuation of a lithium therapy, as suggested by the results of the randomised controlled trial for relapse prevention after successful ECT (Sackeim et al., 2001).

Therefore, a prospective medium-sized multicenter study was started in south-west Germany and Austria to compare the short term efficacy of bifrontal ECT with RUL ECT in the treatment of medicated pharmaco-resistant depression. It was postulated that bifrontal ECT is more effective, as shown by a significantly higher response rate, than RUL ECT. There should be no significant cognitive changes due to the modified Mini-Mental state examination (3MS) (Teng and Chui, 1987) in both procedures. However, bifrontal ECT would have a greater impact on verbal fluency because the left prefrontal lobe is exposed to the main electric current vector (Calev et al., 1995). RUL ECT could lead to increased disturbance of figural memory (Fromm-Auch, 1982, Lawson et al., 1990), as shown by redrawing of a complex figure, because the right temporal lobe is exposed to the electric field.